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Sample records for blight pathogen erwinia

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

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    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.

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

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    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...

  3. 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.

  4. A complete structural characterization of the desferrioxamine E biosynthetic pathway from the fire blight pathogen Erwinia amylovora.

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    Salomone-Stagni, Marco; Bartho, Joseph D; Polsinelli, Ivan; Bellini, Dom; Walsh, Martin A; Demitri, Nicola; Benini, Stefano

    2018-02-08

    The Gram-negative bacterium Erwinia amylovora is the etiological agent of fire blight, a devastating disease which affects Rosaceae such as apple, pear and quince. The siderophore desferrioxamine E plays an important role in bacterial pathogenesis by scavenging iron from the host. DfoJ, DfoA and DfoC are the enzymes responsible for desferrioxamine production starting from lysine. We have determined the crystal structures of each enzyme in the desferrioxamine E pathway and demonstrate that the biosynthesis involves the concerted action of DfoJ, followed by DfoA and lastly DfoC. These data provide the first crystal structures of a Group II pyridoxal-dependent lysine decarboxylase, a cadaverine monooxygenase and a desferrioxamine synthetase. DfoJ is a homodimer made up of three domains. Each monomer contributes to the completion of the active site, which is positioned at the dimer interface. DfoA is the first structure of a cadaverine monooxygenase. It forms homotetramers whose subunits are built by two domains: one for FAD and one for NADP + binding, the latter of which is formed by two subdomains. We propose a model for substrate binding and the role of residues 43-47 as gate keepers for FAD binding and the role of Arg97 in cofactors turnover. DfoC is the first structure of a desferrioxamine synthetase and the first of a multi-enzyme siderophore synthetase coupling an acyltransferase domain with a Non-Ribosomal Peptide Synthetase (NRPS)-Independent Siderophore domain (NIS). Copyright © 2018 Elsevier Inc. All rights reserved.

  5. 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. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  6. 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.

  7. FIRE BLIGHT SUSCEPTIBILITY OF SOME PEAR VARIETIES (ERWINIA AMYLOVORA, BURILL

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    Zsolt Jakab- Ilyefalv

    2012-01-01

    Full Text Available At Bistriţa Fruit Research and Development Station, in a pear collection, planted with 44 varieties, there has been studied the susceptibility to fire blight (Erwinia amylovora,Burill. During the vegetation period, phytosanitary treatments to control the disease have been applied using copper based products (copper sulfate, Champion, Funguran, Kocide. Erwinia amylovora infections have been influenced by the rainfall registered in April (70.9 mm and May (104.7 mm and the temperature fluctuations in April-May. The field observations on Erwinia amylvora attack demonstrate that the pear varieties have a different susceptibility to this dangerous bacterium. Evaluation of attack level in the pear collection was done using an evaluation scale with 9 scores using a reference resistance scale for : ‘Highly resistant’ , ‘Moderately resistant’, ‘Susceptible’, ‘Very susceptible’ cultivars . The most sensitive pear varieties in the collection were: ‘De Noiembrie’, ‘Abatele Fetel’, ’Daciana’, ’Triumf’, ’Williams Boway’, ’Margareta Marillat’, ’Beauty Tomme’, ‘Williams rosu’, ’Aromata de Bistrita’, ’Jeanne d`Arc’, ’Aramiu de Somes’, ’Belle des Arbres’, ’Zorka’ representing 13.64% of the total pear varieties. In several cultivars there have been observed increased symptoms, a very high susceptibility of infections leading to complete scorching of trees: Jeanne d`Arc’, Williams rosu’, ‘Triumf’, ‘Aromata de Bistrita’, ‘Zorka’. Strong attack symtoms were observed at the pear cultivars ‘Cure’, ‘Euras, ’Ciuda’ ‘Highland’, ‘Precoce Morettini’, ’Monica’, ’Cadillac’, ’Juliana’, ’Somesan’, ’Beurré Hardenpont’ these cultivars being susceptible to Erwinia amylovora , representing 40.91 % of total genotypes . Cultivars ‘Untoasa Geoagiu’, ‘Beurre Hardy’, ‘Trivale’ manifested a certain tolerance to Erwinia amylovora , no attack symptoms being

  8. Engineering of Bacteriophages Y2::dpoL1-C and Y2::luxAB for Efficient Control and Rapid Detection of the Fire Blight Pathogen, Erwinia amylovora.

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    Born, Yannick; Fieseler, Lars; Thöny, Valentin; Leimer, Nadja; Duffy, Brion; Loessner, Martin J

    2017-06-15

    Erwinia amylovora is the causative agent of fire blight, a devastating plant disease affecting members of the Rosaceae Alternatives to antibiotics for control of fire blight symptoms and outbreaks are highly desirable, due to increasing drug resistance and tight regulatory restrictions. Moreover, the available diagnostic methods either lack sensitivity, lack speed, or are unable to discriminate between live and dead bacteria. Owing to their extreme biological specificity, bacteriophages are promising alternatives for both aims. In this study, the virulent broad-host-range E. amylovora virus Y2 was engineered to enhance its killing activity and for use as a luciferase reporter phage, respectively. Toward these aims, a depolymerase gene of E. amylovora virus L1 ( dpoL1-C ) or a bacterial luxAB fusion was introduced into the genome of Y2 by homologous recombination. The genes were placed downstream of the major capsid protein orf68 , under the control of the native promoter. The modifications did not affect viability of infectivity of the recombinant viruses. Phage Y2:: dpoL1-C demonstrated synergistic activity between the depolymerase degrading the exopolysaccharide capsule and phage infection, which greatly enhanced bacterial killing. It also significantly reduced the ability of E. amylovora to colonize the surface of detached flowers. The reporter phage Y2:: luxAB transduced bacterial luciferase into host cells and induced synthesis of large amounts of a LuxAB luciferase fusion. After the addition of aldehyde substrate, bioluminescence could be readily monitored, and this enabled rapid and specific detection of low numbers of viable bacteria, without enrichment, both in vitro and in plant material. IMPORTANCE Fire blight, caused by Erwinia amylovora , is the major threat to global pome fruit production, with high economic losses every year. Bacteriophages represent promising alternatives to not only control the disease, but also for rapid diagnostics. To enhance

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

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    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. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The suitability of Finnish climate for fire blight (Erwinia amylovora epidemics on apple

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    Mariela Marinova-Todorova

    2015-03-01

    Full Text Available Fire blight, which is an important disease of apples and pears, has never been detected in continental Finland. In this study the suitability of the Finnish climate for apple blossom blight infections by Erwinia amylovora was evaluated with the epidemiological model MaryblytTM. This was done in fourteen locations, and for two apple cultivars differing in flowering times. Climatic conditions were predicted to be suitable for blossom infections in 18 - 51% of the years, and the annual period of suitable conditions was predicted to last up to two to five days, depending on the location and apple cultivar. The suitable period was predicted to be longer in some locations in central Finland than in those in the southernmost parts of the country. Based on these results the official surveys that are carried out to confirm the absence of fire blight in Finland cannot be targeted only to some parts of the country.

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

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    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.

  12. 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.

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

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    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.

  14. Fire blight in Georgia

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    Dali L. Gaganidze

    2018-03-01

    Full Text Available Fire blight is distinguished among the fruit tree diseases by harmfulness. Fire blight damages about 180 cultural and wild plants belonging to the Rosaceae family. Quince, apple and pear are the most susceptible to the disease. At present, the disease occurs in over 40 countries of Europe and Asia. Economic damage caused by fire blight is expressed not only in crop losses, but also, it poses threat of eradication to entire fruit tree gardens. Erwinia amylovora, causative bacteria of fire blight in fruit trees, is included in the A2 list of quarantine organisms. In 2016, the employees of the Plant Pest Diagnostic Department of the Laboratory of the Georgian Ministry of Agriculture have detected Erwinia amylovora in apple seedlings from Mtskheta district. National Food Agency, Ministry of Agriculture of Georgia informed FAO on pathogen detection. The aim of the study is detection of the bacterium Erwinia amylovora by molecular method (PCR in the samples of fruit trees, suspicious on fire blight collected in the regions of Eastern (Kvemo Kartli, Shida Kartli and Kakheti and Western Georgia (Imereti.The bacterium Erwinia amylovora was detected by real time and conventional PCR methods using specific primers and thus the fire blight disease confirmed in 23 samples of plant material from Shida Kartli (11 apples, 6 pear and 6 quince samples, in 5 samples from Kvemo Kartli (1 quince and 4 apple samples, in 2 samples of apples from Kakheti region and 1 sample of pear collected in Imereti (Zestafoni. Keywords: Fire blight, Erwinia amylovora, Conventional PCR, Real time PCR, DNA, Bacterium

  15. Reduction in bacterial ooze formation on immature fruitlets after preventive treatments of Fosethyl-Al against fire blight Erwinia amylovora.

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    Deckers, T; Schoofs, H; Verjans, W; De Maeyer, L

    2010-01-01

    Fire blight, caused by the bacterium Erwinia amylovora (Burill Winslow et al.), is a very important bacterial disease on apple and pear orchards with devastating effects in some production area and in some years. Fire blight control consists in a whole strategy of measures that should start with control measures in and around the fruit tree nurseries. Only the use of Vacciplant (Laminarin), an inducer of the self-defence mechanism, is registered in Belgium since 2009. In other European countries Fosethyl-Al has been registered for fire blight control. Recently, research trials have been done at Pcfruit research station for several years on the activity of ALiette (fosethyl-Al) against fire blight. Fosethyl-Al, also a plant defence enhancing molecule, applied preventively 3 times at a dose of 3.75 kg/ha standard orchard (3 x 3000 g a.i./ha standard orchard), showed a reduction in the host susceptibility and decreased the disease development on artificial inoculated flower clusters and shoots. Also a clear reduction in the ooze droplet formation on artificially inoculated immature fruitlets has been observed with this molecule. This reduction in the bacterial ooze formation is considered as a very important factor in the spread of the disease in the orchard.

  16. Whole-genome sequence of Pseudomonas fluorescens EK007-RG4, a promising biocontrol agent against a broad range of bacteria, including the fire blight bacterium Erwinia amylovora

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    Habibi, Roghayeh; Tarighi, Saeed; Behravan, Javad

    2017-01-01

    Here, we report the first draft whole-genome sequence of Pseudomonas fluorescens strain EK007-RG4, which was isolated from the phylloplane of a pear tree. P. fluorescens EK007-RG4 displays strong antagonism against Erwinia amylovora, the causal agent for fire blight disease, in addition to several...

  17. Inhibitory activity of plant extracts on the early blight pathogen ...

    African Journals Online (AJOL)

    This study evaluated the effect of two plant extracts, Ricinus communis and Chromolaena odorata on the control of the early blight pathogen, Alternaria solani (Ell. and Mart.). The study was conducted in the Laboratory of the Crop Production and Horticulture Department, Federal University of Technology, Yola, Adamawa ...

  18. Criteria for efficient prevention of dissemination and successful eradication of Erwinia amylovora (the cause of fire blight in Aragón, Spain

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    Ana PALACIO-BIELSA

    2013-01-01

    Full Text Available Erwinia amylovora was detected on pome fruits in the Aragón region (North-Eastern Spain, in a ca. 5 km radius area located in the mid Jalón river (mid Ebro Valley in the province of Zaragoza, during 2000‒2003. Eight years have now passed since this pathogen was last detected, without new infections being reported in the same area. The bases for surveys and rapid eradication performed have been analyzed in detail to understand the reasons for the success in removing fireblight. The results demonstrate that intensive surveillance, risk assessment, plant analyses using accurate identification methods, and, especially, rapid total or selective eradication of infected trees in the plots have been very effective in preventing the generalized spread of fireblight and in delaying economic losses associated with this disease. Eradication and compensation to growers, estimated to cost approx. € 467,000, were clearly counterbalanced by the economic value of apple and pear production in the 2000‒2003 period (approx. € 368 million. Fire blight risk-assessment, using the MARYBLYT system, showed that climatic conditions in the studied area were favourable to infections during the analyzed period (1997‒2006. Molecular characterization of E. amylovora strains had revealed their homogeneity, suggesting that these fire blight episodes could have been caused by just one inoculum source, supporting the hypothesis that there was a unique introduction of E. amylovora in the studied area. Spatial spread of E. amylovora to trees was analyzed within six orchards, indicating an aggregated distribution model. This Spanish experience demonstrates the success of scientifically-based prevention methods that lead to the deployment of a fast and strict containment strategy, useful for other Mediterranean areas.

  19. 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

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    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

  20. Quorum sensing in the plant pathogen Erwinia carotovora subsp. carotovora

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    Sjöblom, Solveig

    2009-01-01

    Erwinia carotovora subsp. carotovora (Ecc) is a Gram-negative enterobacterium that causes soft-rot in potato and other crops. The main virulence determinants, the extracellular plant cell wall -degrading enzymes (PCWDEs), lead to plant tissue maceration. In order to establish a successful infection the production of PCWDEs are controlled by a complex regulatory network, including both specific and global activators and repressors. One of the most important virulence regulation systems in Ecc ...

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

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    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.

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

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    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.

  3. The Phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) Is a Pathogen of the Pea Aphid†

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    Grenier, Anne-Marie; Duport, Gabrielle; Pagès, Sylvie; Condemine, Guy; Rahbé, Yvan

    2006-01-01

    Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, eit...

  4. The phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) is a pathogen of the pea aphid.

    Science.gov (United States)

    Grenier, Anne-Marie; Duport, Gabrielle; Pagès, Sylvie; Condemine, Guy; Rahbé, Yvan

    2006-03-01

    Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. 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...

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

    OpenAIRE

    Ramachandran Kogeethavani; Manaf Uyub Abdul; Zakaria Latiffah

    2015-01-01

    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...

  8. Thermodependence of growth and enzymatic activities implicated in pathogenicity of two Erwinia carotovora subspecies (Pectobacterium spp.).

    Science.gov (United States)

    Smadja, Bruno; Latour, Xavier; Trigui, Sameh; Burini, Jean François; Chevalier, Sylvie; Orange, Nicole

    2004-01-01

    Erwinia carotovora subsp. atroseptica and Erwinia carotovora subsp. carotovora can cause substantial damage to economically important plant crops and stored products. The occurrence of the disease and the scale of the damage are temperature dependent. Disease development consists first of active multiplication of the bacteria in the infection area and then production of numerous extracellular enzymes. We investigated the effects of various temperatures on these two steps. We assayed the specific growth rate and the pectate lyase and protease activities for eight strains belonging to E. carotovora subsp. atroseptica and E. carotovora subsp. carotovora in vitro. The temperature effect on growth rate and on pectate lyase activity is different for the two subspecies, but protease activity appears to be similarly thermoregulated. Our results are in agreement with ecological data implicating E. carotovora subsp. atroseptica in disease when the temperature is below 20 degrees C. The optimal temperature for pathogenicity appears to be different from the optimal growth temperature but seems to be a compromise between this temperature and temperatures at which lytic activities are maximal.

  9. Detection of bacteriocins produced by plant pathogenic bacteria from the general Erwinia, Pseudomonas and Xanthomonas

    International Nuclear Information System (INIS)

    Biagi, C.M.R. de

    1992-01-01

    Detection of bacteriocin production was studied under distinct conditions using strains of plant pathogenic bacteria from the genera Erwinia, Pseudomonas and Xanthomonas. 58.06%, 79.31% and 40.00% of producing strains were found respectively in the three groups of bacteria using the 523 medium which was the best for the detection of bacteriocin production. Increasing agar concentrations added to the medium up to 1,5% improved the detection. The amount of medium added to the Petri dishes did not affect bacteriocin production. The longest incubation time (72 h.) improved the detection of haloes production. Ultra-violet irradiation in low dosages seems to improve the visualization of haloes production but this is dependent on the tested strains. (author)

  10. 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.

  11. Utilizing Bacillus to inhibit the growth and infection by sheath blight pathogen, Rhizoctoniasolani in rice

    Science.gov (United States)

    Margani, R.; Hadiwiyono; Widadi, S.

    2018-03-01

    Rhizoctonia solani Kuhn is a common pathogen of rice. The pathogen causes sheath blight of rice. The pathogen can cause loss in the production of rice up to 45%. So far, the disease however is still poorly taken care of by the farmers and researchers, so the control measures is nearly never practiced by the farmers in the fields. It due to the unavailability of effective control method of the disease. Therefore, development to control the disease is important. Bacillus is one of popular bacteria which is effective as biological control agent of a lot of pathogens in plants, but it has not been used for control sheath blight in rice yet. The current researches were aimed to study the potential of Bacillus collected from healthy rice as candidates of biological control agent of the disease. The results showed that some isolates showed indications to inhibit significantly the growth and infection of the pathogen. We obtained at least five isolates of Bacillus collected from leaves, sheath, and stem of healthy rice fields. All of the isolates could effectively inhibit the growth of R. solani in vitro on potato dextrose medium at range 30.33-58.00%, whereas in vivo B05 isolate was the most effective in inhibiting the infection of pathogen at 30.43%. It was not significantly different (P≥0.05) to application of hexaconazol with dosage of 2 ml L-1.

  12. Functions and origin of plasmids in Erwinia species that are pathogenic to or epiphytically associated with pome fruit trees.

    Science.gov (United States)

    Llop, Pablo; Barbé, Silvia; López, María M

    The genus Erwinia includes plant-associated pathogenic and non-pathogenic species. Among them, all species pathogenic to pome fruit trees ( E. amylovora, E. pyrifoliae, E. piriflorinigrans, Erwinia sp. from Japan) cause similar symptoms, but differ in their degrees of aggressiveness, i.e. in symptoms, host range or both. The presence of plasmids of similar size, in the range of 30 kb, is a common characteristic that they possess. Besides, they share some genetic content with high homology in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes. Knowledge of the content of these plasmids and comparative genetic analyses may provide interesting new clues to understanding the origin and evolution of these pathogens and the level of symptoms they produce. Furthermore, genetic similarities observed among some of the plasmids (and genomes) from the above indicated pathogenic species and E. tasmaniensis or E. billingiae , which are epiphytic on the same hosts, may reveal associations that could expose the mechanisms of origin of pathogens. A summary of the current information on their plasmids and the relationships among them is presented here.

  13. Horizontal Gene Acquisitions, Mobile Element Proliferation, and Genome Decay in the Host-Restricted Plant Pathogen Erwinia Tracheiphila

    Science.gov (United States)

    Shapiro, Lori R.; Scully, Erin D.; Straub, Timothy J.; Park, Jihye; Stephenson, Andrew G.; Beattie, Gwyn A.; Gleason, Mark L.; Kolter, Roberto; Coelho, Miguel C.; De Moraes, Consuelo M.; Mescher, Mark C.; Zhaxybayeva, Olga

    2016-01-01

    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 of the cucurbit bacterial wilt pathogen Erwinia tracheiphila (Enterobacteriaceae) isolated from infected squash plants in New York, Pennsylvania, Kentucky, and Michigan. These genomes exhibit a high proportion of recent horizontal gene acquisitions, invasion and remarkable amplification of mobile genetic elements, and pseudogenization of approximately 20% of the coding sequences. These genome attributes indicate that E. tracheiphila recently emerged as a host-restricted pathogen. Furthermore, chromosomal rearrangements associated with phage and transposable element proliferation contribute to substantial differences in gene content and genetic architecture between the six E. tracheiphila strains and other Erwinia species. Together, these data lead us to hypothesize that E. tracheiphila has undergone recent evolution through both genome decay (pseudogenization) and genome expansion (horizontal gene transfer and mobile element amplification). Despite evidence of dramatic genomic changes, the six strains are genetically monomorphic, suggesting a recent population bottleneck and emergence into E. tracheiphila’s current ecological niche. PMID:26992913

  14. Characterization of indigoidine biosynthetic genes in Erwinia chrysanthemi and role of this blue pigment in pathogenicity.

    Science.gov (United States)

    Reverchon, Sylvie; Rouanet, Carine; Expert, Dominique; Nasser, William

    2002-02-01

    In the plant-pathogenic bacterium Erwinia chrysanthemi production of pectate lyases, the main virulence determinant, is modulated by a complex network involving several regulatory proteins. One of these regulators, PecS, also controls the synthesis of a blue pigment identified as indigoidine. Since production of this pigment is cryptic in the wild-type strain, E. chrysanthemi ind mutants deficient in indigoidine synthesis were isolated by screening a library of Tn5-B21 insertions in a pecS mutant. These ind mutations were localized close to the regulatory pecS-pecM locus, immediately downstream of pecM. Sequence analysis of this DNA region revealed three open reading frames, indA, indB, and indC, involved in indigoidine biosynthesis. No specific function could be assigned to IndA. In contrast, IndB displays similarity to various phosphatases involved in antibiotic synthesis and IndC reveals significant homology with many nonribosomal peptide synthetases (NRPS). The IndC product contains an adenylation domain showing the signature sequence DAWCFGLI for glutamine recognition and an oxidation domain similar to that found in various thiazole-forming NRPS. These data suggest that glutamine is the precursor of indigoidine. We assume that indigoidine results from the condensation of two glutamine molecules that have been previously cyclized by intramolecular amide bond formation and then dehydrogenated. Expression of ind genes is strongly derepressed in the pecS background, indicating that PecS is the main regulator of this secondary metabolite synthesis. DNA band shift assays support a model whereby the PecS protein represses indA and indC expression by binding to indA and indC promoter regions. The regulatory link, via pecS, between indigoidine and virulence factor production led us to explore a potential role of indigoidine in E. chrysanthemi pathogenicity. Mutants impaired in indigoidine production were unable to cause systemic invasion of potted Saintpaulia ionantha

  15. Quorum sensing in the plant pathogen Erwinia carotovora subsp. carotovora: the role of expR(Ecc).

    Science.gov (United States)

    Andersson, R A; Eriksson, A R; Heikinheimo, R; Mäe, A; Pirhonen, M; Kõiv, V; Hyytiäinen, H; Tuikkala, A; Palva, E T

    2000-04-01

    The production of the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, the extracellular cell wall-degrading enzymes, is partly controlled by the diffusible signal molecule N-(3-oxohexanoyl)-L-homoserine lactone (OHHL). OHHL is synthesized by the product of the expI/carI gene. Linked to expI we found a gene encoding a putative transcriptional regulator of the LuxR-family. This gene, expR(Ecc), is transcribed convergently to the expI gene and the two open reading frames are partially overlapping. The ExpR(Ecc) protein showed extensive amino acid sequence similarity to the repressor EsaR from Pantoea stewartii subsp. stewartii (formerly Erwinia stewartii subsp. stewartii) and to the ExpR(Ech) protein of Erwinia chrysanthemi. Inactivation of the E. carotovora subsp. carotovora expR(Ecc) gene caused no decrease in virulence or production of virulence determinants in vitro. In contrast, there was a slight increase in the maceration capacity of the mutant strain. The effects of ExpR(Ecc) were probably mediated by changes in OHHL levels. Inactivation of expR(Ecc) resulted in increased OHHL levels during early logarithmic growth. In addition, overexpression of expR(Ecc) caused a clear decrease in the production of virulence determinants and part of this effect was likely to be caused by OHHL binding to ExpR(Ecc). ExpR(Ecc) did not appear to exhibit transcriptional regulation of expI, but the effect on OHHL was apparently due to other mechanisms.

  16. The Perfect Match: Simultaneous Strawberry Pollination and Bio-Sampling of the Plant Pathogenic Bacterium Erwinia pyrifoliae by Honey Bees Apis mellifera

    NARCIS (Netherlands)

    Steen, van der Sjef; Bergsma-Vlami, M.; Wenneker, M.

    2018-01-01

    In this study we show that honey bee colonies placed in a greenhouse for pollination of strawberry can simultaneously be used to indicate the presence of the plant pathogenic bacterium Erwinia pyrifoliae. This was demonstrated by using two methods of qualitative sacrificial and non-sacrificial bio

  17. Gene expression profiling during asexual development of the late blight pathogen Phytophthora infestans reveals a highly dynamic transcriptome

    NARCIS (Netherlands)

    Judelson, H.S.; Ah-Fong, A.M.V.; Aux, G.; Avrova, A.O.; Bruce, C.; Cakir, C.; Cunha, da L.; Grenville-Briggs, L.; Latijnhouwers, M.; Ligterink, W.; Meijer, H.J.G.; Roberts, S.; Thurber, C.S.; Whisson, S.C.; Birch, P.R.J.; Govers, F.; Kamoun, S.; West, van P.; Windass, J.

    2008-01-01

    Much of the pathogenic success of Phytophthora infestans, the potato and tomato late blight agent, relies on its ability to generate from mycelia large amounts of sporangia, which release zoospores that encyst and form infection structures. To better understand these stages, Affymetrix GeneChips

  18. A small diffusible signal molecule is responsible for the global control of virulence and exoenzyme production in the plant pathogen Erwinia carotovora.

    OpenAIRE

    Pirhonen, M; Flego, D; Heikinheimo, R; Palva, E T

    1993-01-01

    Virulence of the plant pathogen Erwinia carotovora subsp. carotovora is dependent on the production and secretion of a complex arsenal of plant cell wall-degrading enzymes. Production of these exoenzymes is controlled by a global regulatory mechanism. A virulent mutants in one of the regulatory loci, expI, show a pleiotropic defect in the growth phase-dependent transcriptional activation of exoenzyme gene expression. The expI gene encodes a 26 kDa polypeptide that is structurally and function...

  19. Biological relevance of volatile organic compounds emitted during the pathogenic interactions between apple plants and Erwinia amylovora.

    Science.gov (United States)

    Cellini, Antonio; Buriani, Giampaolo; Rocchi, Lorenzo; Rondelli, Elena; Savioli, Stefano; Rodriguez Estrada, Maria T; Cristescu, Simona M; Costa, Guglielmo; Spinelli, Francesco

    2018-01-01

    Volatile organic compounds emitted during the infection of apple (Malus pumila var. domestica) plants by Erwinia amylovora or Pseudomonas syringae pv. syringae were studied by gas chromatography-mass spectrometry and proton transfer reaction-mass spectrometry, and used to treat uninfected plants. Infected plants showed a disease-specific emission of volatile organic compounds, including several bio-active compounds, such as hexenal isomers and 2,3-butanediol. Leaf growth promotion and a higher resistance to the pathogen, expressed as a lower bacterial growth and migration in plant tissues, were detected in plants exposed to volatile compounds from E. amylovora-infected plants. Transcriptional analysis revealed the activation of salicylic acid synthesis and signal transduction in healthy plants exposed to volatiles produced by E. amylovora-infected neighbour plants. In contrast, in the same plants, salicylic acid-dependent responses were repressed after infection, whereas oxylipin metabolism was activated. These results clarify some metabolic and ecological aspects of the pathogenic adaptation of E. amylovora to its host. © 2016 BSPP AND JOHN WILEY & SONS LTD.

  20. Role of RpoS in virulence and stress tolerance of the plant pathogen Erwinia carotovora subsp. carotovora.

    Science.gov (United States)

    Andersson, R A; Kõiv, V; Norman-Setterblad, C; Pirhonen, M

    1999-12-01

    The plant-pathogenic bacterium Erwinia carotovora subsp. carotovora causes plant disease mainly through a number of extracellular plant-cell-wall-degrading enzymes. In this study, the ability of an rpoS mutant of the Er. carotovora subsp. carotovora strain SCC3193 to infect plants and withstand environmental stress was characterized. This mutant was found to be sensitive to osmotic and oxidative stresses in vitro and to be deficient in glycogen accumulation. The production of extracellular enzymes in vitro was similar in the mutant and in the wild-type strains. However, the rpoS mutant caused more severe symptoms than the wild-type strain on tobacco plants and also produced more extracellular enzymes in planta, but did not grow to higher cell density in planta compared to the wild-type strain. When tested on plants with reduced catalase activities, which show higher levels of reactive oxygen species, the rpoS mutant was found to cause lower symptom levels and to have impaired growth. In addition, the mutant was unable to compete with the wild-type strain in planta and in vitro. These results suggest that a functional rpoS gene is needed mainly for survival in a competitive environment and during stress conditions, and not for effective infection of plants.

  1. 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.

  2. Endophytic Streptomyces spp. as Biocontrol Agents of Rice Bacterial Leaf Blight Pathogen (Xanthomonas oryzae pv. oryzae

    Directory of Open Access Journals (Sweden)

    RATIH DEWI HASTUTI

    2012-12-01

    Full Text Available Xanthomonas oryzae pv. oryzae (Xoo, a causal agent of bacterial leaf blight (BLB, is one of the most important pathogens of rice. The effectiveness of ten Streptomyces spp. isolates in suppressing Xoo disease was assessed in planta and in vitro. In planta experiments were carried out in a greenhouse and arranged in a randomized completely block design (RCBD with three replications. Twenty treatments were tested which included plants inoculated with both Streptomyces spp. and Xoo, and plants inoculated with only Streptomyces spp. Plants inoculated with Xoo and sprayed with a chemical bactericide, and plants inoculated with only Xoo served as positive controls, whereas plants not inoculated with either Streptomyces spp. or Xoo were used as negative controls. The results showed that the effect of endophytic Streptomyces spp. on BLB disease expressed as area under disease progress curve (AUDPC was not significantly different to that on control plants (P > 0.05. However, plants inoculated with endophytic Streptomyces spp. were significantly taller and produced higher tiller number than control plants (P < 0.05. Streptomyces spp. isolate AB131-1 gave the highest plant height. In vitro studies on biocontrol mechanisms of selected Streptomyces spp. isolates showed that isolate LBR02 gave the highest inhibition activity on Xoo growth, followed by AB131-1 and AB131-2. Two isolates (AB131-1 and LBR02 were able to produce chitinase, phosphatase, and siderophore which included biocontrol characteristics. Morphological and colonization studies under SEM and light microscopy confirmed that the three isolates were endophytic Streptomyces spp. from different species. These studies found that the paddy plant which was inoculated with endophytic Streptomyces spp. AB131-1 and infected by Xoo could increase the height of plant and number of tillers.

  3. 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.

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

    Science.gov (United States)

    Blair, Jaime E; Coffey, Michael D; Martin, Frank N

    2012-01-01

    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.

  5. 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...

  6. Oligogalacturonide-mediated induction of a gene involved in jasmonic acid synthesis in response to the cell-wall-degrading enzymes of the plant pathogen Erwinia carotovora.

    Science.gov (United States)

    Norman, C; Vidal, S; Palva, E T

    1999-07-01

    Identification of Arabidopsis thaliana genes responsive to plant cell-wall-degrading enzymes of Erwinia carotovora subsp. carotovora led to the isolation of a cDNA clone with high sequence homology to the gene for allene oxide synthase, an enzyme involved in the biosynthesis of jasmonates. Expression of the corresponding gene was induced by the extracellular enzymes from this pathogen as well as by treatment with methyl jasmonate and short oligogalacturonides (OGAs). This suggests that OGAs are involved in the induction of the jasmonate pathway during plant defense response to E. carotovora subsp. carotovora attack.

  7. 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.

  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. A small diffusible signal molecule is responsible for the global control of virulence and exoenzyme production in the plant pathogen Erwinia carotovora.

    Science.gov (United States)

    Pirhonen, M; Flego, D; Heikinheimo, R; Palva, E T

    1993-06-01

    Virulence of the plant pathogen Erwinia carotovora subsp. carotovora is dependent on the production and secretion of a complex arsenal of plant cell wall-degrading enzymes. Production of these exoenzymes is controlled by a global regulatory mechanism. A virulent mutants in one of the regulatory loci, expI, show a pleiotropic defect in the growth phase-dependent transcriptional activation of exoenzyme gene expression. The expI gene encodes a 26 kDa polypeptide that is structurally and functionally related to the luxI gene product of Vibrio fischeri. Functional similarity of expI and luxI has been demonstrated by reciprocal genetic complementation experiments. LuxI controls bioluminescence in V.fischeri in a growth phase-dependent manner by directing the synthesis of the diffusible autoinducer, N-(3-oxohexanoyl) homoserine lactone. E.c. subsp. carotovora expI+ strains or Escherichia coli harboring the cloned expI gene excrete a small diffusible signal molecule that complements the expI mutation of Erwinia as well as a luxI mutation of V.fischeri. This extracellular complementation can also be achieved by E.coli harboring the luxI gene from V.fischeri or by adding the synthetic V.fischeri autoinducer. Both the production of the plant tissue-macerating exoenzymes and the ability of the bacteria to propagate in planta are restored in expI mutants by autoinducer addition. These data suggest that the same signal molecule is employed in control of such diverse processes as virulence in a plant pathogen and bioluminescence in a marine bacterium, and may represent a general mechanism by which bacteria modulate gene expression in response to changing environmental conditions.

  11. Gene expression profiling during asexual development of the late blight pathogen Phytophthora infestans reveals a highly dynamic transcriptome.

    Science.gov (United States)

    Judelson, Howard S; Ah-Fong, Audrey M V; Aux, George; Avrova, Anna O; Bruce, Catherine; Cakir, Cahid; da Cunha, Luis; Grenville-Briggs, Laura; Latijnhouwers, Maita; Ligterink, Wilco; Meijer, Harold J G; Roberts, Samuel; Thurber, Carrie S; Whisson, Stephen C; Birch, Paul R J; Govers, Francine; Kamoun, Sophien; van West, Pieter; Windass, John

    2008-04-01

    Much of the pathogenic success of Phytophthora infestans, the potato and tomato late blight agent, relies on its ability to generate from mycelia large amounts of sporangia, which release zoospores that encyst and form infection structures. To better understand these stages, Affymetrix GeneChips based on 15,650 unigenes were designed and used to profile the life cycle. Approximately half of P. infestans genes were found to exhibit significant differential expression between developmental transitions, with approximately (1)/(10) being stage-specific and most changes occurring during zoosporogenesis. Quantitative reverse-transcription polymerase chain reaction assays confirmed the robustness of the array results and showed that similar patterns of differential expression were obtained regardless of whether hyphae were from laboratory media or infected tomato. Differentially expressed genes encode potential cellular regulators, especially protein kinases; metabolic enzymes such as those involved in glycolysis, gluconeogenesis, or the biosynthesis of amino acids or lipids; regulators of DNA synthesis; structural proteins, including predicted flagellar proteins; and pathogenicity factors, including cell-wall-degrading enzymes, RXLR effector proteins, and enzymes protecting against plant defense responses. Curiously, some stage-specific transcripts do not appear to encode functional proteins. These findings reveal many new aspects of oomycete biology, as well as potential targets for crop protection chemicals.

  12. Genome Sequences of 19 Novel Erwinia amylovora Bacteriophages.

    Science.gov (United States)

    Esplin, Ian N D; Berg, Jordan A; Sharma, Ruchira; Allen, Robert C; Arens, Daniel K; Ashcroft, Cody R; Bairett, Shannon R; Beatty, Nolan J; Bickmore, Madeline; Bloomfield, Travis J; Brady, T Scott; Bybee, Rachel N; Carter, John L; Choi, Minsey C; Duncan, Steven; Fajardo, Christopher P; Foy, Brayden B; Fuhriman, David A; Gibby, Paul D; Grossarth, Savannah E; Harbaugh, Kala; Harris, Natalie; Hilton, Jared A; Hurst, Emily; Hyde, Jonathan R; Ingersoll, Kayleigh; Jacobson, Caitlin M; James, Brady D; Jarvis, Todd M; Jaen-Anieves, Daniella; Jensen, Garrett L; Knabe, Bradley K; Kruger, Jared L; Merrill, Bryan D; Pape, Jenny A; Payne Anderson, Ashley M; Payne, David E; Peck, Malia D; Pollock, Samuel V; Putnam, Micah J; Ransom, Ethan K; Ririe, Devin B; Robinson, David M; Rogers, Spencer L; Russell, Kerri A; Schoenhals, Jonathan E; Shurtleff, Christopher A; Simister, Austin R; Smith, Hunter G; Stephenson, Michael B; Staley, Lyndsay A; Stettler, Jason M; Stratton, Mallorie L; Tateoka, Olivia B; Tatlow, P J; Taylor, Alexander S; Thompson, Suzanne E; Townsend, Michelle H; Thurgood, Trever L; Usher, Brittian K; Whitley, Kiara V; Ward, Andrew T; Ward, Megan E H; Webb, Charles J; Wienclaw, Trevor M; Williamson, Taryn L; Wells, Michael J; Wright, Cole K; Breakwell, Donald P; Hope, Sandra; Grose, Julianne H

    2017-11-16

    Erwinia amylovora is the causal agent of fire blight, a devastating disease affecting some plants of the Rosaceae family. We isolated bacteriophages from samples collected from infected apple and pear trees along the Wasatch Front in Utah. We announce 19 high-quality complete genome sequences of E. amylovora bacteriophages. Copyright © 2017 Esplin et al.

  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. Genetic Divergence and Chemotype Diversity in the Fusarium Head Blight Pathogen Fusarium poae.

    Science.gov (United States)

    Vanheule, Adriaan; De Boevre, Marthe; Moretti, Antonio; Scauflaire, Jonathan; Munaut, Françoise; De Saeger, Sarah; Bekaert, Boris; Haesaert, Geert; Waalwijk, Cees; van der Lee, Theo; Audenaert, Kris

    2017-08-23

    Fusarium head blight is a disease caused by a complex of Fusarium species. F. poae is omnipresent throughout Europe in spite of its low virulence. In this study, we assessed a geographically diverse collection of F. poae isolates for its genetic diversity using AFLP (Amplified Fragment Length Polymorphism). Furthermore, studying the mating type locus and chromosomal insertions, we identified hallmarks of both sexual recombination and clonal spread of successful genotypes in the population. Despite the large genetic variation found, all F. poae isolates possess the nivalenol chemotype based on Tri7 sequence analysis. Nevertheless, Tri gene clusters showed two layers of genetic variability. Firstly, the Tri1 locus was highly variable with mostly synonymous mutations and mutations in introns pointing to a strong purifying selection pressure. Secondly, in a subset of isolates, the main trichothecene gene cluster was invaded by a transposable element between Tri5 and Tri6 . To investigate the impact of these variations on the phenotypic chemotype, mycotoxin production was assessed on artificial medium. Complex blends of type A and type B trichothecenes were produced but neither genetic variability in the Tri genes nor variability in the genome or geography accounted for the divergence in trichothecene production. In view of its complex chemotype, it will be of utmost interest to uncover the role of trichothecenes in virulence, spread and survival of F. poae .

  15. 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.

  16. Regional differences in the composition of Fusarium Head Blight pathogens and mycotoxins associated with wheat in Mexico.

    Science.gov (United States)

    Cerón-Bustamante, Minely; Ward, Todd J; Kelly, Amy; Vaughan, Martha M; McCormick, Susan P; Cowger, Christina; Leyva-Mir, Santos G; Villaseñor-Mir, Héctor E; Ayala-Escobar, Victoria; Nava-Díaz, Cristian

    2018-05-20

    Fusarium Head Blight (FHB) is a destructive disease of small grain cereals and a major food safety concern. Epidemics result in substantial yield losses, reduction in crop quality, and contamination of grains with trichothecenes and other mycotoxins. A number of different fusaria can cause FHB, and there are significant regional differences in the occurrence and prevalence of FHB pathogen species and their associated mycotoxins. Information on FHB pathogen and mycotoxin diversity in Mexico has been extremely limited, but is needed to improve disease and mycotoxin control efforts. To address this, we used a combination of DNA sequence-based methods and in-vitro toxin analyses to characterize FHB isolates collected from symptomatic wheat in Mexico during the 2013 and 2014 growing seasons. Among 116 Fusarium isolates, we identified five species complexes including nine named Fusarium species and 30 isolates representing unnamed or potentially novel species. Significant regional differences (P 90% of isolates from the Mixteca region in southern Mexico, whereas F. avenaceum and related members of the F. tricinctum species complex (FTSC) accounted for nearly 75% of isolates from the Highlands region in Central Mexico. F. graminearum, which is the dominant FHB pathogen in other parts of North America, was not present among the isolates from Mexico. F. boothii isolates had the 15-acetyldeoxynivalenol toxin type, and some of the minor FHB species produced trichothecenes, such as nivalenol, T-2 toxin and diacetoxyscirpenol. None of the FTSC isolates tested was able to produce trichothecenes, but many produced chlamydosporol and enniatin B. Published by Elsevier B.V.

  17. 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.

    2014-01-01

    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

  18. Phage induction by UV and mitomycin C in Pseudomonas mori, the pathogen of bacterial blight of mulberry

    International Nuclear Information System (INIS)

    Sato, Mamoru

    1979-01-01

    Phage induction by ultraviolet radiation (UV) and mitomycin C (MMC) in some lysogenic strains of Pseudomonas mori, the pathogen of bacterial blight of mulberry, was examined. Among 5 strains tested, in the strains S 6804 and S 6805, phage was induced by both UV and MMC, and in the strain M 5, only by MMC. In the strains S 6807 and S 6808, it was not induced by both these inducers. The rate of phage production in the strain 6805 was highest when it was exposed to UV (15 W UV lamp, 40 cm) for 5 seconds, by which about 90% of the bacteria were killed, and decreased rapidly by further extending the exposure time. The bacteria suspended in 0.02 M magnesium solution were more sensitive in responding to UV than those suspended in nutrient broth, but after the UV treatment, nutrient broth was more favorable than magnesium solution for phage production. The MMC added to nutrient broth induced phage production at the concentration from 0.5 to 5 μg/ml. The strains induced by either UV or MMC their temperate phages after about 3 hours of latent period. The phage induction by UV was almost completely suppressed by 40 minute exposure to fluorescent light (a 15 W fluorescent lamp, 10 cm) or by 5 minute exposure to sunlight, given within 45 minutes after the UV treatment, i.e. within 1/4 of the latent period. Thus, the photoreversion of the UV effect on phage induction was observed in Ps. mori as well as in Ps. pyocyanea and E. coli. (Kaihara, S.)

  19. 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.

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

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    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.

  1. A two-component regulatory system, pehR-pehS, controls endopolygalacturonase production and virulence in the plant pathogen Erwinia carotovora subsp. carotovora.

    Science.gov (United States)

    Flego, D; Marits, R; Eriksson, A R; Kõiv, V; Karlsson, M B; Heikinheimo, R; Palva, E T

    2000-04-01

    Genes coding for the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, the plant cell wall-degrading enzymes, are under the coordinate control of global regulator systems including both positive and negative factors. In addition to this global control, some virulence determinants are subject to specific regulation. We have previously shown that mutations in the pehR locus result in reduced virulence and impaired production of one of these enzymes, an endopolygalacturonase (PehA). In contrast, these pehR strains produce essentially wild-type levels of other extracellular enzymes including pectate lyases and cellulases. In this work, we characterized the pehR locus and showed that the DNA sequence is composed of two genes, designated pehR and pehS, present in an operon. Mutations in either pehR or pehS caused a Peh-negative phenotype and resulted in reduced virulence on tobacco seedlings. Complementation experiments indicated that both genes are required for transcriptional activation of the endopolygalacturonase gene, pehA, as well as restoration of virulence. Structural characterization of the pehR-pehS operon demonstrated that the corresponding polypeptides are highly similar to the two-component transcriptional regulators PhoP-PhoQ of both Escherichia coli and Salmonella typhimurium. Functional similarity of PehR-PehS with PhoP-PhoQ of E. coli and S. typhimurium was demonstrated by genetic complementation.

  2. Virulence Factors of Erwinia amylovora: A Review

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    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.

  3. Fire blight resistance in wild accessions of Malus sieversii

    Science.gov (United States)

    Fire blight (Erwinia amylovora) is a devastating bacterial disease in apple that results in severe economic losses. Epidemics are becoming more common as susceptible cultivars and rootstocks are being planted, and control is becoming more difficult as antibiotic-resistant strains develop. Resistan...

  4. 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...

  5. 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...

  6. 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

  7. Soft rot erwiniae: from genes to genomes.

    Science.gov (United States)

    Toth, Ian K; Bell, Kenneth S; Holeva, Maria C; Birch, Paul R J

    2003-01-01

    SUMMARY The soft rot erwiniae, Erwinia carotovora ssp. atroseptica (Eca), E. carotovora ssp. carotovora (Ecc) and E. chrysanthemi (Ech) are major bacterial pathogens of potato and other crops world-wide. We currently understand much about how these bacteria attack plants and protect themselves against plant defences. However, the processes underlying the establishment of infection, differences in host range and their ability to survive when not causing disease, largely remain a mystery. This review will focus on our current knowledge of pathogenesis in these organisms and discuss how modern genomic approaches, including complete genome sequencing of Eca and Ech, may open the door to a new understanding of the potential subtlety and complexity of soft rot erwiniae and their interactions with plants. The soft rot erwiniae are members of the Enterobacteriaceae, along with other plant pathogens such as Erwinia amylovora and human pathogens such as Escherichia coli, Salmonella spp. and Yersinia spp. Although the genus name Erwinia is most often used to describe the group, an alternative genus name Pectobacterium was recently proposed for the soft rot species. Ech mainly affects crops and other plants in tropical and subtropical regions and has a wide host range that includes potato and the important model host African violet (Saintpaulia ionantha). Ecc affects crops and other plants in subtropical and temperate regions and has probably the widest host range, which also includes potato. Eca, on the other hand, has a host range limited almost exclusively to potato in temperate regions only. Disease symptoms: Soft rot erwiniae cause general tissue maceration, termed soft rot disease, through the production of plant cell wall degrading enzymes. Environmental factors such as temperature, low oxygen concentration and free water play an essential role in disease development. On potato, and possibly other plants, disease symptoms may differ, e.g. blackleg disease is associated

  8. Direct detection of the plant pathogens Burkholderia glumae, Burkholderia gladioli pv. gladioli, and Erwinia chrysanthemi pv. zeae in infected rice seedlings using matrix assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Kajiwara, Hideyuki

    2016-01-01

    The plant pathogens Burkholderia glumae, Burkholderia gladioli pv. gladioli, and Erwinia chrysanthemi pv. zeae were directly detected in extracts from infected rice seedlings by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method did not require culturing of the pathogens on artificial medium. In the MALDI-TOF MS analysis, peaks originating from bacteria were found in extracts from infected rice seedlings. The spectral peaks showed significantly high scores, in spite of minor differences in spectra. The spectral peaks originating from host plant tissues did not affect this direct MALDI-TOF MS analysis for the rapid identification of plant pathogens. Copyright © 2015 Elsevier B.V. All rights reserved.

  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

    Science.gov (United States)

    2012-01-01

    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 transcription factor

  11. 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

    2011-01-01

    Full Text Available 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.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.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.

  12. 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...

  13. 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. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  14. Application of amplified fragment length polymorphism fingerprinting for taxonomy and identification of the soft rot bacteria Erwinia carotovora and Erwinia chrysanthemi.

    Science.gov (United States)

    Avrova, Anna O; Hyman, Lizbeth J; Toth, Rachel L; Toth, Ian K

    2002-04-01

    The soft rot bacteria Erwinia carotovora and Erwinia chrysanthemi are important pathogens of potato and other crops. However, the taxonomy of these pathogens, particularly at subspecies level, is unclear. An investigation using amplified fragment length polymorphism (AFLP) fingerprinting was undertaken to determine the taxonomic relationships within this group based on their genetic relatedness. Following cluster analysis on the similarity matrices derived from the AFLP gels, four clusters (clusters 1 to 4) resulted. Cluster 1 contained Erwinia carotovora subsp. carotovora (subclusters 1a and 1b) and Erwinia carotovora subsp. odorifera (subcluster 1c) strains, while cluster 2 contained Erwinia carotovora subsp. atroseptica (subcluster 2a) and Erwinia carotovora subsp. betavasculorum (subcluster 2b) strains. Clusters 3 and 4 contained Erwinia carotovora subsp. wasabiae and E. chrysanthemi strains, respectively. While E. carotovora subsp. carotovora and E. chrysanthemi showed a high level of molecular diversity (23 to 38% mean similarity), E. carotovora subsp. odorifera, E. carotovora subsp. betavasculorum, E. carotovora subsp. atroseptica, and E. carotovora subsp. wasabiae showed considerably less (56 to 76% mean similarity), which may reflect their limited geographical distributions and/or host ranges. The species- and subspecies-specific banding profiles generated from the AFLPs allowed rapid identification of unknown isolates and the potential for future development of diagnostics. AFLP fingerprinting was also found to be more differentiating than other techniques for typing the soft rot erwinias and was applicable to all strain types, including different serogroups.

  15. Signaling requirements for Erwinia amylovora-induced disease resistance, callose deposition, and cell growth in the nonhost Arabidopsis thaliana

    Science.gov (United States)

    Erwinia amylovora is the causal agent of the fire blight disease in some plants of the Rosaceae family. The nonhost plant Arabidopsis serves as a powerful system to dissect mechanisms of resistance to E. amylovora. Although not yet known to mount gene-for-gene resistance to E. amylovora, we found ...

  16. Conductimetric detection of Pseudomonas syringae pathover pisi in pea seeds and soft rot Erwinia spp. on potato tubers

    NARCIS (Netherlands)

    Fraaije, B.

    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

  17. Application of Amplified Fragment Length Polymorphism Fingerprinting for Taxonomy and Identification of the Soft Rot Bacteria Erwinia carotovora and Erwinia chrysanthemi

    OpenAIRE

    Avrova, Anna O.; Hyman, Lizbeth J.; Toth, Rachel L.; Toth, Ian K.

    2002-01-01

    The soft rot bacteria Erwinia carotovora and Erwinia chrysanthemi are important pathogens of potato and other crops. However, the taxonomy of these pathogens, particularly at subspecies level, is unclear. An investigation using amplified fragment length polymorphism (AFLP) fingerprinting was undertaken to determine the taxonomic relationships within this group based on their genetic relatedness. Following cluster analysis on the similarity matrices derived from the AFLP gels, four clusters (c...

  18. Rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae produces multiple DSF-family signals in regulation of virulence factor production

    Directory of Open Access Journals (Sweden)

    Cha Jae-Soon

    2010-07-01

    Full Text Available Abstract Background Xanthomonas oryzae pv. oryzae (Xoo is the causal agent of rice bacterial blight disease. Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are collectively essential for virulence. Genetic and genomics evidence suggest that Xoo might use the diffusible signal factor (DSF type quorum sensing (QS system to regulate the virulence factor production. However, little is known about the chemical structure of the DSF-like signal(s produced by Xoo and the factors influencing the signal production. Results Xoo genome harbours an rpf cluster comprising rpfB, rpfF, rpfC and rpfG. The proteins encoded by these genes are highly homologous to their counterparts in X. campestris pv. campestris (Xcc, suggesting that Xcc and Xoo might use similar mechanisms for DSF biosynthesis and autoregulation. Consistent with in silico analysis, the rpfF mutant was DSF-deficient and the rpfC mutant produced about 25 times higher DSF-like activity than the wild type Xoo strain KACC10331. From the supernatants of rpfC mutant, we purified three compounds showing strong DSF-like activity. Mass spectrometry and NMR analysis revealed that two of them were the previously characterized DSF and BDSF; the third one was a novel unsaturated fatty acid with 2 double bonds and was designated as CDSF in this study. Further analysis showed that all the three DSF-family signals were synthesized via the enzyme RpfF encoded by Xoo2868. DSF and BDSF at a final concentration of 3 μM to the rpfF mutant could fully restore its extracellular xylanase activity and EPS production to the wild type level, but CDSF was less active than DSF and BDSF in induction of EPS and xylanase. DSF and CDSF shared a similar cell density-dependent production time course with the maximum production being detected at 42 h after inoculation, whereas the maximum production of BDSF was observed

  19. Evidence that the Ceratobasidium-like white-thread blight and black rot fungal pathogens from persimmon and tea crops in the Brazilian Atlantic Forest agroecosystem are two distinct phylospecies

    Directory of Open Access Journals (Sweden)

    Paulo C. Ceresini

    2012-01-01

    Full Text Available The white-thread blight and black rot (WTBR caused by basidiomycetous fungi of the genus Ceratobasidium is emerging as an important plant disease in Brazil, particularly for crop species in the Ericales such as persimmon (Diospyros kaki and tea (Camellia sinensis. However, the species identity of the fungal pathogen associated with either of these hosts is still unclear. In this work, we used sequence variation in the internal transcribed spacer regions, including the 5.8S coding region of rDNA (ITS-5.8S rDNA, to determine the phylogenetic placement of the local white-thread-blight-associated populations of Ceratobasidium sp. from persimmon and tea, in relation to Ceratobasidium species already described world-wide. The two sister populations of Ceratobasidium sp. from persimmon and tea in the Brazilian Atlantic Forest agroecosystem most likely represent distinct species within Ceratobasidium and are also distinct from C. noxium, the etiological agent of the first description of white-thread blight disease that was reported on coffee in India. The intraspecific variation for the two Ceratobasidium sp. populations was also analyzed using three mitochondrial genes (ATP6, nad1 and nad2. As reported for other fungi, variation in nuclear and mitochondrial DNA was incongruent. Despite distinct variability in the ITS-rDNA region these two populations shared similar mitochondrial DNA haplotypes.

  20. Evidence that the Ceratobasidium-like white-thread blight and black rot fungal pathogens from persimmon and tea crops in the Brazilian Atlantic Forest agroecosystem are two distinct phylospecies.

    Science.gov (United States)

    Ceresini, Paulo C; Costa-Souza, Elaine; Zala, Marcello; Furtado, Edson L; Souza, Nilton L

    2012-04-01

    The white-thread blight and black rot (WTBR) caused by basidiomycetous fungi of the genus Ceratobasidium is emerging as an important plant disease in Brazil, particularly for crop species in the Ericales such as persimmon (Diospyros kaki) and tea (Camellia sinensis). However, the species identity of the fungal pathogen associated with either of these hosts is still unclear. In this work, we used sequence variation in the internal transcribed spacer regions, including the 5.8S coding region of rDNA (ITS-5.8S rDNA), to determine the phylogenetic placement of the local white-thread-blight-associated populations of Ceratobasidium sp. from persimmon and tea, in relation to Ceratobasidium species already described world-wide. The two sister populations of Ceratobasidium sp. from persimmon and tea in the Brazilian Atlantic Forest agroecosystem most likely represent distinct species within Ceratobasidium and are also distinct from C. noxium, the etiological agent of the first description of white-thread blight disease that was reported on coffee in India. The intraspecific variation for the two Ceratobasidium sp. populations was also analyzed using three mitochondrial genes (ATP6, nad1 and nad2). As reported for other fungi, variation in nuclear and mitochondrial DNA was incongruent. Despite distinct variability in the ITS-rDNA region these two populations shared similar mitochondrial DNA haplotypes.

  1. 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

    2015-01-01

    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. PMID:23234799

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

    Science.gov (United States)

    Gusberti, Michele; Klemm, Urs; Meier, Matthias S; Maurhofer, Monika; Hunger-Glaser, Isabel

    2015-09-11

    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 and aluminum

  3. A novel plant ferredoxin-like protein and the regulator Hor are quorum-sensing targets in the plant pathogen Erwinia carotovora.

    Science.gov (United States)

    Sjöblom, Solveig; Harjunpää, Heidi; Brader, Günter; Palva, E Tapio

    2008-07-01

    Quorum sensing (QS), a population-density-sensing mechanism, controls the production of the main virulence determinants, the plant cell-wall-degrading enzymes (PCWDEs) of the soft-rot phytopathogen Erwinia carotovora subsp. carotovora. In this study, we used random transposon mutagenesis with a gusA reporter construct to identify two new QS-controlled genes encoding the regulator Hor and a plant ferredoxin-like protein, FerE. The QS control of the identified genes was executed by the QS regulators ExpR1 and ExpR2 and mediated by the global repressor RsmA. Hor was shown to contribute to bacterial virulence at least partly through its control of PCWDE production. Our results showed that FerE contributes to oxidative stress tolerance and in planta fitness of the bacteria and suggest that QS could be central to control of oxidative stress tolerance. The presence of the FerE protein appears to be rather unique in heterotrophic bacteria and suggests an acquisition of the corresponding gene from plant host by horizontal gene transfer.

  4. '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.

  5. Novel Chitinase Gene LOC_Os11g47510 from Indica Rice Tetep Provides Enhanced Resistance against Sheath Blight Pathogen Rhizoctonia solani in Rice

    Directory of Open Access Journals (Sweden)

    Tilak R. Sharma

    2017-04-01

    Full Text Available Sheath blight disease (ShB, caused by the fungus Rhizoctonia solani Kühn, is one of the most destructive diseases of rice (Oryza sativa L., causing substantial yield loss in rice. In the present study, a novel rice chitinase gene, LOC_Os11g47510 was cloned from QTL region of R. solani tolerant rice line Tetep and used for functional validation by genetic transformation of ShB susceptible japonica rice line Taipei 309 (TP309. The transformants were characterized using molecular and functional approaches. Molecular analysis by PCR using a set of primers specific to CaMv 35S promoter, chitinase and HptII genes confirmed the presence of transgene in transgenic plants which was further validated by Southern hybridization. Further, qRT-PCR analysis of transgenic plants showed good correlation between transgene expression and the level of sheath blight resistance among transformants. Functional complementation assays confirmed the effectiveness of the chitinase mediated resistance in all the transgenic TP309 plants with varying levels of enhanced resistance against R. solani. Therefore, the novel chitinase gene cloned and characterized in the present study from the QTL region of rice will be of significant use in molecular plant breeding program for developing sheath blight resistance in rice.

  6. Sirococcus Shoot Blight

    Science.gov (United States)

    Thomas H. Nicholls; Kathryn Robbins

    1984-01-01

    Sirococcus shoot blight, caused by the fungus Sirococcus strobilinus Preuss, affects conifers in the Northern United States and southern Canada. The fungus infects the new shoots; diseased seedlings and saplings are especially affected. In the United States, sirococcus shoot blight has become increasingly widespread since the early 1970's. When favorable...

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

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    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.

  8. 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.

  9. Selective inhibition of Erwinia amylovora by the herbicidally active germination-arrest factor (GAF) produced by Pseudomonas bacteria.

    Science.gov (United States)

    Halgren, A; Azevedo, M; Mills, D; Armstrong, D; Thimmaiah, M; McPhail, K; Banowetz, G

    2011-10-01

     The germination-arrest factor (GAF) produced by Pseudomonas fluorescens WH6, and identified as 4-formylaminooxyvinylglycine, specifically inhibits the germination of a wide range of grassy weeds. This study was undertaken to determine whether GAF has antimicrobial activity in addition to its inhibitory effects on grass seed germination. Culture filtrate from Ps. fluorescens WH6 had little or no effect on 17 species of bacteria grown in Petri dish lawns, but the in vitro growth of Erwinia amylovora, the causal agent of the disease of orchard crops known as fire blight, was strongly inhibited by the filtrate. The anti-Erwinia activity of WH6 culture filtrate was shown to be due to its GAF content, and a commercially available oxyvinylglycine, 4-aminoethoxyvinylglycine (AVG), exhibited anti-Erwinia activity similar to that of GAF. The effects of GAF on Erwinia were reversed by particular amino acids. The biological properties of GAF include a rather specific antimicrobial activity against Erw. amylovora. This may be a general property of oxyvinylglycines as AVG exhibited similar activity. The ability of particular amino acids to reverse GAF inhibition is consistent with a potential effect of this compound on the activity of aminotransferases. The results presented here demonstrate a novel antimicrobial activity of oxyvinylglycines and suggest that GAF and/or GAF-producing bacteria may have potential for the control of fire blight. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology. No claim to US Government works.

  10. Potatoes, pathogens and pests

    NARCIS (Netherlands)

    Lazebnik, Jenny

    2017-01-01

    Currently, fungicides are necessary to protect potato crops against late blight, Phytophthora infestans, one of the world’s most damaging crop pathogens. The introgression of plant resistance genes from wild potato species targeted specifically to the late blight pathogen into

  11. Silencing of flavanone-3-hydroxylase in apple (Malus × domestica Borkh.) leads to accumulation of flavanones, but not to reduced fire blight susceptibility.

    Science.gov (United States)

    Flachowsky, Henryk; Halbwirth, Heidi; Treutter, Dieter; Richter, Klaus; Hanke, Magda-Viola; Szankowski, Iris; Gosch, Christian; Stich, Karl; Fischer, Thilo C

    2012-02-01

    Transgenic antisense flavanone-3-hydroxylase apple plants were produced to mimic the effect of the agrochemical prohexadione-Ca on apple leaves. This enzyme inhibitor for 2-oxoglutarate dependent dioxygenases is used as a growth retardant and for control of secondary fire blight of leaves. Like using the agent, silencing of flavanone-3-hydroxylase leads to an accumulation of flavanones in leaves, but in contrast not to the formation of 3-deoxyflavonoids. In prohexadione-Ca treated leaves the 3-deoxyflavonoid luteoforol is formed from accumulating flavanones, acting as an antimicrobial compound against the fire blight pathogen Erwinia amylovora. Seemingly, the silencing of just one of the 2-oxoglutarate dependent dioxygenases (in apple also flavonol synthase and anthocyanidin synthase take part downstream in the pathway) does not provide a sufficiently high ratio of flavanones to dihydroflavonols. This seems to be needed to let the dihydroflavonol-4-reductase/flavanone-4-reductase enzyme reduce flavanones to luteoforol, and to let this be reduced by the leucoanthocyanidin-4-reductase/3-deoxyleucoanthocyanidin-4-reductase, each acting with their respective weak secondary activities. Accordingly, also the intended inducible resistance to fire blight by prohexadione-Ca is not observed with the antisense flavanone-3-hydroxylase apple plants. On the other hand, for most transgenic lines with strong flavanone-4-reductase down-regulation, up-regulation of gene expression for the other flavonoid genes was found. This provides further evidence for the feedback regulation of flavonoid gene expression having been previously reported for the prohexadione-Ca inhibited apple plants. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  12. Biological control of chestnut blight in Croatia: an interaction between host sweet chestnut, its pathogen Cryphonectria parasitica and the biocontrol agent Cryphonectria hypovirus 1.

    Science.gov (United States)

    Krstin, Ljiljana; Katanić, Zorana; Ježić, Marin; Poljak, Igor; Nuskern, Lucija; Matković, Ivana; Idžojtić, Marilena; Ćurković-Perica, Mirna

    2017-03-01

    Chestnut blight, caused by the fungus Cryphonectria parasitica, is a severe chestnut disease that can be controlled with naturally occurring hypoviruses in many areas of Europe. The aim of this research was to measure the effect of different Cryphonectria hypovirus 1 (CHV1) strains on the growth of the fungal host and select strains that could potentially be used for human-mediated biocontrol in forests and orchards, and to investigate whether and how chestnut-fungus-virus interactions affect the development and growth of the lesion area on cut stems. Two Croatian CHV1 strains (CR23 and M56/1) were selected as potential biocontrol agents. The sequencing of CHV1/ORF-A showed that both of these virus strains belonged to the Italian subtype of CHV1. In vitro transfection of selected virus strains from hypovirulent to genetically diverse virus-free fungal isolates and subsequent inoculation of all virus/fungus combinations on stems of genetically diverse sweet chestnut trees revealed that Croatian virus strain CR23 had an equally hypovirulent effect on the host as the strong French strain CHV1-EP713, while M56/1 had a weaker effect. Furthermore, it was shown that in some cases the same hypovirus/fungus combinations induced various degrees of canker development on different chestnut genotypes. Some CHV1 strains belonging to the Italian subtype have similar hypovirulent effects on C. parasitica to those belonging to the French subtype. Furthermore, chestnut susceptibility and recovery could be influenced by the response of chestnut trees to particular hypovirulent C. parasitica isolates, and virus-fungus-chestnut interactions could have significant implications for the success of chestnut blight biocontrol. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  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. Protocollering van toetsen op Erwinia

    NARCIS (Netherlands)

    Dees, R.H.L.; Martin, W.S.; Doorn, van J.

    2009-01-01

    De problemen in de bloembollenteelt zijn de laatste tien jaar sterk toegenomen. Voorheen was de aanwezigheid van Erwinia carotovora subsp. carotovora (Ecc, nu Pectobacterium caotovorum) als witsnot in vooral hyacint bekend, maar gaf vrijwel nooit grote uitval in de teelt. Er zijn momenteel geen

  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. 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

  17. Investigation of Viability of Pantoea agglomerans (Formerly Erwinia herbicola) After Aerosolization From Media Containing Enriching and Coating Chemicals

    Science.gov (United States)

    2008-02-01

    conducted. 14. ABSTRACT Percent viability of the sensitive bacteria Pantoea agglomerans (ATCC_33243, formerly Erwinia herbicola or Eh), is an important ...effect of several nitrogen and carbon sources on the growth of Eh (strain CPA-2). Synthetic yeast extract enhanced maximum growth and disaccharides...recently-evolved pathogens? Mol. Plant Pathology 2003; 20, pp 307-314. 4. Vanneste, J.L.; Yu, J.; Beer , S.V. Role of antibiotic production by Erwinia

  18. 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.

  19. 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

    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...

  20. Harnessing the microbiome to reduce Fusarium head blight

    Science.gov (United States)

    Fusarium graminearum (Fg), the primary fungal pathogen responsible for Fusarium head blight (FHB), reduces crop yield and contaminates grain with trichothecene mycotoxins that are deleterious to plant, human and animal health. In this presentation, we will discuss two different research projects tha...

  1. CONTROl.. DE ERWINIA UREDOVORA CON MICROORGANISMOS ANTAGÓNICOS EN CUI..TIVOS DE PYRUS SP~ (PERO)

    OpenAIRE

    De Rico, Myriam E.; Departamento de Microbiología Facultad de Ciencias Pontificia Universidad Javeriana, Bogotá; Parra, Diana P.; Departamento de Microbiología Facultad de Ciencias Pontificia Universidad Javeriana, Bogotá; Baquero, Sandra L.; Departamento de Microbiología Facultad de Ciencias Pontificia Universidad Javeriana, Bogotá

    2013-01-01

    In order to dirninish the use of high doses of the chemical substances employed for the control of fire blight (Erwinia uredovora) in pear crops (Pyrus sp.), antagonistic microorganisms were isolated from the soil near healthy trees, from the rhizosphere, leaves, and stems of the sarne trees. To determine the antagonism in vitro, of these microorganisms against Erwinza uredovora, methods were used: channel, disk and strip. The best results were obtained with the disk method. The microorganism...

  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

  3. Nieuwe Erwinia-varianten vragen meer kennis en specifieke toetsen

    NARCIS (Netherlands)

    Wolf, van der J.M.

    2015-01-01

    Lange tijd kenden we in Nederland twee soorten Erwinia bacteriën namelijk Erwinia carotovora subsp. atroseptica en Erwinia chrysanthemi. Deze zijn/waren verantwoordelijk voor de aardappelziekten zwartbenigheid en stengelnatrot. De naamgeving van deze ziekteverwekkende bacteriën is echter op de schop

  4. 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.

  5. Nucleotide sequence, organization and expression of rdgA and rdgB genes that regulate pectin lyase production in the plant pathogenic bacterium Erwinia carotovora subsp. carotovora in response to DNA-damaging agents.

    Science.gov (United States)

    Liu, Y; Chatterjee, A; Chatterjee, A K

    1994-12-01

    In most soft-rotting Erwinia spp., including E. carotovora subsp. carotovora strain 71 (Ecc71), production of the plant cell wall degrading enzyme pectin lyase (Pnl) is activated by DNA-damaging agents such as mitomycin C (MC). Induction of Pnl production in Ecc71 requires a functional recA gene and the rdg locus. DNA sequencing and RNA analyses revealed that the rdg locus contains two regulatory genes, rdgA and rdgB, in separate transcriptional units. There is high homology between RdgA and repressors of lambdoid phages, specially phi 80. RdgB, however, has significant homology with transcriptional activators of Mu phage. Both RdgA and RdgB are also predicted to possess helix-turn-helix motifs. By replacing the rdgB promoter with the IPTG-inducible tac promoter, we have determined that rdgB by itself can activate Pnl production in Escherichia coli. However, deletion analysis of rdg+ DNA indicated that, when driven by their native promoters, functions of both rdgA and rdgB are required for the induction of pnlA expression by MC treatment. While rdgB transcription occurs only after MC treatment, a substantial level of rdgA mRNA is detected in the absence of MC treatment. Moreover, upon induction with MC, a new rdgA mRNA species, initiated from a different start site, is produced at a high level. Thus, the two closely linked rdgA and rdgB genes, required for the regulation of Pnl production, are expressed differently in Ecc71.

  6. [The influence of colonizing methylobacteria on morphogenesis and resistance of sugar beet and white cabbage plants to Erwinia carotovora].

    Science.gov (United States)

    Pigoleva, S V; Zakharchenko, N S; Pigolev, A V; Trotsenko, Iu A; Bur'ianov, Ia I

    2009-01-01

    The influence of colonization of sugar beet (Beta vulgaris var. saccharifera (Alef) Krass) and white cabbage (Brassica oleracea var. capitata L.) plants by methylotrophic bacteria Methylovorus mays on the growth, rooting, and plant resistance to phytopathogen bacteria Erwinia carotovora was investigated. The colonization by methylobacteria led to their steady association with the plants which had increased growth speed, root formation and photosynthetic activity. The colonized plants had increased resistance to Erwinia carotovora phytopathogen and were better adapted to greenhouse conditions. The obtained results showed the perspectives for the practical implementation of methylobacteria in the ecologically clean microbiology substances used as the plant growth stimulators and for the plant protection from pathogens.

  7. Urban blight and urban redesign

    OpenAIRE

    Zsilincsar, Walter

    2018-01-01

    The phenomenon of urban blight dates back to the 19th century when industrialisation starting in Europe and North America initiated an uncontrolled urban growth in combination with strong demand in cheap an quickly constructed housing. Ghettoisation of mainly the working-class population and other “marginal groups” were the consequence together with a constant decay of single buildings, whole blocks and quarters. These general aspects of urban blight with its additional facettes or aspects re...

  8. 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%.

  9. Characterization of Erwinia amylovora strains from different host plants using repetitive-sequences PCR analysis, and restriction fragment length polymorphism and short-sequence DNA repeats of plasmid pEA29.

    Science.gov (United States)

    Barionovi, D; Giorgi, S; Stoeger, A R; Ruppitsch, W; Scortichini, M

    2006-05-01

    The three main aims of the study were the assessment of the genetic relationship between a deviating Erwinia amylovora strain isolated from Amelanchier sp. (Maloideae) grown in Canada and other strains from Maloideae and Rosoideae, the investigation of the variability of the PstI fragment of the pEA29 plasmid using restriction fragment length polymorphism (RFLP) analysis and the determination of the number of short-sequence DNA repeats (SSR) by DNA sequence analysis in representative strains. Ninety-three strains obtained from 12 plant genera and different geographical locations were examined by repetitive-sequences PCR using Enterobacterial Repetitive Intergenic Consensus, BOX and Repetitive Extragenic Palindromic primer sets. Upon the unweighted pair group method with arithmetic mean analysis, a deviating strain from Amelanchier sp. was analysed using amplified ribosomal DNA restriction analysis (ARDRA) analysis and the sequencing of the 16S rDNA gene. This strain showed 99% similarity to other E. amylovora strains in the 16S gene and the same banding pattern with ARDRA. The RFLP analysis of pEA29 plasmid using MspI and Sau3A restriction enzymes showed a higher variability than that previously observed and no clear-cut grouping of the strains was possible. The number of SSR units reiterated two to 12 times. The strains obtained from pear orchards showing for the first time symptoms of fire blight had a low number of SSR units. The strains from Maloideae exhibit a wider genetic variability than previously thought. The RFLP analysis of a fragment of the pEA29 plasmid would not seem a reliable method for typing E. amylovora strains. A low number of SSR units was observed with first epidemics of fire blight. The current detection techniques are mainly based on the genetic similarities observed within the strains from the cultivated tree-fruit crops. For a more reliable detection of the fire blight pathogen also in wild and ornamentals Rosaceous plants the genetic

  10. Inhibition of Erwinia chrysanthemi growth to different concentrations of folic acid: possible use of folic acid as bacteriostatic agent and fortifying of Solanum tuberosum potato

    Directory of Open Access Journals (Sweden)

    Andrea Marcelo Correa

    2017-05-01

    Full Text Available Introduction:The enterobacteria of the Erwinia spp genus produce disease in potatoes, which is a tuber of mass consumption. The regulation of DNA methylation can regulate the proliferation of Erwinia in such a way that the concentrations of folic acid may have an effect on the microorganism pathogenic ability. On the other hand, the folic acid prevents the appearance of neural tube defects in humans. Objective: To evaluate folic acid as a bacteriostatic agent of Erwinia and, at the same time, as part of the fortification of mass consumption food such as the potatoes. Materials and methods: The biochemical characterization of the Erwinia chrysanthemi was carried out and its growth compared to different concentrations of folic acid was studied. Results: When increasing the concentrations of the vitamin from 0.3 µg/L up to 6.8 µg/L, the bacterial growth of Erwinia chrysanthemi is inhibited. The vitamin inhibits the growth in cultivation of Erwinia chrysanthemi and acts as a bacteriostatic agent. This aspect is of great importance given that, theoretically, if potatoes were fortified with micro-nutrient, this would act against the infectious agent and, at the same time, contribute to the adequate intake of the vitamin in the general population.

  11. PENGARUH SUMBER MINERAL TERHADAP PENEKANAN Erwinia carotovora OLEH PSEUDOMONAS PENDAR-FLUOR SECARA IN VITRO

    Directory of Open Access Journals (Sweden)

    Hardian Susilo Addy .

    2012-02-01

    Full Text Available Antimicrobial Stimulation of Fluorescent Pseudomonad to Inhibit Soft-rot Pathogen Caused by Erwinia carotovora subsp. Carotovora. This research was conducted to study effect of mineral sources on inhibition Erwinia carotovora by fluorescent pseudomonad. We used several mineral sources to stimulate antimicrobial substances from fluorescent pseudomonad that responsible to inhibit E. carotovora subsp. carotovora in vitro. The results showed that zinc 0,5 mM were the best to increase antagonistics of fluorescent psudomonad againts E. carotovora. Zinc were increased antimicrobial substances twohold compared with control without stimulant agent. Detection of antimicrobial substance using TLC showed that only one antimicrobial was detected with retention factor (Rf of 0,68 – 0,72. However, identification and characterization of that substance is still needed.

  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...

  13. Op weg naar een Erwinia-vrije pootgoedteelt

    NARCIS (Netherlands)

    Velvis, H.; Haar, van der J.; Wolf, van der J.M.

    2006-01-01

    De laatste jaren zijn er toenemende problemen in de pootgoedteelt met de bacterieziekten zwartbenigheid en stengelnatrot, veroorzaakt door Erwinia's. Een dieptepunt was 2003, toen 15,8% van het areaal pootgoed door de NAK werd verlaagd vanwege bacterieziek (Erwinia), waarvan 4% afgekeurd. In 2005

  14. 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.

  15. 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. © 2015 by The Mycological Society of America.

  16. Cloned Erwinia chrysanthemi out genes enable Escherichia coli to selectively secrete a diverse family of heterologous proteins to its milieu.

    OpenAIRE

    He, S Y; Lindeberg, M; Chatterjee, A K; Collmer, A

    1991-01-01

    The out genes of the enterobacterial plant pathogen Erwinia chrysanthemi are responsible for the efficient extracellular secretion of multiple plant cell wall-degrading enzymes, including four isozymes of pectate lyase, exo-poly-alpha-D-galacturonosidase, pectin methylesterase, and cellulase. Out- mutants of Er. chrysanthemi are unable to export any of these proteins beyond the periplasm and are severely reduced in virulence. We have cloned out genes from Er. chrysanthemi in the stable, low-c...

  17. PecS Is a Global Regulator of the Symptomatic Phase in the Phytopathogenic Bacterium Erwinia chrysanthemi 3937▿ †

    OpenAIRE

    Hommais, Florence; Oger-Desfeux, Christine; Van Gijsegem, Frédérique; Castang, Sandra; Ligori, Sandrine; Expert, Dominique; Nasser, William; Reverchon, Sylvie

    2008-01-01

    Pathogenicity of the enterobacterium Erwinia chrysanthemi (Dickeya dadantii), the causative agent of soft-rot disease in many plants, is a complex process involving several factors whose production is subject to temporal regulation during infection. PecS is a transcriptional regulator that controls production of various virulence factors. Here, we used microarray analysis to define the PecS regulon and demonstrated that PecS notably regulates a wide range of genes that could be linked to path...

  18. Overleving van Erwinia in grond en op materialen onderzocht : onderzoek : Erwinia

    NARCIS (Netherlands)

    Doorn, van J.; Kampen, van D.; Jollinger, van T.; Zouwen, van der P.S.; Speksnijder, A.G.C.L.; Wolf, van der J.M.

    2007-01-01

    In Nederland veroorzaken Erwiniabacteriën veel schade in bloembollen, aardappel, ui, witlof en bloemisterijgewassen. Er heerst nog steeds veel onduidelijkheid over de vraag waar deze Erwinia's vandaan komen. Ook is onduidelijk hoe lang deze kunnen overleven in grond, water of op materialen die in de

  19. Deltaplan Erwinia C : praktijkgericht (C-) onderzoek aan Erwinia-problemen in bloembolgewassen 2009-2013

    NARCIS (Netherlands)

    Doorn, van J.; Vreeburg, P.J.M.; Leeuwen, van P.J.; Martin, W.S.; Dees, R.H.L.

    2013-01-01

    Erwinia vormt een groot probleem in bloembolgewassen als hyacint, iris, Dahlia en Zantedeschia. Geschat wordt (precieze cijfers ontbreken) dat de economische schade door o.a. uitval van aangetaste bollen en kosten als gevolg van extra uitzoeken ongeveer 5- 8 miljoen euro op jaarbasis bedraagt. Daar

  20. Debate on the Exploitation of Natural Plant Diversity to Create Late Blight Resistance in Potato

    NARCIS (Netherlands)

    Goverse, A.; Struik, P.C.

    2009-01-01

    This paper reports on a debate on intriguing propositions relating to the scientific, agronomic, societal and economic impact of the BIOEXPLOIT project, focusing on late blight resistance in potato. It discusses (i) whether identifying pathogen effectors will facilitate selecting durable R genes,

  1. First record of Glomerella cingulata causing leaf blight on Talauma ovata (Magnoliaceae)

    OpenAIRE

    Vieira,Bruno Sérgio; Pereira,Olinto Liparini; Batista,Márcio Luiz; Barreto,Robert Weingart

    2005-01-01

    Glomerella cingulata was found causing severe leaf blight on Talauma ovata, a common tree species in the Atlantic tropical rain forest floodplains of Southern Brazil. The disease and pathogen are described and illustrated and patogenicity is also demonstrated. This is the first report of this disease.

  2. 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)

  3. 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.

  4. New Erwinia-Like Organism Causing Cervical Lymphadenitis▿

    Science.gov (United States)

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

    2008-01-01

    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. PMID:18614665

  5. Fatty acid analysis of Erwinia amylovora from Serbia and Montenegro

    Directory of Open Access Journals (Sweden)

    Milan Ivanović

    2011-01-01

    Full Text Available Automated method of fatty acid analysis was used to identify and study heterogeneity of 41 Erwinia amylovora strains, originating from 8 plant species grown in 13 locations in Serbia and one in Montenegro. All strains contained 14:0 3OH fatty acid,characteristic for the “amylovora” group. According to fatty acid composition 39 strains were identified as E. amylovora as the first choice from the database. Due to their specific fatty acid composition, two strains were identified as E. amylovora, but as a second choice. Fatty acid analysis also showed that E. amylovora population from Serbia could be differentiated in three groups, designated in this study as α, β and γ. All strains originating from central or south Serbia, as well as four strains from north Serbia clustered into group α. Group β and γ contained only strains isolated in northern Serbia (Vojvodina. The results show that E. amylovora population in this area is heterogeneous and indicate pathogen introduction from different directions. Fatty acid analysis enabled identificationat species level, as well as new insights of heterogeneity of E. amylovora population.

  6. 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.

  7. Population pharmacokinetics of intravenous Erwinia asparaginase in pediatric acute lymphoblastic leukemia patients

    NARCIS (Netherlands)

    Sassen, Sebastiaan D. T.; Mathôt, Ron A. A.; Pieters, Rob; Kloos, Robin Q. H.; de Haas, Valérie; Kaspers, Gertjan J. L.; van den Bos, Cor; Tissing, Wim J. E.; te Loo, Maroeska; Bierings, Marc B.; Kollen, Wouter J. W.; Zwaan, Christian M.; van der Sluis, Inge M.

    2017-01-01

    Erwinia asparaginase is an important component in the treatment of pediatric acute lymphoblastic leukemia. A large variability in serum concentrations has been observed after intravenous Erwinia asparaginase. Currently, Dutch Childhood Oncology Group protocols dose alterations are based on trough

  8. Population pharmacokinetics of intravenous Erwinia asparaginase in pediatric acute lymphoblastic leukemia patients

    NARCIS (Netherlands)

    Sassen, Sebastiaan D. T.; Mathot, Ron A. A.; Pieters, Rob; Kloos, Robin Q. H.; de Haas, Valerie; Kaspers, Gertjan J. L.; van den Bos, Cor; Tissing, Wim J. E.; te Loo, D. Maroeska W. M.; Bierings, Marc B.; Kollen, Wouter J. W.; Zwaan, Christian M.; van der Sluis, Inge M.

    Erwinia asparaginase is an important component in the treatment of pediatric acute lymphoblastic leukemia. A large variability in serum concentrations has been observed after intravenous Erwinia asparaginase. Currently, Dutch Childhood Oncology Group protocols dose alterations are based on trough

  9. 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.

  10. Genetic Characterization Of Syrian Erwinia Amylovora Strains By Amplified Fragment Length Polymorphism Technique

    International Nuclear Information System (INIS)

    Ammouneh, H.; Arabi, M.; Shoaib, A.

    2011-01-01

    Thirty Erwinia amylovora strains, collected from the main rosaceous crop-growing regions in Syria, were chosen as representatives of all major pathogenicity groups and were genetically studied by AFLP. Eight primer combinations were utilized and approximately 300 scorable bands in total were generated. Based on similarity coefficient, E. amylovora strains were placed into a main cluster containing two sub clusters, indicating very low genetic variations among the studied pathogen. The existence of two plasmids, pEA29 (present in nearly all E. amylovora isolates) and pEL60 (present mainly in Lebanese strains), was confirmed using multiplex PCR in all tested Syrian E. amylovora strains, indicating that Lebanese and Syrian isolates may share a common origin.(author)

  11. 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.

  12. Genomic analysis of Bacillus subtilis OH 131.1 and coculturing with Cryptococcus flavescens for control of fusarium head blight

    Science.gov (United States)

    Bacillus subtilis OH131.1 is a bacterial antagonist of Fusarium graminearum, a plant pathogen which causes Fusarium head blight in wheat. The genome of B. subtilis OH131.1 was sequenced, annotated and analyzed to understand its potential to produce bioactive metabolites. The analysis identified 6 sy...

  13. Chitosan-induced immunity in Camellia sinensis (L.) O. Kuntze against blister blight disease is mediated by nitric-oxide.

    Science.gov (United States)

    Chandra, Swarnendu; Chakraborty, Nilanjan; Panda, Koustubh; Acharya, Krishnendu

    2017-06-01

    Blister blight disease, caused by an obligate biotrophic fungal pathogen, Exobasidium vexans Massee is posing a serious threat for tea cultivation in Asia. As the use of chemical pesticides on tea leaves substantially increases the toxic risks of tea consumption, serious attempts are being made to control such pathogens by boosting the intrinsic natural defense responses against invading pathogens in tea plants. In this study, the nature and durability of resistance offered by chitosan and the possible mechanism of chitosan-induced defense induction in Camellia sinensis (L.) O. Kuntze plants against blister blight disease were investigated. Foliar application of 0.01% chitosan solution at 15 days interval not only reduced the blister blight incidence for two seasons, but also maintained the induced expressions of different defense related enzymes and total phenol content compared to the control. Defense responses induced by chitosan were found to be down regulated under nitric oxide (NO) deficient conditions in vivo, indicating that the observed chitosan-induced resistance is probably activated via NO signaling. Such role of NO in host defense response was further established by application of the NO donor, sodium nitroprusside (SNP), which produced similar defense responses accomplished through chitosan treatment. Taken together, our results suggest that increased production of NO in chitosan-treated tea plants may play a critical role in triggering the innate defense responses effective against plant pathogens, including that causing the blister blight disease. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  14. 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.

  15. The Status of Erwinia amylovora in the Former Yugoslav Republics over the Past Two Decades

    Directory of Open Access Journals (Sweden)

    Mila Grahovac

    2013-01-01

    Full Text Available Erwinia amylovora, the causal agent of fire blight (FB on fruit trees and ornamentalplants, rapidly spread across eastern Mediterranean countries in the early 1980s. This quarantinebacterium probably arrived in the southern parts of the former Yugoslavia (nowFYR Macedonia from Greece. Based on symptoms, and isolation and identification data, itwas concluded that Erwinia amylovora was the causal agent of pear drying in Macedonia(1989. It was the first experimental confirmation of a presence of E. amylovora in the territoryof the former Yugoslavia. The presence of E. amylovora was also proved in Serbia thatsame year. In Bosnia and Herzegovina, FB was detected during 1990. Based on an officialreport filed with the Federal Ministry of Agriculture in Belgrade, the presence of E. amylovorain Yugoslavia was confirmed (EPPO – Reporting Service, 1991. Therefore, the presenceof the bacterium E. amylovora in the territory of Yugoslavia was officially confirmedin 1990. In Croatia, FB was first observed in villages near the border on Serbia in 1995.In Montenegro, FB was first detected in 1996. In Slovenia, FB appeared as late as in 2001.E. amylovora is now present on 10 hosts (pear, wild pear, apple, quince, medlar, mountainash,hawthorn, firethorn, cotoneaster and Japanese quince in the territory ofthe former Yugoslav republics. Based on literature data, losses caused by FB in theformer Yugoslav republics in the period 1989-1992 were estimated at about12,000,000 DEM (mostly in Macedonia and in the period 1992–1996 at 6,000,000 DEM.Total damage in a more recent epiphytotic year in Slovenia (2003 was estimated atabout 474,200 EUR.Conventional and up-to-date rapid methods (PCR, ELISA and IF, BIOLOG and API System,FAME and SDS-PAGE have been used to identify E. amylovora. Mainly preventive measures have been used to control E. amylovora in the former Yugoslav republics. Spraying withcopper products has been practiced during the dormant period and in early

  16. 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.

  17. 75 FR 16102 - Kasugamycin; Receipt of Application for Emergency Exemption, Solicitation of Public Comment

    Science.gov (United States)

    2010-03-31

    ... pesticide manufacturer. Potentially affected entities may include, but are not limited to: Crop production... control streptomycin-resistant strains of Erwinia amylovora, the causal pathogen of fire blight, due to...

  18. 76 FR 11454 - Kasugamycin; Receipt of Application for Emergency Exemption for Use on Apples in Michigan...

    Science.gov (United States)

    2011-03-02

    ..., or pesticide manufacturer. Potentially affected entities may include, but are not limited to: Crop...-resistant strains of Erwinia amylovora, the causal pathogen of fire blight, due to the lack of available...

  19. 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.

  20. Efficacy of different fungicides against Rhizoctonia brown patch and Pythium blight on turfgrass in Italy.

    Science.gov (United States)

    Mocioni, M; Titone, P; Garibaldi, A; Gullino, M L

    2003-01-01

    Brown patch, incited by Rhizoctonia solani Kuhn, and Pythium blight, caused by Pythium spp. are two of the diseases most frequently observed on turfgrass in high maintenance stands, as on golf courses. In such conditions the control strategies, based on chemicals, are particularly difficult due to the scarcity of fungicides registered for turf in Italy. The results obtained in experimental trials carried out to evaluate the efficacy of chemical and biological products against brown patch and Pythium blight are reported. On mature turfgrass, maintained under fairway conditions, azoxystrobin, and trifoxystrobin, not yet registered on turf, were very effective against brown patch. Tebuconazole, applied in three different formulations, was very effective against R. solani, while Trichoderma spp. and azadiractine did not control the pathogen. In greenhouse conditions on Agrostis stolonifera, in the presence of severe disease incidence, due to artificial inoculation, benalaxyl-M satisfactorily controlled Pythium blight; Trichoderma spp. as well as a commercial formulation of T. harzianum, applied one week before the inoculation, were not effective. Among the fungicides not yet registered for use on turfgrass in Italy, metalaxyl-M + mancozeb was effective against Pythium blight.

  1. Some fungal endophytes from vegetable crops and their anti-oomycete activities against tomato late blight.

    Science.gov (United States)

    Kim, H-Y; Choi, G J; Lee, H B; Lee, S-W; Lim, H K; Jang, K S; Son, S W; Lee, S O; Cho, K Y; Sung, N D; Kim, J-C

    2007-03-01

    To isolate endophytic fungi from vegetable plants and examine their in vivo anti-oomycete activity against Phytophthora infestans in tomato plants. Endophytic fungi were isolated from surface-sterilized plant tissues and anti-oomycete activity was measured by in vivo assay using tomato seedlings. Endophytic fungi showing potent anti-oomycete activity were identified by morphological characteristics and nuclear ribosomal ITS1-5.8S-ITS2 sequence analysis. A total of 152 isolates were obtained from 66 healthy tissue samples of cucumber, red pepper, tomato, pumpkin and Chinese cabbage and the fermentation broths of 23 isolates showed potent in vivo anti-oomycete activity against tomato late blight with control values over 90%. The Fusarium oxysporum strain EF119, which was isolated from roots of red pepper, showed the most potent disease control efficacy against tomato late blight. In dual-culture tests, it inhibited the growth of Pythium ultimum, P. infestans and Phytophthora capsici. Among endophytic fungi isolated from healthy tissues of vegetable plants, F. oxysporum EF119 showed the most potent in vivo anti-oomycete activity against tomato late blight and in vitro anti-oomycete activity against several oomycete pathogens. Endophytic fungi showing anti-oomycete activity in vitro and in vivo may be used as biocontrol agents particularly of tomato late blight.

  2. 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...

  3. Cloned Erwinia chrysanthemi out genes enable Escherichia coli to selectively secrete a diverse family of heterologous proteins to its milieu.

    Science.gov (United States)

    He, S Y; Lindeberg, M; Chatterjee, A K; Collmer, A

    1991-02-01

    The out genes of the enterobacterial plant pathogen Erwinia chrysanthemi are responsible for the efficient extracellular secretion of multiple plant cell wall-degrading enzymes, including four isozymes of pectate lyase, exo-poly-alpha-D-galacturonosidase, pectin methylesterase, and cellulase. Out- mutants of Er. chrysanthemi are unable to export any of these proteins beyond the periplasm and are severely reduced in virulence. We have cloned out genes from Er. chrysanthemi in the stable, low-copy-number cosmid pCPP19 by complementing several transposon-induced mutations. The cloned out genes were clustered in a 12-kilobase chromosomal DNA region, complemented all existing out mutations in Er. chrysanthemi EC16, and enabled Escherichia coli strains to efficiently secrete the extracellular pectic enzymes produced from cloned Er. chrysanthemi genes, while retaining the periplasmic marker protein beta-lactamase. DNA sequencing of a 2.4-kilobase EcoRI fragment within the out cluster revealed four genes arranged colinearly and sharing substantial similarity with the Klebsiella pneumoniae genes pulH, pulI, pulJ, and pulK, which are necessary for pullulanase secretion. However, K. pneumoniae cells harboring the cloned Er. chrysanthemi pelE gene were unable to secrete the Erwinia pectate lyase. Furthermore, the Er. chrysanthemi Out system was unable to secrete an extracellular pectate lyase encoded by a gene from a closely related plant pathogen. Erwinia carotovora ssp. carotovora. The results suggest that these enterobacteria secrete polysaccharidases by a conserved mechanism whose protein-recognition capacities have diverged.

  4. Erwinia besmet de plant ook via de wortels

    NARCIS (Netherlands)

    Wolf, van der J.M.; Czajkowski, R.L.; Velvis, H.; Doorn, van J.

    2008-01-01

    Door een viertal Nederlandse wetenschappers is onlangs aanvullend onderzoek verricht naar besmettingen van Erwinia chrysanthemi in plantenwortels. Daaruit is gebleken dat de bacterie veel makkelijker de plant binnenkomt en zich in de plant verspreidt dan ooit gedacht. Binnen één dag kan de bacterie

  5. 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

  6. Resistance to Erwinia spp. in potato (Solanum tuberosum L.)

    NARCIS (Netherlands)

    Allefs, S.

    1995-01-01

    Blackleg is a disease of potato, Solanum tuberosum , which is caused by the bacteria Erwinia carotovora subsp. carotovora ( Ecc ), E.c. subsp. atroseptica ( Eca ) or

  7. Erwinia chrysanthemi ook bij ploffers in Dahlia boosdoener

    NARCIS (Netherlands)

    Leeuwen, van P.J.; Trompert, J.P.T.

    2006-01-01

    Sinds een aantal jaren komt bij de stekproduktie van Dahlia veel uitval voor door ploffers. Na het verhogen van de kastemperatuur vallen de knollen natrot weg. Bovendien kan verdere besmetting snel om zich heen grijpen. Onderzoek heeft aangetoond dat de bacterie Erwinia chrysanthemi de veroorzaker

  8. Nicotinic acid and nicotinamide on pear and apple flowers are not limiting factors for Erwinia amylovora growth when these chemicals are considered in relation to cultivar and flower age

    Directory of Open Access Journals (Sweden)

    Thomas PATERNOSTER

    2011-05-01

    Full Text Available Normal 0 14 false false false IT ZH-TW X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabella normale"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Fire blight, caused by Erwinia amylovora, is a devastating disease of pear (Pyrus communis and apple (Malus × domestica in many areas of the world. The disease is often initiated by epiphytic populations that multiply on flowers and colonize the hypanthia. In vitro, E. amylovora requires nicotinic acid (NicAc and/or nicotinamide (NicNH2 as essential growth factors. The amount of NicAc on pear hypanthia was positively correlated with the altitude of the growing site and was inversely correlated with the sum of the maximum temperatures in the 30 days before flowering. The sum of the amounts of NicAc and NicNH2 on the hypanthia was about 6 to 23 times higher in pear, and about 1.2 to 3.5 times higher in apple, than the amounts of NicAc or NicNH2 necessary to support maximum E. amylovora growth  in vitro. No correlation was found between the amounts of NicAc and NicNH2 on the hypanthia of different pear and apple cultivars and at different growth stages and the growth of E. amylovora after experimental inoculation. In conclusion, NicAc and NicNH2 are essential for E. amylovora growth but the amounts of these chemicals on pear and apple flowers do not limit the establishment of the pathogen when competing bacteria

  9. The regulation of virulence in phytopathogenic Erwinia species: quorum sensing, antibiotics and ecological considerations.

    Science.gov (United States)

    Whitehead, Neil A; Byers, Joseph T; Commander, Paul; Corbett, Mark J; Coulthurst, Sarah J; Everson, Lee; Harris, Abigail K P; Pemberton, Clare L; Simpson, Natalie J L; Slater, Holly; Smith, Debra S; Welch, Martin; Williamson, Neil; Salmond, George P C

    2002-08-01

    Erwinia carotovora is a Gram-negative bacterial phytopathogen that causes soft-rot disease and potato blackleg. The organism is environmentally widespread and exhibits an opportunistic plant pathogenesis. The ability to secrete multiple plant cell wall-degrading enzymes is a key virulence trait and exoenzyme production is responsive to multiple environmental and physiological cues. One important cue is the cell population density of the pathogen. Cell density is monitored via an acylated homoserine lactone (acyl HSL) signalling molecule, which is thought to diffuse between Erwinia cells in a process now commonly known as 'quorum sensing'. This molecule also acts as the chemical communication signal controlling production of a broad-spectrum beta-lactam antibiotic (1-carbapen-2-em-3-carboxylic acid; carbapenem) synthesised in concert with exoenzyme elaboration, possibly for niche defence. In antibiotic production control, quorum sensing acts at the level of transcriptional activation of the antibiotic biosynthetic cluster. This is achieved via a dedicated LuxR-type protein, CarR that is bound to the signalling molecule. The molecular relay connecting acyl HSL production and exoenzyme induction is not clear, despite the identification of a multitude of global regulatory genes, including those of the RsmA/rsmB system, impinging on enzyme synthesis. Quorum sensing control mediated by acyl HSLs is widespread in Gram-negative bacteria and is responsible for the regulation of diverse phenotypes. Although there is still a paucity of meaningful information on acyl HSL availability and in-situ biological function, there is growing evidence that such molecules play significant roles in microbial ecology.

  10. Efficacy of Newer Molecules, Bioagents and Botanicals against Maydis Leaf Blight and Banded Leaf and Sheath Blight of Maize

    Science.gov (United States)

    Malik, Vinod Kumar; Singh, Manjeet; Hooda, Karambir Singh; Yadav, Naresh Kumar; Chauhan, Prashant Kumar

    2018-01-01

    Maize (Zea mays L.; 2N=20) is major staple food crop grown worldwide adapted to several biotic and abiotic stresses. Maydis leaf blight (MLB) and banded leaf and sheath blight (BLSB) are serious foliar fungal diseases may cause up to 40% and 100% grain yield loss, respectively. The present studies were undertaken to work out the efficacy of chemicals, botanicals and bioagents for the management of MLB and BLSB under field condition for two seasons Kharif 2014 and 2015. Five molecules (propiconazole 25 EC, hexaconazole 25 EC, carbendazim 50 WP, mancozeb 75 WP and carbedazim 12 WP + mancozeb 63 WP), two bioagents i.e. Trichoderma harzianum and T. viridae and three botanicals namely azadirachtin, sarpagandha and bel pathar were tested for their efficacy against MLB. Eight newer fungicides viz., difenconazole 250 SC, hexaconazole 5 EC, carbendazim 50WP, validamycin 3 L, tebuconazole 250 EC, trifloxystrobin 50 WG + tebuconazole 50 WG, azoxystrobin 250 EC and pencycuron 250 SC were evaluated against BLSB. Analysis revealed significant effects of propiconazole at 0.1%, carbendazim 12 WP + mancozeb 63 WP at 0.125% and sarpagandha leaves at 10% against MLB pathogen, whereas validamycin at 0.1% and trifloxystrobin 25 WG + tebuconazole 50 WG at 0.05% were found effective against BLSB. The slow rate of disease control virtually by the bioagents might have not shown instant effect on plant response to the yield enhancing components. The identified sources of management can be used further in strengthening the plant protection in maize against MLB and BLSB. PMID:29628818

  11. Efficacy of Newer Molecules, Bioagents and Botanicals against Maydis Leaf Blight and Banded Leaf and Sheath Blight of Maize.

    Science.gov (United States)

    Malik, Vinod Kumar; Singh, Manjeet; Hooda, Karambir Singh; Yadav, Naresh Kumar; Chauhan, Prashant Kumar

    2018-04-01

    Maize ( Zea mays L.; 2N=20) is major staple food crop grown worldwide adapted to several biotic and abiotic stresses. Maydis leaf blight (MLB) and banded leaf and sheath blight (BLSB) are serious foliar fungal diseases may cause up to 40% and 100% grain yield loss, respectively. The present studies were undertaken to work out the efficacy of chemicals, botanicals and bioagents for the management of MLB and BLSB under field condition for two seasons Kharif 2014 and 2015. Five molecules (propiconazole 25 EC, hexaconazole 25 EC, carbendazim 50 WP, mancozeb 75 WP and carbedazim 12 WP + mancozeb 63 WP), two bioagents i.e. Trichoderma harzianum and T. viridae and three botanicals namely azadirachtin, sarpagandha and bel pathar were tested for their efficacy against MLB. Eight newer fungicides viz., difenconazole 250 SC, hexaconazole 5 EC, carbendazim 50WP, validamycin 3 L, tebuconazole 250 EC, trifloxystrobin 50 WG + tebuconazole 50 WG, azoxystrobin 250 EC and pencycuron 250 SC were evaluated against BLSB. Analysis revealed significant effects of propiconazole at 0.1%, carbendazim 12 WP + mancozeb 63 WP at 0.125% and sarpagandha leaves at 10% against MLB pathogen, whereas validamycin at 0.1% and trifloxystrobin 25 WG + tebuconazole 50 WG at 0.05% were found effective against BLSB. The slow rate of disease control virtually by the bioagents might have not shown instant effect on plant response to the yield enhancing components. The identified sources of management can be used further in strengthening the plant protection in maize against MLB and BLSB.

  12. Efficacy of Newer Molecules, Bioagents and Botanicals against Maydis Leaf Blight and Banded Leaf and Sheath Blight of Maize

    Directory of Open Access Journals (Sweden)

    2018-04-01

    Full Text Available Maize (Zea mays L.; 2N=20 is major staple food crop grown worldwide adapted to several biotic and abiotic stresses. Maydis leaf blight (MLB and banded leaf and sheath blight (BLSB are serious foliar fungal diseases may cause up to 40% and 100% grain yield loss, respectively. The present studies were undertaken to work out the efficacy of chemicals, botanicals and bioagents for the management of MLB and BLSB under field condition for two seasons Kharif 2014 and 2015. Five molecules (propiconazole 25 EC, hexaconazole 25 EC, carbendazim 50 WP, mancozeb 75 WP and carbedazim 12 WP + mancozeb 63 WP, two bioagents i.e. Trichoderma harzianum and T. viridae and three botanicals namely azadirachtin, sarpagandha and bel pathar were tested for their efficacy against MLB. Eight newer fungicides viz., difenconazole 250 SC, hexaconazole 5 EC, carbendazim 50WP, validamycin 3 L, tebuconazole 250 EC, trifloxystrobin 50 WG + tebuconazole 50 WG, azoxystrobin 250 EC and pencycuron 250 SC were evaluated against BLSB. Analysis revealed significant effects of propiconazole at 0.1%, carbendazim 12 WP + mancozeb 63 WP at 0.125% and sarpagandha leaves at 10% against MLB pathogen, whereas validamycin at 0.1% and trifloxystrobin 25 WG + tebuconazole 50 WG at 0.05% were found effective against BLSB. The slow rate of disease control virtually by the bioagents might have not shown instant effect on plant response to the yield enhancing components. The identified sources of management can be used further in strengthening the plant protection in maize against MLB and BLSB.

  13. Melatonin Attenuates Potato Late Blight by Disrupting Cell Growth, Stress Tolerance, Fungicide Susceptibility and Homeostasis of Gene Expression in Phytophthora infestans

    Directory of Open Access Journals (Sweden)

    Shumin Zhang

    2017-11-01

    Full Text Available Phytophthora infestans (P. infestans is the causal agent of potato late blight, which caused the devastating Irish Potato Famine during 1845-1852. Until now, potato late blight is still the most serious threat to potato growth and has caused significant economic losses worldwide. Melatonin can induce plant innate immunity against pathogen infection, but the direct effects of melatonin on plant pathogens are poorly understood. In this study, we investigated the direct effects of melatonin on P. infestans. Exogenous melatonin significantly attenuated the potato late blight by inhibiting mycelial growth, changing cell ultrastructure, and reducing stress tolerance of P. infestans. Notably, synergistic anti-fungal effects of melatonin with fungicides on P. infestans suggest that melatonin could reduce the dose levels and enhance the efficacy of fungicide against potato late blight. A transcriptome analysis was carried out to mine downstream genes whose expression levels were affected by melatonin. The analysis of the transcriptome suggests that 66 differentially expressed genes involved in amino acid metabolic processes were significantly affected by melatonin. Moreover, the differentially expressed genes associated with stress tolerance, fungicide resistance, and virulence were also affected. These findings contribute to a new understanding of the direct functions of the melatonin on P. infestans and provide a potential ecofriendly biocontrol approach using a melatonin-based paradigm and application to prevent potato late blight.

  14. Study the Stability of SSR Repeats of pEA29 Plasmid of the Casual Agent of Fire Blight

    Directory of Open Access Journals (Sweden)

    S. Baghaee Ravari

    2016-02-01

    Full Text Available Introduction Fire blight disease causes by Erwinia amylovora infects a wide variety of rosaceous plants. It was first recorded from pear trees in Karaj in year 1990. After that it was observed in many pear and apple orchards of the country. E. amylovora isolates differed slightly in virulence, symptoms and host range which ca be related to different plasmid content. The presence of an universal plasmid, pEA29, has been observed in majority of E. amylovora strains. Short-sequence DNA repeat with eight nt were repeated 3 to 15 times in the PstI fragment of the pEA29 plasmid. Here, the stability of SSR units and efficiency of this method to categorize strains was checked. For this reseaon two methods including amplification and cloning of whole and part of PstI fragment was done and the sequences were compared to eachother. In addition stability was evaluated based on three treatments including long time propagation, keeping strains in cold situation and re-isolation of infected tissues. Materials and Methods In this study 20 strains were purchased from the Iranian Plant Protection Research Institute. Their typical phenotypic tests were examined for all strains. All of then were checked with lateral flow immune chromatography in different serial dilutions. The pathogenicity were aassayed using complete fruit. Direct PCR with A/B primers and nested PCR with AJ75/AJ76 were applied for studied strains. Ten representative strains were selected snf part of PstI fragment amplified using RS1/RS2 primers. The PCR products were purified by QIAquick PCR purification kit (Qiagen, USA, cloned in pGEM-T and were sequenced (Macrogen Inc., Korea. Five of 10 were chosen for stability tests including long time propagation and sub culturing each two week for three months, keeping strains in refrigerator for three months and re-isolation of infected tissues. Results and Discussion In phenotypic tests all studies strains were facultative anaerobic growth, oxidase

  15. 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.

  16. UV-induced filamentation in bacteria of the generum Erwinia

    Energy Technology Data Exchange (ETDEWEB)

    Prokulevich, V A; Tomichev, Yu K

    1988-09-01

    It is experimentally shown that cells of 56 pectolytic Erwinia strains isolated at different tomus in different states from various natural sources are converted into filaments under UV-light effect in relatively low doses which allows one to refer them to natural Fil/sup +/ - organisms. Ability to filamentation in Erwinia bacterium correlates with secretion process to the environment of pectolytic enzymes. Bacteria of 9 E.herbicola strains investigated (without pectatlyase secretion) after irradiation do not form stretched cells. Based on the results obtained a conclusion is drawn that increased ENA49 E.chrysanthemic cell sensitivity to UV light results from its natural defect in the system, providing for cell division processes like the one revealed in E.CoLiB and Lon/sup -/ - mutants of E.Coli K-12.

  17. Erwinia carotovora extracellular proteases : characterization and role in soft rot

    OpenAIRE

    Kyöstiö, Sirkka R. M.

    1990-01-01

    Erwinia carotovora subsp. carotovora (Ecc) strain EC14, a Gram-negative bacterium, causes soft rot on several crops, including potato. Maceration of potato tuber tissue is caused by secreted pectolytic enzymes. Other cell-degrading enzymes may also have roles in pathogenesis, including cellulases, phospholipases, and protease(s). The objectives of this research were to (1) characterize Ecc extracellular protease (Prt) and (2) elucidate its role in potato soft rot. A gene enc...

  18. Morphological, cultural, pathogenic and molecular variability ...

    African Journals Online (AJOL)

    Alternaria blight (Alternaria brassicae) causes severe foliar damage to Indian mustard in Uttarakhand. Ten (10) isolates of A. brassicae were collected from different hosts and characterized for cultural, morphological, pathogenic and molecular variations. A. brassicae colonies varied in their cultural behaviour ranging from ...

  19. Influence of day-length and isolates of Phytophthora infestans on field resistance to late blight of potato.

    Science.gov (United States)

    Mihovilovich, E; Munive, S; Bonierbale, M

    2010-04-01

    Main and interaction effects of day-length and pathogen isolate on the reaction and expression of field resistance to Phytophthora infestans were analyzed in a sample of standard clones for partial resistance to potato late blight, and in the BCT mapping population derived from a backcross of Solanum berthaultii to Solanum tuberosum. Detached leaves from plants grown in field plots exposed to short- and long day-length conditions were independently inoculated with two P. infestans isolates and incubated in chambers under short- and long photoperiods, respectively. Lesion growth rate (LGR) was used for resistance assessment. Analysis of variance revealed a significant contribution of genotype x isolate x day-length interaction to variation in LGR indicating that field resistance of genotypes to foliar late blight under a given day-length depended on the infecting isolate. An allele segregating from S. berthaultii with opposite effects on foliar resistance to late blight under long- and short day-lengths, respectively, was identified at a quantitative trait locus (QTL) that mapped on chromosome 1. This allele was associated with positive (decreased resistance) and negative (increased resistance) additive effects on LGR, under short- and long day-length conditions, respectively. Disease progress on whole plants inoculated with the same isolate under field conditions validated the direction of its effect in short day-length regimes. The present study suggests the occurrence of an isolate-specific QTL that displays interaction with isolate behavior under contrasting environments, such as those with different day-lengths. This study highlights the importance of exposing genotypes to a highly variable population of the pathogen under contrasting environments when stability to late blight resistance is to be assessed or marker-assisted selection is attempted for the manipulation of quantitative resistance to late blight.

  20. Late Blight of Potato (Phytophthora infestans I: Fungicides Application and Associated Challenges

    Directory of Open Access Journals (Sweden)

    Abdul Majeed

    2017-03-01

    Full Text Available Potato (Solanum tuberosum L. has been remained an important agricultural crop in resolving global food issues through decades. The crop has experienced enormous growth in terms of production throughout the world in recent decades because of improvement in agricultural mechanization, fertilizers application and irrigation practices. Nevertheless, a significant proportion of this valuable crop is still vulnerable to losses due to prevalence of different viral, bacterial, fungal and nematodes infestations. Late blight, caused by Phytophthora infestans (Mont. de Bary, is one of the most threatening pathogenic diseases which not only results in direct crop losses but also cause farmers to embrace huge monetary expenses for disease control and preventive measures. The disease is well known for notorious ‘Irish Famine’ which resulted in drop of Irish population by more than 20% as result of hunger and potato starvation. Globally, annual losses of crop and money spend on fungicides for late blight control exceeds one trillion US dollars. This paper reviews the significance of late blight of potato and controlling strategies adopted for minimizing yield losses incurred by this disease by the use of synthetic fungicides. Advantages and disadvantages of fungicides application are discussed.

  1. 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.

  2. Pathogen-Induced Defense Signaling and Signal Crosstalk in Arabidopsis

    OpenAIRE

    Kariola, Tarja

    2006-01-01

    Erwinia carotovora subsp. carotovora is a bacterial phytopathogen that causes soft rot in various agronomically important crop plants. A genetically specified resistance to E. carotovora has not been defined, and plant resistance to this pathogen is established through nonspecific activation of basal defense responses. This, together with the broad host range, makes this pathogen a good model for studying the activation of plant defenses. Production and secretion of plant cell wall-degrading ...

  3. First report of shoot blight and dieback caused by Diplodia pinea on Pinus pinaster and P. radiata trees in Tunisia

    Directory of Open Access Journals (Sweden)

    B.T. Linaldeddu

    2009-01-01

    Full Text Available Damage caused by Diplodia pinea on Pinus pinaster and P. radiata forests are reported for the fi rst time in Tunisia. The affected plants show shoot blight, canker and branch dieback. On decaying and dead branches pycnidia of D. pinea are observed. The fungus was repeatedly isolated from the bark of symptomatic branches. The results of pathogenicity tests confirm the virulence of D. pinea and the susceptibility of both Pinus species to infection.

  4. 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

  5. Development of a method for testing the susceptibility of Salix alba to Erwinia salicis

    Energy Technology Data Exchange (ETDEWEB)

    Dingjan-Versteegh, A M; de Kam, M [Institute for Forestry and Urban Ecology, Wageningen (Netherlands)

    1990-01-01

    Salix is one of the faster growing tree species that has potential for biomass plantations in Europe. This potential, however, is limited by the occurrence of a vascular disease caused by the bacterium Erwinia salicis (Day) Chester. Selection and breeding of disease resistance is hampered by insufficient knowledge of the infection biology and ecology of the pathogen. The availability of specific antisera is of vital importance in the study of the infection biology and in monitoring bacterial populations inside the host. Therefore, one of the aims of the research was to improve the antisera. The composition of the soluble antigens of E. salicis was studied by enzyme-linked immunosorbent assay (ELISA), polyacrylamide gel electrophoresis (PAGE) and electro-immunoblotting. Antiserum prepared to whole cells of E. salicis mainly contains antibodies to bacterial surface antigens or to soluble antigens. ELISA demonstrated the presence of bacterial soluble antigens in leaves of diseased willow trees and also in leaves of willow shoots which were placed in a solution of bacterial soluble antigens. An inoculation experiment was carried out to ascertain if there is a statistically significant correlation between plant water potential and response to artificial inoculation with E. salicis. To elucidate the mechanisms involved in pathogenicity and virulence of E. salicis, attempts were made to isolate the plasmids of the bacterium, however, it appears that E. salicis does not have plasmids. In collaboration with Ch. Maceau (21), the E. salicis genome was isolated and a genomic library was constructed in E. coli. 28 refs., 10 figs., 4 tabs.

  6. 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

  7. 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

    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...

  8. Identification of bacterial blight resistance genes Xa4 in Pakistani ...

    African Journals Online (AJOL)

    SERVER

    2008-03-04

    Mar 4, 2008 ... Bacterial blight (BB) caused by Xanthomonas oryzae pv oryzae (Xoo) is a major biotic constraint in the irrigated rice belts. Genetic resistance is the most effective and economical control for bacterial blight. Molecular survey was conducted to identify the rice germplasm/lines for the presence of Xa4, a.

  9. 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

  10. Reactions of some potato genotypes to late blight in Cameroon ...

    African Journals Online (AJOL)

    Reactions of some potato genotypes to late blight in Cameroon. D. K. Njualem, P. Demo, H. A. Mendoza, J. T. Koi, S. F. Nana. Abstract. Field experiments were conducted in Cameroon in 1995 and 1996 to evaluate reactions of different potato genotypes to late blight. There were significant differences among genotypes for ...

  11. 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.

  12. 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.

  13. Role of motility and chemotaxis in the pathogenesis of Dickeya dadantii 3937 (ex Erwinia chrysanthemi 3937).

    Science.gov (United States)

    Antúnez-Lamas, María; Cabrera-Ordóñez, Ezequiel; López-Solanilla, Emilia; Raposo, Rosa; Trelles-Salazar, Oswaldo; Rodríguez-Moreno, Andrés; Rodríguez-Palenzuela, Pablo

    2009-02-01

    Dickeya dadantii 3937 (ex Erwinia chrysanthemi), a member of the Enterobacteriaceae, causes soft rot in many economically important crops. A successful pathogen has to reach the interior of the plant in order to cause disease. To study the role of motility and chemotaxis in the pathogenicity of D. dadantii 3937, genes involved in the chemotactic signal transduction system (cheW, cheB, cheY and cheZ) and in the structure of the flagellar motor (motA) were mutagenized. All the mutant strains grew like the wild-type in culture media, and the production and secretion of pectolytic enzymes was not affected. As expected, the swimming ability of the mutant strains was reduced with respect to the wild-type: motA (94%), cheY (80%), cheW (74%), cheB (54%) and cheZ (48%). The virulence of the mutant strains was analysed in chicory, Saintpaulia and potato. The mutant strains were also tested for their capability to enter into Arabidopsis leaves. All the mutants showed a significant decrease of virulence in certain hosts; however, the degree of virulence reduction varied depending on the virulence assay. The ability to penetrate Arabidopsis leaves was impaired in all the mutants, whereas the capacity to colonize potato tubers after artificial inoculation was affected in only two mutant strains. In general, the virulence of the mutants could be ranked as motApathogenicity of this bacterium.

  14. Biocontrol Activity of Myxococcus sp. KYC 1126 against Phytophthora Blight on Hot Pepper

    Directory of Open Access Journals (Sweden)

    Sung Chul Yun

    2011-08-01

    Full Text Available Bacteriolytic myxobacteria have been known to secrete various antifungal metabolites against several soilborne phytopathogens including Phytophthora. Among the three isolates of Myxococcus spp., KYC 1126 and KYC 1136 perfectly inhibited the mycelial growth of Phytophtora capsici in vitro. In order to show the biocontrol activity on Phytophthora blight of hot pepper, we tried to find the best way of application of myxobacterial isolate. Although KYC 1126 fruiting body was easily grown on the colony of Escherichia coli as a nutrient source, it did not control the disease when it was pre-applied in soil. Before the bioassay of a liquid culture filtrate of KYC 1126 was conducted, its antifungal activity was confirmed on the seedlings applying with the mixture of the pathogen`s zoospore suspension and KYC 1126 filtrate. On greenhouse experiments with five and four replications, the control value of KYC 1126 on phyllosphere and rhizosphere was 88% and 36%, respectively. Whereas, the control value of dimetnomorph+propineb on phyllosphere was 100% and that of propamorcarb on rhizosphere was 44%. There was a phytotoxicity of the myxobacterial filtrate when seedlings were washed and soaked for 24 hours. Gummy materials were covered with roots. And stem and petiole were constricted, then a whole seedling was eventually blighted.

  15. SH1 leaf rust and bacterial halo blight coffee resistances are genetically independent

    Directory of Open Access Journals (Sweden)

    Lucas Mateus Rivero Rodrigues

    Full Text Available ABSTRACT Coffee resistance to Pseudomonas syringae pv. garcae has been associated to pleiotropic effect of SH1 allele, present in coffee plants resistant to certain races of Hemileia vastatrix, the causal agent of leaf rust, or genetic linkage between resistance alleles to both pathogens. To validate this hypothesis, 63 coffee plants in F2 generation were evaluated for resistance to 2 isolates of H. vastatrix carriers of alleles, respectively, v2, v5 (isolate I/2015 and v1; v2; v5 (isolate II/2015 with the objective to confirm presence of SH1 allele in resistant plants to isolate I/2015. The same coffee plants were evaluated for resistance to a mixture of P. syringae pv. garcae strains highly pathogenic to coffee. Results showed that, among F2 coffee allele SH1 carriers, resistant to isolate I/2015, resistant and susceptible plants to bacterial halo blight were found; the same segregation occurs between F2 homozygous for SH1 allele, susceptible to the same isolate (I/2015 of H. vastatrix. Results also indicate that there is no pleiotropic effect of gene or allele SH1 connection between genes conferring resistance to leaf rust caused by H. vastatrix and bacterial halo blight caused by P. syringae pv. garcae.

  16. Kinetic Properties of α-Galactosidase and the Localization of Total Proteins in Erwinia chrysanthemi

    Directory of Open Access Journals (Sweden)

    John Morgan Brand

    2004-01-01

    Full Text Available Erwinia chrysanthemi is an enterobacterium that causes soft-rot in plants in general, resulting in enormous economic losses annually. For the pathogen to survive in the host plant, it has to use the readily assimilable compounds from the host fluids and degrade the host tissue. To accomplish this, E. chrysanthemi produces several extracellular and intracellular enzymes. Among the intracellular enzymes there is a special digestive class, the galactosidases, which can be either periplasmic or cytoplasmic. α-Galactosidase is known to degrade melibiose and raffinose into glucose and galactose, and into galactose and sucrose respectively. The aim of the present study was to investigate the kinetic properties of α-galactosidase in E. chrysanthemi, and the localization of total proteins, after culturing it in the presence of raffinose and melibiose. The α-galactosidase that degrades melibiose seems to be the same enzyme that is also responsible for the breakdown of raffinose in E. chrysanthemi. It is localized mainly in the cytoplasm with a fraction of between 2.4 and 5.4 % localized in the periplasm. The majority of E. chrysanthemi proteins have cytoplasmic localization.

  17. Two-component regulators involved in the global control of virulence in Erwinia carotovora subsp. carotovora.

    Science.gov (United States)

    Eriksson, A R; Andersson, R A; Pirhonen, M; Palva, E T

    1998-08-01

    Production of extracellular, plant cell wall degrading enzymes, the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, is coordinately controlled by a complex regulatory network. Insertion mutants in the exp (extracellular enzyme production) loci exhibit pleiotropic defects in virulence and the growth-phase-dependent transcriptional activation of genes encoding extracellular enzymes. Two new exp mutations, designated expA and expS, were characterized. Introduction of the corresponding wild-type alleles to the mutants complemented both the lack of virulence and the impaired production of plant cell wall degrading enzymes. The expA gene was shown to encode a 24-kDa polypeptide that is structurally and functionally related to the uvrY gene product of Escherichia coli and the GacA response regulator of Pseudomonas fluorescens. Functional similarity of expA and uvrY was demonstrated by genetic complementation. The expA gene is organized in an operon together with a uvrC-like gene, identical to the organization of uvrY and uvrC in E. coli. The unlinked expS gene encodes a putative sensor kinase that shows 92% identity to the recently described rpfA gene product from another E. carotovora subsp. carotovora strain. Our data suggest that ExpS and ExpA are members of two-component sensor kinase and response regulator families, respectively. These two proteins might interact in controlling virulence gene expression in E. carotovora subsp. carotovora.

  18. 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%.

  19. Burkholderia glumae: next major pathogen of rice?

    Science.gov (United States)

    Ham, Jong Hyun; Melanson, Rebecca A; Rush, Milton C

    2011-05-01

    Burkholderia glumae causes bacterial panicle blight of rice, which is an increasingly important disease problem in global rice production. Toxoflavin and lipase are known to be major virulence factors of this pathogen, and their production is dependent on the TofI/TofR quorum-sensing system, which is mediated by N-octanoyl homoserine lactone. Flagellar biogenesis and a type III secretion system are also required for full virulence of B. glumae. Bacterial panicle blight is thought to be caused by seed-borne B. glumae; however, its disease cycle is not fully understood. In spite of its economic importance, neither effective control measures for bacterial panicle blight nor rice varieties showing complete resistance to the disease are currently available. A better understanding of the molecular mechanisms underlying B. glumae virulence and of the rice defence mechanisms against the pathogen would lead to the development of better methods of disease control for bacterial panicle blight. Bacteria; Proteobacteria; Betaproteobacteria; Burkholderiales; Burkholderiaceae; Burkholderia. Gram-negative, capsulated, motile, lophotrichous flagella, pectolytic. Aborted seed, empty grains as a result of failure of grain filling, brown spots on panicles, seedling rot. Seed sterilization, planting partially resistant lines (no completely resistant line is available). KNOWN VIRULENCE FACTORS: Toxoflavin, lipase, type III effectors. © 2010 LSU AGCENTER. MOLECULAR PLANT PATHOLOGY © 2010 BSPP AND BLACKWELL PUBLISHING LTD.

  20. 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

  1. 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. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  2. Renewal strategies and neighborhood participation on urban blight

    OpenAIRE

    Ali Hosseini; Ahmad Pourahmad; Ali Taeeb; Milad Amini; Sara Behvandi

    2017-01-01

    Urban blight had its own rational and hierarchical function in the past. Nowadays it is featured with structural and functional shortage. Therefore, it has lost the capacity to meet the residents’ needs. Along with intensification of urban blight problems in cities, and downtowns in particular, which affects different aspects of urban life, many urban planners have shown special attention to such districts. Laleh-Zar neighborhood is an example of these neighborhoods, which on the one hand due...

  3. An efficient method for zoospore production, infection and real-time quantification of Phytophthora cajani causing Phytophthora blight disease in pigeonpea under elevated atmospheric CO₂.

    Science.gov (United States)

    Sharma, Mamta; Ghosh, Raju; Tarafdar, Avijit; Telangre, Rameshwar

    2015-03-25

    Phytophthora blight caused by Phytophthora cajani is an emerging disease of pigeonpea (Cajanus cajan L.) affecting the crop irrespective of cropping system, cultivar grown and soil types. Current detection and identification methods for Phytophthora species rely primarily on cultural and morphological characteristics, the assessment of which is time-consuming and not always suitable. Sensitive and reliable methods for isolation, identification, zoospore production and estimating infection severity are therefore desirable in case of Phytophthora blight of pigeonpea. In this study, protocols for isolation and identification of Phytophthora blight of pigeonpea were standardized. Also the method for zoospore production and in planta infection of P. cajani was developed. Quantification of fungal colonization by P. cajani using real-time PCR was further standardized. Phytophthora species infecting pigeonpea was identified based on mycological characters such as growth pattern, mycelium structure and sporangial morphology of the isolates and confirmed through molecular characterization (sequence deposited in GenBank). For Phytophthora disease development, zoospore suspension of 1 × 10(5) zoospores per ml was found optimum. Phytophthora specific real-time PCR assay was developed using specific primers based on internal transcribed spacer (ITS) 1 and 2. Use of real-time PCR allowed the quantitative estimation of fungal biomass in plant tissues. Detection sensitivities were within the range of 0.001 pg fungal DNA. A study to see the effect of elevated CO₂ on Phytophthora blight incidence was also conducted which indicated no significant difference in disease incidence, but incubation period delayed under elevated CO₂ as compared to ambient level. The zoospore infection method for Phytophthora blight of pigeonpea will facilitate the small and large scale inoculation experiments and thus devise a platform for rapid and reliable screening against Phytophthora blight

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

    Directory of Open Access Journals (Sweden)

    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

  5. Interacting signal pathways control defense gene expression in Arabidopsis in response to cell wall-degrading enzymes from Erwinia carotovora.

    Science.gov (United States)

    Norman-Setterblad, C; Vidal, S; Palva, E T

    2000-04-01

    We have characterized the role of salicylic acid (SA)-independent defense signaling in Arabidopsis thaliana in response to the plant pathogen Erwinia carotovora subsp. carotovora. Use of pathway-specific target genes as well as signal mutants allowed us to elucidate the role and interactions of ethylene, jasmonic acid (JA), and SA signal pathways in this response. Gene expression studies suggest a central role for both ethylene and JA pathways in the regulation of defense gene expression triggered by the pathogen or by plant cell wall-degrading enzymes (CF) secreted by the pathogen. Our results suggest that ethylene and JA act in concert in this regulation. In addition, CF triggers another, strictly JA-mediated response inhibited by ethylene and SA. SA does not appear to have a major role in activating defense gene expression in response to CF. However, SA may have a dual role in controlling CF-induced gene expression, by enhancing the expression of genes synergistically induced by ethylene and JA and repressing genes induced by JA alone.

  6. Transgenic plants producing the bacterial pheromone N-acyl-homoserine lactone exhibit enhanced resistance to the bacterial phytopathogen Erwinia carotovora.

    Science.gov (United States)

    Mäe, A; Montesano, M; Koiv, V; Palva, E T

    2001-09-01

    Bacterial pheromones, mainly different homoserine lactones, are central to a number of bacterial signaling processes, including those involved in plant pathogenicity. We previously demonstrated that N-oxoacyl-homoserine lactone (OHL) is essential for quorum sensing in the soft-rot phytopathogen Erwinia carotovora. In this pathogen, OHL controls the coordinate activation of genes encoding the main virulence determinants, extracellular plant cell wall degrading enzymes (PCWDEs), in a cell density-dependent manner. We suggest that E. carotovora employ quorum sensing to avoid the premature production of PCWDEs and subsequent activation of plant defense responses. To test whether modulating this sensory system would affect the outcome of a plant-pathogen interaction, we generated transgenic tobacco, producing OHL. This was accomplished by ectopic expression in tobacco of the E. carotovora gene expI, which is responsible for OHL biosynthesis. We show that expI-positive transgenic tobacco lines produced the active pheromone and partially complemented the avirulent phenotype of expI mutants. The OHL-producing tobacco lines exhibited enhanced resistance to infection by wild-type E. carotovora. The results were confirmed by exogenous addition of OHL to wild-type plants, which also resulted in increased resistance to E. carotovora.

  7. Sources of resistance in chickpea (cicer arietinum l.) land races against ascochyta rabiei causal agent of ascochyta blight disease

    International Nuclear Information System (INIS)

    Duzdemir, O.; Selvi, B.; Yanar, Y.

    2014-01-01

    Ascochyta blight disease, caused by the fungus Ascochyta rabiei, is a major yield limiting factor of chickpea in Turkey and around the world. This study was conducted to identify sources of genetic resistance against chickpea blight caused by Ascochyta rabiei. For this purpose, 68 chickpea land races of different origins were evaluated in both field and growth chamber conditions during 2008-2009 growing seassons. Two standard cultivars were used as a reference, Inci (resistant) and Canitez (susceptible). Disease severity scoring was conducted on a 1-9 rating scale 21 days after inoculation in growth chamber test and at flowering and pot filling stages in field tests. Analysis of variance (ANOVA) test showed a significant difference among the chickpea landraces in ascochyta blight resistance at p<0.05. None of the chickpea land races was highly resistant to the pathogen in growth chamber and field conditions. Only two landraces (10A and 28B) were moderately resistant to the disease. Some of the landraces resulted in a particular plant to exhibit no disease symptoms, indicating that the variation within chickpea land races was high. Therefore, seeds of this plant were harvested separately and preserved for further evaluations. (author)

  8. 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.

  9. The use of tissue culture techniques with irradiation to improve potato resistance to late blight

    International Nuclear Information System (INIS)

    Al-Safadi, B.; Arabi, M.I.E.

    2004-01-01

    A mutation breeding program was conducted to improve potato (Solanum tuberosum) resistance to late blight disease caused by Phytophthora infestans. In vitro cultured explants from potato cvs. Draga, Diamant, Spunta were irradiated with gamma ray doses 25, 30, and 35 Gy. Growing shoots were cut and re-cultured every 2 weeks until the 4 t h generation (MV 4 ) to make sure no chimeral tissues still existed in the mutant material. Plantlets were subsequently propagated to obtain enough explants for in vitro selection pressure. Around 3000 plantlets from the three cultivars were subjected to selection pressure using co-culture technique. MV 4 explants were incubated in jars, containing MS medium, with mycelia of P. infestans. Surviving plantlets were propagated and re-incubated with the pathogen for three consecutive generations. Resistant plantlets were acclimatized and transferred to pots and grown under glasshouse conditions. Plants were later inoculated, at the adult stage, with sporangial suspension. Cultivar Draga produced the highest number of resistant plants. Ten plants of Draga appeared to be resistant to late blight whereas only one plant from each of the other 2 cultivars was resistant. Mutant plants varied in number of produced minitubers from 13 to 70, Also, weight of these minitubers varied from less than 1 to 35 grams. Selected mutant lines will undergo further testing under field conditions for P. infestans resistance and other agronomic characteristics. (author)

  10. In vitro induction, isolation and selection of potato mutants resistant to late blight

    International Nuclear Information System (INIS)

    Al-Safadi, B.; Arabi, M.I.E.

    2003-01-01

    A mutation breeding program was conducted to improve potato resistance to late blight disease caused by Phytophthora infestans. In vitro cultured explants from cvs Draga, Diamant, Spunta were irradiated with gamma ray doses 25, 30, and 35 Gy. Growing shoots were cut and re-cultured every 2 weeks until the 4 th generation (MV 4 ) to make sure no chimeral tissues still existed in the mutant material. Plantlets were subsequently propagated to obtain enough explants for in vitro selection pressure. Around 3,000 plantlets from the 3 cultivars were subjected to selection pressure using co-culture technique. MV 4 explants were incubated in jars, containing MS medium, with mycelia of P. infestans. Surviving plantlets were propagated and re-incubated with the pathogen for 3 consecutive generations. Resistant plantlets were acclimatized and transferred to pots and grown under glasshouse conditions. Plants were later inoculated, at the adult stage, with sporangial suspension. Cv Draga produced the highest number of resistant plants. Ten plants of Draga appeared to be resistant to late blight, whereas only one plant from each of the other 2 cvs was resistant. Mutant plants varied in number of produced minitubers from 13 to 70. Also, weight of these minitubers varied from less than 1 to 35 grams. Selected mutant lines will undergo further testing under field conditions for P. infestans resistance and other agronomic characteristics

  11. Genome Analyses of an Aggressive and Invasive Lineage of the Irish Potato Famine Pathogen

    NARCIS (Netherlands)

    Cooke, D.E.L.; Cano, L.M.; Raffaele, S.; Bain, R.A.; Cooke, L.R.; Etherington, G.J.; Deahl, K.L.; Farrer, R.A.; Gilroy, E.M.; Goss, E.M.; Grünwald, N.J.; Hein, I.; Maclean, D.; McNicol, J.W.; Randall, E.; Oliva, R.F.; Pel, M.; Shaw, D.S.; Squires, J.N.; Taylor, M.C.; Vleeshouwers, V.G.A.A.; Birch, P.R.J.; Lees, A.K.; Kamoun, S.

    2012-01-01

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

  12. Population genomics of Fusarium graminearum reveals signatures of divergent evolution within a major cereal pathogen

    Science.gov (United States)

    The cereal pathogen Fusarium graminearum is the primary cause of Fusarium head blight (FHB) and a significant threat to food safety and crop production. To elucidate population structure and identify genomic targets of selection within major FHB pathogen populations in North America we sequenced the...

  13. Gamma radiation-induced mutant of NSIC RC144 with broad-spectrum resistance to bacterial blight

    International Nuclear Information System (INIS)

    Alfonso, A.A.; Avellanoza, E.S.; Miranda, R.T.; Espejo, E.O.; Garcia, N.S.

    2014-01-01

    Mutant lines derived from gamma radiation-treated commercial variety NSIC RC144 were produced and screened for novel resistance to bacterial blight, one of the most serious diseases of rice. Preliminary screening of a bulk M2 population through induced method using race 3 of the pathogen Xanthomonas oryzae pv. oryzae (Xoo) resulted in the selection of 89 resistant plants. Subsequent repeated bacterial blight screenings and generation advance for five seasons resulted in the selection of two highly resistant M7 sister lines whose origin can be traced to a single M2 plant. DNA fingerprinting using 63 genome-wide simple sequence repeat (SSR) markers revealed an identical pattern in these lines. Using the same set of markers, they also exhibited 98% similarity to wild type NSIC RC144 indicating that the resistance is due to mutation and not due to genetic admixture or seed impurity. Two seasons of bacterial blight screening using 14 local isolates representing ten races of Xoo revealed an identical reaction pattern in these lines. The reaction pattern was observed to be unique compared to known patterns in four IRBB isolines (IRBB 4, 5, 7 and 21) with strong resistant reaction to bacterial blight suggesting possible novel resistance. The susceptible reaction in F1 testcrosses using Xoo race 6 and the segregation patterns in two F2 populations that fit with the expected 3 susceptible: 1 resistant ratio (P = 0.4, ns) suggest a single-gene recessive mutation in these lines. These mutants are now being used as resistance donor in the breeding program while further molecular characterization to map and characterize the mutated gene is being pursued

  14. Fungicides and Application Timing for Control of Early Leafspot, Southern Blight, and Sclerotinia Blight of Peanut

    Directory of Open Access Journals (Sweden)

    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.

  15. 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.

  16. Evaluation of salivary catalase activity in blighted ovum gestation

    Directory of Open Access Journals (Sweden)

    Maryam Ahmadizadeh

    2016-05-01

    Full Text Available Background: Anembryonic gestation (blighted ovum is the most common identifiable pathology in the first trimester of pregnancy, always leads to miscarriage. Early pregnancy failures from blighted ovum are often due to chromosomal abnormalities and a poor quality of sperm or egg. Oxidative stresses as a factor of disturbance balance between the production of free radicals and antioxidant defenses is involved in the pathogenesis of many diseases, including mouth and throat cancer and cardiovascular disease. Catalase is one of the defensive systems against damages caused by oxidative stress in human. The aim of this study was to compare the activity of salivary catalase in women with blighted ovum and women with history of normal pregnancy. Methods: This case-control study was performed on 34 patient women with blighted ovum and 34 healthy women as a control group. The study was performed in biochemistry laboratory at the University of Guilan from October 2015 to July 2015. The age range was 20-44 years and 18-45 years in patient and control groups, respectively. Unstimulated saliva samples were collected using spitting method. Catalase activity was measured by evaluating the constant rate of hydrogen peroxide decomposition in patient and control groups. Results: The patient group matched with healthy subjects in average age and having no other diseases history. The biochemical enzymatic assays indicate that the average catalase activities of saliva in patient and control groups were 14.47±3.8 and 16.42±3.48, respectively. Therefore, the catalase activity was significantly reduced in patient group as compared to the control group (P=0.03. Conclusion: The obtained results suggested that oxidative stress plays an important role in the pathogenesis of blighted ovum. Therefore, determination the activity of other antioxidant enzymes, in addition to catalse, may be used as a marker for diagnosis of blighted ovum. More studies with larger studied

  17. Mycotoxins produced by Fusarium spp. associated with Fusarium head blight of wheat in Western Australia.

    Science.gov (United States)

    Tan, Diana C; Flematti, Gavin R; Ghisalberti, Emilio L; Sivasithamparam, Krishnapillai; Chakraborty, Sukumar; Obanor, Friday; Jayasena, Kithsiri; Barbetti, Martin J

    2012-05-01

    An isolated occurrence of Fusarium head blight (FHB) of wheat was detected in the south-west region of Western Australia during the 2003 harvest season. The molecular identity of 23 isolates of Fusarium spp. collected from this region during the FHB outbreak confirmed the associated pathogens to be F. graminearum, F. acuminatum or F. tricinctum. Moreover, the toxicity of their crude extracts from Czapek-Dox liquid broth and millet seed cultures to brine shrimp (Artemia franciscana) was associated with high mortality levels. The main mycotoxins detected were type B trichothecenes (deoxynivalenol and 3-acetyldeoxynivalenol), enniatins, chlamydosporol and zearalenone. This study is the first report on the mycotoxin profiles of Fusarium spp. associated with FHB of wheat in Western Australia. This study highlights the need for monitoring not just for the presence of the specific Fusarium spp. present in any affected grain but also for their potential mycotoxin and other toxic secondary metabolites.

  18. Respuesta al glifosato de un aislamiento de Rhizoctonia solani agente causal del anublo de la vaina del arroz, y de cuatro aislamientos de Trichoderma, bajo condiciones in vitro In vitro response of one isolate of Rhizoctonia solani, the pathogen of the rice sheath blight and four isolates of Trichoderma to glyphosate

    Directory of Open Access Journals (Sweden)

    Vargas de Álvarez Amparo

    2002-08-01

    de las malezas, estuviera afectando el crecimiento de R. solani o de su antagonista Trichoderma. Una posible relación entre el uso intensivo del herbicida y la incidencia del añublo de la vaina del arroz, debería investigarse en términos de supervivencia
    y germinación de esclerocios del patógeno.
    Rhizoctonia solani Kuhn is the causal agent ofthe sheath
    blight of rice (Orysa saliva L., one of the most important
    rice diseases in Colombia. G1yphosate (N-phosphonomethyl
    glicine acid is sprayed in rice fields as a preplant herbicide, specially aimed at red rice (O. saliva. Preliminary field observations in Tolima, Colombia suggested a relationship between intensive use of glyphosate and sheath blight incidence. Thus, the present study was undertaken to shed light on the effect of glyphosate on R. solani and Thrichoderma sp., a.putative antagonist, under laboratory conditions. The effect of the herbicide was assessed on the growth ofR. solani in summerged culture and solid media and of Thrichoderma on solid media. R. sotaní withstood up to 300 mg L-! without expressing reduction in growth, Increasing concentrations of the herbicide caused growth reduction, and the detrimental effect reached a plateau at 2500 mg L-1. Rhizoctonia growth was not enhanced at any herbicide concentration. The expected concentration of glyphosate in the soil after spraying at commercial dosages would be O, 75 mg Kg', which is well below the observed in vitro threshold. The response of Thrichoderma was similar to that of R. sotaní. Glyphosate did not affect the antagonistic ability of Thrichoderma against R. solani. These results do not support the view that glyphosate, as an herbicide treatment in rice
    field, may affect in any way the population densities of R.
    sotaní or its antagonist Thrichoderma sp. Therefore, the
    postulated connection between intensive herbicide use
    and increased sheath blight incidence is not substantiated
    on

  19. Creation of initial breeding material of potato with complex resistance to Fusarium dry rot and tuber late blight

    Directory of Open Access Journals (Sweden)

    В. В. Гордієнко

    2017-09-01

    Full Text Available Purpose. To select the initial breeding material with complex resistance to Fusarium dry rot and tuber late blight among the created potato of secondary interspecific hyb­rids. Methods. Interspecific hybridization, laboratory test, analytical approach. Results. Based on the interspecific hybridization, the initial breeding material was created and the degree of its resistance to the above pathogens was determined by way of artificial infection of tubers with the inoculum of such fungi as Fusarium sambucinum Fuck and Phytophthora infestans (Mont. De Bary. During interspecific hybridization based on schemes of saturating and enriching crosses, using forms of various species with a high phenotypic expression of resistance to Fusarium dry rot, the result of the cumulative effect of genes that control resistance to the pathogen was observed. Crossing combinations differed significantly for the degree of population average manifestation of resistance to the diseases. Conclusions. Combinations В54, В53, В61 with a mean resistance (above 7 grades to Fusarium dry rot have been selected. Such combinations as B52, B50 and B54 had increased resistance to tuber late blight. It was found that the combination В54 is characterized by complex resistance to both diseases. For further work, the following samples with complex resistance to Fusarium dry rot and tuber late blight (7 grades or more were selected: В59с42, В59с43, В50с16, В50с19, В50с44, В51с1, В51с26, В51с28, В52с11, В52с23, В52с24, В52с29, В53с1, В53с11, В53с17 , В53с23, В54с13, В54с14.

  20. 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.

  1. 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...

  2. Impact of fungicide applications for late blight management on ...

    African Journals Online (AJOL)

    The influence of late blight infections, caused by Phytophthora infestans, was evaluated on thirteen huckleberry (Solanum scabrum) varieties during the 2000 and 2001 cropping seasons in Dschang, Cameroon. A randomised split block design was used. Plants were sprayed four times with Ridomil Plus® (12% metalaxyl + ...

  3. Field management of Phytophthora blight disease of cocoyam ...

    African Journals Online (AJOL)

    Cocoyam (Colocasia esculenta L). is an important edible tuber crop, but taro leaf blight caused by Phytophthora colocasiae has been the greatest constraint to cocoyam production in Nigeria since 2009. Field trials were conducted to determine the effect of fungicides and the spray regimes on leaf growth, disease incidence, ...

  4. Pyramiding of blast and bacterial leaf blight resistance genes into ...

    African Journals Online (AJOL)

    Blast caused by the fungus Magnaporthe oryzae (Hebert) Barr. and bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) are two major diseases of rice (Oryza sativa). The use of varietal resistance is the most appropriate strategy for controlling the diseases, and molecular assisted selection can ...

  5. Control of Late Blight of Tomato and Potato by Oilgochitosan

    Directory of Open Access Journals (Sweden)

    Yong Ho Choi

    2011-08-01

    Full Text Available Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4-linked D-glucosamine and Nacetyl- D-glucosamine. There have been many reports on the induced systemic resistance and in vivo antifungal activities of higher molecular weight chitosans with molecular weights over 3,000 amu (atomatic mass unit, but there are few papers on in vivo antifungal activities of low molecular weight chitosans (oligochitosans with molecular weights less than 3,000 amu. In our study, an oligochitosan sample (320?3,000 amu showed a potent 1-day protective activity with control values more than 94% at concentrations of 500 and 1,000 ?g/ml especially against tomato late blight caused by Phytophthora infestans under growth chamber conditions. It also displayed a moderate 1-day protective activity with control values of 67?89% at concentrations of 500 and 1,000 ?g/ml against wheat leaf rust and red pepper anthracnose. On the other hand, it showed a 16-hr curative activity against red pepper anthracnose, but not against tomato late blight and wheat leaf rust. In field experiments, oligochitosan effectively suppressed the development of late blight on potato and tomato plants with control values of 72% and 48%, respectively. The results strongly indicate that oligochitosan can be used as an eco-friendly organic material for the control of late blight on tomato and potato plants.

  6. Chemical control of blossom blight disease of sarpagandha caused ...

    African Journals Online (AJOL)

    ONOS

    2010-09-20

    Sep 20, 2010 ... Chemical control of blossom blight disease of sarpagandha caused by Colletotrichum capsici. R. S. Shukla, Abdul-Khaliq and M. Alam*. Department of Plant Pathology, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial. Research, P. O. CIMAP, Lucknow–226 015, India.

  7. Cassava bacterial blight in Africa: the state of knowledge and ...

    African Journals Online (AJOL)

    Introduced to Africa in the 1970s, cassava bacterial blight caused by Xanthomonas campestris pv. manihotis (XCM) is present in almost all cropping areas. In the past fifteen years, advances have been made in knowledge of the biology and molecular genetics of XCM, host-parasite relationships and epidemiology of the ...

  8. Improvement of common bacterial blight resistance in South African ...

    African Journals Online (AJOL)

    Common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli is an important seed-borne disease of dry beans in South Africa. Development of resistant cultivars is considered the best control measurement for the disease. Backcross breeding was used to improve BB resistance in the small white ...

  9. Field reaction of cassava genotypes to anthracnose, bacterial blight ...

    African Journals Online (AJOL)

    Field reaction of cassava genotypes to anthracnose, bacterial blight, cassava mosaic disease and their effects on yield. ... The BYDV-PAV and BYDV-RPV serotypes were identified from 9 and 10 of the 11 surveyed fields, respectively, with the two serotypes co-infecting some plants. Of the nine wheat cultivars surveyed, four ...

  10. Epidemiology and integrated control of Potato Late Blight in Europe

    NARCIS (Netherlands)

    Cooke, R.J.; Schepers, H.T.A.M.; Hermansen, A.; Bain, R.; Bradshaw, N.; Ritchie, F.; Shaw, D.S.; Evenhuis, A.; Kessel, G.J.T.; Wander, J.G.N.; Andersson, B.; Hansen, J.G.; Hannukkala, A.; Naerstad, R.; Nielsen, B.

    2011-01-01

    Phytophthora infestans, the causal agent of late blight, is a major threat to potato production in northwestern Europe. Before 1980, the worldwide population of P. infestans outside Mexico appeared to be asexual and to consist of a single clonal lineage of A1 mating type characterized by a single

  11. Molecular characterization of early blight disease resistant and ...

    African Journals Online (AJOL)

    Potato early blight disease caused by Alternaria solani is one of the major factors limiting potato production worldwide. Developing highly resistant cultivars is the most effective way to control the disease. In this study, 20 random amplified polymorphic DNA (RAPD) and 6 simple sequence repeats (SSR) primers were ...

  12. Phytophthora infestans effectors IPI-O1 and IPI-O4 each contribute to pathogen virulence

    Science.gov (United States)

    Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is one of the most destructive plant diseases. Despite decades of intensive breeding efforts, it remains a threat to potato production worldwide, in part because newly evolved pathogen isolates quickly overcome major resista...

  13. Dickeya dadantii, a plant pathogenic bacterium producing Cyt-like entomotoxins, causes septicemia in the pea aphid Acyrthosiphon pisum

    OpenAIRE

    Costechareyre, Denis; Balmand, Severine; Condemine, Guy; Rahbé, Yves

    2012-01-01

    International audience; Dickeya dadantii (syn. Erwinia chrysanthemi) is a plant pathogenic bacteria that harbours a cluster of four horizontally-transferred, insect-specific toxin genes. It was recently shown to be capable of causing an acute infection in the pea aphid Acyrthosiphon pisum (Insecta: Hemiptera). The infection route of the pathogen, and the role and in vivo expression pattern of these toxins, remain unknown. Using bacterial numeration and immunolocalization, we investigated the ...

  14. Impact of transgenic potatoes expressing anti-bacterial agents on bacterial endophytes is comparable with the effects of plant genotype, soil type and pathogen infection

    NARCIS (Netherlands)

    Rasche, F; Velvis, H; Zachow, C; Berg, G; Van Elsas, JD; Sessitsch, A

    1. Blackleg and soft rot disease of potatoes Solanum tuberosum L., mainly caused by the bacterial pathogen Erwinia carotovora ssp. atrospetica (Eca), lead to enormous yield losses world-wide. Genetically modified (GM) potatoes producing anti-bacterial agents, such as cecropin/attacin and T4

  15. Impact of transgenic potatoes expressing anti-bacterial agents on bacterial endophytes is comparable with the effects of plant genotype, soil type and pathogen infection

    NARCIS (Netherlands)

    Rasche, F.; Velvis, H.; Zachow, C.; Berg, G.; Elsas, van J.D.; Sessitsch, A.

    2006-01-01

    1. Blackleg and soft rot disease of potatoes Solanum tuberosum L., mainly caused by the bacterial pathogen Erwinia carotovora ssp. atrospetica (Eca), lead to enormous yield losses world-wide. Genetically modified (GM) potatoes producing anti-bacterial agents, such as cecropin/attacin and T4

  16. 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

  17. 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

  18. Effectieve kolonisatie van aardappelplanten door Dickeya-soorten (Erwinia chrysanthemi) : themanummer fytobacteriologie

    NARCIS (Netherlands)

    Wolf, van der J.M.; Czajkowski, R.L.; Velvis, H.

    2009-01-01

    De bacterieziekten zwartbenigheid en stengelnatrot, veroorzaakt door Pectobacterium en Dickeya (Erwinia)- soorten, berokkenen grote schade aan de pootaardappelteelt. Bij PRI en HZPC wordt onderzoek verricht naar de verspreiding van deze pathogenen tijdens teelt- en (na)oogst. Het was al bekend dat

  19. Besmetting en erwinia-vrij pootgoed uit diverse bronnen : een literatuuroverzicht

    NARCIS (Netherlands)

    Roozen, N.

    1990-01-01

    In dit verslag wordt het risico besproken van diverse potentiële besmettingsbronnen van erwinia-vrij pootgoed. Het doel hiervan is te achterhalen waar de kennis over het risico van de diverse besmettingsbronnen gebreken vertoont en aangevuld dient te worden middels onderzoek. Er zijn criteria

  20. Comparison of specificity and sensitivity of immunochemical and molecular techniques for reliable detection of Erwinia amylovora

    Czech Academy of Sciences Publication Activity Database

    Kokošková, B.; Mráz, Ivan; Hýblová, Jana

    2007-01-01

    Roč. 52, č. 2 (2007), s. 175-182 ISSN 0015-5632 R&D Projects: GA AV ČR(CZ) 1QS500510558 Institutional research plan: CEZ:AV0Z50510513 Keywords : Erwinia amylovora * detection Subject RIV: EE - Microbiology, Virology Impact factor: 0.989, year: 2007

  1. 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.

  2. Erwinia gerundensis sp. nov., a cosmopolitan epiphyte originally isolated from pome fruit trees.

    Science.gov (United States)

    Rezzonico, Fabio; Smits, Theo H M; Born, Yannick; Blom, Jochen; Frey, Jürg E; Goesmann, Alexander; Cleenwerck, Ilse; de Vos, Paul; Bonaterra, Anna; Duffy, Brion; Montesinos, Emilio

    2016-03-01

    A survey to obtain potential antagonists of pome fruit tree diseases yielded two yellow epiphytic bacterial isolates morphologically similar to Pantoea agglomerans , but showing no biocontrol activity. Whole-cell MALDI-TOF mass spectrometry and analysis of 16S rRNA gene and gyrB sequences suggested the possibility of a novel species with a phylogenetic position in either the genus Pantoea or the genus Erwinia . Multi-locus sequence analysis (MLSA) placed the two strains in the genus Erwinia and supported their classification as a novel species. The strains showed general phenotypic characteristics typical of this genus and results of DNA-DNA hybridizations confirmed that they represent a single novel species. Both strains showed a DNA G+C content, as determined by HPLC, of 54.5 mol% and could be discriminated from phylogenetically related species of the genus Erwinia by their ability to utilize potassium gluconate, potassium 2-ketogluconate, maltose, melibiose and raffinose. Whole-genome sequencing of strain EM595 T revealed the presence of a chromosomal carotenoid biosynthesis gene cluster similar to those found in species of the genera Cronobacter and Pantoea that explains the pigmentation of the strain, which is atypical for the genus Erwinia . Additional strains belonging to the same species were recovered from different plant hosts in three different continents, revealing the cosmopolitan nature of this epiphyte. The name Erwinia gerundensis sp. nov. is proposed, with EM595 T ( = LMG 28990 T  = CCOS 903 T ) as the designated type strain.

  3. Inhibition of Plant-Pathogenic Bacteria by Short Synthetic Cecropin A-Melittin Hybrid Peptides

    OpenAIRE

    Ferre, Rafael; Badosa, Esther; Feliu, Lidia; Planas, Marta; Montesinos, Emili; Bardají, Eduard

    2006-01-01

    Short peptides of 11 residues were synthesized and tested against the economically important plant pathogenic bacteria Erwinia amylovora, Pseudomonas syringae, and Xanthomonas vesicatoria and compared to the previously described peptide Pep3 (WKLFKKILKVL-NH2). The antimicrobial activity of Pep3 and 22 analogues was evaluated in terms of the MIC and the 50% effective dose (ED50) for growth. Peptide cytotoxicity against human red blood cells and peptide stability toward protease degradation wer...

  4. A prospective study on drug monitoring of PEGasparaginase and Erwinia asparaginase and asparaginase antibodies in pediatric acute lymphoblastic leukemia

    NARCIS (Netherlands)

    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.

    2014-01-01

    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

  5. A prospective study on drug monitoring of PEGasparaginase and Erwinia asparaginase and asparaginase antibodies in pediatric acute lymphoblastic leukemia

    NARCIS (Netherlands)

    W.H. Tong (Wing); R. Pieters (Rob); G.J. Kaspers (Gertjan); D.M.W.M. Te Loo (D. Maroeska W.); M. Bierings (Marc); C. van den Bos (Cor); W.J.W. Kollen (Wouter); W.C.J. Hop (Wim); C. Lanvers-Kaminsky (Claudia); M.V. Relling (Mary); W.J.E. Tissing (Wim); I.M. van der Sluis (Inge)

    2014-01-01

    textabstractThis 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/m2 every 2

  6. Direct suppression of a rice bacterial blight (Xanthomonas oryzae pv. oryzae) by monoterpene (S)-limonene.

    Science.gov (United States)

    Lee, Gun Woong; Chung, Moon-Soo; Kang, Mihyung; Chung, Byung Yeoup; Lee, Sungbeom

    2016-05-01

    Rice bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a severe disease of rice plants. Upon pathogen infection, rice biosynthesizes phytoalexins, including diterpenoids such as momilactones, phytocassanes, and oryzalexins. However, information on headspace volatiles in response to Xoo infection is limited. We have examined headspace volatile terpenes, induced by the infection of Xoo, and investigated their biological roles in the rice plant. Monoterpenes α-thujene, α-pinene, sabinene, myrcene, α-terpene, and (S)-limonene and sesquiterpenes cyclosativene, α-copaene, and β-elemene were detected from 1-week-old Xoo-infected rice seedlings, by solid-phase microextraction-gas chromatography-mass spectrometry. All monoterpenes were constitutively released from rice seedlings before Xoo infection. However, (S)-limonene emission was further elicited after exposure of the seedlings to Xoo in coincidence with upregulation of limonene synthase gene (OsTPS20) transcripts. Only the stereospecific (S)-limonene [and not (R)-limonene or other monoterpenes] severely inhibited Xoo growth, as confirmed by disc diffusion and liquid culture assays. Rice seedlings showed suppressed pathogenic symptoms suggestive of resistance to Xoo infection after foliar treatment with (S)-limonene. Collectively, our findings suggest that (S)-limonene is a volatile phytoanticipin, which plays a significant role in suppressing Xoo growth in rice seedlings.

  7. 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.

  8. Studies on the cost-effective management of Alternaria blight of rapeseed-mustard (Brassica spp.

    Directory of Open Access Journals (Sweden)

    M.M. Khan

    2007-08-01

    Full Text Available Three systemic fungicides: Topsin-M (Thiophanate methyl, 70%WP, Ridomil MZ (Mancozeb, 64% + Metalaxyl, 8%WP, and Bavistin (Carbendazim, 50%WP alone and in combination with four non-systemic fungicides Captaf (Captan, 50%WP, Indofil M-45 (Mancozeb, 75%WP, Indofil Z-78 (Zineb, 75%WP, and Thiram (Thiram, 75%WP were evaluated both in vitro and in vivo for their effectiveness to manage Alternaria blight of rapeseedmustard caused by Alternaria brassicae. A pure culture of the pathogenic fungus was applied in the field at 2 g colonized sorghum seeds kg-1 soil. All the fungicides were evaluated for their efficacy at various concentrations, 50, 100, 150, 200 and 500 ppm, and were sprayed in the field at 0.2% a.i. l-1. All fungicides significantly reduced the severity of the disease but Ridomil MZ was most effective. Topsin-M at a concentration of 500 ppm was the most effective in reducing radial growth of the pathogenic fungi (74.2%. Ridomil MZ reduced disease severity by 32% and was followed in effectiveness by the combination Bavistin+Captaf (26.5%. Maximum yield was obtained in plots sprayed with Bavistin+Captaf (1198 kg ha-1 followed by Bavistin+Indofil Z-78 (1172 kg ha-1. It was worth noting that the highest net profit as well as the highest cost-benefit ratio was obtained with Bavistin+Indofil Z-78 (1:3.2, followed by Bavistin+Captaf (1:1.3.

  9. Mechanisms of induced susceptibility to Diplodia tip blight in drought-stressed Austrian pine.

    Science.gov (United States)

    Sherwood, Patrick; Villari, Caterina; Capretti, Paolo; Bonello, Pierluigi

    2015-05-01

    Plants experiencing drought stress are frequently more susceptible to pathogens, likely via alterations in physiology that create favorable conditions for pathogens. Common plant responses to drought include the production of reactive oxygen species (ROS) and the accumulation of free amino acids (AAs), particularly proline. These same phenomena also frequently occur during pathogenic attack. Therefore, drought-induced perturbations in AA and ROS metabolism could potentially contribute to the observed enhanced susceptibility. Furthermore, nitrogen (N) availability can influence AA accumulation and affect plant resistance, but its contributions to drought-induced susceptibility are largely unexplored. Here we show that drought induces accumulation of hydrogen peroxide (H2O2) in Austrian pine (Pinus nigra Arnold) shoots, but that shoot infection by the blight and canker pathogen Diplodia sapinea (Fr.) Fuckel leads to large reductions in H2O2 levels in droughted plants. In in vitro assays, H2O2 was toxic to D. sapinea, and the fungus responded to this oxidative stress by increasing catalase and peroxidase activities, resulting in substantial H2O2 degradation. Proline increased in response to drought and infection when examined independently, but unlike all other AAs, proline further increased in infected shoots of droughted trees. In the same tissues, the proline precursor, glutamate, decreased significantly. Proline was found to protect D. sapinea from H2O2 damage, while also serving as a preferred N source in vitro. Fertilization increased constitutive and drought-induced levels of some AAs, but did not affect plant resistance. A new model integrating interactions of proline and H2O2 metabolism with drought and fungal infection of plants is proposed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. PecS is a global regulator of the symptomatic phase in the phytopathogenic bacterium Erwinia chrysanthemi 3937.

    Science.gov (United States)

    Hommais, Florence; Oger-Desfeux, Christine; Van Gijsegem, Frédérique; Castang, Sandra; Ligori, Sandrine; Expert, Dominique; Nasser, William; Reverchon, Sylvie

    2008-11-01

    Pathogenicity of the enterobacterium Erwinia chrysanthemi (Dickeya dadantii), the causative agent of soft-rot disease in many plants, is a complex process involving several factors whose production is subject to temporal regulation during infection. PecS is a transcriptional regulator that controls production of various virulence factors. Here, we used microarray analysis to define the PecS regulon and demonstrated that PecS notably regulates a wide range of genes that could be linked to pathogenicity and to a group of genes concerned with evading host defenses. Among the targets are the genes encoding plant cell wall-degrading enzymes and secretion systems and the genes involved in flagellar biosynthesis, biosurfactant production, and the oxidative stress response, as well as genes encoding toxin-like factors such as NipE and hemolysin-coregulated proteins. In vitro experiments demonstrated that PecS interacts with the regulatory regions of five new targets: an oxidative stress response gene (ahpC), a biosurfactant synthesis gene (rhlA), and genes encoding exported proteins related to other plant-associated bacterial proteins (nipE, virK, and avrL). The pecS mutant provokes symptoms more rapidly and with more efficiency than the wild-type strain, indicating that PecS plays a critical role in the switch from the asymptomatic phase to the symptomatic phase. Based on this, we propose that the temporal regulation of the different groups of genes required for the asymptomatic phase and the symptomatic phase is, in part, the result of a gradual modulation of PecS activity triggered during infection in response to changes in environmental conditions emerging from the interaction between both partners.

  11. Characterization of stuA mutants in the mycotoxigenic maize pathogen Fusarium verticillioides

    Science.gov (United States)

    Fusarium verticillioides is a major pathogen of maize, causing root, stalk and ear rots and seedling blight. It also produces fumonisin mycotoxins. Ingestion of fumonisin-contaminated corn causes acute toxicity in livestock and is a potential carcinogen to humans. StuA, an APSES protein class transc...

  12. 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. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  13. 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

  14. Lon protease modulates virulence traits in Erwinia amylovora by direct monitoring of major regulators and indirectly through the Rcs and Gac-Csr regulatory systems.

    Science.gov (United States)

    Lee, Jae Hoon; Ancona, Veronica; Zhao, Youfu

    2018-04-01

    Lon, an ATP-dependent protease in bacteria, influences diverse cellular processes by degrading damaged, misfolded and short-lived regulatory proteins. In this study, we characterized the effects of lon mutation and determined the molecular mechanisms underlying Lon-mediated virulence regulation in Erwinia amylovora, an enterobacterial pathogen of apple. Erwinia amylovora depends on the type III secretion system (T3SS) and the exopolysaccharide (EPS) amylovoran to cause disease. Our results showed that mutation of the lon gene led to the overproduction of amylovoran, increased T3SS gene expression and the non-motile phenotype. Western blot analyses showed that mutation in lon directly affected the accumulation and stability of HrpS/HrpA and RcsA. Mutation in lon also indirectly influenced the expression of flhD, hrpS and csrB through the accumulation of the RcsA/RcsB proteins, which bind to the promoter of these genes. In addition, lon expression is under the control of CsrA, possibly at both the transcriptional and post-transcriptional levels. Although mutation in csrA abolished both T3SS and amylovoran production, deletion of the lon gene in the csrA mutant only rescued amylovoran production, but not T3SS. These results suggest that CsrA might positively control both T3SS and amylovoran production partly by suppressing Lon, whereas CsrA may also play a critical role in T3SS by affecting unknown targets. © 2017 BSPP AND JOHN WILEY & SONS LTD.

  15. Partial resistance of tomatoes against Phytophthora infestans, the late blight fungus

    NARCIS (Netherlands)

    Turkensteen, L.J.

    1973-01-01

    In the Netherlands, the source of inoculum of the late blight fungus on tomatoes is the late blight fungus on potato crops. In regions of Europe mentioned, where tomatoes are grown in the open, P. infestans on tomatoes is the main source of inoculum. Especially in

  16. Induced mutation for disease resistance in rice with special reference to blast, bacterial blight and tungro

    International Nuclear Information System (INIS)

    Mathur, S.C.

    1983-01-01

    Rice varieties Ratna, Pusa 2-21, Vijaya and Pankaj have been treated with gamma rays, EMS or sodium azide to improve their resistance against blast, bacterial leaf blight or tungro virus. For blast and tungro, mutants with improved resistance were selected. Variation in reaction to bacterial leaf blight has been used in crossbreeding to accumulate genes for resistance. (author)

  17. Mapping, isolation and characterization of genes responsible for late blight resistance in potato

    NARCIS (Netherlands)

    Pel, M.

    2010-01-01

    Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most
    devastating diseases on potato. Resistance (R) genes from the wild species Solanum demissum
    have been used by breeders to generate late blight resistant cultivars, but resistance was soon
    overcome

  18. Differentiating needle blights of white pine in the interpretation of fume damage

    Energy Technology Data Exchange (ETDEWEB)

    Hepting, G H; Berry, C R

    1961-01-01

    In white pines it is difficult to differentiate between needle blight caused by air pollution and numerous other causes. White pines are regarded as sensitive to sulfur dioxide and fluorine. The authors attempt to provide means of identifying and separating blights of white pines in the southern Appalachians.

  19. Long-term impact of shoot blight disease on red pine saplings

    Science.gov (United States)

    Linda M. Haugen; Michael E. Ostry

    2013-01-01

    Damage from Sirococcus and Diplodia shoot blights of red pine is widespread and periodically severe in the Lake States. An outbreak of shoot blight occurred in red pine sapling plantations across northern Wisconsin, northern Minnesota, and the Upper Peninsula of Michigan in 1993. We established monitoring plots in red pine sapling...

  20. 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

  1. The Cultivation of Antagonistic Bacteria in Irradiated Sludge for Biological Control of Soft Rot Erwinias : Screening of Antagonistic Bacteria for biological Control of Soft Rot Erwinias

    International Nuclear Information System (INIS)

    Sermkiattipong, Ng.; Sangsuk, L; Rattanapiriyakul, P; Dejsirilert, S.; Thaveechai, N.

    1998-01-01

    Pure cultures of 57 bacterial isolates for antagonistic activity screening were isolated from three areas of soft rot infested vegetable soil and 58 isolates were obtained from commercial seed compost and seed compost product of Division of Soil and Water Conservation, Department of Land Development. A total of 115 bacterial isolates were evaluated for antagonizing activity against Erwinia carotovora subsp. atroceptica in vitro. Out of them, 18 isolates were antagonists by showing zone of inhibition ranging from 1 to 17 mm by diameter. Most of antagonistic bacteria were identified as Bacillus spp. whereas only one isolate was Pseudomonas vesicularis

  2. First record of Glomerella cingulata causing leaf blight on Talauma ovata (Magnoliaceae) Primeiro relato de Glomerella cingulata causando queima foliar em Talauma ovata (Magnoliaceae)

    OpenAIRE

    Bruno Sérgio Vieira; Olinto Liparini Pereira; Márcio Luiz Batista; Robert Weingart Barreto

    2005-01-01

    Glomerella cingulata was found causing severe leaf blight on Talauma ovata, a common tree species in the Atlantic tropical rain forest floodplains of Southern Brazil. The disease and pathogen are described and illustrated and patogenicity is also demonstrated. This is the first report of this disease.Glomerella cingulata foi encontrado causando severa queima-foliar em Talauma ovata, uma espécie arbórea comum em florestas úmidas tropicais do Sudeste do Brasil. A doença e o patógeno foram descr...

  3. Lipid transfer proteins and protease inhibitors as key factors in the priming of barley responses to Fusarium head blight disease by a biocontrol strain of Pseudomonas fluorescens.

    Science.gov (United States)

    Petti, Carloalberto; Khan, Mojibur; Doohan, Fiona

    2010-11-01

    Strains of non-pathogenic pseudomonad bacteria, can elicit host defence responses against pathogenic microorganisms. Pseudomonas fluorescens strain MKB158 can protect cereals from pathogenesis by Fusarium fungi, including Fusarium head blight which is an economically important disease due to its association with both yield loss and mycotoxin contamination of grain. Using the 22 K barley Affymetrix chip, trancriptome studies were undertaken to determine the local effect of P. fluorescens strain MKB158 on the transcriptome of barley head tissue, and to discriminate transcripts primed by the bacterium to respond to challenge by Fusarium culmorum, a causal agent of the economically important Fusarium head blight disease of cereals. The bacterium significantly affected the accumulation of 1203 transcripts and primed 74 to positively, and 14 to negatively, respond to the pathogen (P = 0.05). This is the first study to give insights into bacterium priming in the Triticeae tribe of grasses and associated transcripts were classified into 13 functional classes, associated with diverse functions, including detoxification, cell wall biosynthesis and the amplification of host defence responses. In silico analysis of Arabidopsis homologs of bacterium-primed barley genes indicated that, as is the case in dicots, jasmonic acid plays a role in pseudomonad priming of host responses. Additionally, the transcriptome studies described herein also reveal new insights into bacterium-mediated priming of host defences against necrotrophs, including the positive effects on grain filling, lignin deposition, oxidative stress responses, and the inhibition of protease inhibitors and proteins that play a key role in programmed cell death.

  4. Plant Growth Promotion and Suppression of Bacterial Leaf Blight in Rice by Inoculated Bacteria.

    Directory of Open Access Journals (Sweden)

    Sumera Yasmin

    Full Text Available 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. Karakterisasi Erwinia Chrysanthemi Penyebab Penyakit Busuk Bakteri Pada Daun Lidah Buaya (Aloe Vera)

    OpenAIRE

    SUPRIADI,; IBRAHIM, NILDAR; TARYONO,

    2002-01-01

    Characteristics o/Envinia chysanthemi causing bacterial soft rot ofAloe (Aloe VeraJThe bacterial sot rot of aloe, caused by Erwinia chrysanthemi, was first identified in Caibbean Island in 1992. In early 2001, similar symptoms were found on the aloe plants grown in Semplak, Bogor, West Java. Based on its symptom and progressively spread, especially on the leaf and basal stem, it appeared that the disease was serious and therefore threatened the current development of die plants. This study wa...

  6. Improvement of DNA transfer frequency and transposon mutagenesis of Erwinia carotovora subsp. betavasculorum.

    OpenAIRE

    Rella, M; Axelrood, P E; Weinhold, A R; Schroth, M N

    1989-01-01

    The production of antibiotics and their role in microbial competition under natural conditions can be readily studied by the use of transposon mutants. Several antibiotic-producing strains of Erwinia carotovora subsp. betavasculorum were unable to accept foreign DNA. A plasmid delivery system was developed, using ethyl methanesulfonate mutagenesis, which entailed isolating E. carotovora subsp. betavasculorum mutants able to accept foreign DNA and transfer it to other strains. This enabled tra...

  7. Complete Genome Sequence of EtG, the First Phage Sequenced from Erwinia tracheiphila.

    Science.gov (United States)

    Andrade-Domínguez, Andrés; Kolter, Roberto; Shapiro, Lori R

    2018-02-22

    Erwinia tracheiphila is the causal agent of bacterial wilt of cucurbits. Here, we report the genome sequence of the temperate phage EtG, which was isolated from an E. tracheiphila -infected cucumber plant. Phage EtG has a linear 30,413-bp double-stranded DNA genome with cohesive ends and 45 predicted open reading frames. Copyright © 2018 Andrade-Domínguez et al.

  8. 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.

  9. A review of the Mycrocylus ulei Ascomycetes fungus, causative agent of South American rubber-leaf blight

    Directory of Open Access Journals (Sweden)

    Ibonne Aydee García-Romero

    2006-07-01

    Full Text Available The Microcyclus ulei Ascomycetes fungus is the causal agent of south-American leaf blight (SALB, this being one of the most important diseases affecting the natural rubber tree (Hevea brasiliensis in Latina-America and has been responsible for numerous economic losses. This fungus has presented high physiological variability, suggesting its great adaptability. HCN tolerance has been described as being one of the mechanisms associated with its virulence. Resistant Hevea clones have been obtained by genetic improvement; however, the mechanisms associated with this are still not well known. Greater knowledge of this pathogen will lead to developing new control strategies and better understanding of the mechanisms associated with host resistance. Key words: Microcyclus ulei, SALB, Hevea brasiliensis.

  10. Met goede hygiëne en vochtbeheersing Erwinia in paprika te lijf (onderzoek van Jantineke Hofland-Zijlstra en Rozemarijn de Vries)

    NARCIS (Netherlands)

    Arkesteijn, M.; Hofland-Zijlstra, J.D.; Vries, de R.S.M.

    2012-01-01

    Zomer 2010 had een groot aantal paprikabedrijven verspreid over het hele land last van Erwinia vruchtrot. Waar komt Erwinia vandaan en wat is er tegen te doen? Met deze vragen gingen onderzoekers Jantineke Hofland- Zijlstra en Rozemarijn de Vries aan de slag. Hygiëne, een goede vochtbeheersing en

  11. 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.

  12. Incorporation of Bacterial Blight Resistance Genes Into Lowland Rice Cultivar Through Marker-Assisted Backcross Breeding.

    Science.gov (United States)

    Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Pandit, Elssa; Behera, Lambodar; Anandan, Annamalai; Mukherjee, Arup Kumar; Lenka, Srikanta; Barik, Durga Prasad

    2016-07-01

    Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.

  13. Changes in Cryphonectria parasitica populations affects natural biological control of chestnut blight.

    Science.gov (United States)

    Ježić, Marin; Mlinarec, Jelena; Vuković, Rosemary; Katanić, Zorana; Krstin, Ljiljana; Nuskern, Lucija; Poljak, Igor; Idžojtić, Marilena; Tkalec, Mirta; Curkovic-Perica, Mirna

    2018-02-14

    Invasive species, especially plant pathogens have a potential to completely eradicate native plant species and remodel landscapes. Tripartite interaction among sweet chestnut, Castanea sativa, chestnut blight-causing invasive fungus, Cryphonectria parasitica, and a hyperparasitic virus, Cryphonectria parasitica hypovirus 1 (CHV1) were studied in two populations. The number of different vegetative compatibility (vc) types of C. parasitica more than doubled over the ten years, while the hypovirulence incidence dropped in one population, and slightly increased in the other one. Over the course of our short term, three year monitoring experiment, the prevalence of hypovirulent isolates obtained from monitored cankers increased slowly, i.e. more hypovirulent isolates were being obtained from the same cankers over time. Within studied cankers considerable changes in vc type and CHV1 presence were observed, indicating a highly dynamic system in which virulent and hypovirulent mycelia, sometimes of discordant vc types, often appeared together. The increase in hypovirulence prevalence did not have any observable curative effect on the cankers, and occasionally reactivation of healed cankers by new, virulent C. parasitica isolates was observed. Both, short and long term observations and revalidation of the infected plant populations are necessary to accurately estimate disease progress and formulate an adequate disease management strategy.

  14. RNA-Seq analysis reveals insight into enhanced rice Xa7-mediated bacterial blight resistance at high temperature.

    Directory of Open Access Journals (Sweden)

    Stephen P Cohen

    Full Text Available Plant disease is a major challenge to agriculture worldwide, and it is exacerbated by abiotic environmental factors. During some plant-pathogen interactions, heat stress allows pathogens to overcome host resistance, a phenomenon which could severely impact crop productivity considering the global warming trends associated with climate change. Despite the importance of this phenomenon, little is known about the underlying molecular mechanisms. To better understand host plant responses during simultaneous heat and pathogen stress, we conducted a transcriptomics experiment for rice plants (cultivar IRBB61 containing Xa7, a bacterial blight disease resistance (R gene, that were infected with Xanthomonas oryzae, the bacterial blight pathogen of rice, during high temperature stress. Xa7-mediated resistance is unusual relative to resistance mediated by other R genes in that it functions better at high temperatures. Using RNA-Seq technology, we identified 8,499 differentially expressed genes as temperature responsive in rice cultivar IRBB61 experiencing susceptible and resistant interactions across three time points. Notably, genes in the plant hormone abscisic acid biosynthesis and response pathways were up-regulated by high temperature in both mock-treated plants and plants experiencing a susceptible interaction and were suppressed by high temperature in plants exhibiting Xa7-mediated resistance. Genes responsive to salicylic acid, an important plant hormone for disease resistance, were down-regulated by high temperature during both the susceptible and resistant interactions, suggesting that enhanced Xa7-mediated resistance at high temperature is not dependent on salicylic acid signaling. A DNA sequence motif similar to known abscisic acid-responsive cis-regulatory elements was identified in the promoter region upstream of genes up-regulated in susceptible but down-regulated in resistant interactions. The results of our study suggest that the plant

  15. Green tissue-specific co-expression of chitinase and oxalate oxidase 4 genes in rice for enhanced resistance against sheath blight.

    Science.gov (United States)

    Karmakar, Subhasis; Molla, Kutubuddin Ali; Chanda, Palas K; Sarkar, Sailendra Nath; Datta, Swapan K; Datta, Karabi

    2016-01-01

    Green tissue-specific simultaneous overexpression of two defense-related genes ( OsCHI11 & OsOXO4 ) in rice leads to significant resistance against sheath blight pathogen ( R. solani ) without distressing any agronomically important traits. Overexpressing two defense-related genes (OsOXO4 and OsCHI11) cloned from rice is effective at enhancing resistance against sheath blight caused by Rhizoctonia solani. These genes were expressed under the control of two different green tissue-specific promoters, viz. maize phosphoenolpyruvate carboxylase gene promoter, PEPC, and rice cis-acting 544-bp DNA element, immediately upstream of the D54O translational start site, P D54O-544 . Putative T0 transgenic rice plants were screened by PCR and integration of genes was confirmed by Southern hybridization of progeny (T1) rice plants. Successful expression of OsOXO4 and OsCHI11 in all tested plants was confirmed. Expression of PR genes increased significantly following pathogen infection in overexpressing transgenic plants. Following infection, transgenic plants exhibited elevated hydrogen peroxide levels, significant changes in activity of ROS scavenging enzymes and reduced membrane damage when compared to their wild-type counterpart. In a Rhizoctonia solani toxin assay, a detached leaf inoculation test and an in vivo plant bioassay, transgenic plants showed a significant reduction in disease symptoms in comparison to non-transgenic control plants. This is the first report of overexpression of two different PR genes driven by two green tissue-specific promoters providing enhanced sheath blight resistance in transgenic rice.

  16. The genetic variance of resistance in M3 lines of rice against leaf blight disease

    International Nuclear Information System (INIS)

    Mugiono

    1979-01-01

    Seeds of Pelita I/1 rice variety were irradiated with 20, 30, 40 and 50 krad of gamma rays from a 60 Co source. Plants of M 3 lines were inoculated with bacterial leaf blight, Xanthomonas oryzae (Uzeda and Ishiyama) Downson, using clipping method. The coefficient of genetic variability of resistance against leaf blight disease increased with increasing dose. Highly significant difference in the genetic variance of resistance were found between the treated samples and the control. Dose of 20 krad gave good probability for selection of plants resistant against leaf blight disease. (author)

  17. Anti-Erwinia asparaginase antibodies during treatment of childhood acute lymphoblastic leukemia and their relationship to outcome

    DEFF Research Database (Denmark)

    Albertsen, BK; Schmiegelow, Kjeld; Schrøder, Henrik

    2002-01-01

    PURPOSE: A case-control study was performed to determine whether patients who had been treated with Erwinia asparaginase as part of their treatment for childhood acute lymphoblastic leukemia (ALL) and who showed relapsed of their disease more often developed anti-asparaginase antibodies than...... (median follow-up 70 months). Anti- Erwinia asparaginase antibodies were measured (ELISA method) during maintenance therapy after asparaginase treatment (30,000 IU/m(2) daily for 10 days in all patients plus twice weekly for 2 weeks in intermediate-risk and high-risk ALL patients). RESULTS: The overall...... incidence of anti- Erwinia asparaginase antibodies was 8% (3 of 39 patients). There was no statistically significant difference in the incidence of antibody formation between patients who had suffered relapse (1 of 13) and those who had not (2 of 26). In two of the three patients who developed antibodies...

  18. Candidate Genes for Aggressiveness in a Natural Fusarium culmorum Population Greatly Differ between Wheat and Rye Head Blight

    Directory of Open Access Journals (Sweden)

    Valheria Castiblanco

    2018-01-01

    Full Text Available Fusarium culmorum is one of the species causing Fusarium head blight (FHB in cereals in Europe. We aimed to investigate the association between the nucleotide diversity of ten F. culmorum candidate genes and field ratings of aggressiveness in winter rye. A total of 100 F. culmorum isolates collected from natural infections were phenotyped for FHB at two locations and two years. Variance components for aggressiveness showed significant isolate and isolate-by-environment variance, as expected for quantitative host-pathogen interactions. Further analysis of the isolate-by-environment interaction revealed the dominant role of the isolate-by-year over isolate-by-location interaction. One single-nucleotide polymorphism (SNP in the cutinase (CUT gene was found to be significantly (p < 0.001 associated with aggressiveness and explained 16.05% of the genotypic variance of this trait in rye. The SNP was located 60 base pairs before the start codon, which suggests a role in transcriptional regulation. Compared to a previous study in winter wheat with the same nucleotide sequences, a larger variation of pathogen aggressiveness on rye was found and a different candidate gene was associated with pathogen aggressiveness. This is the first report on the association of field aggressiveness and a host-specific candidate gene codifying for a protein that belongs to the secretome in F. culmorum.

  19. 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

  20. Integrating cultural control methods for tomato late blight (Phytophthora infestans) in Uganda

    NARCIS (Netherlands)

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

    2002-01-01

    Cultural control measures against tomato late blight (Phytophthora infestans) were evaluated in six field experiments over 3 years in Uganda. Each experiment included sanitation (removal of diseased plant tissues), fungicide (mancozeb) application, and an untreated control, as standard treatments.

  1. Population pharmacokinetics of intravenous Erwinia asparaginase in pediatric acute lymphoblastic leukemia patients.

    Science.gov (United States)

    Sassen, Sebastiaan D T; Mathôt, Ron A A; Pieters, Rob; Kloos, Robin Q H; de Haas, Valérie; Kaspers, Gertjan J L; van den Bos, Cor; Tissing, Wim J E; Te Loo, Maroeska; Bierings, Marc B; Kollen, Wouter J W; Zwaan, Christian M; van der Sluis, Inge M

    2017-03-01

    Erwinia asparaginase is an important component in the treatment of pediatric acute lymphoblastic leukemia. A large variability in serum concentrations has been observed after intravenous Erwinia asparaginase. Currently, Dutch Childhood Oncology Group protocols dose alterations are based on trough concentrations to ensure adequate asparaginase activity (≥100 IU/L). The aim of this study was to describe the population pharmacokinetics of intravenous Erwinia asparaginase to quantify and gather insight into inter-individual and inter-occasion variability. The starting dose was evaluated on the basis of the derived population pharmacokinetic parameters. In a multicenter prospective observational study, a total of 714 blood samples were collected from 51 children (age 1-17 years) with acute lymphoblastic leukemia. The starting dose was 20,000 IU/m 2 three times a week and adjusted according to trough levels from week three onwards. A population pharmacokinetic model was developed using NONMEM ® A 2-compartment linear model with allometric scaling best described the data. Inter-individual and inter-occasion variability of clearance were 33% and 13%, respectively. Clearance in the first month of treatment was 14% higher ( P <0.01). Monte Carlo simulations with our pharmacokinetic model demonstrated that patients with a low weight might require higher doses to achieve similar concentrations compared to patients with high weight. The current starting dose of 20,000 IU/m 2 might result in inadequate concentrations, especially for smaller, lower weight patients, hence dose adjustments based on individual clearance are recommended. The protocols were approved by the institutional review boards. (Registered at NTR 3379 Dutch Trial Register; www.trialregister.nl). Copyright© Ferrata Storti Foundation.

  2. Novas ocorrências de Erwinia carotovora subsp. carotovora e de E. chrysanthemi

    Directory of Open Access Journals (Sweden)

    Irene M. G. Almeida

    1997-05-01

    Full Text Available Em continuidade a trabalhos de caracterização de bactérias pectinolíticas do gênero Eruia ocorrendo no Brasil, são relacionadas novas ocorrências dessas fitobactérias em plantios comerciais, que ocasionam podridão mole em cinco espécies de plantas ornamentais. Testes bioquímicas, fisiológicos, culturais e de patogenicidade permitiram comprovar a ocorrência de Erwinia carotovora subsp. carotovora em plantas de afelandra, amarílis e copo-de-leite, e de Erwiniachr santhemiemcordilineekalanchoe.

  3. Artificial neural network for prediction of the area under the disease progress curve of tomato late blight

    Directory of Open Access Journals (Sweden)

    Daniel Pedrosa Alves

    Full Text Available ABSTRACT: Artificial neural networks (ANN are computational models inspired by the neural systems of living beings capable of learning from examples and using them to solve problems such as non-linear prediction, and pattern recognition, in addition to several other applications. In this study, ANN were used to predict the value of the area under the disease progress curve (AUDPC for the tomato late blight pathosystem. The AUDPC is widely used by epidemiologic studies of polycyclic diseases, especially those regarding quantitative resistance of genotypes. However, a series of six evaluations over time is necessary to obtain the final area value for this pathosystem. This study aimed to investigate the utilization of ANN to construct an AUDPC in the tomato late blight pathosystem, using a reduced number of severity evaluations. For this, four independent experiments were performed giving a total of 1836 plants infected with Phytophthora infestans pathogen. They were assessed every three days, comprised six opportunities and AUDPC calculations were performed by the conventional method. After the ANN were created it was possible to predict the AUDPC with correlations of 0.97 and 0.84 when compared to conventional methods, using 50 % and 67 % of the genotype evaluations, respectively. When using the ANN created in an experiment to predict the AUDPC of the other experiments the average correlation was 0.94, with two evaluations, 0.96, with three evaluations, between the predicted values of the ANN and they were observed in six evaluations. We present in this study a new paradigm for the use of AUDPC information in tomato experiments faced with P. infestans. This new proposed paradigm might be adapted to different pathosystems.

  4. Cultural Heritage in the Gulf: Blight or Blessing?

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    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.

  5. Effect of aqueous vitamin B on the growth of blister blight pathogen, Exobasidium vexans

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    Hideyuki Nagao

    2012-12-01

    Full Text Available The effect of three aqueous solution of biotin, thiamine and calcium pantothenate, on the growth of Exobasidiumvexans was examined in vitro. The germination process of basidiospores of E. vexans differed from those of the otherExobasidium species. Basidiospore germination commenced after 19.5 hr incubation and chlamydospore-like bodies wereformed after 96 hr of incubation. Addition of biotin, calcium pantothenate, and thiamine to Difco PDA and Czapek’s mediumdid not affect the proportion of germinating basidiospores. The length of germ tubes was enhanced only by addition ofthiamine in the media. Larger size germ tubes (thick germ tubes were occasionally observed among the ordinary hyphae.Most germlings of basidiospores developed chlamydospore-like bodies or autolysed on the media. Thick germ tubesfrequently appeared on the calcium pantothenate amended media and developed into a colony when these hyphae weretransferred to new calcium pantothenate amended media. However, further transfer of colonies did not successfully bring anew colony to grow on the calcium pantothenate amended media. Vitamin B5, calcium pantothenate, was only partially effective in generating the thick germ tubes and to induce the initial colony formation, whereas amendment of biotin and thiamineto the media did not induce visible colony growth.

  6. Code-assisted discovery of TAL effector targets in bacterial leaf streak of rice reveals contrast with bacterial blight and a novel susceptibility gene.

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    Raul A Cernadas

    2014-02-01

    Full Text Available Bacterial leaf streak of rice, caused by Xanthomonas oryzae pv. oryzicola (Xoc is an increasingly important yield constraint in this staple crop. A mesophyll colonizer, Xoc differs from X. oryzae pv. oryzae (Xoo, which invades xylem to cause bacterial blight of rice. Both produce multiple distinct TAL effectors, type III-delivered proteins that transactivate effector-specific host genes. A TAL effector finds its target(s via a partially degenerate code whereby the modular effector amino acid sequence identifies nucleotide sequences to which the protein binds. Virulence contributions of some Xoo TAL effectors have been shown, and their relevant targets, susceptibility (S genes, identified, but the role of TAL effectors in leaf streak is uncharacterized. We used host transcript profiling to compare leaf streak to blight and to probe functions of Xoc TAL effectors. We found that Xoc and Xoo induce almost completely different host transcriptional changes. Roughly one in three genes upregulated by the pathogens is preceded by a candidate TAL effector binding element. Experimental analysis of the 44 such genes predicted to be Xoc TAL effector targets verified nearly half, and identified most others as false predictions. None of the Xoc targets is a known bacterial blight S gene. Mutational analysis revealed that Tal2g, which activates two genes, contributes to lesion expansion and bacterial exudation. Use of designer TAL effectors discriminated a sulfate transporter gene as the S gene. Across all targets, basal expression tended to be higher than genome-average, and induction moderate. Finally, machine learning applied to real vs. falsely predicted targets yielded a classifier that recalled 92% of the real targets with 88% precision, providing a tool for better target prediction in the future. Our study expands the number of known TAL effector targets, identifies a new class of S gene, and improves our ability to predict functional targeting.

  7. PecS and PecT coregulate the synthesis of HrpN and pectate lyases, two virulence determinants in Erwinia chrysanthemi 3937.

    Science.gov (United States)

    Nasser, William; Reverchon, Sylvie; Vedel, Regine; Boccara, Martine

    2005-11-01

    Erwinia chrysanthemi strain 3937 is a necrotrophic bacterial plant pathogen. Pectinolytic enzymes and, in particular, pectate lyases play a key role in soft rot symptoms; however, the efficient colonization of plants by E. chrysanthemi requires additional factors. These factors include HrpN (harpin), a heat-stable, glycine-rich hydrophilic protein, which is secreted by the type III secretion system. We investigated the expression of hrpN in E. chrysanthemi 3937 in various environmental conditions and different regulatory backgrounds. Using lacZ fusions, hrpN expression was markedly influenced by the carbon source, osmolarity, growth phase, and growth substrate. hrpN was repressed when pectinolysis started and negatively regulated by the repressors of pectate lyase synthesis, PecS and PecT. Primer extension data and in vitro DNA-protein interaction experiments support a model whereby PecS represses hrpN expression by binding to the hrpN regulatory region and inhibiting transcript elongation. The results suggest coordinated regulation of HrpN and pectate lyases by PecS and PecT. A putative model of the synthesis of these two virulence factors in E. chrysanthemi during pathogenesis is presented.

  8. Two Genomic Regions Involved in Catechol Siderophore Production by Erwinia carotovora

    Science.gov (United States)

    Bull, Carolee T.; Ishimaru, Carol A.; Loper, Joyce E.

    1994-01-01

    Two regions involved in catechol biosynthesis (cbs) of Erwinia carotovora W3C105 were cloned by functional complementation of Escherichia coli mutants that were deficient in the biosynthesis of the catechol siderophore enterobactin (ent). A 4.3-kb region of genomic DNA of E. carotovora complemented the entB402 mutation of E. coli. A second genomic region of 12.8 kb complemented entD, entC147, entE405, and entA403 mutations of E. coli. Although functions encoded by catechol biosynthesis genes (cbsA, cbsB, cbsC, cbsD, and cbsE) of E. carotovora were interchangeable with those encoded by corresponding enterobactin biosynthesis genes (entA, entB, entC, entD, and entE), only cbsE hybridized to its functional counterpart (entE) in E. coli. The cbsEA region of E. carotovora W3C105 hybridized to genomic DNA of 21 diverse strains of E. carotovora but did not hybridize to that of a chrysobactin-producing strain of Erwinia chrysanthemi. Strains of E. carotovora fell into nine groups on the basis of sizes of restriction fragments that hybridized to the cbsEA region, indicating that catechol biosynthesis genes were highly polymorphic among strains of E. carotovora. PMID:16349193

  9. Role of Antibiosis in Competition of Erwinia Strains in Potato Infection Courts

    Science.gov (United States)

    Axelrood, Paige E.; Rella, Manuela; Schroth, Milton N.

    1988-01-01

    Erwinia carotovora subsp. betavasculorum strains produced a bactericidal antibiotic in vitro that inhibited a wide spectrum of gram-negative and gram-positive bacteria. The optimum temperature for production was 24°C, and the addition of glycerol to culture media enhanced antibiotic production. Antibiotic production by these strains in the infection court of potato was the principal determinant enabling it to gain ascendancy over competing antibiotic-sensitive Erwinia carotovora subsp. carotovora strains. There was a complete correlation between antibiotic production by E. carotovora subsp. betavasculorum in vitro and inhibition of competing E. carotovora subsp. carotovora strains in planta. Inhibition of the latter by the former was apparent after 10 h of incubation in potato tuber wounds. Population densities of sensitive E. carotovora subsp. carotovora strains in mixed potato tuber infections with E. carotovora subsp. betavasculorum were approximately 106-fold lower after 48 h of incubation than in corresponding single sensitive strain infections. E. carotovora subsp. carotovora were not inhibited in tuber infections that were incubated anaerobically. This correlated with the absence of antibiotic production during anaerobic incubation in vitro. Antibiotic-resistant strains of E. carotovora subsp. carotovora were not inhibited in planta or in vitro by E. carotovora subsp. betavasculorum. Moreover, isogenic antibiotic-negative (Ant−) mutant E. carotovora subsp. betavasculorum strains were not inhibitory to sensitive E. carotovora subsp. carotovora strains in tuber infections. PMID:16347633

  10. Alternative control of early blight of tomato using plant extracts from Acacia nilotica, Achillea fragrantissima and Calotropis procera

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    Zakaria A.M. BAKA

    2016-05-01

    Full Text Available The in vitro and in vivo antifungal potential of extracts of three wild medicinal plants, (Acacia nilotica (L. Delile, Achillea fragrantissima (Forssk. Sch.Bip. and Calotropis procera (Aiton W. T. Aiton was examined against Alternaria solani, the causal agent of the early blight of tomato. Aqueous or ethanol extracts of all tested plants reduced the mycelial growth and conidium germination of A. solani in vitro. Ethanol extracts were more effective against the pathogen than the aqueous extracts. Extract of C. procera exhibited more antifungal potential against the pathogen than other plant extracts. Observations by scanning and transmission electron microscopy showed dramatic alterations in the morphology and ultrastructure of A. solani when treated with the ethanol extract of C. procera at a concentration of 20%. Phytochemical screening confirmed the presence of many bioactive constituents in the extracts which were in greater amounts in C. procera than the other two plants. In a plot experiment, both types of extracts from C. procera reduced disease severity. Tomato fruit yield was increased after the treatment with the plant extracts.

  11. A phenome-based functional analysis of transcription factors in the cereal head blight fungus, Fusarium graminearum.

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    Hokyoung Son

    2011-10-01

    Full Text Available Fusarium graminearum is an important plant pathogen that causes head blight of major cereal crops. The fungus produces mycotoxins that are harmful to animal and human. In this study, a systematic analysis of 17 phenotypes of the mutants in 657 Fusarium graminearum genes encoding putative transcription factors (TFs resulted in a database of over 11,000 phenotypes (phenome. This database provides comprehensive insights into how this cereal pathogen of global significance regulates traits important for growth, development, stress response, pathogenesis, and toxin production and how transcriptional regulations of these traits are interconnected. In-depth analysis of TFs involved in sexual development revealed that mutations causing defects in perithecia development frequently affect multiple other phenotypes, and the TFs associated with sexual development tend to be highly conserved in the fungal kingdom. Besides providing many new insights into understanding the function of F. graminearum TFs, this mutant library and phenome will be a valuable resource for characterizing the gene expression network in this fungus and serve as a reference for studying how different fungi have evolved to control various cellular processes at the transcriptional level.

  12. Biocontrol of Late Blight (Phytophthora capsici Disease and Growth Promotion of Pepper by Burkholderia cepacia MPC-7

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    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.

  13. Evolution of an invasive species research program and implications for large-scale management of a non-native, invasive plant pathogen

    Science.gov (United States)

    Christopher A. Lee; Janice M. Alexander; Susan J. Frankel; Yana Valachovic

    2012-01-01

    We conducted a research needs assessment (RNA) in 2010 to gather opinions of "experts" and a larger public on research priorities for Phytophthora ramorum, the pathogen that causes sudden oak death in forest trees and Ramorum blight in ornamental plants. We place these 2010 findings in context with findings of similar P. ramorum...

  14. Gene Profiling in Late Blight Resistance in Potato Genotype SD20

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    Xiaohui Yang

    2018-06-01

    Full Text Available Late blight caused by the oomycete fungus Phytophthora infestans (Pi is the most serious obstacle to potato (Solanum tuberosum production in the world. A super race isolate, CN152, which was identified from Sichuan Province, China, could overcome nearly all known late blight resistance genes and caused serious damage in China. The potato genotype SD20 was verified to be highly resistant to CN152; however, the molecular regulation network underlying late blight resistance pathway remains unclear in SD20. Here, we performed a time-course experiment to systematically profile the late blight resistance response genes using RNA-sequencing in SD20. We identified 3354 differentially expressed genes (DEGs, which mainly encoded transcription factors and protein kinases, and also included four NBS-LRR genes. The late blight responsive genes showed time-point-specific induction/repression. Multi-signaling pathways of salicylic acid, jasmonic acid, and ethylene signaling pathways involved in resistance and defense against Pi in SD20. Gene Ontology and KEGG analyses indicated that the DEGs were significantly enriched in metabolic process, protein serine/threonine kinase activity, and biosynthesis of secondary metabolites. Forty-three DEGs were involved in immune response, of which 19 were enriched in hypersensitive response reaction, which could play an important role in broad-spectrum resistance to Pi infection. Experimental verification confirmed the induced expression of the responsive genes in the late blight resistance signaling pathway, such as WRKY, ERF, MAPK, and NBS-LRR family genes. Our results provided valuable information for understanding late blight resistance mechanism of potato.

  15. Quorum sensing controls the synthesis of virulence factors by modulating rsmA gene expression in Erwinia carotovora subsp. carotovora.

    Science.gov (United States)

    Kõiv, V; Mäe, A

    2001-04-01

    The plant-pathogenic bacterium Erwinia carotovora subsp. carotovora (Ecc) causes disease mainly by means of a number of extracellular plant cell wall-degrading enzymes (PCWDEs), also referred to as virulence factors. The production of PCWDEs is coordinately activated by the diffusible signal molecule N-acyl-homoserine lactone (HSL) in a population density-dependent manner ("quorum sensing"). ExpI is the enzyme responsible for the synthesis of HSL. The Rsm system negatively regulates the production of PCWDEs. It includes three components: RsmA is an RNA-binding protein which promotes mRNA decay; rsmB is a unique regulator RNA, and RsmC regulates expression of rsmA positively and of rsmB negatively. We report here that in an expI knockout mutant of Ecc strain SCC3193, the levels of rsmA and rsmB RNA are remarkably enhanced in comparison to the wild-type strain, while the level of the rsmC transcript is not affected. The increase in transcription of rsmA in the expI strain represses production of PCWDEs, which in turn leads to the avirulent phenotype of this mutant. In the expI- mutant, addition of exogenous HSL caused repression of rsmA and rsmB transcription to the wild-type level, whereas the expression of rsmC was not affected. Taken together, these data suggest that HSL affects the expression of rsmA, and that this effect is not mediated by RsmC. This specific effect and the previous demonstration that HSL is required for PCWDE production in Ecc support the hypothesis that regulation by quorum sensing in Ecc, in contrast to most other systems already described, requires HSL to repress rsmA transcription, which in turn leads to the activation of PCWDE production. A model is presented that explains how HSL controls the production of PCWDEs by modulating the expression of rsmA.

  16. Leaf blight of catharanthus roseus (l). g. don caused by macrophomina phaseolina (tassi) goid and its in vitro control through bio-pesticides

    International Nuclear Information System (INIS)

    Mridha, M.A.U.; Rehman, M.M.

    2015-01-01

    Catharanthus roseus (L.).G. Don, a highly valued medicinal plant suffers from a serious disease. A survey on the symptom and severity of the leaf blight of C. roseus was performed in the nurseries of the Institute of Forestry and Environmental Sciences (IFESCU), Bangladesh Council of Industrial Research (BCSIR) and Bangladesh Forest Research Institute (BFRI), Bangladesh. An observation was also made in the avenues and garden of King Saud University (KSU), Kingdom of Saudi Arabia. No disease was recorded in KSU, but severe infections were found in all the locations surveyed in Bangladesh. The highest infection percentage and the highest disease index were found in BCSIR nursery followed by BFRI and the lowest was recorded in IFESCU nursery. Macrophomina phaseolina (Tassi) Goid was isolated and it was proved to be pathogenic. This is the first report of leaf blight of C. roseus caused by M. phaseolina. Azadirachta indica, Ocimum sanctum Vitex negundo, Mucuna pruriens, Calotropis procera, Terminalia arjuna, Allium sativum, Zingiber officinalis and Allium cepa were used as biopesticides. Out of the nine plant species screened, T. arjuna showed the highest (58.37%) inhibition percentage which was followed by A. indica (55.72%) and the lowest (27.4%) inhibition percentage were obtained with V. negundo whereas the rest of the plant extracts showed more or less same inhibitory effect. (author)

  17. Generation of pea mutants for resistance to Ascochyta blight and powdery mildew and their characterization using isozyme markers [Pisum sativum L.; India

    International Nuclear Information System (INIS)

    Sharma, R.; Kant, A.; Kaushal, R.P.

    2004-01-01

    To induce resistance in pea against Ascochyta blight and powdery mildew through mutagenesis, two locally grown cultivars Lincoln and Palam Priya were subjected to three doses each of gamma rays (10, 15 and 20 kR) and chemical mutagen ethylmethane sulfonate (0.1, 0.2 and 0.3%). Reduced germination was observed in response to mutagen treatment in both cultivars. Phenotypic changes were observed in M1 and M2 generations of both the cultivars. In M2 generation twenty-seven mutants of Lincoln and sixteen of Palam Priya were found resistant to Ascochyta blight under natural epiphytotic conditions. High level of resistance in M2 generation against powdery mildew could not be achieved. Plant progenies in the M3 generation were also evaluated for resistance to Ascochyta pinodes as well as Erysiphe pisi through detached leaf technique. Six mutants of Lincoln and only one of Palam Priya were found resistant to A. pinodes. One mutant of Palam Priya (P15-3) showed resistance to both the pathogens. Increased phenylalanine ammonia lyase activity was observed in all the resistant mutants. New isoforms of peroxidase could be detected in the mutant P15-3 (Palam Priya) and also in L0.2-1 (Lincoln). However, not much variation for esterase could be observed [it

  18. Ocorrência e sintomas da mancha de Ascochyta em feijão-vagem Occurrence and symptoms of Ascochyta blight on snap bean

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    Maria Aparecida de Souza Tanaka

    1996-01-01

    Full Text Available A mancha de ascochita (Ascochyta phaseolorum Sacc. foi identificada como uma das principais doenças do feijão-vagem (Phaseolus vulgaris L., na região de Itatiba (SP, em levantamento realizado de abril de 1991 a março de 92. Seus sintomas são manchas foliares arredondadas, tipicamente zonadas e de tamanho variável, necrosando, às vezes, extensas áreas do limbo e provocando desfolha prematura. Associado a esse sintoma foliar, o patógeno pode causar lesões nas hastes, pecíolos e vagens, assumindo proporções severas. As lesões necróticas das hastes podem estrangula-las e provocar a morte da planta acima da região afetada. Nas vagens, as lesões tendem a ser circulares e zonadas, como as das folhas, porém os anéis concêntricos são menos evidentes. Isolamentos, características culturais e morfológicas e testes de patogenicidade permitiram diagnosticar a moléstia, que vinha sendo confundida com a mancha foliar de alternária, ou com a podridão de macrofomina, quando atacava a parte inferior da haste. A identificação do patógeno, por ter permitido o diagnóstico preciso da doença. poderá embasar o emprego de métodos adequados de controle.A severe Ascochyta blight (Ascochyta phaseolorum Sacc., was found during a survey carried out in farmer's fields of snap bean (Phaseolus vulgaris L. at Itatiba county, São Paulo State, Brazil. Foliar lesions were usually circular to irregular shaped, brown to dark brown and usually contained concentric circles of picnidia. These lesions often blighted the entire leaves, that die and fall. The pathogen also infected the stems, petioles and pods, and the disease incidence ranged from trace to severe. The stems and petioles lesions were elongated and cankerous, often girdling them, killing the plant above the infected region. The pod lesions were initially circular and zonate, as the foliar spots, but the concentric circles are of little evidence. Diagnosis were confirmed by isolation

  19. Generation of advanced fire blight-resistant apple (Malus × domestica) selections of the fifth generation within 7 years of applying the early flowering approach.

    Science.gov (United States)

    Schlathölter, Ina; Jänsch, Melanie; Flachowsky, Henryk; Broggini, Giovanni Antonio Lodovico; Hanke, Magda-Viola; Patocchi, Andrea

    2018-03-14

    The approach presented here can be applied to reduce the time needed to introduce traits from wild apples into null segregant advanced selections by one-fourth. Interesting traits like resistances to pathogens are often found within the wild apple gene pool. However, the long juvenile phase of apple seedlings hampers the rapid introduction of these traits into new cultivars. The rapid crop cycle breeding approach used in this paper is based on the overexpression of the birch (Betula pendula) MADS4 transcription factor in apple. Using the early flowering line T1190 and 'Evereste' as source of the fire blight resistance (Fb_E locus), we successfully established 18 advanced selections of the fifth generation in the greenhouse within 7 years. Fifteen individuals showed the habitus expected of a regular apple seedling, while three showed very short internodes. The null segregants possessing a regular habitus maintained the high level of fire blight resistance typical for 'Evereste'. Using SSR markers, we estimated the percentage of genetic drag from 'Evereste' still associated with Fb_E on linkage group 12 (LG12). Eight out of the 18 selections had only 4% of 'Evereste' genome left. Since genotypes carrying the apple scab resistance gene Rvi6 and the fire blight resistance QTL Fb_F7 were used as parents in the course of the experiments, these resistances were also identified in some of the null segregants. One seedling is particularly interesting as, beside Fb_E, it also carries Fb_F7 heterozygously and Rvi6 homozygously. If null segregants obtained using this method will be considered as not genetically modified in Europe, as is already the case in the USA, this genotype could be a very promising parent for breeding new fire blight and scab-resistant apple cultivars in European apple breeding programs.

  20. Quantitative Effects of Early and Late Blights on Tomato Yields in Cameroon

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    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.

  1. Expression of a mineral phosphate solubilizing gene from Erwinia herbicola in two rhizobacterial strains.

    Science.gov (United States)

    Rodríguez, H; Gonzalez, T; Selman, G

    2001-11-30

    A genetic construction was carried out using the broad host range vector pKT230 and plasmid pMCG898, which encodes the Erwinia herbicola pyrroloquinoline quinone (PQQ) synthase, a gene involved in mineral phosphate solubilization (mps). The final construction was transformed and expressed in Escherichia coli MC1061, and the recombinant plasmids were transferred to Burkholderia cepacia IS-16 and Pseudomonas sp. PSS recipient cells by conjugation. Clones containing recombinant plasmids produced higher clearing halos in plates with insoluble phosphate as the unique (P) source, in comparison with those of strains without plasmids, demonstrating the heterologous expression of the E. herbicola gene in the recipient strains. This genetic manipulation allowed the increase in mps ability of both strains, enhancing their potentialities as growth promoters of agricultural crops. These results represent the first report on the application of the recombinant DNA methodology for the obtaining of improved phosphate solubilizing ability from rhizobacterial strains for biofertilization purposes.

  2. Improvement of DNA transfer frequency and transposon mutagenesis of Erwinia carotovora subsp. betavasculorum.

    Science.gov (United States)

    Rella, M; Axelrood, P E; Weinhold, A R; Schroth, M N

    1989-01-01

    The production of antibiotics and their role in microbial competition under natural conditions can be readily studied by the use of transposon mutants. Several antibiotic-producing strains of Erwinia carotovora subsp. betavasculorum were unable to accept foreign DNA. A plasmid delivery system was developed, using ethyl methanesulfonate mutagenesis, which entailed isolating E. carotovora subsp. betavasculorum mutants able to accept foreign DNA and transfer it to other strains. This enabled transposon mutagenesis of a wild-type antibiotic-producing strain of E. carotovora subsp. betavasculorum. Twelve antibiotic-negative mutants were isolated, and one of these showed a reduction in antibiotic production in vitro. Many of these mutants also showed a reduction in their ability to macerate potato tissue. The mutants were classified into four genetic groups on the basis of their genetic and phenotypic characteristics, indicating that several genes are involved in antibiotic biosynthesis by E. carotovora subsp. betavasculorum. PMID:2543291

  3. Podridão em cravo causada por Erwinia carotovora subsp. carotovora no Brasil.

    Directory of Open Access Journals (Sweden)

    Irene M. G. Almeida

    2000-05-01

    Full Text Available De fevereiro a abril de 1999, coletaram-se estacas e mudas de cravo (Dianthus caryophyllus em propriedades dos municípios paulistas de Atibaia e Santo Antônio de Posse. Esse material apresentava sintomas caracterizados por não-emissão de raízes ou por podridão de raízes, colo e folhas basais, diferindo daqueles da doença denominada "slow wilt" e dos de escurecimento de vasos e necrose na região do colo, haste e folhas, já relatados em cravo. A partir de material com tais sintomas, isolaram-se bactérias, caracterizadas, mediante testes bioquímicos, culturais, fisiológicos e de patogenicidade, como Erwinia carotovora subsp. carotovora. Trata-se do primeiro relato desse patógeno em cravo no Brasil.

  4. Novel receptor-like protein kinases induced by Erwinia carotovora and short oligogalacturonides in potato.

    Science.gov (United States)

    Montesano, M; Kõiv, V; Mäe, A; Palva, E T

    2001-11-01

    summary Identification of potato genes responsive to cell wall-degrading enzymes of Erwinia carotovora resulted in the isolation of cDNA clones for four related receptor-like protein kinases. One of the putative serine-threonine protein kinases might have arisen through alternative splicing. These potato receptor-like kinases (PRK1-4) were highly equivalent (91-99%), most likely constituting a family of related receptors. All PRKs and four other plant RLKs share in their extracellular domain a conserved bi-modular pattern of cysteine repeats distinct from that in previously characterized plant RLKs, suggesting that they represent a new class of receptors. The corresponding genes were rapidly induced by E. carotovora culture filtrate (CF), both in the leaves and tubers of potato. Furthermore, the genes were transiently induced by short oligogalacturonides. The structural identity of PRKs and their induction pattern suggested that they constitute part of the early response of potato to E. carotovora infection.

  5. Characterization of a new pathovar of Agrobacterium vitis causing banana leaf blight in China.

    Science.gov (United States)

    Huang, Siliang; Long, Mengling; Fu, Gang; Lin, Shanhai; Qin, Liping; Hu, Chunjin; Cen, Zhenlu; Lu, Jie; Li, Qiqin

    2015-01-01

    A new banana leaf blight was found in Nanning city, China, during a 7-year survey (2003-2009) of the bacterial diseases on banana plants. Eight bacterial strains were isolated from affected banana leaves, and identified as an intraspecific taxon of Agrobacterium vitis based on their 16S rDNA sequence similarities with those of 37 randomly selected bacterial strains registered in GenBank database. The representative strain Ag-1 was virulent on banana leaves and shared similar growth and biochemical reactions with the reference strain IAM14140 of A. vitis. The strains causing banana leaf blight were denominated as A. vitis pv. musae. The traditional A. vitis strains virulent to grapevines were proposed to be revised as A. vitis pv. vitis. This is the first record of a new type of A. vitis causing banana leaf blight in China. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Enhanced resistance to blister blight in transgenic tea (Camellia sinensis [L.] O. Kuntze) by overexpression of class I chitinase gene from potato (Solanum tuberosum).

    Science.gov (United States)

    Singh, H Ranjit; Deka, Manab; Das, Sudripta

    2015-07-01

    Tea is the second most consumed beverage in the world. A crop loss of up to 43 % has been reported due to blister blight disease of tea caused by a fungus, Exobasidium vexans. Thus, it directly affects the tea industry qualitatively and quantitatively. Solanum tuberosum class I chitinase gene (AF153195) is a plant pathogenesis-related gene. It was introduced into tea genome via Agrobacterium-mediated transformation with hygromycin phosphotransferase (hpt) gene conferring hygromycin resistance as plant selectable marker. A total of 41 hygromycin resistant plantlets were obtained, and PCR analysis established 12 plantlets confirming about the stable integration of transgene in the plant genome. Real-time PCR detected transgene expression in four transgenic plantlets (T28, C57, C9, and T31). Resistance to biotrophic fungal pathogen, E. vexans, was tested by detached leaf infection assay of greenhouse acclimated plantlets. An inhibitory activity against the fungal pathogen was evident from the detached leaves from the transformants compared with the control. Fungal lesion formed on control plantlet whereas the transgenic plantlets showed resistance to inoculated fungal pathogen by the formation of hypersensitivity reaction area. This result suggests that constitutive expression of the potato class I chitinase gene can be exploited to improve resistance to fungal pathogen, E. vexans, in economical perennial plantation crop like tea.

  7. Mapping Quantitative Trait Loci (QTL for Resistance to Late Blight in Tomato

    Directory of Open Access Journals (Sweden)

    Dilip R. Panthee

    2017-07-01

    Full Text Available Late blight caused by Phytophthora infestans (Montagne, Bary is a devastating disease of tomato worldwide. There are three known major genes, Ph-1, Ph-2, and Ph-3, conferring resistance to late blight. In addition to these three genes, it is also believed that there are additional factors or quantitative trait loci (QTL conferring resistance to late blight. Precise molecular mapping of all those major genes and potential QTL is important in the development of suitable molecular markers and hence, marker-assisted selection (MAS. The objective of the present study was to map the genes and QTL associated with late blight resistance in a tomato population derived from intra-specific crosses. To achieve this objective, a population, derived from the crossings of NC 1CELBR × Fla. 7775, consisting of 250 individuals at F2 and F2-derived families, were evaluated in replicated trials. These were conducted at Mountain Horticultural Crops Reseach & Extension Center (MHCREC at Mills River, NC, and Mountain Research Staion (MRS at Waynesville, NC in 2011, 2014, and 2015. There were two major QTL associated with late blight resistance located on chromosomes 9 and 10 with likelihood of odd (LOD scores of more than 42 and 6, explaining 67% and 14% of the total phenotypic variation, respectively. The major QTLs are probably caused by the Ph-2 and Ph-3 genes. Furthermore, there was a minor QTL on chromosomes 12, which has not been reported before. This minor QTL may be novel and may be worth investigating further. Source of resistance to Ph-2, Ph-3, and this minor QTL traces back to line L3707, or Richter’s Wild Tomato. The combination of major genes and minor QTL may provide a durable resistance to late blight in tomato.

  8. First record of Glomerella cingulata causing leaf blight on Talauma ovata (Magnoliaceae Primeiro relato de Glomerella cingulata causando queima foliar em Talauma ovata (Magnoliaceae

    Directory of Open Access Journals (Sweden)

    Bruno Sérgio Vieira

    2005-10-01

    Full Text Available Glomerella cingulata was found causing severe leaf blight on Talauma ovata, a common tree species in the Atlantic tropical rain forest floodplains of Southern Brazil. The disease and pathogen are described and illustrated and patogenicity is also demonstrated. This is the first report of this disease.Glomerella cingulata foi encontrado causando severa queima-foliar em Talauma ovata, uma espécie arbórea comum em florestas úmidas tropicais do Sudeste do Brasil. A doença e o patógeno foram descritos e ilustrados, e sua patogenicidade também foi demonstrada. Esse é o primeiro relato dessa doença.

  9. Survival of Fusarium graminearum, the causal agent of Fusarium head blight. A review

    OpenAIRE

    Leplat , Johann; Friberg , Hanna; Abid , Muhammad; Steinberg , Christian

    2012-01-01

    International audience; Wheat is one of the most cultivated crops worldwide. In 2010, 20 % of wheat and durum wheat were cultivated in Europe, 17 % in China and 9 % in Russia and in North America. Wheat yield can be highly decreased by several factors. In particular Fusarium graminearum Schwabe is a worldwide fungal pest impacting wheat production. F. graminearum is the causal agent of Fusarium head blight, root and stem-base rot of cereals. Losses caused by Fusarium head blight in Northern a...

  10. Bio-protective microbial agents from rhizosphere eco-systems trigger plant defense responses provide protection against sheath blight disease in rice (Oryza sativa L.).

    Science.gov (United States)

    Singh, Udai B; Malviya, Deepti; Wasiullah; Singh, Shailendra; Pradhan, Jatindra K; Singh, Bhanu P; Roy, Manish; Imram, Mohd; Pathak, Neelam; Baisyal, B M; Rai, Jai P; Sarma, B K; Singh, Rajiv K; Sharma, P K; Kaur, Saman Deep; Manna, M C; Sharma, Sushil K; Sharma, Arun K

    2016-11-01

    Sheath blight of rice (Oryza sativa L.) caused by Rhizoctonia solani is a major disease and attempts are being made to develop microbe based technologies for biocontrol of this pathogen. However, the mechanisms of biocontrol are not fully understood and still require indepth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed at deciphering the mechanisms of biocontrol of sheath blight of rice employing Pseudomonas fluorescens and Trichoderma harzianum as model agents for biocontrol. Initially 25, 5 and 5 strains of P. fluorescens, T. viride and T. harzianum, respectively, were screened for their biocontrol potential. Out of which, six strains with higher value of percent inhibition of fungal mycelium in dual plate assay were selected. The role of P. fluorescens, T. viride and T. harzianum were investigated in induction and bioaccumulation of natural antioxidants, defence-related biomolecules and other changes in plant which lead not only to growth promotion but also protection from pathogenic stress conditions in rice. The two most promising strains, P. fluorescens PF-08 and T. harzianum UBSTH-501 selected on the basis of in planta evaluation, when applied individually or in combination, significantly enhanced the accumulation of defence-related biomolecules, enzymes and exhibited biocontrol potential against R. solani. A modified/newly developed delivery system was applied for the first time in the experiments involving inoculation of plants with both bioagents, viz. P. fluorescens PF-08 and T. harzianum UBSTH-501. Results suggested that application of P. fluorescens PF-08 and T. harzianum UBSTH-501 alone or in combination, not only helps in control of the disease but also increases plant growth along with reduction in application of toxic chemical pesticides. Copyright © 2016 Elsevier GmbH. All rights reserved.

  11. A network approach to predict pathogenic genes for Fusarium graminearum.

    Science.gov (United States)

    Liu, Xiaoping; Tang, Wei-Hua; Zhao, Xing-Ming; Chen, Luonan

    2010-10-04

    Fusarium graminearum is the pathogenic agent of Fusarium head blight (FHB), which is a destructive disease on wheat and barley, thereby causing huge economic loss and health problems to human by contaminating foods. Identifying pathogenic genes can shed light on pathogenesis underlying the interaction between F. graminearum and its plant host. However, it is difficult to detect pathogenic genes for this destructive pathogen by time-consuming and expensive molecular biological experiments in lab. On the other hand, computational methods provide an alternative way to solve this problem. Since pathogenesis is a complicated procedure that involves complex regulations and interactions, the molecular interaction network of F. graminearum can give clues to potential pathogenic genes. Furthermore, the gene expression data of F. graminearum before and after its invasion into plant host can also provide useful information. In this paper, a novel systems biology approach is presented to predict pathogenic genes of F. graminearum based on molecular interaction network and gene expression data. With a small number of known pathogenic genes as seed genes, a subnetwork that consists of potential pathogenic genes is identified from the protein-protein interaction network (PPIN) of F. graminearum, where the genes in the subnetwork are further required to be differentially expressed before and after the invasion of the pathogenic fungus. Therefore, the candidate genes in the subnetwork are expected to be involved in the same biological processes as seed genes, which imply that they are potential pathogenic genes. The prediction results show that most of the pathogenic genes of F. graminearum are enriched in two important signal transduction pathways, including G protein coupled receptor pathway and MAPK signaling pathway, which are known related to pathogenesis in other fungi. In addition, several pathogenic genes predicted by our method are verified in other pathogenic fungi, which

  12. Fusarium head blight incidence and mycotoxin accumulation in three durum wheat cultivars in relation to sowing date and density

    Science.gov (United States)

    Gorczyca, Anna; Oleksy, Andrzej; Gala-Czekaj, Dorota; Urbaniak, Monika; Laskowska, Magdalena; Waśkiewicz, Agnieszka; Stępień, Łukasz

    2018-02-01

    Durum wheat ( Triticum turgidum var. durum) is an important crop in Europe, particularly in the Mediterranean countries. Fusarium head blight (FHB) is considered as one of the most damaging diseases, resulting in yield and quality reduction as well as contamination of grain with mycotoxins. Three winter durum wheat cultivars originating from Austria, Slovakia, and Poland were analyzed during 2012-2014 seasons for FHB incidence and Fusarium mycotoxin accumulation in harvested grain. Moreover, the effects of sowing density and delayed sowing date were evaluated in the climatic conditions of Southern Poland. Low disease severity was observed in 2011/2012 in all durum wheat cultivars analyzed, and high FHB occurrence was recorded in 2012/2013 and 2013/2014 seasons. Fusarium graminearum was the most abundant pathogen, followed by Fusarium avenaceum. Through all three seasons, cultivar Komnata was the most susceptible to FHB and to mycotoxin accumulation, while cultivars Auradur and IS Pentadur showed less symptoms. High susceptibility of cv. Komnata was reflected by the number of Fusarium isolates and elevated mycotoxin (deoxynivalenol, zearalenone, and moniliformin) content in the grain of this cultivar across all three seasons. Nivalenol was identified in the samples of cv. Komnata only. Genotype-dependent differences in FHB susceptibility were observed for the plants sown at optimal date but not at delayed sowing date. It can be hypothesized that cultivars bred in Austria and Slovakia show less susceptibility towards FHB than the cultivar from Poland because of the environmental conditions allowing for more efficient selection of breeding materials.

  13. Screening of wheat endophytes as biological control agents against Fusarium head blight using two different in vitro tests.

    Science.gov (United States)

    Comby, Morgane; Gacoin, Marie; Robineau, Mathilde; Rabenoelina, Fanja; Ptas, Sébastien; Dupont, Joëlle; Profizi, Camille; Baillieul, Fabienne

    2017-09-01

    In order to find biological control agents (BCAs) for the management of Fusarium head blight (FHB), a major disease on wheat crops worldwide, 86 microorganisms isolated from inner tissues of wheat plants were discriminated for their ability to inhibit the growth of Fusarium graminearum and Fusarium culmorum by in vitro dual culture assays. A group of 22 strains appeared very effective to inhibit F. graminearum (inhibition of 30-51%) and they were also globally effective in controlling F. culmorum (inhibition of 15-53%). Further evaluation of a subselection of strains by screening on detached spikelets in vitro confirmed three species, namely Phoma glomerata, Aureobasidium proteae and Sarocladium kiliense, that have not yet been reported for their efficacy against Fusarium spp., indicating that looking for BCAs toward FHB among wheat endophytes proved to be promising. The efficacy of some strains turned out different between both in vitro screening approaches, raising the importance of finding the most appropriate screening approach for the search of BCAs. This study pointed out the interest of the test on detached wheat spikelets that provided information about a potential pathogenicity, the growth capacity and efficacy of the endophyte strains on the targeted plant, before testing them on whole plants. Copyright © 2017 Elsevier GmbH. All rights reserved.

  14. Soil Baiting, Rapid PCR Assay and Quantitative Real Time PCR to Diagnose Late Blight of Potato in Quarantine Programs

    Directory of Open Access Journals (Sweden)

    Touseef Hussain

    2018-05-01

    Full Text Available Phytophthora infestans (mont de Bary is a pathogen of great concern across the globe, and accurate detection is an important component in responding to the outbreaks of potential disease. Although the molecular diagnostic protocol used in regulatory programs has been evaluated but till date methods implying direct comparison has rarely used. In this study, a known area soil samples from potato fields where light blight appear every year (both A1 and A2 mating type was assayed by soil bait method, PCR assay detection and quantification of the inoculums. Suspected disease symptoms appeared on bait tubers were further confirmed by rapid PCR, inoculums were quantified through Real Time PCR, which confirms presence of P. infestans. These diagnostic methods can be highly correlated with one another. Potato tuber baiting increased the sensitivity of the assay compared with direct extraction of DNA from tuber and soil samples. Our study determines diagnostic sensitivity and specificity of the assays to determine the performance of each method. Overall, molecular techniques based on different types of PCR amplification and Real-time PCR can lead to high throughput, faster and more accurate detection method which can be used in quarantine programmes in potato industry and diagnostic laboratory.

  15. Members of the amylovora group of Erwinia are cellulolytic and possess genes homologous to the type II secretion pathway.

    Science.gov (United States)

    Riekki, R; Palomäki, T; Virtaharju, O; Kokko, H; Romantschuk, M; Saarilahti, H T

    2000-07-01

    A cellulase-producing clone was isolated from a genomic library of the Erwinia rhapontici (Millard) Burkholder strain NCPPB2989. The corresponding gene, named celA, encodes an endoglucanase (EC 3.2.1.4) with the extremely low pH optimum of 3.4 and a temperature optimum between 40 and 50 degrees C. A single ORF of 999 nt was found to be responsible for the Cel activity. The corresponding protein, named CelA, showed 67% identity to the endoglucanase Y of E. chrysanthemi and 51.5% identity to the endoglucanase of Cellulomonas uda, and thus belongs to the glycosyl hydrolase family 8. The celA gene, or its homologue, was found to be present in all E. rhapontici isolates analysed, in E. chrysanthemi, and in E. amylovora. The presence of plant cell wall-degrading enzymes in the amylovora group of Erwinia spp. had not previously been established. Furthermore, the DNA of both E. rhapontici and E. amylovora was found to exhibit homology to genes encoding the type II (GSP) secretion pathway, which is known to be responsible for extracellular targeting of cellulases and pectinases in Erwinia spp. that cause soft rotting, such as E. carotovora and E. chrysanthemi. Secretion of the CelA protein by E. rhapontici could not be verified. However, the CelA protein itself was found to include the information necessary for heterologous secretion by E. chrysanthemi.

  16. Genetic mapping of ascochyta blight resistance in chickpea (Cicer arietinum L.) using a simple sequence repeat linkage map.

    Science.gov (United States)

    Tar'an, B; Warkentin, T D; Tullu, A; Vandenberg, A

    2007-01-01

    Ascochyta blight, caused by the fungus Ascochyta rabiei (Pass.) Lab., is one of the most devastating diseases of chickpea (Cicer arietinum L.) worldwide. Research was conducted to map genetic factors for resistance to ascochyta blight using a linkage map constructed with 144 simple sequence repeat markers and 1 morphological marker (fc, flower colour). Stem cutting was used to vegetatively propagate 186 F2 plants derived from a cross between Cicer arietinum L. 'ICCV96029' and 'CDC Frontier'. A total of 556 cutting-derived plants were evaluated for their reaction to ascochyta blight under controlled conditions. Disease reaction of the F1 and F2 plants demonstrated that the resistance was dominantly inherited. A Fain's test based on the means and variances of the ascochyta blight reaction of the F3 families showed that a few genes were segregating in the population. Composite interval mapping identified 3 genomic regions that were associated with the reaction to ascochyta blight. One quantitative trait locus (QTL) on each of LG3, LG4, and LG6 accounted for 13%, 29%, and 12%, respectively, of the total estimated phenotypic variation for the reaction to ascochyta blight. Together, these loci controlled 56% of the total estimated phenotypic variation. The QTL on LG4 and LG6 were in common with the previously reported QTL for ascochyta blight resistance, whereas the QTL on LG3 was unique to the current population.

  17. Induction of Xa10-like Genes in Rice Cultivar Nipponbare Confers Disease Resistance to Rice Bacterial Blight.

    Science.gov (United States)

    Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao

    2017-06-01

    Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice-growing regions in the world. The rice disease resistance (R) gene Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effector AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. 'Nipponbare' rice carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from 'CBB23' rice. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here, we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALE). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino-acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni, and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic reticulum (ER) membrane

  18. Combining Ascochyta blight and Botrytis grey mould resistance in chickpea through interspecific hybridization

    Directory of Open Access Journals (Sweden)

    Livinder KAUR

    2013-05-01

    Full Text Available Ascochyta blight (AB caused by Ascochyta rabiei (Pass. Labr. and Botrytis grey mould (BGM caused by Botrytis cinerea (Pers. ex Fr. are important diseases of the aerial plant parts of chickpea in most chickpea growing areas of the world. Although conventional approaches have contributed to reducing disease, the use of new technologies is expected to further reduce losses through these biotic stresses. Reliable screening techniques were developed: ‘field screening technique’ for adult plant screening, ‘cloth chamber technique’ and ‘growth chamber technique’ for the study of races of the pathogen and for segregating generations. Furthermore, the ‘cut twig technique’ for interspecific population for AB and BGM resistance was developed. For introgression of high levels of AB and BGM resistance in cultivated chickpea from wild relatives, accessions of seven annual wild Cicer spp. were evaluated and identified: C. judaicum accessions 185, ILWC 95 and ILWC 61, C. pinnatifidum accessions 188, 199 and ILWC 212 as potential donors. C. pinnatifidum accession188 was crossed with ICCV 96030 and 62 F9 lines resistant to AB and BGM were derived. Of the derived lines, several are being evaluated for agronomic traits and yield parameters while four lines, GL 29029, GL29206, GL29212, GL29081 possessing high degree of resistance were crossed with susceptible high yielding cultivars BG 256 to improve resistance and to undertake molecular studies. Genotyping of F2 populations with SSR markers from the chickpea genome was done to identify markers potentially linked with AB and BGM resistance genes. In preliminary studies, of 120 SSR markers used, six (Ta 2, Ta 110, Ta 139, CaSTMS 7, CaSTMS 24 and Tr 29 were identified with polymorphic bands between resistant derivative lines and the susceptible parent. The study shows that wild species of Cicer are the valuable gene pools of resistance to AB and BGM. The resistant derivative lines generated here can

  19. Polymorphic sequence-characterized codominant loci in the chestnut blight fungus, Cryphonectria parasitica

    Science.gov (United States)

    J. E. Davis; Thomas L. Kubisiak; M. G. Milgroom

    2005-01-01

    Studies on the population biology of the chestnut blight fungus, Cryphonectria parasitica, have previously been carried out with dominant restriction fragment length polymorphism (RFLP) fingerprinting markers. In this study, we described the development of 11 condominant markers from randomly amplified polymorphic DNAs (RAPDs). RAPD fragments were...

  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. Aspects of resistance to fusarium head blight caused by Fusarium culmorum in wheat

    NARCIS (Netherlands)

    Snijders, C.H.A.

    1990-01-01

    In the Netherlands, Fusarium head blight of wheat is predominantly caused by Fusarium culmorum . A low infection level leads to important yield losses and contaminates the grain with mycotoxins, particularly deoxynivalenol. This mycotoxin is suggested to have toxic

  2. Fusarium spp. associated with head blight of wheat in South Africa

    Science.gov (United States)

    Fusarium head blight (FHB) of wheat is caused by numerous Fusarium species, including trichothecene-producers. In South Africa, FHB is mostly associated with irrigated wheat rotated with maize. Twenty symptomatic wheat heads were collected from four cultivars each in irrigated fields in the Northern...

  3. 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...

  4. In Vitro Screening of Antibacterial Agents for Suppression of Fire Blight Disease in Korea

    Directory of Open Access Journals (Sweden)

    Min Su Lee

    2018-03-01

    Full Text Available Since fire blight disease on apple and pear was produced in Korea in 2015, there were no registered chemicals to control against this disease. Instead, several antibacterial chemicals that were registered for other bacterial diseases such as soft rot and bacterial spot have been authorized by Rural Development Administration (RDA. However, these chemicals are not tested efficacy for fire blight disease except damage by those treatments on apple and pear in Korea. Thus, we evaluated efficiency using in vitro and in planta assays of antibacterial chemicals such as antibiotics and copper compounds including kasugamycin, oxytetracycline, oxolinic acid and streptomycin, and copper hydroxide, copper sulfate, oxine copper and tribasic copper sulfate, respectively. We also tested two kinds of biological agents. As expected, significant antibacterial effect was observed in vitro test of both antibiotics and copper-based chemicals. In planta test based on disease severity including ooze and water-soaked formation on immature pears, bacterial populations on blooms, and blight lesion formation in artificially inoculated shoots, kasugamycin, oxytetracycline and streptomycin have been shown the most efficiency among tested antibiotics. Four copper-based chemicals tested in this study, control effects are little bit lower than agricultural antibiotics but they seem to be available to use in terms of winter season. Biocontrol agents were also shown possibility to treat in eco-friendly farms. In addition, there are no antibiotic resistance genes in Korean isolates against antibiotics, which were selected for suppression of fire blight in this study.

  5. Toward positional cloning of Fhb1, a major QTL for Fusarium head blight resistance in wheat

    Czech Academy of Sciences Publication Activity Database

    Liu, S. X.; Pumphrey, M. O.; Gill, B. S.; Trick, H. N.; Zhang, J. X.; Doležel, Jaroslav; Chalhoub, B.; Anderson, J. A.

    2008-01-01

    Roč. 36, suppl. B (2008), s. 195-201 ISSN 0133-3720 Institutional research plan: CEZ:AV0Z50380511 Keywords : map-based cloning * Fusarium head blight * Fhb1 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.190, year: 2007

  6. QTL identification for early blight resistance (Alternaria solani) in a Solanum lycopersicum x S. arcanum cross.

    NARCIS (Netherlands)

    Chaerani, R.; Smulders, M.J.M.; Linden, van der C.G.; Vosman, B.; Stam, P.; Voorrips, R.E.

    2007-01-01

    Alternaria solani (Ellis and Martin) Sorauer, the causal agent of early blight (EB) disease, infects aerial parts of tomato at both seedling and adult plant stages. Resistant cultivars would facilitate a sustainable EB management. EB resistance is a quantitatively expressed character, a fact that

  7. 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...

  8. 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…

  9. Shoot Blight and Leaf Spot of Blueberry Anthracnose Caused by Colletotrichum acutatum

    OpenAIRE

    Shigenobu, YOSHIDA; Takao, TSUKIBOSHI; National Institute for Agro-Environmental Sciences; National Institute for Agro-Environmental Sciences

    2002-01-01

    Shoot blight and leaf spots were found on highbush blueberry trees in Tsukuba, Ibaraki, in 1999. The causal fungus was identified morphologically as Colletotrichum acutatum Simmonds ex Simmonds. This is the first report of blueberry anthracnose caused by C. acutatum in Japan.

  10. Molecular mapping of resistance to blight in an interspecific cross in the genus Castanea

    Science.gov (United States)

    Thomas L. Kubisiak; F.V. Hebard; C. Dana Nelson; Jiansu Zhang; R. Bernatzky; H. Huang; S.L. Anagnostakis; R.L. Doudrick

    1997-01-01

    A three-generation American chestnut x Chinese chestnut pedigree was used to construct a genetic linkage map for chestnut and to investigate the control of resistance to Endothia parasitica (chestnut blight fungus). DNA genotypes for 241 polymorphic markers (eight isozymes, 17 restriction fragment length polymorphisms [RFLPs], and 216 random...

  11. Large-spored Alternaria pathogens in section Porri disentangled.

    Science.gov (United States)

    Woudenberg, J H C; Truter, M; Groenewald, J Z; Crous, P W

    2014-09-01

    The omnipresent fungal genus Alternaria was recently divided into 24 sections based on molecular and morphological data. Alternaria sect. Porri is the largest section, containing almost all Alternaria species with medium to large conidia and long beaks, some of which are important plant pathogens (e.g. Alternaria porri, A. solani and A. tomatophila). We constructed a multi-gene phylogeny on parts of the ITS, GAPDH, RPB2, TEF1 and Alt a 1 gene regions, which, supplemented with morphological and cultural studies, forms the basis for species recognition in sect. Porri. Our data reveal 63 species, of which 10 are newly described in sect. Porri, and 27 species names are synonymised. The three known Alternaria pathogens causing early blight on tomato all cluster in one clade, and are synonymised under the older name, A. linariae. Alternaria protenta, a species formerly only known as pathogen on Helianthus annuus, is also reported to cause early blight of potato, together with A. solani and A. grandis. Two clades with isolates causing purple blotch of onion are confirmed as A. allii and A. porri, but the two species cannot adequately be distinguished based on the number of beaks and branches as suggested previously. This is also found among the pathogens of Passifloraceae, which are reduced from four to three species. In addition to the known pathogen of sweet potato, A. bataticola, three more species are delineated of which two are newly described. A new Alternaria section is also described, comprising two large-spored Alternaria species with concatenate conidia.

  12. Molecular Characterization and Functional Analysis of PR-1-Like Proteins Identified from the Wheat Head Blight Fungus Fusarium graminearum.

    Science.gov (United States)

    Lu, Shunwen; Edwards, Michael C

    2018-04-01

    The group 1 pathogenesis-related (PR-1) proteins originally identified from plants and their homologs are also found in other eukaryotic kingdoms. Studies on nonplant PR-1-like (PR-1L) proteins have been pursued widely in humans and animals but rarely in filamentous ascomycetes. Here, we report the characterization of four PR-1L proteins identified from the ascomycete fungus Fusarium graminearum, the primary cause of Fusarium head blight of wheat and barley (designated FgPR-1L). Molecular cloning revealed that the four FgPR-1L proteins are all encoded by small open reading frames (612 to 909 bp) that are often interrupted by introns, in contrast to plant PR-1 genes that lack introns. Sequence analysis indicated that all FgPR-1L proteins contain the PR-1-specific three-dimensional structure, and one of them features a C-terminal transmembrane (TM) domain that has not been reported for any stand-alone PR-1 proteins. Transcriptional analysis revealed that the four FgPR-1L genes are expressed in axenic cultures and in planta with different spatial or temporal expression patterns. Phylogenetic analysis indicated that fungal PR-1L proteins fall into three major groups, one of which harbors FgPR-1L-2-related TM-containing proteins from both phytopathogenic and human-pathogenic ascomycetes. Low-temperature sodium dodecyl sulfate polyacrylamide gel electrophoresis and proteolytic assays indicated that the recombinant FgPR-1L-4 protein exists as a monomer and is resistant to subtilisin of the serine protease family. Functional analysis confirmed that deletion of the FgPR-1L-4 gene from the fungal genome results in significantly reduced virulence on susceptible wheat. This study provides the first example that the F. graminearum-wheat interaction involves a pathogen-derived PR-1L protein that affects fungal virulence on the host.

  13. In vitro and in vivo effect of poplar bud (Populi gemma Extracts on late blight (Phytophthora infestans

    Directory of Open Access Journals (Sweden)

    Bálint János

    2014-11-01

    Full Text Available The effect of populin extract from black poplar (Populus nigra on late blight was assessed under laboratory and field conditions. The growth rate of hyphae was found to be significantly lower after 1v/v% populin application, and no hyphae growth was detected under 3 and 6v/v% populin application. Populin also reduced the light blight severity on potato leaves under field conditions. From our results, we have concluded that populin extract can be considered as a new and environmentally-friendly alternative for the control of late blight under field conditions.

  14. Pathogen intelligence

    Directory of Open Access Journals (Sweden)

    Michael eSteinert

    2014-01-01

    Full Text Available 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 behaviour, but also collective sensing, interbacterial communication, distributed information processing, joint decision making, dissociative behaviour, 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.

  15. Top 10 plant pathogenic bacteria in molecular plant pathology.

    Science.gov (United States)

    Mansfield, John; Genin, Stephane; Magori, Shimpei; Citovsky, Vitaly; Sriariyanum, Malinee; Ronald, Pamela; Dow, Max; Verdier, Valérie; Beer, Steven V; Machado, Marcos A; Toth, Ian; Salmond, George; Foster, Gary D

    2012-08-01

    Many plant bacteriologists, if not all, feel that their particular microbe should appear in any list of the most important bacterial plant pathogens. However, to our knowledge, no such list exists. The aim of this review was to survey all bacterial pathologists with an association with the journal Molecular Plant Pathology and ask them to nominate the bacterial pathogens they would place in a 'Top 10' based on scientific/economic importance. The survey generated 458 votes from the international community, and allowed the construction of a Top 10 bacterial plant pathogen list. The list includes, in rank order: (1) Pseudomonas syringae pathovars; (2) Ralstonia solanacearum; (3) Agrobacterium tumefaciens; (4) Xanthomonas oryzae pv. oryzae; (5) Xanthomonas campestris pathovars; (6) Xanthomonas axonopodis pathovars; (7) Erwinia amylovora; (8) Xylella fastidiosa; (9) Dickeya (dadantii and solani); (10) Pectobacterium carotovorum (and Pectobacterium atrosepticum). Bacteria garnering honourable mentions for just missing out on the Top 10 include Clavibacter michiganensis (michiganensis and sepedonicus), Pseudomonas savastanoi and Candidatus Liberibacter asiaticus. This review article presents a short section on each bacterium in the Top 10 list and its importance, with the intention of initiating discussion and debate amongst the plant bacteriology community, as well as laying down a benchmark. It will be interesting to see, in future years, how perceptions change and which bacterial pathogens enter and leave the Top 10. © 2012 The Authors. Molecular Plant Pathology © 2012 BSPP and Blackwell Publishing Ltd.

  16. Genetic Diversity of Alternaria alternata Causal Agent of Early Blight of Tomato in Khuzestan Province Using SSRs Marker

    Directory of Open Access Journals (Sweden)

    Khoshnood Nourollahi

    2017-03-01

    Full Text Available Introduction: The early blight of tomato caused by Alternaria alternata is one of the most important and destructive diseases in Khuzestan province. Study genetic structure of A. alternata populations provides different levels of information in the management of early blight disease in tomato farms. Short sequence repeat (SSR markers were used to determine the genetic structure and estimate genetic diversity in A. alternata isolates in Khuzestan province. Materials and Methods: In this study to evaluate the genetic diversity and genetic populations of A. alternata pathogen, sampling was randomly carried out on aerial parts of tomato plants with leaf brown lesions in farms and glasshouses from five different regions in Khuzestan province such as: Shoshtar, Omidiyeh, Dashte azadagan, Ahvaz, and Dezful. Each sample was cut into 2–5-mm long pieces, were surface-sterilized with 1% sodium hypochlorite for 3 min and rinsed three times with sterile distilled water and air-dried with sterile filter paper. The sterilized samples were placed onto a general medium potato dextrose agar (PDA. A total of 64 A. alternata isolates were obtained from infected samples. Pathogenicity test was carried out on local susceptible cultivar under an artificial condition in the greenhouse. For obtaining the mycelia mass, liquid cultures were initiated by adding 2–4 mm 2 pieces of filter paper to 250-mL Erlenmeyer flasks containing 100 mL PDB medium (potato dextrose broth. Mycelium was collected by filtration through sterile filter paper with a vacuum funnel. Mycelia were harvested, frozen and stored at -20°C. DNA was extracted using a modified hexadecyl trimethyl-ammonium bromide (CTAB procedure. A set of five paired sequence repeat primers (SSR were used to determine the genetic diversity of A. alternata isolates. PCR amplification was performed in a 25 μl reaction volume. The bands generated by SSR primers that were repeatable and clearly visible with a high

  17. Management of blight of bell pepper (Capsicum annuum var. grossum) caused by Drechslera bicolor.

    Science.gov (United States)

    Jadon, Kuldeep Singh; Shah, Rakesh; Gour, Hari Narayan; Sharma, Pankaj

    Sweet or bell pepper is a member of the Solanaceae family and is regarded as one of the most popular and nutritious vegetable. Blight, in the form of leaf and fruit blight, has been observed to infect bell pepper crops cultivated at the horticulture farm in Rajasthan College of Agriculture, Udaipur, India. Based on disease severity, we attempted to curb this newly emerged problem using different fungicides, plant extracts, bio-control agents, and commercial botanicals against the fungus in laboratory and pot experiments. Bio-control agent Trichoderma viride and plant growth promoting Rhizobacteria (PGPR) isolate Neist-2 were found to be quite effective against bell pepper blight. All evaluated fungicides, botanicals, commercial botanicals, and bio-control agents in vitro were further studied as seed dressers and two foliar sprays at ten days interval in pot experiments. The combinations of Vitavax, PGPR isolate Neist-2, and Mehandi extract were found to be very effective against bell pepper blight followed by Vitavax, T. viride, and Mehandi extract used individually. All treatments in the pot experiments were found to significantly reduce seedling mortality and enhance plant biomass of bell pepper. Thus, these experimental findings suggest that a better integrated management of bell pepper blight could be achieved by conducting field trials in major bell pepper- and chilli-cultivated areas of the state. Besides fungicides, different botanicals and commercial botanicals also seem to be promising treatment options. Therefore, the outcome of the present study provides an alternate option of fungicide use in minimizing loss caused by Drechslera bicolor. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  18. 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.

  19. Analysis of the pelE promoter in Erwinia chrysanthemi EC16.

    Science.gov (United States)

    Gold, S; Nishio, S; Tsuyumu, S; Keen, N T

    1992-01-01

    The pelE gene of Erwinia chrysanthemi strain EC16 encodes an extracellular pectate lyase protein that is important in virulence on plants. Control of pelE expression is complex, because the gene is regulated by catabolite repression, substrate induction, and growth-phase inhibition. A Tn7-lux reporter gene system was employed to define DNA sequences comprising the pelE promoter. When EC16 cells were grown on medium containing sodium polypectate, pelE transcriptional start sites were observed only at 95 and 96 bases upstream of the translational start site. However, DNA sequences required for pelE expression were also shown by deletion analysis to reside between 196 and 215 base pairs upstream of the translational start site. In addition to these upstream elements, two putative operator sequences that interact with negative regulatory factors occurred downstream of the transcriptional start. Finally, deletion of three bases from a putative catabolite gene activator protein binding site in the pelE promoter eliminated activity. The data demonstrate that the pelE promoter is complex and suggest that it interacts with several regulatory proteins.

  20. Production of endo-pectate lyase by two stage cultivation of Erwinia carotovora

    Energy Technology Data Exchange (ETDEWEB)

    Fukuoka, Satoshi; Kobayashi, Yoshiaki

    1987-02-26

    The productivity of endo-pectate lyase from Erwinia carotovora GIR 1044 was found to be greatly improved by two stage cultivation: in the first stage the bacterium was grown with an inducing carbon source, e.g., pectin, and in the second stage it was cultivated with glycerol, xylose, or fructose with the addition of monosodium L-glutamate as nitrogen source. In the two stage cultivation using pectin or glycerol as the carbon source the enzyme activity reached 400 units/ml, almost 3 times as much as that of one stage cultivation in a 10 liter fermentor. Using two stage cultivation in the 200 liter fermentor improved enzyme productivity over that in the 10 liter fermentor, with 500 units/ml of activity. Compared with the cultivation in Erlenmeyer flasks, fermentor cultivation improved enzyme productivity. The optimum cultivating conditions were agitation of 480 rpm with aeration of 0.5 vvm at 28 /sup 0/C. (4 figs, 4 tabs, 14 refs)

  1. Erwinia carotovora contamination of Finnish seed potatoes and the prevalence of bacterial subspecies and serogroups

    Directory of Open Access Journals (Sweden)

    Pirkko Harju

    1993-07-01

    Full Text Available Symptomless contamination with the rot-inducing bacterium Erwinia carotovora was detectable by the tuber incubation method in 82% of the commercial seed potato stocks surveyed. E. carotovora subsp. atroseptica (Eca was more common than E. carotovora subsp. carotovora (Ecc among the tuber contaminants. In a four-year survey of ten meristem-based seed stocks, recontamination with both Eca and Ecc occurred typically during the second field generation, but three stocks remained free of detectable contamination throughout the survey period. The first blackleg symptoms occurred typically during the third field generation. The serogroup distribution of Finnish Eca isolates was different from that reported from other countries. The predominant serogroup, I, constituted only 74% of all Eca isolates, since serogroups XXXV and XLI occurred relatively frequently. Serogroup I was more common among isolates from diseased stems than among those from latently contaminated tubers. The results also suggest that serogroup I is more dominant in the southern than in the northern parts of the country.

  2. Purification, Characterization, and Effect of Thiol Compounds on Activity of the Erwinia carotovora L-Asparaginase

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    Suchita C. Warangkar

    2010-01-01

    Full Text Available L-asparaginase was extracted from Erwinia carotovora and purified by ammonium sulfate fractionation (60–70%, Sephadex G-100, CM cellulose, and DEAE sephadex chromatography. The apparent Mr of enzyme under nondenaturing and denaturing conditions was 150 kDa and 37±0.5 kDa, respectively. L-asparaginase activity was studied in presence of thiols, namely, L-cystine (Cys, L-methionine (Met, N-acetyl cysteine (NAC, and reduced glutathione (GSH. Kinetic parameters in presence of thiols (10–400 M showed an increase in Vmax values (2000, 2223, 2380, 2500, and control 1666.7 moles mg−1min−1 and a decrease in K values (0.086, 0.076, 0.062, 0.055 and control 0.098 mM indicating nonessential mode of activation. KA values displayed propensity to bind thiols. A decrease in Vmax/K ratio in concentration plots showed inverse relationship between free thiol groups (NAC and GSH and bound thiol group (Cys and Met. Enzyme activity was enhanced in presence of thiol protecting reagents like dithiothreitol (DTT, 2-mercaptoethanol (2-ME, and GSH, but inhibited by p-chloromercurybenzoate (PCMB and iodoacetamide (IA.

  3. Partitioning of the variance in the growth parameters of Erwinia carotovora on vegetable products.

    Science.gov (United States)

    Shorten, P R; Membré, J-M; Pleasants, A B; Kubaczka, M; Soboleva, T K

    2004-06-01

    The objective of this paper was to estimate and partition the variability in the microbial growth model parameters describing the growth of Erwinia carotovora on pasteurised and non-pasteurised vegetable juice from laboratory experiments performed under different temperature-varying conditions. We partitioned the model parameter variance and covariance components into effects due to temperature profile and replicate using a maximum likelihood technique. Temperature profile and replicate were treated as random effects and the food substrate was treated as a fixed effect. The replicate variance component was small indicating a high level of control in this experiment. Our analysis of the combined E. carotovora growth data sets used the Baranyi primary microbial growth model along with the Ratkowsky secondary growth model. The variability in the microbial growth parameters estimated from these microbial growth experiments is essential for predicting the mean and variance through time of the E. carotovora population size in a product supply chain and is the basis for microbiological risk assessment and food product shelf-life estimation. The variance partitioning made here also assists in the management of optimal product distribution networks by identifying elements of the supply chain contributing most to product variability. Copyright 2003 Elsevier B.V.

  4. Cloning and study of the pectate lyase gene of Erwinia carotovora

    International Nuclear Information System (INIS)

    Bukanov, N.O.; Fonshtein, M.Yu.; Evtushenkov, A.N.; Syarinskii, M.A.; Strel'chenko, P.P.; Yankovski, N.K.; Alikhanyan, S.I.; Fomichev, Yu.K.; Debabov, V.G.

    1986-01-01

    The cloning of the gene of a secretable protein of Erwinia carotovora, pectate lyase, in Escherichia coli was described. Primary cloning was conducted using the phage vector λ 47.1. In the gene library of E. carotovora obtained, eight phages carrying the gene sought were identified according to the appearance of enzymatic activity of the gene product, pectate lyase, in situ. The BamHI fragment of DNA, common to all these phages, was recloned on the plasmid pUC19. It was shown that the cloned pectate lyase gene is represented on the E. carotovora chromosome in one copy. Methods of production of representative gene libraries on phage vectors from no less than 1 μg of cloned DNA even for the genomes of eukaryotes have now been developed. Vectors have been created, for example, λ 47.1, permitting the selection only of hybrid molecules. A number of methods have been developed for the search for a required gene in the library, depending on whether the cloned gene can be expressed or not, and if it can, what properties it will impart to the hybrid clone containing it

  5. Development of a Selective Medium for the Fungal Pathogen Fusarium graminearum Using Toxoflavin Produced by the Bacterial Pathogen Burkholderia glumae

    Directory of Open Access Journals (Sweden)

    Boknam Jung

    2013-12-01

    Full Text Available The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting.

  6. Production of glucosyltransferase by Erwinia sp. using experimental design and response surface methodology Produção de glicosiltransferase por Erwinia sp. utilizando planejamento experimental e metodologia de superfície de resposta

    Directory of Open Access Journals (Sweden)

    Haroldo Yukio Kawaguti

    2005-09-01

    Full Text Available Glucosyltransferase produced by strain Erwinia sp. is an intracellular enzyme that catalyzes the formation of isomaltulose from sucrose. Isomaltulose is a non-cariogenic reducing dissacharide commercially used in foods. Response surface methodology and 2³-factorial central composite design were employed to optimize a fermentation medium for the production of glucosyltransferase by Erwinia sp. in shaken flasks at 200 rpm and 30ºC. The three variables involved in this study were sugar cane molasses (SCM, corn steep liquor (CSL and yeast extract Prodex Lac SD (YEP. The statistical analysis of the results showed that, in the range studied, all the factors had a significant effect on glucosyltransferase production and the optimum medium composition for enzyme production was (in g l-1 SCM-100, CSL-60 and YEP-8, which lead to a glucosyltransferase activity of 6.65 U mL-1.A glicosiltransferase obtida pela linhagem Erwinia sp. é uma enzima intracelular que catalisa a conversão de sacarose em isomaltulose. A isomaltulose é um dissacarídeo redutor, não cariogênico e comercialmente utilizado em alimentos como substituto da sacarose. A metodologia de superfície de resposta e planejamento fatorial composto central-2³ foram utilizados para otimizar o meio de cultivo para a produção de glicosiltransferase de Erwinia sp. em frascos sob agitação a 200 rpm e 30ºC. As três variáveis independentes envolvidas no estudo foram o melaço de cana de açúcar, a água de maceração de milho e o extrato de levedura Prodex Lac SD. As análises estatísticas dos resultados mostraram que, dentro da faixa estudada das concentrações dos componentes de meio de cultivo, todas as variáveis apresentaram efeito significativo na produção de glicosiltransferase. O meio de cultivo otimizado foi composto de 100 gL-1 de melaço de cana de açúcar, 60 gL-1 de água de maceração de milho e 8 gL-1 de extrato de levedura Prodex Lac SD, apresentando atividade de

  7. Early activation of wheat polyamine biosynthesis during Fusarium head blight implicates putrescine as an inducer of trichothecene mycotoxin production

    Directory of Open Access Journals (Sweden)

    Rusu Anca

    2010-12-01

    Full Text Available Abstract Background The fungal pathogen Fusarium graminearum causes Fusarium Head Blight (FHB disease on wheat which can lead to trichothecene mycotoxin (e.g. deoxynivalenol, DON contamination of grain, harmful to mammalian health. DON is produced at low levels under standard culture conditions when compared to plant infection but specific polyamines (e.g. putrescine and agmatine and amino acids (e.g. arginine and ornithine are potent inducers of DON by F. graminearum in axenic culture. Currently, host factors that promote mycotoxin synthesis during FHB are unknown, but plant derived polyamines could contribute to DON induction in infected heads. However, the temporal and spatial accumulation of polyamines and amino acids in relation to that of DON has not been studied. Results Following inoculation of susceptible wheat heads by F. graminearum, DON accumulation was detected at two days after inoculation. The accumulation of putrescine was detected as early as one day following inoculation while arginine and cadaverine were also produced at three and four days post-inoculation. Transcripts of ornithine decarboxylase (ODC and arginine decarboxylase (ADC, two key biosynthetic enzymes for putrescine biosynthesis, were also strongly induced in heads at two days after inoculation. These results indicated that elicitation of the polyamine biosynthetic pathway is an early response to FHB. Transcripts for genes encoding enzymes acting upstream in the polyamine biosynthetic pathway as well as those of ODC and ADC, and putrescine levels were also induced in the rachis, a flower organ supporting DON production and an important route for pathogen colonisation during FHB. A survey of 24 wheat genotypes with varying responses to FHB showed putrescine induction is a general response to inoculation and no correlation was observed between the accumulation of putrescine and infection or DON accumulation. Conclusions The activation of the polyamine biosynthetic

  8. Antimicrobial activities of the essential oils of various plants against tomato late blight disease agent Phytophthora infestans.

    Science.gov (United States)

    Soylu, E Mine; Soylu, Soner; Kurt, Sener

    2006-02-01

    The aim of this study was to find an alternative to synthetic fungicides currently used in the control of devastating oomycete pathogen Phytophthora infestans, causal agent of late blight disease of tomato. Antifungal activities of essential oils obtained from aerial parts of aromatic plants such as oregano (Origanum syriacum var. bevanii), thyme (Thymbra spicata subsp. spicata), lavender (Lavandula stoechas subsp. stoechas), rosemary (Rosmarinus officinalis), fennel (Foeniculum vulgare), and laurel (Laurus nobilis), were investigated against P. infestans. Both contact and volatile phase effects of different concentrations of the essential oils used were determined by using two in vitro methods. Chemical compositions of the essential oils were also determined by GC-MS analysis. Major compounds found in essential oils of thyme, oregano, rosemary, lavender, fennel and laurel were carvacrol (37.9%), carvacrol (79.8), borneol (20.4%), camphor (20.2%), anethole (82.8%) and 1,8-cineole (35.5%), respectively. All essential oils were found to inhibit the growth of P. infestans in a dose-dependent manner. Volatile phase effect of oregano and thyme oils at 0.3 microg/ml air was found to completely inhibit the growth of P. infestans. Complete growth inhibition of pathogen by essential oil of fennel, rosemary, lavender and laurel was, however, observed at 0.4-2.0 microg/ml air concentrations. For the determination of the contact phase effects of the tested essential oils, oregano, thyme and fennel oils at 6.4 microg/ml were found to inhibit the growth of P. infestans completely. Essential oils of rosemary, lavender and laurel were inhibitory at relatively higher concentrations (12.8, 25.6, 51.2 microg/ml respectively). Volatile phase effects of essential oils were consistently found to be more effective on fungal growth than contact phase effect. Sporangial production was also inhibited by the essential oil tested. Light and scanning electron microscopic (SEM) observation on

  9. Molecular cloning and characterization of an Erwinia carotovora subsp. carotovora pectin lyase gene that responds to DNA-damaging agents.

    OpenAIRE

    McEvoy, J L; Murata, H; Chatterjee, A K

    1990-01-01

    recA-mediated production of pectin lyase (PNL) and the bacteriocin carotovoricin occurs in Erwinia carotovora subsp. carotovora 71 when this organism is subjected to agents that damage or inhibit the synthesis of DNA. The structural gene pnlA was isolated from a strain 71 cosmid gene library following mobilization of the cosmids into a moderate PNL producer, strain 193. The cosmid complemented pnl::Tn5 but not ctv::Tn5 mutations. A constitutive level of PNL activity was detected in RecA+ and ...

  10. The effect of disinfectants on Clavibacter michiganensis subsp. sepedonicus and Erwinia carotovora subsp. atroseptica on different surface materials

    Directory of Open Access Journals (Sweden)

    Hilkka Koponen

    1992-12-01

    Full Text Available The effect of seven disinfectants on Clavibacter michiganensis subsp. sepedonicus and Erwinia carotovora subsp. atroseptica was tested on metal, plastic and wood surfaces in laboratory trials. lobac P was the most effective disinfectant in the control of E. carotovora on clean and dirty surfaces. Ipasept and Menno-Ter-forte were effective on plastic surfaces, but dirt reduced their efficacy. The least effective preparations were Deskem-1, Virkon S and Korsolin. lobac P, Korsolin and Virkon S were the most effective disinfectants against C. michiganensis. The efficacy of Ipasept and Menno-Ter-forte was reduced by dirt. The least effective preparation was Deskem-1.

  11. [The sugar cane blight of the 1860s: science applied to agriculture].

    Science.gov (United States)

    Bediaga, Begonha

    2012-12-01

    The Imperial Instituto Fluminense de Cultura (Fluminense Imperial Institute of Agriculture) encouraged debate with a view to eradicating the blight that devastated sugar cane plantations in the State of Bahia. Rural landowners, government officials and men of science participated in the discussions. The article presents the context of the sciences applied to agriculture, especially agricultural chemistry and the repercussions of the 'discoveries' of Justus Liebig in Brazil. The debate at the Imperial Instituto about the sugar cane blight was analyzed, together with the ideas espoused there and the characters involved in the issue. The procedures and solutions presented are studied, as well as the formation of knowledge networks around the agricultural sciences, which was in the process of institutionalization at the time.

  12. Fusarium species as pathogen on orchids.

    Science.gov (United States)

    Srivastava, Shikha; Kadooka, Chris; Uchida, Janice Y

    2018-03-01

    The recent surge in demand for exotic ornamental crops such as orchids has led to a rise in international production, and a sharp increase in the number of plant and plant products moving between countries. Along with the plants, diseases are also being transported and introduced into new areas. Fusarium is one of the major diseases causing pathogens infecting orchids that is spreading through international trade. Studies have identified several species of Fusarium associated with orchids, some are pathogenic and cause symptoms such as leaf and flower spots, leaf or sheath blights, pseudostem or root rots, and wilts. Infection and damage caused by Fusarium reduces the quality of plants and flowers, and can cause severe economic losses. This review documents the current status of the Fusarium-orchid interaction, and illustrates challenges and future perspectives based on the available literature. This review is the first of Fusarium and orchid interactions, and integrates diverse results that both furthers the understanding and knowledge of this disease complex, and will enable the development of effective disease management practices. Copyright © 2017 Elsevier GmbH. All rights reserved.

  13. Potential of Microbispora sp. V2 as biocontrol agent against Sclerotium rolfsii, the causative agent of southern blight of Zea mays L (Baby corn)--in vitro studies.

    Science.gov (United States)

    Patil, N N; Waghmode, M S; Gaikwad, P S; Gajbhiye, M H; Gunjal, A B; Nawani, N N; Kapadnis, B P

    2014-11-01

    The study was undertaken with the aim of exploring novel and beneficial agro activities of rare actinomycetes like Microbispora sp. V2. The antagonistic activity of Microbispora sp. V2 was evaluated as a biocontrol agents against Sclerotium rolfsii, a soil-borne fungal plant pathogen. The methodology performed for evaluation of biocontrol agent was in vitro evaluation assay which comprised of three tests viz., cellophane overlay technique, seed germination test and Thiram (fungicide) tolerance of Microbispora sp. V2. The isolate was found to inhibit the fungal pathogen Sclerotium rolfsii to 91.43% in cellophane assay. In seed germination assay, Microbispora sp. V2 treated seeds resulted in 25.75% increased germination efficiency, as compared to seeds infected by Sclerotium rolfsii. The isolate Microbispora sp. V2 could tolerate 1000 microg mL(-1) of Thiram (fungicide). The in vitro assay studies proved that Microbispora sp. V2 can be used as antifungal antagonist and thus posses' great potential as biocontrol agent against southern blight caused by Sclerotium rolfsii in Zea mays L (Baby corn) which causes large economical losses.

  14. Analysis of DNA methylation related to rice adult plant resistance to bacterial blight based on methylation-sensitive AFLP (MSAP) analysis.

    Science.gov (United States)

    Sha, A H; Lin, X H; Huang, J B; Zhang, D P

    2005-07-01

    DNA methylation is known to play an important role in the regulation of gene expression in eukaryotes. The rice cultivar Wase Aikoku 3 becomes resistant to the blight pathogen Xanthomonas oryzae pv. oryzae at the adult stage. Using methylation-sensitive amplified polymorphism (MSAP) analysis, we compared the patterns of cytosine methylation in seedlings and adult plants of the rice cultivar Wase Aikoku 3 that had been inoculated with the pathogen Xanthomonas oryzae pv. oryzae, subjected to mock inoculation or left untreated. In all, 2000 DNA fragments, each representing a recognition site cleaved by either or both of two isoschizomers, were amplified using 60 pairs of selective primers. A total of 380 sites were found to be methylated. Of these, 45 showed differential cytosine methylation among the seedlings and adult plants subjected to different treatments, and overall levels of methylation were higher in adult plants than in seedlings. All polymorphic fragments were sequenced, and six showed homology to genes that code for products of known function. Northern analysis of three fragments indicated that their expression varied with methylation pattern, with hypermethylation being correlated with repression of transcription, as expected. The results suggest that significant differences in cytosine methylation exist between seedlings and adult plants, and that hypermethylation or hypomethylation of specific genes may be involved in the development of adult plant resistance (APR) in rice plants.

  15. Screening for resistance to Fusarium head blight in spring wheat cultivars

    OpenAIRE

    Scholten, Dr. Olga E.; Steenhuis-Broers, Greet; Osman, Aart; Bremer, Esther

    2006-01-01

    Fusarium fungi cause Fusarium head blight in wheat. This disease is a problem that occurs both in organic and conventional farming systems. As Fusarium fungi produce mycotoxins in wheat kernels they are a threat to human and animal health. Breeding for disease resistance is the only way to prevent or reduce the occurrence of the disease. The aim of the current research project is to identify different mechanisms of resistance in cultivars and breeding lines to be used in further breeding pro...

  16. Sweetgum Blight as Related to Alluvial Soils of the Mississippi River Floodplain

    Science.gov (United States)

    E. Richard Toole; W. M. Broadfoot

    1959-01-01

    A BLIGHT OF UNKNOWN origin and cause has been very common throughout much of the range of sweetgum (Liquidambar styraci flua L.) since 1950. It is characterized by a gradual dying of the tree, often from the top down. The first visible indication is a thinning of a portion of the crown, caused when some buds fail to open and others produce only dwarfed, yellowish...

  17. Resistant and susceptible responses in alfalfa (Medicago sativa to bacterial stem blight caused by Pseudomonas syringae pv. syringae.

    Directory of Open Access Journals (Sweden)

    Lev G Nemchinov

    Full Text Available Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L. Little is known about host-pathogen interactions and host defense mechanisms. Here, individual resistant and susceptible plants were selected from cultivars Maverick and ZG9830 and used for transcript profiling at 24 and 72 hours after inoculation (hai with the isolate PssALF3. Bioinformatic analysis revealed a number of differentially expressed genes (DEGs in resistant and susceptible genotypes. Although resistant plants from each cultivar produced a hypersensitive response, transcriptome analyses indicated that they respond differently at the molecular level. The number of DEGs was higher in resistant plants of ZG9830 at 24 hai than in Maverick, suggesting that ZG9830 plants had a more rapid effector triggered immune response. Unique up-regulated genes in resistant ZG9830 plants included genes encoding putative nematode resistance HSPRO2-like proteins, orthologs for the rice Xa21 and soybean Rpg1-b resistance genes, and TIR-containing R genes lacking both NBS and LRR domains. The suite of R genes up-regulated in resistant Maverick plants had an over-representation of R genes in the CC-NBS-LRR family including two genes for atypical CCR domains and a putative ortholog of the Arabidopsis RPM1 gene. Resistance in both cultivars appears to be mediated primarily by WRKY family transcription factors and expression of genes involved in protein phosphorylation, regulation of transcription, defense response including synthesis of isoflavonoids, and oxidation-reduction processes. These results will further the identification of mechanisms involved in resistance to facilitate selection of parent populations and development of commercial varieties.

  18. QTL and candidate genes associated with common bacterial blight resistance in the common bean cultivar Longyundou 5 from China

    Institute of Scientific and Technical Information of China (English)

    Jifeng Zhu; Jing Wu; Lanfen Wang; Matthew W. Blair; Zhendong Zhu; Shumin Wang

    2016-01-01

    Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans (Xff), is a worldwide disease of common bean (Phaseolus vulgaris L.). Longyundou 5, a Chinese cultivar in the Mesoamerican gene pool of common bean, displays resistance to the Xff strain XSC3-1. To identify the genetic mechanisms behind this resistance, we crossed Long 5 with a susceptible genotype to develop a mapping population of F2 plants. Plant resistance to CBB was identified at 14 and 21 days after inoculation with Xff strain XSC3-1. A major QTL at 14 and 21 days after inoculation was mapped on chromosome Pv10 with LOD scores of 6.41 and 5.35, respectively. This locus was associated with SAP6, a previously-identified and much-used dominant marker, but in a 4.2 cM interval between new codominant markers BMp10s174 and BMp10s244. Ten candidate genes were found between markers BMp10s174 and BMp10s244 on chromosome Pv10 and could encode defense response proteins responding to CBB pathogens. Four pairs each of epistatic QTL for CBB resistance were detected at 14 and 21 days after inoculation. Phenotypic variation explained by the epistatic QTL ranged from 7.19%to 12.15%and 7.72%to 8.80%at 14 and 21 days after inoculation, respectively. These results confirmed the importance of epistasis in CBB resistance in common bean. The adjacent markers found may be more efficient for marker assisted selection in common bean breeding for CBB resistance owing to their closer linkage to the target QTL.

  19. QTL and candidate genes associated with common bacterial blight resistance in the common bean cultivar Longyundou 5 from China

    Institute of Scientific and Technical Information of China (English)

    Jifeng; Zhu; Jing; Wu; Lanfen; Wang; Matthew; W.Blair; Zhendong; Zhu; Shumin; Wang

    2016-01-01

    Common bacterial blight(CBB), caused by Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans(Xff), is a worldwide disease of common bean(Phaseolus vulgaris L.).Longyundou 5, a Chinese cultivar in the Mesoamerican gene pool of common bean, displays resistance to the Xff strain XSC3-1. To identify the genetic mechanisms behind this resistance,we crossed Long 5 with a susceptible genotype to develop a mapping population of F2 plants.Plant resistance to CBB was identified at 14 and 21 days after inoculation with Xff strain XSC3-1.A major QTL at 14 and 21 days after inoculation was mapped on chromosome Pv10 with LOD scores of 6.41 and 5.35, respectively. This locus was associated with SAP6, a previouslyidentified and much-used dominant marker, but in a 4.2 cM interval between new codominant markers BMp10s174 and BMp10s244. Ten candidate genes were found between markers BMp10s174 and BMp10s244 on chromosome Pv10 and could encode defense response proteins responding to CBB pathogens. Four pairs each of epistatic QTL for CBB resistance were detected at 14 and 21 days after inoculation. Phenotypic variation explained by the epistatic QTL ranged from 7.19% to 12.15% and 7.72% to 8.80% at 14 and 21 days after inoculation, respectively. These results confirmed the importance of epistasis in CBB resistance in common bean. The adjacent markers found may be more efficient for marker assisted selection in common bean breeding for CBB resistance owing to their closer linkage to the target QTL.

  20. Biological control of fusarium seedling blight disease of wheat and barley.

    Science.gov (United States)

    Khan, Mojibur R; Fischer, Sven; Egan, Damian; Doohan, Fiona M

    2006-04-01

    ABSTRACT Fusarium fungi, including F. culmorum, cause seedling blight, foot rot, and head blight diseases of cereals, resulting in yield loss. In a screen for potential disease control organisms and agents, Pseudomonas fluorescens strains MKB 100 and MKB 249, P. frederiksbergensis strain 202, Pseudomonas sp. strain MKB 158, and chitosan all significantly reduced the extent of both wheat coleoptile growth retardation and wheat and barley seedling blight caused by F. culmorum (by 53 to 91%). Trichodiene synthase is a Fusarium enzyme necessary for trichothecene mycotoxin biosynthesis; expression of the gene encoding this enzyme in wheat was 33% lower in stem base tissue coinoculated with Pseudomonas sp. strain MKB 158 and F. culmorum than in wheat treated with bacterial culture medium and F. culmorum. When wheat and barley were grown in soil amended with either chitosan, P. fluorescens strain MKB 249, Pseudomonas sp. strain MKB 158, or culture filtrates of these bacteria, the level of disease symptoms on F. culmorum-inoculated stem base tissue (at 12 days post- F. culmorum inoculation) was >/=31% less than the level on F. culmorum-inoculated plants grown in culture medium-amended soil. It seems likely that at least part of the biocontrol activity of these bacteria and chitosan may be due to the induction of systemic disease resistance in host plants. Also, in coinoculation studies, Pseudomonas sp. strain MKB 158 induced the expression of a wheat class III plant peroxidase gene (a pathogenesis-related gene).

  1. Anthesis, the infectious process and disease progress curves for fusarium head blight in wheat

    Directory of Open Access Journals (Sweden)

    Erlei Melo Reis

    2016-06-01

    Full Text Available ABSTRACT Fusarium head blight of wheat (Triticum aestivum, caused by the fungus Gibberella zeae, is a floral infecting disease that causes quantitative and qualitative losses to winter cereals. In Brazil, the sanitary situation of wheat has led to research in order to develop strategies for sustainable production, even under adverse weather conditions. To increase the knowledge of the relationship among the presence of anthesis, the infectious process, the disease progress and the saprophytic fungi present in wheat anthers, studies were conducted in the experimental field of University of Passo Fundo (UPF, using the cultivar Marfim, in the 2011 growing season. The disease incidence in spikes and spikelets was evaluated. The presence of exserted anthers increased the spike exposure time to the inoculum. The final incidence of fusarium head blight, in the field, was dependent on the presence of exserted anthers. The disease followed an aggregation pattern and its evolution increased with time, apparently showing growth according to secondary cycles. The fungi isolated from exserted anthers (Alternaria sp., Fusarium sp., Drechslera spp. and Epicoccum sp. did not compete for the infection site of fusarium head blight in wheat, not interfering with the incidence of F. graminearum.

  2. Association between QTLs and morphological traits toward sheath blight resistance in rice (Oryza sativa L.)

    Science.gov (United States)

    Hossain, Md Kamal; Jena, Kshirod Kumar; Bhuiyan, Md Atiqur Rahman; Wickneswari, Ratnam

    2016-01-01

    Sheath blight is considered the most significant disease of rice and causes enormous yield losses over the world. Breeding for resistant varieties is the only viable option to combat the disease efficiently. Seventeen diverged rice genotypes along with 17 QTL-linked SSR markers were evaluated under greenhouse conditions. Pearson’s correlation showed only the flag leaf angle had a significant correlation with sheath blight resistance under greenhouse screening. Multivariate analysis based on UPGMA clustering and principal component analysis (PCA) indicated that the flag leaf angle, flag leaf length, and plant compactness were significantly associated with the following SSR marker alleles: RM209 (116,130), RM202 (176), RM224 (126), RM257 (156), RM426 (175), and RM6971 (196), which are linked to the SB QTLs: QRlh11, qSBR11-3, qSBR11-1, qSBR9-1, qShB3-2, and qSB-9. A Mantel test suggested a weak relationship between the observed phenotypes and allelic variation patterns, implying the independent nature of morphological and molecular variations. Teqing and Tetep were found to be the most resistant cultivars. IR65482-4-136-2-2, MR219-4, and MR264 showed improved resistance potentials. These results suggest that the morphological traits and QTLs which have been found to associate with sheath blight resistance are a good choice to enhance resistance through pyramiding either 2 QTLs or QTLs and traits in susceptible rice cultivars. PMID:27795687

  3. In vitro induction of variability through radiation for late blight resistance and heat tolerance in potato

    International Nuclear Information System (INIS)

    Gosal, S.S.; Das, A.; Gopal, J.; Minocha, J.L.; Chopra, H.R.; Dhaliwal, H.S.

    2001-01-01

    In vitro cultured shoots of potato, cvs. 'Kufri Jyoti' and 'Kufri Chandramukhi', were irradiated with 20 and 40 Gy gamma rays. Microtubers, obtained from MIV3 shoots multiplied in vitro, were planted in pots. The resulting plants were screened for resistance to late blight, using detached leaf method. In 'Kufri Chandramukhi', 42% plants and in 'Kufri Jyoti' 36% plants, obtained from 40 Gy treatment, showed resistance to late blight. The frequency of resistant plants was lower from 20 Gy treatment. The progenies of putatively resistant plants were grown in field, and inoculated with sporangial inoculum of late blight fungus. The field grown progeny segregated for disease resistance, and approximately 56% plants showed resistance. During the next propagation, the frequency of resistant plants increased to 72%. For developing heat tolerance, microtubers obtained from 20 and 40 Gy treatments and in vitro multiplied M 1 V 3 shoots were cultured at high temperature of 28C. In both varieties, the number of the microtubers per plant was highly reduced and the resulting microtubers had distorted shape but showed better germination (62%), even in early sowing at relatively higher temperature. Of the two radiation doses, the higher dose of 40 Gy gave better results in both the varieties. Heat tolerance was also assessed from chlorophyll persistence. The progenies from putative heat-tolerant plants were tested in field by planting at higher temperature in two subsequent generations. The heat tolerant plants segregated in each generation, but the frequency of heat-tolerant plants increased. (author)

  4. Crystallization and preliminary crystallographic analysis of l-asparaginase from Erwinia carotovora

    International Nuclear Information System (INIS)

    Wikman, Linnea E. K.; Krasotkina, Julya; Kuchumova, Anastasia; Sokolov, Nikolay N.; Papageorgiou, Anastassios C.

    2005-01-01

    Er. carotovoral-asparaginase, a potential antileukaemic agent, has been crystallized. Crystals diffract to 2.6 Å using a rotating-anode source and belong to space group P2 1 , with unit-cell parameters a = 78.0, b = 112.3, c = 78.7 Å, β = 101.9° and a homotetramer in the crystallographic asymmetric unit. Bacterial l-asparaginases have been used as therapeutic agents in the treatment of acute childhood lymphoblastic leukaemia for over 30 y. However, their use is limited owing to the glutaminase activity of the administered enzymes, which results in serious side effects. In contrast, l-asparaginase from Erwinia carotovora exhibits low glutaminase activity at physiological concentrations of l-asparagine and l-glutamine in the blood. Recombinant Er. carotovoral-asparaginase was crystallized in the presence of l-glutamate by the hanging-drop vapour-diffusion method using 10 mg ml −1 purified enzyme, 16–18%(w/v) PEG 3350 and 0.2 M NaF. X-ray diffraction data were collected to 2.6 Å at 293 K using an in-house rotating-anode generator. The crystals belong to the monoclinic P2 1 space group, with unit-cell parameters a = 78.0, b = 112.3, c = 78.7 Å, β = 101.9° and a homotetramer in the crystallographic asymmetric unit. A molecular-replacement solution has been found and refinement is currently in progress. The crystal structure may provide leads towards protein-engineering efforts aimed at safer asparaginase administration in leukaemia treatment

  5. Genetic and virulence variability among Erwinia tracheiphila strains recovered from different cucurbit hosts.

    Science.gov (United States)

    Rojas, E Saalau; Dixon, P M; Batzer, J C; Gleason, M L

    2013-09-01

    The causal agent of cucurbit bacterial wilt, Erwinia tracheiphila, has a wide host range in the family Cucurbitaceae, including economically important crops such as muskmelon (Cucumis melo), cucumber (C. sativus), and squash (Cucurbita spp.). Genetic variability of 69 E. tracheiphila strains was investigated by repetitive-element polymerase chain reaction (rep-PCR) using BOXA1R and ERIC1-2 primers. Fingerprint profiles revealed significant variability associated with crop host; strains isolated from Cucumis spp. were clearly distinguishable from Cucurbita spp.-isolated strains regardless of geographic origin. Twelve E. tracheiphila strains isolated from muskmelon, cucumber, or summer squash were inoculated onto muskmelon and summer squash seedlings, followed by incubation in a growth chamber. Wilt symptoms were assessed over 3 weeks, strains were reisolated, and rep-PCR profiles were compared with the inoculated strains. Wilting occurred significantly faster when seedlings were inoculated with strains that originated from the same crop host genus (P<0.001). In the first run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon seedlings at a median of 7.8 and 5.6 days after inoculation (dai), respectively. Summer squash seedlings wilted 18.0, 15.7, and 5.7 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. In a second run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon at 7.0 and 6.9 dai, respectively, whereas summer squash seedlings wilted at 23.6, 29.0 and 9.0 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. Our results provide the first evidence of genetic diversity within E. tracheiphila and suggest that strain specificity is associated with plant host. This advance is a first step toward understanding the genetic and population structure of E. tracheiphila.

  6. Crystallization and preliminary crystallographic analysis of l-asparaginase from Erwinia carotovora

    Energy Technology Data Exchange (ETDEWEB)

    Wikman, Linnea E. K. [Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20521 (Finland); Krasotkina, Julya; Kuchumova, Anastasia; Sokolov, Nikolay N. [Institute for Biomedical Chemistry, Russian Academy of Medical Sciences, 559-B, 10 Pogodinskay St, Moscow 119121 (Russian Federation); Papageorgiou, Anastassios C., E-mail: tassos.papageorgiou@btk.fi [Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20521 (Finland)

    2005-04-01

    Er. carotovoral-asparaginase, a potential antileukaemic agent, has been crystallized. Crystals diffract to 2.6 Å using a rotating-anode source and belong to space group P2{sub 1}, with unit-cell parameters a = 78.0, b = 112.3, c = 78.7 Å, β = 101.9° and a homotetramer in the crystallographic asymmetric unit. Bacterial l-asparaginases have been used as therapeutic agents in the treatment of acute childhood lymphoblastic leukaemia for over 30 y. However, their use is limited owing to the glutaminase activity of the administered enzymes, which results in serious side effects. In contrast, l-asparaginase from Erwinia carotovora exhibits low glutaminase activity at physiological concentrations of l-asparagine and l-glutamine in the blood. Recombinant Er. carotovoral-asparaginase was crystallized in the presence of l-glutamate by the hanging-drop vapour-diffusion method using 10 mg ml{sup −1} purified enzyme, 16–18%(w/v) PEG 3350 and 0.2 M NaF. X-ray diffraction data were collected to 2.6 Å at 293 K using an in-house rotating-anode generator. The crystals belong to the monoclinic P2{sub 1} space group, with unit-cell parameters a = 78.0, b = 112.3, c = 78.7 Å, β = 101.9° and a homotetramer in the crystallographic asymmetric unit. A molecular-replacement solution has been found and refinement is currently in progress. The crystal structure may provide leads towards protein-engineering efforts aimed at safer asparaginase administration in leukaemia treatment.

  7. Fungi of the genus Fusarium as pathogens of soybean seedlings

    Directory of Open Access Journals (Sweden)

    Joanna Marcinkowska

    2013-12-01

    Full Text Available Twenty isolates of fungi of the genus Fusarium collected in the period 1980-1982 from various organs of diseased soybean plants were investigated. Eight of them proved pathogenic to soybean seedlings. The species F. culmorum was most numerously represented among the isolated (4 of 8 pathogens. Isolates of F. sambucinum were also pathogenic (2 of 4 and those of F. soloni (1 of 3, too. The only isolate of F. avenaceum also caused seedling blight. Two isolates of F. oxysporum and two of F. arthrosporioides were not pathogenic. Numerous isolates affected seed gernination and one greatly inhibited growth of the infected seedlings. Pathogenicity was tested in the laboratory in Petri plates on isolate cultures and on filter paper imbibed with fungal inoculum and, in the greenhouse on a peat and perlite substrate. The degree of infection and the character of the disease symptoms depended on the experimental conditions. The results of experiments in plates and in the greenhouse supplemented one another.

  8. Foodborne pathogens

    Directory of Open Access Journals (Sweden)

    Thomas Bintsis

    2017-06-01

    Full Text Available Foodborne pathogens are causing a great number of diseases with significant effects on human health and economy. The characteristics of the most common pathogenic bacteria (Bacillus cereus, Campylobacter jejuni, Clostridium botulinum, Clostridium perfringens, Cronobacter sakazakii, Esherichia coli, Listeria monocytogenes, Salmonella spp., Shigella spp., Staphylococccus aureus, Vibrio spp. and Yersinia enterocolitica, viruses (Hepatitis A and Noroviruses and parasites (Cyclospora cayetanensis, Toxoplasma gondii and Trichinella spiralis, together with some important outbreaks, are reviewed. Food safety management systems based on to classical hazard-based approach has been proved to be inefficient, and risk-based food safety approach is now suggested from leading researchers and organizations. In this context, a food safety management system should be designed in a way to estimate the risks to human health from food consumption and to identify, select and implement mitigation strategies in order to control and reduce these risks. In addition, the application of suitable food safety education programs for all involved people in the production and consumption of foods is suggested.

  9. Outcome of pediatric patients with acute lymphoblastic leukemia/lymphoblastic lymphoma with hypersensitivity to pegaspargase treated with PEGylated Erwinia asparaginase, pegcrisantaspase: A report from the Children's Oncology Group

    Science.gov (United States)

    Rau, Rachel E.; Dreyer, ZoAnn; Choi, Mi Rim; Liang, Wei; Skowronski, Roman; Allamneni, Krishna P.; Devidas, Meenakshi; Raetz, Elizabeth A.; Adamson, Peter C.; Blaney, Susan M.; Loh, Mignon L; Hunger, Stephen P.

    2018-01-01

    Background Erwinia asparaginase is a Food and Drug Administration approved agent for the treatment of acute lymphoblastic leukemia (ALL) for patients who develop hypersensitivity to Escherichia coli derived asparaginases. Erwinia asparaginase is efficacious, but has a short half-life, requiring six doses to replace one dose of the most commonly used first-line asparaginase, pegaspargase, a polyethylene glycol (PEG) conjugated E. coli asparaginase. Pegcristantaspase, a recombinant PEGylated Erwinia asparaginase with improved pharmacokinetics, was developed for patients with hypersensitivity to pegaspargase. Here, we report a series of patients treated on a pediatric phase 2 trial of pegcrisantaspase. Procedure Pediatric patients with ALL or lymphoblastic lymphoma and hypersensitivity to pegaspargase enrolled on Children's Oncology Group trial AALL1421 (Jazz 13-011) and received intravenous pegcrisantaspase. Serum asparaginase activity (SAA) was monitored before and after dosing; immunogenicity assays were performed for antiasparaginase and anti-PEG antibodies and complement activation was evaluated. Results Three of the four treated patients experienced hypersensitivity to pegcrisantaspase manifested as clinical hypersensitivity reactions or rapid clearance of SAA. Immunogenicity assays demonstrated the presence of anti-PEG immunoglobulin G antibodies in all three hypersensitive patients, indicating a PEG-mediated immune response. Conclusions This small series of patients, nonetheless, provides data, suggesting preexisting immunogenicity against the PEG moiety of pegaspargase and poses the question as to whether PEGylation may be an effective strategy to optimize Erwinia asparaginase administration. Further study of larger cohorts is needed to determine the incidence of preexisting antibodies against PEG-mediated hypersensitivity to pegaspargase. PMID:29090524

  10. Efficacies of quorum sensing inhibitors, piericidin A and glucopiericidin A, produced by Streptomyces xanthocidicus KPP01532 for the control of potato soft rot caused by Erwinia carotovora subsp. atroseptica.

    Science.gov (United States)

    Kang, Ji Eun; Han, Jae Woo; Jeon, Byeong Jun; Kim, Beom Seok

    2016-03-01

    To discover potential inhibitors of the quorum sensing (QS) system, a library of microbial culture extracts was screened with Chromobacterium violaceumCV026 strain. The culture extract of Streptomyces xanthocidicus KPP01532 contained quorum-sensing inhibitors (QSIs) of the CV026 strain. The active constituents of the culture extract of strain KPP01532 were purified using a series of chromatographic procedures, and based on data from NMR and mass spectroscopy, piericidin A and glucopiericidin A were identified. Erwinia carotovora subsp. atroseptica (Eca) is a plant pathogen that causes blackleg and soft rot diseases on potato stems and tubers. The virulence factors of Eca are regulated by QS. The expression of virulence genes (pelC, pehA, celV and nip) under the control of QS was monitored using quantitative real-time PCR (qRT-PCR). The transcription levels of the four genes were significantly lower when Eca was exposed to piericidin A or glucopiericidin A. These two compounds displayed similar control efficacies against soft rot caused by Eca in potato slices as furanone C-30. Therefore, piericidin A and glucopiericidin A are potential QSIs that suppress the expression of the virulence genes of Eca, suggesting that they could have potential use as control agents of soft rot disease on potato tubers. Copyright © 2015 Elsevier GmbH. All rights reserved.

  11. The crystal structure of Erwinia amylovora AmyR, a member of the YbjN protein family, shows similarity to type III secretion chaperones but suggests different cellular functions.

    Science.gov (United States)

    Bartho, Joseph D; Bellini, Dom; Wuerges, Jochen; Demitri, Nicola; Toccafondi, Mirco; Schmitt, Armin O; Zhao, Youfu; Walsh, Martin A; Benini, Stefano

    2017-01-01

    AmyR is a stress and virulence associated protein from the plant pathogenic Enterobacteriaceae species Erwinia amylovora, and is a functionally conserved ortholog of YbjN from Escherichia coli. The crystal structure of E. amylovora AmyR reveals a class I type III secretion chaperone-like fold, despite the lack of sequence similarity between these two classes of protein and lacking any evidence of a secretion-associated role. The results indicate that AmyR, and YbjN proteins in general, function through protein-protein interactions without any enzymatic action. The YbjN proteins of Enterobacteriaceae show remarkably low sequence similarity with other members of the YbjN protein family in Eubacteria, yet a high level of structural conservation is observed. Across the YbjN protein family sequence conservation is limited to residues stabilising the protein core and dimerization interface, while interacting regions are only conserved between closely related species. This study presents the first structure of a YbjN protein from Enterobacteriaceae, the most highly divergent and well-studied subgroup of YbjN proteins, and an in-depth sequence and structural analysis of this important but poorly understood protein family.

  12. Role of the PhoP-PhoQ system in the virulence of Erwinia chrysanthemi strain 3937: involvement in sensitivity to plant antimicrobial peptides, survival at acid Hh, and regulation of pectolytic enzymes.

    Science.gov (United States)

    Llama-Palacios, Arancha; López-Solanilla, Emilia; Rodríguez-Palenzuela, Pablo

    2005-03-01

    Erwinia chrysanthemi is a phytopathogenic bacterium that causes soft-rot diseases in a broad number of crops. The PhoP-PhoQ system is a key factor in pathogenicity of several bacteria and is involved in the bacterial resistance to different factors, including acid stress. Since E. chrysanthemi is confronted by acid pH during pathogenesis, we have studied the role of this system in the virulence of this bacterium. In this work, we have isolated and characterized the phoP and phoQ mutants of E. chrysanthemi strain 3937. It was found that: (i) they were not altered in their growth at acid pH; (ii) the phoQ mutant showed diminished ability to survive at acid pH; (iii) susceptibility to the antimicrobial peptide thionin was increased; (iv) the virulence of the phoQ mutant was diminished at low and high magnesium concentrations, whereas the virulence of the phoP was diminished only at low magnesium concentrations; (v) in planta Pel activity of both mutant strains was drastically reduced; and (vi) both mutants lagged behind the wild type in their capacity to change the apoplastic pH. These results suggest that the PhoP-PhoQ system plays a role in the virulence of this bacterium in plant tissues, although it does not contribute to bacterial growth at acid pH.

  13. Global regulators ExpA (GacA) and KdgR modulate extracellular enzyme gene expression through the RsmA-rsmB system in Erwinia carotovora subsp. carotovora.

    Science.gov (United States)

    Hyytiäinen, H; Montesano, M; Palva, E T

    2001-08-01

    The production of the main virulence determinants, the extracellular plant cell wall-degrading enzymes, and hence virulence of Erwinia carotovora subsp. carotovora is controlled by a complex regulatory network. One of the global regulators, the response regulator ExpA, a GacA homolog, is required for transcriptional activation of the extracellular enzyme genes of this soft-rot pathogen. To elucidate the mechanism of ExpA control as well as interactions with other regulatory systems, we isolated second-site transposon mutants that would suppress the enzyme-negative phenotype of an expA (gacA) mutant. Inactivation of kdgR resulted in partial restoration of extracellular enzyme production and virulence to the expA mutant, suggesting an interaction between the two regulatory pathways. This interaction was mediated by the RsmA-rsmB system. Northern analysis was used to show that the regulatory rsmB RNA was under positive control of ExpA. Conversely, the expression of rsmA encoding a global repressor was under negative control of ExpA and positive control of KdgR. This study indicates a central role for the RsmA-rsmB regulatory system during pathogenesis, integrating signals from the ExpA (GacA) and KdgR global regulators of extracellular enzyme production in E. carotovora subsp. carotovora.

  14. Production of isomaltulose obtained by Erwinia sp. cells submitted to different treatments and immobilized in calcium alginate

    Directory of Open Access Journals (Sweden)

    Haroldo Yukio Kawaguti

    2011-03-01

    Full Text Available In recent decades, there has been an increase in the studies of isomaltulose obtainment, due to its physicochemical properties and physiological health benefits. These properties, which include low cariogenicity, low glycemic index and greater stability, allow the use of this sweetener as a substitute for sucrose in foods; besides the fact that it can be converted to isomalt, a dietary non-cariogenic sugar alcohol used in pharmaceuticals as well as in the food industry. Isomaltulose (6-O-α-D-glucopyronosyl-1-6-D-fructofuranose is a disaccharide reducer obtained by the enzymatic conversion of sucrose - the α-glucosyltransferase enzyme. Different treatments were performed for the preparation of whole cells; lysed cells; and crude enzyme extract of Erwinia sp. D12 strain immobilized in calcium alginate. The packed bed column of granules, containing Erwinia sp. cells sonicated and immobilized in calcium alginate (CSI, reached a maximum conversion of 53-59% sucrose into isomaltulose and it presented activity for 480 hours. The converted syrup was purified and the isomaltulose crystallization was performed through the lowering of temperature. The isomaltulose crystals presented purity of 96.5%.

  15. Analysis of Erwinia chrysanthemi EC16 pelE::uidA, pelL::uidA, and hrpN::uidA mutants reveals strain-specific atypical regulation of the Hrp type III secretion system.

    Science.gov (United States)

    Ham, Jong Hyun; Cui, Yaya; Alfano, James R; Rodríguez-Palenzuela, Pablo; Rojas, Clemencia M; Chatterjee, Arun K; Collmer, Alan

    2004-02-01

    The plant pathogen Erwinia chrysanthemi produces a variety of factors that have been implicated in its ability to cause soft-rot diseases in various hosts. These include HrpN, a harpin secreted by the Hrp type III secretion system; PelE, one of several major pectate lyase isozymes secreted by the type II system; and PelL, one of several secondary Pels secreted by the type II system. We investigated these factors in E. chrysanthemi EC16 with respect to the effects of medium composition and growth phase on gene expression (as determined with uidA fusions and Northern analyses) and effects on virulence. pelE was induced by polygalacturonic acid, but pelL was not, and hrpN was expressed unexpectedly in nutrient-rich King's medium B and in minimal salts medium at neutral pH. In contrast, the effect of medium composition on hrp expression in E. chrysanthemi CUCPB1237 and 3937 was like that of many other phytopathogenic bacteria in being repressed in complex media and induced in acidic pH minimal medium. Northern blot analysis of hrpN and hrpL expression by the wild-type and hrpL::omegaCmr and hrpS::omegaCmr mutants revealed that hrpN expression was dependent on the HrpL alternative sigma factor, whose expression, in turn, was dependent on the HrpS putative sigma54 enhancer binding protein. The expression of pelE and hrpN increased strongly in late logarithmic growth phase. To test the possible role of quorum sensing in this expression pattern, the expI/expR locus was cloned in Escherichia coli on the basis of its ability to direct production of acyl-homoserine lactone and then used to construct expI mutations in pelE::uidA, pelL::uidA, and hrpN::uidA Erwinia chrysanthemi strains. Mutation of expI had no apparent effect on the growth-phase-dependent expression of hrpN and pelE, or on the virulence of E. chrysanthemi in witloof chicory leaves. Overexpression of hrpN in E. chrysanthemi resulted in approximately 50% reduction of lesion size on chicory leaves without an

  16. Coincidence in map positions between pathogen-induced defense-responsive genes and quantitative resistance loci in rice

    Institute of Scientific and Technical Information of China (English)

    熊敏; 王石平; 张启发

    2002-01-01

    Quantitative disease resistance conferred by quantitative trait loci (QTLs) is presumably of wider spectrum and durable. Forty-four cDNA clones, representing 44 defense-responsive genes, were fine mapped to 56 loci distributed on 9 of the 12 rice chromosomes. The locations of 32 loci detected by 27 cDNA clones were associated with previously identified resistance QTLs for different rice diseases, including blast, bacterial blight, sheath blight and yellow mottle virus. The loci detected by the same multiple-copy cDNA clones were frequently located on similar locations of different chromosomes. Some of the multiple loci detected by the same clones were all associated with resistance QTLs. These results suggest that some of the genes may be important components in regulation of defense responses against pathogen invasion and they may be the candidates for studying the mechanism of quantitative disease resistance in rice.

  17. Root treatment with rhizobacteria antagonistic to Phytophthora blight affects anthracnose occurrence, ripening, and yield of pepper fruit in the plastic house and field.

    Science.gov (United States)

    Sang, Mee Kyung; Kim, Jeong Do; Kim, Beom Seok; Kim, Ki Deok

    2011-06-01

    We previously selected rhizobacterial strains CCR04, CCR80, GSE09, ISE13, and ISE14, which were antagonistic to Phytophthora blight of pepper. In this study, we investigated the effects of root treatment of rhizobacteria on anthracnose occurrence, ripening, and yield of pepper fruit in the plastic house and field in 2008 and 2009. We also examined the effects of volatiles produced by the strains on fruit ripening and on mycelial growth and spore development of Colletotrichum acutatum and Phytophthora capsici in the laboratory, identifying the volatile compounds by gas chromatography-mass spectrometry (GC-MS). In the house tests, all strains significantly (P anthracnose incidence on pepper fruit; strains GSE09 and ISE14 consistently produced higher numbers of pepper fruit or increased the fresh weight of red fruit more than the controls in both years. In the field tests, all strains significantly (P anthracnose occurrence on either green or red pepper fruit; strain ISE14 consistently produced higher numbers or increased fresh weights of red fruit more than the controls in both years. In the laboratory tests, volatiles produced by strains GSE09 and ISE13 only stimulated maturation of pepper fruit from green (unripe) to red (ripe) fruit; the volatiles of certain strains inhibited the growth and development of C. acutatum and P. capsici. On the other hand, GC-MS analysis of volatiles of strains GSE09 and ISE13 revealed 17 distinct compounds in both strains, including decane, dodecane, 1,3-di-tert-butylbenzene, tetradecane, 2,4-di-tert-butylphenol, and hexadecane. Among these compounds, 2,4-di-tert-butylphenol only stimulated fruit ripening and inhibited growth and development of the pathogens. Taken together, strains GSE09 and ISE14 effectively reduced anthracnose occurrence and stimulated pepper fruit ripening and yield, possibly via bacterial volatiles. Therefore, these two strains could be potential agents for controlling Phytophthora blight and anthracnose, and for

  18. Assessment of the Socio-Economic Impact of Late Blight and State-of-the-Art Management in European Organic Potato Production Systems

    NARCIS (Netherlands)

    Tamm, L.; Smit, A.B.; Hospers, M.; Janssens, S.R.M.; Buurma, J.S.; Molgaard, J.P.; Laerke, P.E.; Hansen, H.H.; Hermans, A.; Bodker, L.; Bertrand, C.; Lambion, J.; Finckh, M.R.; Schuler, C.; Lammerts Van Bueren, E.; Ruissen, T.; Nielsen, B.J.; Solberg, S.; Speiser, B.; Wolfe, M.S.; Philips, S.; Wilcoxon, S.J.; Leifert, C.

    2004-01-01

    In Europe, late blight, caused by Phytophthora infestans, is the most devastating disease affecting organic (and conventional) potato production. Under suitable environmental conditions the disease can spread rapidly and it can cause complete crop loss. The extent of damage due to late blight

  19. Comparative and bioinformatics analyses of pathogenic bacterial secretomes identified by mass spectrometry in Burkholderia species.

    Science.gov (United States)

    Nguyen, Thao Thi; Chon, Tae-Soo; Kim, Jaehan; Seo, Young-Su; Heo, Muyoung

    2017-07-01

    Secreted proteins (secretomes) play crucial roles during bacterial pathogenesis in both plant and human hosts. The identification and characterization of secretomes in the two plant pathogens Burkholderia glumae BGR1 and B. gladioli BSR3, which cause diseases in rice such as seedling blight, panicle blight, and grain rot, are important steps to not only understand the disease-causing mechanisms but also find remedies for the diseases. Here, we identified two datasets of secretomes in B. glumae BGR1 and B. gladioli BSR3, which consist of 118 and 111 proteins, respectively, using mass spectrometry approach and literature curation. Next, we characterized the functional properties, potential secretion pathways and sequence information properties of secretomes of two plant pathogens in a comparative analysis by various computational approaches. The ratio of potential non-classically secreted proteins (NCSPs) to classically secreted proteins (CSPs) in B. glumae BGR1 was greater than that in B. gladioli BSR3. For CSPs, the putative hydrophobic regions (PHRs) which are essential for secretion process of CSPs were screened in detail at their N-terminal sequences using hidden Markov model (HMM)-based method. Total 31 pairs of homologous proteins in two bacterial secretomes were indicated based on the global alignment (identity ≥ 70%). Our results may facilitate the understanding of the species-specific features of secretomes in two plant pathogenic Burkholderia species.

  20. Transcriptome dynamics of a susceptible wheat upon Fusarium head blight reveals that molecular responses to Fusarium graminearum infection fit over the grain development processes.

    Science.gov (United States)

    Chetouhi, Cherif; Bonhomme, Ludovic; Lasserre-Zuber, Pauline; Cambon, Florence; Pelletier, Sandra; Renou, Jean-Pierre; Langin, Thierry

    2016-03-01

    In many plant/pathogen interactions, host susceptibility factors are key determinants of disease development promoting pathogen growth and spreading in plant tissues. In the Fusarium head blight (FHB) disease, the molecular basis of wheat susceptibility is still poorly understood while it could provide new insights into the understanding of the wheat/Fusarium graminearum (Fg) interaction and guide future breeding programs to produce cultivars with sustainable resistance. To identify the wheat grain candidate genes, a genome-wide gene expression profiling was performed in the French susceptible wheat cultivar, Recital. Gene-specific two-way ANOVA of about 40 K transcripts at five grain developmental stages identified 1309 differentially expressed genes. Out of these, 536 were impacted by the Fg effect alone. Most of these Fg-responsive genes belonged to biological and molecular functions related to biotic and abiotic stresses indicating the activation of common stress pathways during susceptibility response of wheat grain to FHB. This analysis revealed also 773 other genes displaying either specific Fg-responsive profiles along with grain development stages or synergistic adjustments with the grain development effect. These genes were involved in various molecular pathways including primary metabolism, cell death, and gene expression reprogramming. An increasingly complex host response was revealed, as was the impact of both Fg infection and grain ontogeny on the transcription of wheat genes. This analysis provides a wealth of candidate genes and pathways involved in susceptibility responses to FHB and depicts new clues to the understanding of the susceptibility determinism in plant/pathogen interactions.

  1. PaeX, a second pectin acetylesterase of Erwinia chrysanthemi 3937.

    Science.gov (United States)

    Shevchik, Vladimir E; Hugouvieux-Cotte-Pattat, Nicole

    2003-05-01

    Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. Pectin is a complex polysaccharide. The main chain is constituted of galacturonate residues, and some of them are modified by methyl and/or acetyl esterification. Esterases are necessary to remove these modifications and, thus, to facilitate the further degradation of the polysaccharidic chain. In addition to PaeY, the first pectin acetylesterase identified in the E. chrysanthemi strain 3937, we showed that this bacterium produces a second pectin acetylesterase encoded by the gene paeX. The paeX open reading frame encodes a 322-residue precursor protein of 34,940 Da, including a 21-amino-acid signal peptide. Analysis of paeX transcription, by using gene fusions, revealed that it is induced by pectic catabolic products and affected by catabolite repression. The expression of paeX is regulated by the repressor KdgR, which controls all the steps of pectin catabolism; by the repressor PecS, which controls most of the pectinase genes; and by catabolite regulatory protein, the global activator of sugar catabolism. The paeX gene is situated in a cluster of genes involved in the catabolism and transport of pectic oligomers. In induced conditions, the two contiguous genes kdgM, encoding an oligogalacturonate-specific porin, and paeX are both transcribed as an operon from a promoter proximal to kdgM, but transcription of paeX can also be uncoupled from that of kdgM in noninduced conditions. PaeX is homologous to the C-terminal domain of the Butyrivibrio fibriosolvens xylanase XynB and to a few bacterial esterases. PaeX contains the typical box (GxSxG) corresponding to the active site of the large family of serine hydrolases. Purified PaeX releases acetate from various synthetic substrates and from sugar beet pectin. The PaeX activity increased after previous depolymerization and demethylation of pectin, indicating that its preferred substrates are

  2. Computational analyses of ancient pathogen DNA from herbarium samples: challenges and prospects.

    Science.gov (United States)

    Yoshida, Kentaro; Sasaki, Eriko; Kamoun, Sophien

    2015-01-01

    The application of DNA sequencing technology to the study of ancient DNA has enabled the reconstruction of past epidemics from genomes of historically important plant-associated microbes. Recently, the genome sequences of the potato late blight pathogen Phytophthora infestans were analyzed from 19th century herbarium specimens. These herbarium samples originated from infected potatoes collected during and after the Irish potato famine. Herbaria have therefore great potential to help elucidate past epidemics of crops, date the emergence of pathogens, and inform about past pathogen population dynamics. DNA preservation in herbarium samples was unexpectedly good, raising the possibility of a whole new research area in plant and microbial genomics. However, the recovered DNA can be extremely fragmented resulting in specific challenges in reconstructing genome sequences. Here we review some of the challenges in computational analyses of ancient DNA from herbarium samples. We also applied the recently developed linkage method to haplotype reconstruction of diploid or polyploid genomes from fragmented ancient DNA.

  3. Effect of Temperature on Growth and Sporulation of US-22, US-23, and US-24 Clonal Lineages of Phytophthora infestans and Implications for Late Blight Epidemiology.

    Science.gov (United States)

    Seidl Johnson, Anna C; Frost, Kenneth E; Rouse, Douglas I; Gevens, Amanda J

    2015-04-01

    Epidemics of late blight, caused by Phytophthora infestans (Mont.) de Bary, have been studied by plant pathologists and regarded with great concern by potato and tomato growers since the Irish potato famine in the 1840s. P. infestans populations have continued to evolve, with unique clonal lineages arising which differ in pathogen fitness and pathogenicity, potentially impacting epidemiology. In 2012 and 2013, the US-23 clonal lineage predominated late blight epidemics in most U.S. potato and tomato production regions, including Wisconsin. This lineage was unknown prior to 2009. For isolates of three recently identified clonal lineages of P. infestans (US-22, US-23, and US-24), sporulation rates were experimentally determined on potato and tomato foliage and the effect of temperature on lesion growth rate on tomato was investigated. The US-22 and US-23 isolates had greater lesion growth rates on tomato than US-24 isolates. Sporulation rates for all isolates were greater on potato than tomato, and the US-23 isolates had greater sporulation rates on both tomato and potato than the US-22 and US-24 isolates. Experimentally determined correlates of fitness were input to the LATEBLIGHT model and epidemics were simulated using archived Wisconsin weather data from four growing seasons (2009 to 2012) to investigate the effect of isolates of these new lineages on late blight epidemiology. The fast lesion growth rates of US-22 and US-23 isolates resulted in severe epidemics in all years tested, particularly in 2011. The greater sporulation rates of P. infestans on potato resulted in simulated epidemics that progressed faster than epidemics simulated for tomato; the high sporulation rates of US-23 isolates resulted in simulated epidemics more severe than simulated epidemics of isolates of the US-22 and US-24 isolates and EC-1 clonal lineages on potato and tomato. Additionally, US-23 isolates consistently caused severe simulated epidemics when lesion growth rate and sporulation

  4. A network approach to predict pathogenic genes for Fusarium graminearum.

    Directory of Open Access Journals (Sweden)

    Xiaoping Liu

    Full Text Available Fusarium graminearum is the pathogenic agent of Fusarium head blight (FHB, which is a destructive disease on wheat and barley, thereby causing huge economic loss and health problems to human by contaminating foods. Identifying pathogenic genes can shed light on pathogenesis underlying the interaction between F. graminearum and its plant host. However, it is difficult to detect pathogenic genes for this destructive pathogen by time-consuming and expensive molecular biological experiments in lab. On the other hand, computational methods provide an alternative way to solve this problem. Since pathogenesis is a complicated procedure that involves complex regulations and interactions, the molecular interaction network of F. graminearum can give clues to potential pathogenic genes. Furthermore, the gene expression data of F. graminearum before and after its invasion into plant host can also provide useful information. In this paper, a novel systems biology approach is presented to predict pathogenic genes of F. graminearum based on molecular interaction network and gene expression data. With a small number of known pathogenic genes as seed genes, a subnetwork that consists of potential pathogenic genes is identified from the protein-protein interaction network (PPIN of F. graminearum, where the genes in the subnetwork are further required to be differentially expressed before and after the invasion of the pathogenic fungus. Therefore, the candidate genes in the subnetwork are expected to be involved in the same biological processes as seed genes, which imply that they are potential pathogenic genes. The prediction results show that most of the pathogenic genes of F. graminearum are enriched in two important signal transduction pathways, including G protein coupled receptor pathway and MAPK signaling pathway, which are known related to pathogenesis in other fungi. In addition, several pathogenic genes predicted by our method are verified in other

  5. Erwinia chrysanthemi: pectolytic bacterium causing soft rot outbreaks of arracacha in Brazil Erwinia chrysanthemi: bactéria pectolítica envolvida na "mela" da mandioquinha-salsa no Brasil

    Directory of Open Access Journals (Sweden)

    Gilmar Paulo Henz

    2006-10-01

    Full Text Available The objetive of this work was to identify the pectolytic bacteria associated with soft rot of arracacha roots in Brazil. From 1998 to 2001, 227 isolates of Erwinia spp. were obtained from arracacha roots and identified by biochemical and physiological tests (pectolytic activity, lecithinase, a-methyl glucoside, phosphatase, erythromycin sensivity, growth at 37ºC. Of these isolates, 89.9% were identified as E. chrysanthemi (Ech, 9.7% as E. carotovora subsp. carotovora (Ecc and 0.5% as E. carotovora subsp. atroseptica. The identity of seventeen out of twenty representative isolates of Ech and Ecc was confirmed by PCR (primers '149f', 'L1r', 'ADE1', 'ADE2'.O objetivo deste trabalho foi identificar as bactérias pectolíticas envolvidas na podridão-mole de raízes de mandioquinha-salsa no Brasil. De 1998 a 2001, 227 isolados de Erwinia spp. foram obtidos de raízes de mandioquinha-salsa e identificados por testes bioquímicos e fisiológicos (atividade pectolítica, lecitinase, a-methyl glucosídeo, fosfatase, sensibilidade à eritromicina, crescimento a 37ºC. Destes isolados, 89,9% foram identificados como E. chrysanthemi (Ech, 9,7% como E. carotovora subsp. carotovora (Ecc e somente 0,5% como E. carotovora subsp. atroseptica. A identidade de 20 isolados representativos de Ech e Ecc foi confirmada por PCR (primers '149f', 'L1r', 'ADE1', 'ADE2', com exceção de dois isolados de Ech e um de Ecc.

  6. Efficacy of epiphytic bacteria to prevent northern leaf blight caused by Exserohilum turcicum in maize.

    Science.gov (United States)

    Sartori, Melina; Nesci, Andrea; García, Julián; Passone, María A; Montemarani, Analía; Etcheverry, Miriam

    Eight potential biological control agents (BCAs) were evaluated in planta in order to assess their effectiveness in reducing disease severity of northern leaf blight caused by Exserohilum turcicum. The assay was carried out in greenhouse. Twenty-six-day-old plants, V4 phenological stage, were inoculated with antagonists by foliar spray. Only one biocontrol agent was used per treatment. Ten days after this procedure, all treatments were inoculated with E. turcicum by foliar application. Treatments performed were: C-Et: control of E. turcicum; T1: isolate 1 (Enterococcus genus)+E. turcicum; T2: isolate 2 (Corynebacterium genus)+E. turcicum; T3: isolate 3 (Pantoea genus)+E. turcicum; T4: isolate 4 (Corynebacterium genus)+E. turcicum; T5: isolate 5 (Pantoea genus)+E. turcicum; T6: isolate 6 (Bacillus genus)+E. turcicum; T7: isolate 7 (Bacillus genus)+E. turcicum; T8: isolate 8 (Bacillus genus)+E. turcicum. Monitoring of antagonists on the phyllosphere was performed at different times. Furthermore, the percentage of infected leaves and, plant and leaf incidence were determined. Foliar application of different bacteria significantly reduced the leaf blight between 30-78% and 39-56% at 20 and 39 days respectively. It was observed that in the V10 stage of maize plants, isolate 8 (Bacillus spp.) caused the greatest effect on reducing the severity of northern leaf blight. Moreover, isolate 8 was the potential BCA that showed more stability in the phyllosphere. At 39 days, all potential biocontrol agents had a significant effect on controlling the disease caused by E. turcicum. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Crop connectivity under climate change: future environmental and geographic risks of potato late blight in Scotland.

    Science.gov (United States)

    Skelsey, Peter; Cooke, David E L; Lynott, James S; Lees, Alison K

    2016-11-01

    The impact of climate change on dispersal processes is largely ignored in risk assessments for crop diseases, as inoculum is generally assumed to be ubiquitous and nonlimiting. We suggest that consideration of the impact of climate change on the connectivity of crops for inoculum transmission may provide additional explanatory and predictive power in disease risk assessments, leading to improved recommendations for agricultural adaptation to climate change. In this study, a crop-growth model was combined with aerobiological models and a newly developed infection risk model to provide a framework for quantifying the impact of future climates on the risk of disease occurrence and spread. The integrated model uses standard meteorological variables and can be easily adapted to various crop pathosystems characterized by airborne inoculum. In a case study, the framework was used with data defining the spatial distribution of potato crops in Scotland and spatially coherent, probabilistic climate change data to project the future connectivity of crop distributions for Phytophthora infestans (causal agent of potato late blight) inoculum and the subsequent risk of infection. Projections and control recommendations are provided for multiple combinations of potato cultivar and CO 2 emissions scenario, and temporal and spatial averaging schemes. Overall, we found that relative to current climatic conditions, the risk of late blight will increase in Scotland during the first half of the potato growing season and decrease during the second half. To guide adaptation strategies, we also investigated the potential impact of climate change-driven shifts in the cropping season. Advancing the start of the potato growing season by 1 month proved to be an effective strategy from both an agronomic and late blight management perspective. © 2016 John Wiley & Sons Ltd.

  8. EVALUATION OF TRICHODERMA SPP. ON BEAN CULTURE, IN ANTHRACNOSE, WEB BLIGHT AND ROOT-KNOT NEMATODE

    Directory of Open Access Journals (Sweden)

    P. E. V. Aguiar

    2014-09-01

    Full Text Available Mato Grosso is the third largest producer of bean from Brazil, being the third harvest (irrigated the most productive, but diseases such as anthracnose, web blight and nematodes of galls cause losses to producers. In addition, a measure widely used and little studied for the control of diseases and nematodes in Mato Grosso is the biological control, which consists of the action of other microorganisms on phytopathogens. Thus, the objective of the present study was to evaluate the effect of Trichoderma harzianum and T. asperellum in the development (height of plants, chlorophyll and number of pods of culture of bean, in the control of anthracnose (Colletotrichum lindemuthianum, web blight (Rhizoctonia solani and in the population of Meloidogyne spp. in the soil. The experiment was accomplished in area experimental of University Federal of Mato Grosso/Campus Sinop. The experimental design was of entirely randomized with 12 parcels of 5m² each, with 3 treatments and 4 replications. The cultivar used was Whitey, carioca group, and the seed treatment performed with product Pyraclostrobin + Thiophanate Methyl + Fipronil and after drying of the inoculation of biocontrol agents and manual seeding. It was observed that the application of T. harzianum and T. asperellum, not promoted increase of chlorophyll, height of plants in bean culture, without reducing the population of Meloidogyne spp.. However, biocontrol agents have reduced the severity of anthracnose and web blight and promoted an increase in the average number of plant pods-1. It is therefore concluded that biocontrol agents show potential for application in bean culture in the North of Mato Grosso.

  9. 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

    involved in primary metabolism and detoxification whereas the majority of down-regulated proteins were plant protease inhibitors. The results suggest that there is a link between increased energy metabolism and oxidative stress in the germinating barley seeds in response to F. graminearum infection, which......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...

  10. Emerging Pathogens Initiative (EPI)

    Data.gov (United States)

    Department of Veterans Affairs — The Emerging Pathogens Initiative (EPI) database contains emerging pathogens information from the local Veterans Affairs Medical Centers (VAMCs). The EPI software...

  11. Bacillus velezensis RC 218 as a biocontrol agent to reduce Fusarium head blight and deoxynivalenol accumulation: Genome sequencing and secondary metabolite cluster profiles.

    Science.gov (United States)

    Palazzini, Juan M; Dunlap, Christopher A; Bowman, Michael J; Chulze, Sofía N

    2016-11-01

    Bacillus subtilis RC 218 was originally isolated from wheat anthers as a potential antagonist of Fusarium graminearum, the causal agent of Fusarium head blight (FHB). It was demonstrated to have antagonist activity against the plant pathogen under in vitro and greenhouse assays. The current study extends characterizing B. subtilis RC 218 with a field study and genome sequencing. The field study demonstrated that B. subtilis RC 218 could reduce disease severity and the associated mycotoxin (deoxynivalenol) accumulation, under field conditions. The genome sequencing allowed us to accurately determine the taxonomy of the strain using a phylogenomic approach, which places it in the Bacillus velezensis clade. In addition, the draft genome allowed us to use bioinformatics to mine the genome for potential metabolites. The genome mining allowed us to identify 9 active secondary metabolites conserved by all B. velezensis strains and one additional secondary metabolite, the lantibiotic ericin, which is unique to this strain. This study represents the first confirmed production of ericin by a B. velezensis strain. The genome also allowed us to do a comparative genomics with its closest relatives and compare the secondary metabolite production of the publically available B. velezensis genomes. The results showed that the diversity in secondary metabolites of strains in the B. velezensis clade is driven by strains making different antibacterials. Copyright © 2016 Elsevier GmbH. All rights reserved.

  12. mQTL-seq and classical mapping implicates the role of an AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED (AHL) family gene in Ascochyta blight resistance of chickpea.

    Science.gov (United States)

    Kumar, Kamal; Purayannur, Savithri; Kaladhar, Vemula Chandra; Parida, Swarup Kumar; Verma, Praveen Kumar

    2018-03-01

    Ascochyta blight (AB) caused by the fungal pathogen Ascochyta rabiei is a serious foliar disease of chickpea (Cicer arietinum L.). Despite many genetic studies on chickpea-Ascochyta interaction, genome-wide scan of chickpea for the identification of AB-associated quantitative trait loci (QTLs) and their gene(s) has not been accomplished. To elucidate narrow QTLs for AB resistance, here, we report the use of multiple QTL-sequencing approach on 2 sets of extreme AB phenotype bulks derived from Cicer intraspecific and interspecific crosses. Two major QTLs, qABR4.1 and qABR4.2, and a minor QTL, qABR4.3, were identified on assembled chickpea pseudomolecule 4. We narrowed qABR4.1 to a "robust region" at 4.568-4.618 Mb through mapping on a larger intraspecific cross-derived population and comparative analysis. Among 4 genes, the CaAHL18 gene showed higher expression under Ascochyta stress in AB resistant parent suggesting that it is the candidate gene under "robust qABR4.1." Dual-luciferase assay with CaAHL18 polymorphic cis-regulatory sequences showed that allelic variation is associated with higher expression. Thus, our findings on chickpea-Ascochyta interaction have narrowed down AB resistance associated QTLs on chickpea physical map. The narrowed QTLs and gene-associated markers will help in biotechnological and breeding programs for chickpea improvement. © 2018 John Wiley & Sons Ltd.

  13. Frost-related dieback of Swedish and Estonian Salix plantations due to pathogenic and ice nucleation-active bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cambours, M.A.

    2004-07-01

    During the past decade, important dieback has been observed in short-rotation forestry plantations of Salix viminalis and S. dasyclados in Sweden and Estonia, plantations from which the isolation of ice nucleation-active (INA) and pathogenic bacteria has also been reported. This thesis investigates the connection between bacterial infection and frost as a possible cause for such damage, and the role played by internal and external factors (e.g. plant frost sensitivity, fertilisation) in the dieback observed. Bacterial floras isolated from ten Salix clones growing on fertilised/unfertilised mineral soil or nitrogen-rich organic soil, were studied. Culturable bacterial communities present both in internal necrotic tissues and on the plant surface (i.e. epiphytes) were isolated on two occasions (spring and autumn). The strains were biochemically characterised (with gram, oxidase and fluorescence tests), and tested for ice nucleation-activity. Their pathogenic properties were studied with and without association to a freezing stress. Certain strains were eventually identified with BIOLOG plates and 16S rRNA analysis. A high number of culturable bacterial strains was found in the plant samplings, belonging mainly to Erwinia and Sphingomonas spp.; pathogenic and INA communities being mostly Erwinia-, Sphingomonas- and Xanthomonas-like. The generally higher plant dieback noted in the field on nutrient-rich soils and for frost sensitive clones was found connected to higher numbers of pathogenic and INA bacteria in the plants. We thus confirm Salix dieback to be related to a synergistic effect of frost and bacterial infection, possibly aggravated by fertilisation.

  14. The Antibacterial Activity of Chitosan Products Blended with Monoterpenes and Their Biofilms against Plant Pathogenic Bacteria

    Directory of Open Access Journals (Sweden)

    Mohamed E. I. Badawy

    2016-01-01

    Full Text Available This study focuses on the biological activities of eleven chitosan products with a viscosity-average molecular weight ranging from 22 to 846 kDa in combination with the most active monoterpenes (geraniol and thymol, out of 10 tested, against four plant pathogenic bacteria, Agrobacterium tumefaciens, Erwinia carotovora, Corynebacterium fascians, and Pseudomonas solanacearum. The antibacterial activity was evaluated in vitro by the agar dilution technique as a minimum inhibitory concentration (MIC that was found to be dependent on the type of the microorganism tested. The most active product of chitosan was used for biofilm production enriched with geraniol and thymol (0.1 and 0.5% and the films were also evaluated against the tested bacteria. The biological bioactivities summarized here may provide novel insights into the functions of chitosan and some monoterpenes and potentially allow their use for food protection from microbial attack.

  15. Development of the variety for resistance against bacterial leaf-blight in rice with thermal neutrons

    International Nuclear Information System (INIS)

    Nakai, Hirokazu

    1990-01-01

    In search for the development of genes for resistance against bacterial leaf-blight in rice, thermal neutrons generated from the Research Reactor at the Kyoto University have been applied to the breeding. In this paper, the developmental outcome is described, and a potential application of thermal neutrons for breeding the variety of resistance against bacterial leaf-blight in rice is reviewed. When thermal neutrons were delivered to the rice, the ratio of absorbed doses by B-10, which is contained in a small quantity in the plant, was found to be larger than expected. This implies characteristic effects of thermal neutrons on the plant. When boric acid was incorporated into the plant before irradiation, the effect of thermal neutrons per irradiation time was considered to become great. The frequency of mutations for resistance was significantly higher by thermal neutron, as compared with that induced by other mutagens, such as gamma radiation, ethylene-imine, ethyl-methane-sulfonate, and nitroso-methyl-urea. Genetic analysis of mutants for resistance revealed recessive genes and polygenes. Finally, the application of thermal neutrons and other radiations would contribute greatly to a resolution of serious pollution problems in global food and environment. (N.K.)

  16. An Assessment of the Impact of Two Late Blight Tolerant Potato Varieties

    International Nuclear Information System (INIS)

    Walingo, A.M.

    2002-01-01

    A study was made to assess the impact of two late blight tolerant potato varieties Tigoni and Asante releases in 1998. The appraisal and impact assessment set out to collect information on the adoption of the two varieties; assess their economic impact; and forecast future prospects for these two varieties and identity constraints to their adoption and diffusion in three divisions of Molo, Timboroa and Laikipia. The methodology adopted was conducting field surveys between September and October 2001, and gathering secondary information from the Ministry of Agriculture, research Centres, seed companies, NGO's and farmers. Results indicated that high yield, early maturity, tolerant to late blight, good market for ware potatoes and good taste were the advantages of Tigoni and Asante, widely recognised in all survey sites. Disadvantages of Tigoni and Asante were poor storage, rapid greening of tubers (mainly for Tigoni), and limited availability of planting material. The two varieties had higher yield benefits, net benefit per hectare and higher rates of return compared to the local varieties. the rate of returns when the local cultivars were substituted by the new improved varieties ranged from 556 to 1070%. Data on diffusion of Tigoni and Asante showed that combined acreage of varieties Tigoni and Asante rose to 196.3, 137.5 and 1476 ha in Molo, Timboroa and Laikipia respectively. The future forecast for the two varieties is good if the limitation on seed availability is addressed

  17. Transgenic expression of lactoferrin imparts enhanced resistance to head blight of wheat caused by Fusarium graminearum.

    Science.gov (United States)

    Han, Jigang; Lakshman, Dilip K; Galvez, Leny C; Mitra, Sharmila; Baenziger, Peter Stephen; Mitra, Amitava

    2012-03-09

    The development of plant gene transfer systems has allowed for the introgression of alien genes into plant genomes for novel disease control strategies, thus providing a mechanism for broadening the genetic resources available to plant breeders. Using the tools of plant genetic engineering, a broad-spectrum antimicrobial gene was tested for resistance against head blight caused by Fusarium graminearum Schwabe, a devastating disease of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) that reduces both grain yield and quality. A construct containing a bovine lactoferrin cDNA was used to transform wheat using an Agrobacterium-mediated DNA transfer system to express this antimicrobial protein in transgenic wheat. Transformants were analyzed by Northern and Western blots to determine lactoferrin gene expression levels and were inoculated with the head blight disease fungus F. graminearum. Transgenic wheat showed a significant reduction of disease incidence caused by F. graminearum compared to control wheat plants. The level of resistance in the highly susceptible wheat cultivar Bobwhite was significantly higher in transgenic plants compared to control Bobwhite and two untransformed commercial wheat cultivars, susceptible Wheaton and tolerant ND 2710. Quantification of the expressed lactoferrin protein by ELISA in transgenic wheat indicated a positive correlation between the lactoferrin gene expression levels and the levels of disease resistance. Introgression of the lactoferrin gene into elite commercial wheat, barley and other susceptible cereals may enhance resistance to F. graminearum.

  18. OCCURENCE OF FUSARIUM HEAD BLIGHT OF WHEAT IN SLOVAKIA UNDER THE NATURAL INFECTION

    Directory of Open Access Journals (Sweden)

    Kamil Hudec

    2013-09-01

    Full Text Available Occurrence of Fusarium head blight FHB was documented during two consecutive years in June 2011 2012 under the natural conditions in winter wheat Triticum aestivum L. Observations were conducted at six different localities in four climatic regions in Slovakia. Incidence and severity of FHB were evaluated at the end of flowering stage in three replications. Each replication contained 100 spikes. These data served as a basis for FHB index calculations. Obtained FHB index values indicated that the environmental conditions of the year 2011 were more favourable to the development of FHB infection. Higher FHB index values were reached at localities with precipitation higher than 100% of long-term average. Although significantly higher incidence of heads with FHB symptoms was recorded in climatic region 02 quite warm, dry, hilly, correlation between the climatic regions was not confirmed. Except of the climatic conditions, the FHB development can be influenced by nitrogen application. The highest levels of FHB index was in coincidence with the highest and the lowest nitrogen rates applied. In all other cases, the effect of the mineral nutrition on head blight attack was unclear. Analyses of nitrogen forms applied revealed that nitrogen forms had no impact on FHB index value.

  19. Future prospects for ascochyta blight resistance breeding in cool season food legumes

    Directory of Open Access Journals (Sweden)

    Diego eRubiales

    2012-02-01

    Full Text Available Legume cultivation is strongly hampered by the occurrence of ascochyta blights. Strategies of control have been developed but only marginal successes have been achieved. Breeding for disease resistance is regarded the most cost efficient method of control. Significant genetic variation for disease resistance exists in most legume crops with numerous germplasm lines maintained, providing an excellent resource for plant breeders. Fast and reliable screening methods have been adjusted to fulfil breeding programmes needs. However, the complex inheritance controlled quantitatively by multiple genes, have been difficult to manipulate. Successful application of biotechnology to ascochyta blight resistance breeding in legume crops will facilitate both a good biological knowledge of the crops and of the mechanisms underlying resistance. The current focus in applied breeding is leveraging biotechnological tools to develop more and better markers to speed up the delivery of improved cultivars to the farmer. To date, however, progress in marker development and delivery of useful markers has been slow. The limited saturation of the genomic regions bearing putative QTLs in legume crops makes difficult to identify the most tightly-linked markers

  20. Transgenic expression of lactoferrin imparts enhanced resistance to head blight of wheat caused by Fusarium graminearum

    Directory of Open Access Journals (Sweden)

    Han Jigang

    2012-03-01

    Full Text Available Abstract Background The development of plant gene transfer systems has allowed for the introgression of alien genes into plant genomes for novel disease control strategies, thus providing a mechanism for broadening the genetic resources available to plant breeders. Using the tools of plant genetic engineering, a broad-spectrum antimicrobial gene was tested for resistance against head blight caused by Fusarium graminearum Schwabe, a devastating disease of wheat (Triticum aestivum L. and barley (Hordeum vulgare L. that reduces both grain yield and quality. Results A construct containing a bovine lactoferrin cDNA was used to transform wheat using an Agrobacterium-mediated DNA transfer system to express this antimicrobial protein in transgenic wheat. Transformants were analyzed by Northern and Western blots to determine lactoferrin gene expression levels and were inoculated with the head blight disease fungus F. graminearum. Transgenic wheat showed a significant reduction of disease incidence caused by F. graminearum compared to control wheat plants. The level of resistance in the highly susceptible wheat cultivar Bobwhite was significantly higher in transgenic plants compared to control Bobwhite and two untransformed commercial wheat cultivars, susceptible Wheaton and tolerant ND 2710. Quantification of the expressed lactoferrin protein by ELISA in transgenic wheat indicated a positive correlation between the lactoferrin gene expression levels and the levels of disease resistance. Conclusions Introgression of the lactoferrin gene into elite commercial wheat, barley and other susceptible cereals may enhance resistance to F. graminearum.

  1. Effects of Fungicides, Time of Application, and Application Method on Control of Sclerotinia Blight in Peanut

    Directory of Open Access Journals (Sweden)

    Jason E. Woodward

    2015-01-01

    Full Text Available Field studies were conducted from 2007 to 2010 to evaluate the response of peanut cultivars to different fungicides, application timings, and methods. Overall, fungicides reduced Sclerotinia blight incidence and increased pod yields when applied to susceptible and partially resistant cultivars. Disease suppression was greater when full fungicide rates were applied preventatively; however, yields between fungicide treated plots were similar. Lower levels of disease and higher yields were achieved with the partially resistant cultivar Tamrun OL07 compared to the susceptible cultivars Flavor Runner 458 and Tamrun OL 02. Despite possessing improved resistance Tamrun OL07 responded to all fungicide applications. While similar levels of disease control were achieved with broadcast or banded applications made during the day or at night, the yield response for the different application methods was inconsistent among years. A negative relationship (slope = −73.8; R2=0.73; P<0.01 was observed between final disease incidence ratings and yield data from studies where a fungicide response was observed. These studies suggest that both boscalid and fluazinam are effective at controlling Sclerotinia blight in peanuts. Alternative management strategies such as nighttime and banded applications could allow for lower fungicide rates to be used; however, additional studies are warranted.

  2. Stemphylium Leaf Blight of Garlic (Allium sativum in Spain: Taxonomy and In Vitro Fungicide Response

    Directory of Open Access Journals (Sweden)

    Laura Gálvez

    2016-10-01

    Full Text Available The most serious aerial disease of garlic is leaf blight caused by Stemphylium spp. Geographical variation in the causal agent of this disease is indicated. Stemphylium vesicarium has been reported in Spain, whereas S. solani is the most prevalent species recorded in China. In this study, Stemphylium isolates were obtained from symptomatic garlic plants sampled from the main Spanish production areas. Sequence data for the ITS1–5.8S–ITS2 region enabled assignation of the isolates to the Pleospora herbarum complex and clearly distinguished the isolates from S. solani. Conidial morphology of the isolates corresponded to that of S. vesicarium and clearly discriminated them from S. alfalfae and S. herbarum on the basis of the size and septation pattern of mature conidia. Conidial morphology as well as conidial length, width and length:width ratio also allowed the Spanish isolates to be distinguished from S. botryosum and S. herbarum. Control of leaf blight of garlic is not well established. Few studies are available regarding the effectiveness of chemical treatments to reduce Stemphylium spp. incidence on garlic. The effectiveness of nine fungicides of different chemical groups to reduce Stemphylium mycelial growth in vitro was tested. Boscalid + pyraclostrobin (group name, succinate dehydrogenase inhibitors + quinone outside inhibitors, iprodione (dicar-boximide, and prochloraz (demethylation inhibitors were highly effective at reducing mycelial growth in S. vesicarium with EC₅₀ values less than 5 ppm. In general, the effectiveness of the fungicide was enhanced with increasing dosage.

  3. Bacterial spot and early blight biocontrol by epiphytic bacteria in tomato plants

    Directory of Open Access Journals (Sweden)

    Roberto Lanna Filho

    2010-12-01

    Full Text Available The objective of this work was to evaluate in vitro and in vivo biocontrol of bacterial spot (Xanthomonas vesicatoria and early blight (Alternaria solani by the epiphytic bacteria Paenibacillus macerans and Bacillus pumilus. Tomato plants were previously sprayed with epiphytic bacteria, benzalkonium chloride and PBS buffer and, after four days, they were inoculated with A. solani and X. vesicatoria. To determine the phytopathogenic bacteria population, leaflet samples were collected from each treatment every 24 hours, for seven days, and plated on semi-selective medium. The effect of epiphytic bacteria over phytopathogens was performed by the antibiosis test and antagonistic activity measured by inhibition zone diameter. The epiphytic and benzalkonium chloride drastically reduced the severity of early blight and bacterial spot in comparison to the control (PBS. In detached leaflets, the epiphytic bacteria reduced in 70% the number of phytopathogenic bacteria cells in the phylloplane. The antibiosis test showed that the epiphytic bacteria efficiently inhibit the phytopathogens growth. In all the bioassays, the epiphytic bacteria protect tomato plants against the phytopathogens

  4. Deoxynivalenol in wheat and wheat products from a harvest affected by fusarium head blight

    Directory of Open Access Journals (Sweden)

    Lidiane Viera MACHADO

    Full Text Available Abstract Fusarium head blight is an important disease occurring in wheat, caused mainly by the fungus Fusarium graminearum. In addition to direct damage to crops, reduced quality and yield losses, the infected grains can accumulate mycotoxins (toxic metabolites originating from prior fungal growth, especially deoxynivalenol (DON. Wheat crops harvested in 2014/2015 in southern Brazil were affected by high levels of Fusarium head blight. In this context, the aim of this study was evaluate the mycotoxicological quality of Brazilian wheat grains and wheat products (wheat flour and wheat bran for DON. DON contamination was evaluated in 1,504 wheat and wheat product samples produced in Brazil during 2014. It was determined by high performance liquid chromatograph fitted to a mass spectrometer (LC-MS / MS. The results showed that 1,000 (66.5% out of the total samples tested were positive for DON. The mean level of sample contamination was 1047 µg.kg-1, but only 242 samples (16.1% had contamination levels above the maximum permissible levels (MPL - the maximum content allowed by current Brazilian regulation. As of 2017, MPL will be stricter. Thus, research should be conducted on DON contamination of wheat and wheat products, since wheat is a raw material widely used in the food industry, and DON can cause serious harm to public health.

  5. Stemphylium Leaf Blight of Garlic (Allium sativum ) in Spain: Taxonomy and In Vitro Fungicide Response

    Science.gov (United States)

    Gálvez, Laura; Gil-Serna, Jéssica; García, Marta; Iglesias, Concepción; Palmero, Daniel

    2016-01-01

    The most serious aerial disease of garlic is leaf blight caused by Stemphylium spp. Geographical variation in the causal agent of this disease is indicated. Stemphylium vesicarium has been reported in Spain, whereas S. solani is the most prevalent species recorded in China. In this study, Stemphylium isolates were obtained from symptomatic garlic plants sampled from the main Spanish production areas. Sequence data for the ITS1–5.8S–ITS2 region enabled assignation of the isolates to the Pleospora herbarum complex and clearly distinguished the isolates from S. solani. Conidial morphology of the isolates corresponded to that of S. vesicarium and clearly discriminated them from S. alfalfae and S. herbarum on the basis of the size and septation pattern of mature conidia. Conidial morphology as well as conidial length, width and length:width ratio also allowed the Spanish isolates to be distinguished from S. botryosum and S. herbarum. Control of leaf blight of garlic is not well established. Few studies are available regarding the effectiveness of chemical treatments to reduce Stemphylium spp. incidence on garlic. The effectiveness of nine fungicides of different chemical groups to reduce Stemphylium mycelial growth in vitro was tested. Boscalid + pyraclostrobin (group name, succinate dehydrogenase inhibitors + quinone outside inhibitors), iprodione (dicar-boximide), and prochloraz (demethylation inhibitors) were highly effective at reducing mycelial growth in S. vesicarium with EC50 values less than 5 ppm. In general, the effectiveness of the fungicide was enhanced with increasing dosage. PMID:27721688

  6. Integrated Metabolo-Transcriptomics Reveals Fusarium Head Blight Candidate Resistance Genes in Wheat QTL-Fhb2.

    Directory of Open Access Journals (Sweden)

    Dhananjay Dhokane

    Full Text Available Fusarium head blight (FHB caused by Fusarium graminearum not only causes severe losses in yield, but also reduces quality of wheat grain by accumulating mycotoxins. Breeding for host plant resistance is considered as the best strategy to manage FHB. Resistance in wheat to FHB is quantitative in nature, involving cumulative effects of many genes governing resistance. The poor understanding of genetics and lack of precise phenotyping has hindered the development of FHB resistant cultivars. Though more than 100 QTLs imparting FHB resistance have been reported, none discovered the specific genes localized within the QTL region, nor the underlying mechanisms of resistance.In our study recombinant inbred lines (RILs carrying resistant (R-RIL and susceptible (S-RIL alleles of QTL-Fhb2 were subjected to metabolome and transcriptome profiling to discover the candidate genes. Metabolome profiling detected a higher abundance of metabolites belonging to phenylpropanoid, lignin, glycerophospholipid, flavonoid, fatty acid, and terpenoid biosynthetic pathways in R-RIL than in S-RIL. Transcriptome analysis revealed up-regulation of several receptor kinases, transcription factors, signaling, mycotoxin detoxification and resistance related genes. The dissection of QTL-Fhb2 using flanking marker sequences, integrating metabolomic and transcriptomic datasets, identified 4-Coumarate: CoA ligase (4CL, callose synthase (CS, basic Helix Loop Helix (bHLH041 transcription factor, glutathione S-transferase (GST, ABC transporter-4 (ABC4 and cinnamyl alcohol dehydrogenase (CAD as putative resistance genes localized within the QTL-Fhb2 region.Some of the identified genes within the QTL region are associated with structural resistance through cell wall reinforcement, reducing the spread of pathogen through rachis within a spike and few other genes that detoxify DON, the virulence factor, thus eventually reducing disease severity. In conclusion, we report that the wheat

  7. Requirement for two or more Erwinia carotovora subsp. carotovora pectolytic gene products for maceration of potato tuber tissue by Escherichia coli.

    OpenAIRE

    Roberts, D P; Berman, P M; Allen, C; Stromberg, V K; Lacy, G H; Mount, M S

    1986-01-01

    Several genes encoding enzymes capable of degrading plant cell wall components have been cloned from Erwinia carotovora subsp. carotovora EC14. Plasmids containing cloned EC14 DNA mediate the production of endo-pectate lyases, exo-pectate lyase, endo-polygalacturonase, and cellulase(s). Escherichia coli strains containing one of these plasmids or combinations of two plasmids were tested for their ability to macerate potato tuber slices. Only one E. coli strain, containing two plasmids that en...

  8. Palisade Russet: A late blight resistant potato cultivar having a low incidence of sugar ends and high specific gravity

    Science.gov (United States)

    Palisade Russet is a medium-late maturing, lightly russeted potato breeding clone notable for its resistance to late blight (Phytophthora infestans) infection of foliage and tuber. Palisade Russet is suitable for processing with low tuber glucose concentrations observed following long-term storage ...

  9. Regional spore dispersal as a factor in disease risk warnings for potato late blight: a proof of concept

    NARCIS (Netherlands)

    Kessel, G.J.T.; Skelsey, P.; Holtslag, A.A.M.; Moene, A.F.; Werf, van der W.

    2009-01-01

    This study develops and tests novel approaches that significantly reduce the fungicide input necessary for potato late blight control while maintaining the required high level of disease control. The central premise is that fungicide inputs can be reduced by reducing dose rates on more resistant

  10. Regional spore dispersal as a factor in disease risk warnings for potato late blight: A proof of concept

    NARCIS (Netherlands)

    Skelsey, P.; Kessel, G.J.T.; Holtslag, A.A.M.; Moene, A.F.; Werf, van der W.

    2009-01-01

    This study develops and tests a novel approach for including regional risk factors in operational disease risk warnings against potato late blight. The central premise is that fungicide inputs can be reduced by omitting applications on days when conditions are unsuitable for the atmospheric

  11. Regional spore dispersal as a factor in disease risk warnings for potato late blight : A proof of concept

    NARCIS (Netherlands)

    Skelsey, P.; Kessel, G. J. T.; Holtslag, A. A. M.; Moene, A. F.; van der Werf, W.

    2009-01-01

    This study develops and tests a novel approach for including regional risk factors in operational disease risk warnings against potato late blight. The central premise is that fungicide inputs can be reduced by omitting applications on days when conditions are unsuitable for the atmospheric

  12. First report of boxwood blight caused by Calonectria pseudonaviculata in Delaware, Maryland, New Jersey and New York

    Science.gov (United States)

    Boxwood (Buxus spp.) are commercially important evergreen ornamental plants with an annual market value of over $103 million in the United States. The recent U.S. incursion of boxwood blight disease caused by the fungus Calonectria pseudonaviculata (syn. Cylindrocladium pseudonaviculatum, Cy. buxico...

  13. Resistant and susceptible responses in alfalfa (Medicago sativa) to bacterial stem blight caused by Pseudomonas syringae pv. syringae

    Science.gov (United States)

    Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L.) in the central and western U.S. and has been reported in Australia and Europe. The disease is not always recognized because symptoms are often associated with frost damage. Two culti...

  14. Control of seedling blight in winter wheat by seed treatments - impact on emergence, crop stand, yield and deoxynivalenol

    DEFF Research Database (Denmark)

    Jørgensen, Lise N; K. Nielsen, Linda; Nielsen, Bent J

    2012-01-01

    germination by approximately 100%, which led to an improved crop stand and yield increases in the range of 1.2–1.5 tonnes ha−1. Attacks of Fusarium head blight were relatively slight in the two trials and the content of deoxynivalenol was below the EU limits of 1250 ppb in the harvested grain. Even so, seed...

  15. Discovering novel Alternaria solani succinate dehydrogenase inhibitors by in silico modeling and virtual screening strategies to combat early blight

    NARCIS (Netherlands)

    Iftikhar, Sehrish; Shahid, Ahmad A.; Halim, Sobia A.; Wolters, Pieter J.; Vleeshouwers, Vivianne G.A.A.; Khan, Ajmal; Al-Harrasi, Ahmed; Ahmad, Shahbaz

    2017-01-01

    Alternaria blight is an important foliage disease caused by Alternaria solani. The enzyme Succinate dehydrogenase (SDH) is a potential drug target because of its role in tricarboxylic acid cycle. Hence targeting Alternaria solani SDH enzyme could be efficient tool to design novel fungicides against

  16. A simple culture method inducing sexual reproduction by Fusarium graminearum, the primary causal agent of Fusarium head blight

    Science.gov (United States)

    The homothallic ascomycete fungus Fusarium graminearum is the primary causal agent of Fusarium head blight (FHB), a devastating disease of wheat and barley worldwide. The fungus undergoes both asexual and sexual stages in its life cycle. The asexual stage produces conidiospores, whereas the sexual s...

  17. An arabinobio-hydrolase (Arb93B) from Fusarium graminearum is associated with wheat head blight disease

    Science.gov (United States)

    Fusarium head blight (FHB), caused by the fungus Fusarium graminearum, is one of the most important diseases of wheat and barley worldwide. FHB not only reduces crop yield, but the fungus also contaminates grains with mycotoxins, which are harmful to humans and animals. A previous study demonstrated...

  18. Mummy Berry Fruit Rot and Shoot Blight Incidence in Blueberry: Prediction, Ranking, and Stability in a Long-term Study

    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 blueberry cultivar resistance to both phases of the disease and, utilizing ‘stan...

  19. Rainfall thresholds as support for timing fungicide applications in the control of potato late blight in Ecuador and Peru

    DEFF Research Database (Denmark)

    Kromann, Peter; Taipe, Arturo; Perez, Willmer G.

    2009-01-01

    Accumulated rainfall thresholds were studied in seven field experiments conducted in Ecuador and Peru for their value in timing applications of fungicide to control potato late blight, caused by Phytophthora infestans. Fungicide regimes based on accumulated rainfall thresholds ranging from 10 to 70...

  20. Molecular cytogenetic characterization of alien introgressions with gene Fhb3 for resistance to Fusarium head blight disease of wheat

    Science.gov (United States)

    Fusarium head blight (FHB) resistance was identified in the alien species Leymus racemosus, and wheat-Leymus introgression lines with FHB resistance were reported previously. Detailed molecular cytogenetic analysis of alien introgressions T01, T09, and T14 and the mapping of Fhb3, a new gene for FHB...

  1. Bacterial blight (Pseudomonas pisi Sackett) of peas in South Africa, with special reference to frost as a predisposing factor

    NARCIS (Netherlands)

    Boelema, B.H.

    1972-01-01

    In the beginning of the nineteen fifties bacterial blight caused much damage to pea crops in South Africa, particularly to those grown for seed production. A study has been made of the causal organism and the conditioning factors of the disease, special attention being paid to frost as a

  2. Citywide cluster randomized trial to restore blighted vacant land and its effects on violence, crime, and fear

    Science.gov (United States)

    Charles C. Branas; Eugenia South; Michelle C. Kondo; Bernadette C. Hohl; Philippe Bourgois; Douglas J. Wiebe; John M. MacDonald

    2018-01-01

    Vacant and blighted urban land is a widespread and potentially risky environmental condition encountered by millions of people on a daily basis. About 15% of the land in US cities is deemed vacant or abandoned, an area roughly the size of Switzerland. In a citywide cluster randomized controlled trial, we investigated the effects of standardized, reproducible...

  3. Efficacy of fungicide combinations, phosphoric acid, and plant extract from stinging nettle on potato late blight management and tuber yield

    Science.gov (United States)

    Late blight, caused by Phytophthora infestans is a major constraint to potato production. Inadequate management of the disease has often resulted in heavy losses in various production regions. We assessed the efficacy of fungicides, phosphoric acid, and stinging nettle plant extract combinations for...

  4. Phytophthora betacei, a new species within Phytophthora clade 1c causing late blight on Solanum betaceum in Colombia

    NARCIS (Netherlands)

    Mideros, M.F.; Turissini, D.A.; Guayazán, N.; Ibarra-Avila, H.; Danies, G.; Cárdenas, M.; Myers, K.; Tabima, J.; Goss, E.M.; Bernal, A.; Lagos, L.E.; Grajales, A.; Gonzalez, L.N.; Cooke, D.E.L.; Fry, W.E.; Grünwald, N.; Matute, D.R.; Restrepo, S.

    2018-01-01

    Over the past few years, symptoms akin to late blight disease have been reported on a variety of crop plants in South America. Despite the economic importance of these crops, the causal agents of the diseases belonging to the genus Phytophthora have not been completely characterized. In this study,

  5. Characterization of Triticum aestivum Abscisic Acid Receptors and a Possible Role for These in Mediating Fusairum Head Blight Susceptibility in Wheat

    Science.gov (United States)

    Gordon, Cameron S.; Rajagopalan, Nandhakishore; Risseeuw, Eddy P.; Surpin, Marci; Ball, Fraser J.; Barber, Carla J.; Buhrow, Leann M.; Clark, Shawn M.; Page, Jonathan E.; Todd, Chris D.; Abrams, Suzanne R.; Loewen, Michele C.

    2016-01-01

    Abscisic acid (ABA) is a well-characterized plant hormone, known to mediate developmental aspects as well as both abiotic and biotic stress responses. Notably, the exogenous application of ABA has recently been shown to increase susceptibility to the fungal pathogen Fusarium graminearum, the causative agent of Fusarium head blight (FHB) in wheat and other cereals. However roles and mechanisms associated with ABA’s modulation of pathogen responses remain enigmatic. Here the identification of putative ABA receptors from available genomic databases for Triticum aestivum (bread wheat) and Brachypodium distachyon (a model cereal) are reported. A number of these were cloned for recombinant expression and their functionality as ABA receptors confirmed by in vitro assays against protein phosphatases Type 2Cs. Ligand selectivity profiling of one of the wheat receptors (Ta_PYL2DS_FL) highlighted unique activities compared to Arabidopsis AtPYL5. Mutagenic analysis showed Ta_PYL2DS_FL amino acid D180 as being a critical contributor to this selectivity. Subsequently, a virus induced gene silencing (VIGS) approach was used to knockdown wheat Ta_PYL4AS_A (and similar) in planta, yielding plants with increased early stage resistance to FHB progression and decreased mycotoxin accumulation. Together these results confirm the existence of a family of ABA receptors in wheat and Brachypodium and present insight into factors modulating receptor function at the molecular level. That knockdown of Ta_PYL4AS_A (and similar) leads to early stage FHB resistance highlights novel targets for investigation in the future development of disease resistant crops. PMID:27755583

  6. Some new and noteworthy diseases of poplars in India. [Botryodiplodia sett-rot; Alternaria tip blight; Cladosporium leaf spot; Fusarium pink incrustation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.

    1983-09-01

    Four new diseases of poplars namely Botryodiplodia sett-rott, Alternaria tip blight, Cladosporium leaf spot and Fusarium pink incrustation are described in this paper. Botryodiplodia palmarum causes sett-rott of poplars both at pre-sprouting and post-sprouting stage. The pathogen also causes mortality of poplar plants in the field within 4-6 weeks after planting. Alternaria stage of Pleuspora infectoria has been found as the cause of blackening and dying of growing tips and young leaves of a Populus sp. and P. deltoides in nurseries. Cladosporium humile has been recorded as the cause of brown spot followed by crumpling and premature shedding of leaves in P. ciliata, P. nigra and P. alba. The cause of Fusarium incrustation disease on P. cilata has been identified as Fusarium sp. of Gibbosum group. Pathogenicity of Botryodiplodia palmarum and Alternaria stage of Pleospora infectoria was confirmed by artificial inoculations. Brief descriptions of Alternaria, Cladosporium and Fusarium are also given. The paper also gives a short account of some noteworthy diseases recorded on poplars namely Ganoderma root rot, foliage ruts and stem cankers. Ganoderma root-rot is found to reach alarming proportions in closely spaced poplar plantations. Melampsora ciliata, an indigenous rust, is found to attack mainly clones of P. deltoides, P. yunnanensis, P. trichocarpa, P. alba and some cultivars of P. x euramericana in nurseries. A brief account of three types of stem cankers i.e. cankers due to pink disease fungus, Corticium salmonicolor, sun-scaled cankers and cankers associated with slime flux on various clones of P. deltoides is also given.

  7. Defense reactions of bean genotypes to bacterial pathogens in controlled conditions

    Science.gov (United States)

    Uysal, B.; Bastas, K. K.

    2018-03-01

    This study was focused on the role of antioxidant enzymes and total protein in imparting resistance against common bacterial blight caused by Xanthomonas axonopodis pv. phaseoli (Xap) and halo blight caused by Pseudomonas syringae pv. phaseolicola (Psp) in bean. Activities of Ascorbate peroxidase (APX), Catalase (CAT) and total protein were studied in resistant and susceptible bean genotypes. Five-day-old seedlings were inoculated with a bacterial suspension (108 CFU ml-1) and harvested at different time intervals (0, 12, 24 and 36 up to 72 h) under controlled growing conditions and assayed for antioxidant enzymes and total protein. Temporal increase of CAT, APX enzymes activities showed maximum activity at 12 h after both pathogens inoculation (hpi) in resistant cultivar, whereas in susceptible it increased at 72 h after both pathogens inoculation for CAT and 12, 24 h for APX enzymes. Maximum total protein activities were observed at 12 h and 24 h respectively after Xap, Psp inoculation (hpi) in resistant and maximum activities were observed at 24 h and 72 h respectively after Xap, Psp inoculation (hpi) in susceptible. Increase of antioxidant enzyme and total protein activities might be an important component in the defense strategy of resistance and susceptible bean genotypes against the bacterial infection. These findings suggest that disease protection is proportional to the amount of enhanced CAT, APX enzyme and total protein activity.

  8. Identification and Pathogenicity of Phytopathogenic Bacteria Associated with Soft Rot Disease of Girasole Tuber

    Directory of Open Access Journals (Sweden)

    Mamdoh Ewis ISMAIL

    2012-02-01

    Full Text Available During 2010-2011 growing seasons six bacterial isolates were separated from naturally infected girasole plants tubers (Helianthus tuberosus L. cv. �Balady�, showing soft rot, collected from experimental Farm of the Faculty of Agriculture, in El-Minia University, Egypt. Pathogenicity tests showed various virulence for the bacteria isolated from girasole tubers, found pathogenic. These organisms were characterized as rod-shaped, Gram negative, ?-methyl-d-glucoside medium, reducing substances from sucrose, phos, phatase activity and deep cavities on pectate medium. Otherwise, diagnostic tests suggested that the pathogen was Erwinia carotovora ssp. carotovora. The isolated bacteria caused soft rot of wounded tubers when inoculated into tissues. The bacterial isolates were compared for their degree of pathogenicity as well as for differences in specific symptoms, induced in different hosts. The tested isolates could infect several host ranges, such as fruits of apricot, apple, olive, lemon, squash, eggplant and potato tubers, bulbs and garlic and onion cloves, roots radish, carrot, sweet potato and rape. On the other hand, no symptoms were exhibited on pods of bean and cowpea, faba bean, fruits of pepper and tomato. The extracts of experimentally diseased girasole tubers were active in pectinase and also in caboxymethyl cellulose at pH 6 compared to enzyme activities in healthy tissues. Also, the isolated bacteria increased the total and reducing sugars in infected tissues.

  9. Frost related dieback in Estonian energy plantations of willows in relation to fertilisation and pathogenic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cambours, M.A.; Nejad, P. [Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, Box 7026, 750 07 Uppsala (Sweden); Heinsoo, K. [Institute of Zoology and Botany, Estonian Agricultural University, Riia 181, 51014 Tartu (Estonia); Granhall, U. [Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala (Sweden)

    2006-03-15

    Two 9-year old Estonian Salix plantations suffering from dieback were studied: one situated on poor mineral soil and divided into fertilised and unfertilised plots (Saare plantation) and another growing on a well-decomposed and nitrogen-rich organic soil, without fertiliser application (Kambja plantation). Bacteria from internal tissues of visually damaged shoots from seven clones were isolated in spring and autumn. The strains were subsequently biochemically characterised and tested for ice nucleation activity and pathogenicity on Salix. Some strains were also analysed with 16S rRNA. High numbers of culturable bacteria were found, belonging mainly to Erwinia, Sphingomonas, Pseudomonas and Xanthomonas spp. Fertilised plots were significantly more colonised by bacteria than unfertilised plots and also more extensively damaged, showing a lower density of living plants after 7 years of culture. More ice nucleation active (INA) strains were found in Saare fertilised plots and at Kambja than in Saare unfertilised plots. Likewise, most pathogenic strains were isolated from Saare fertilised plots and from Kambja. For some of the willow clones studied, dieback appeared to be related to both clonal frost sensitivity and abundance of INA and pathogenic bacteria. The plantations probably suffered from the presence of high amounts of pathogens and from frost related injuries aggravated by INA bacteria. Most probably the fertilisation at Saare and the nitrogen-rich soil at Kambja created a favourable environment for bacterial development and led to high dieback levels after the first harvest. (author)

  10. Comparative genome analysis of rice-pathogenic Burkholderia provides insight into capacity to adapt to different environments and hosts.

    Science.gov (United States)

    Seo, Young-Su; Lim, Jae Yun; Park, Jungwook; Kim, Sunyoung; Lee, Hyun-Hee; Cheong, Hoon; Kim, Sang-Mok; Moon, Jae Sun; Hwang, Ingyu

    2015-05-06

    In addition to human and animal diseases, bacteria of the genus Burkholderia can cause plant diseases. The representative species of rice-pathogenic Burkholderia are Burkholderia glumae, B. gladioli, and B. plantarii, which primarily cause grain rot, sheath rot, and seedling blight, respectively, resulting in severe reductions in rice production. Though Burkholderia rice pathogens cause problems in rice-growing countries, comprehensive studies of these rice-pathogenic species aiming to control Burkholderia-mediated diseases are only in the early stages. We first sequenced the complete genome of B. plantarii ATCC 43733T. Second, we conducted comparative analysis of the newly sequenced B. plantarii ATCC 43733T genome with eleven complete or draft genomes of B. glumae and B. gladioli strains. Furthermore, we compared the genome of three rice Burkholderia pathogens with those of other Burkholderia species such as those found in environmental habitats and those known as animal/human pathogens. These B. glumae, B. gladioli, and B. plantarii strains have unique genes involved in toxoflavin or tropolone toxin production and the clustered regularly interspaced short palindromic repeats (CRISPR)-mediated bacterial immune system. Although the genome of B. plantarii ATCC 43733T has many common features with those of B. glumae and B. gladioli, this B. plantarii strain has several unique features, including quorum sensing and CRISPR/CRISPR-associated protein (Cas) systems. The complete genome sequence of B. plantarii ATCC 43733T and publicly available genomes of B. glumae BGR1 and B. gladioli BSR3 enabled comprehensive comparative genome analyses among three rice-pathogenic Burkholderia species responsible for tissue rotting and seedling blight. Our results suggest that B. glumae has evolved rapidly, or has undergone rapid genome rearrangements or deletions, in response to the hosts. It also, clarifies the unique features of rice pathogenic Burkholderia species relative to other

  11. Infection processes of xylem-colonizing pathogenic bacteria: possible explanations for the scarcity of qualitative disease resistance genes against them in crops.

    Science.gov (United States)

    Bae, Chungyun; Han, Sang Wook; Song, Yu-Rim; Kim, Bo-Young; Lee, Hyung-Jin; Lee, Je-Min; Yeam, Inhwa; Heu, Sunggi; Oh, Chang-Sik

    2015-07-01

    Disease resistance against xylem-colonizing pathogenic bacteria in crops. Plant pathogenic bacteria cause destructive diseases in many commercially important crops. Among these bacteria, eight pathogens, Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, X. campestris pv. campestris, Erwinia amylovora, Pantoea stewartii subsp. stewartii, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. actinidiae, and Xylella fastidiosa, infect their host plants through different infection sites and paths and eventually colonize the xylem tissues of their host plants, resulting in wilting symptoms by blocking water flow or necrosis of xylem tissues. Noticeably, only a relatively small number of resistant cultivars in major crops against these vascular bacterial pathogens except X. oryzae pv. oryzae have been found or generated so far, although these pathogens threaten productivity of major crops. In this review, we summarize the lifestyles of major xylem-colonizing bacterial pathogens and then discuss the progress of current research on disease resistance controlled by qualitative disease resistance genes or quantitative trait loci against them. Finally, we propose infection processes of xylem-colonizing bacterial pathogens as one of possible reasons for why so few qualitative disease resistance genes against these pathogens have been developed or identified so far in crops.

  12. Functional Marker Assisted Improvement of Stable Cytoplasmic Male Sterile Lines of Rice for Bacterial Blight Resistance

    Directory of Open Access Journals (Sweden)

    Jegadeesan Ramalingam

    2017-06-01

    Full Text Available Bacterial blight (BB, caused by Xanthomonas oryzae pv.oryzae is one among the major diseases in rice, which in severe condition cause losses up to 60% in total yield. Marker assisted pyramiding of three broad spectrum BB resistance genes (xa5, xa13, and Xa21 in prominent rice varieties is the most economical and effective strategy for the management of the BB disease. We report here the pyramiding of three genes (xa5, xa13, and Xa21 in maintainer lines (CO 2B, CO 23B, and CO 24B of three promising wild abortive cytoplasmic male sterile lines (CO 2A, CO 23A, and CO 24A through functional markers assisted back cross breeding. IRBB60 with xa5, xa13, and Xa21 genes is used as a donor parent. BC2F1 and BC2F2 generations from a cross of CO 2B, CO 23B, and CO 24B with IRBB60 were evaluated for bacterial blight and non-fertility restoration. In BC2F1, plants with all three resistance genes (xa5, xa13, and Xa21 and high parent genome recovery was identified. In BC2F2, plants with all resistance genes and without fertility restorer (Rf3 and Rf4 were selected. Based on agronomic traits, BB resistance and maintenance of sterility, two plants each in CO 2B × IRBB60, CO 24B × IRBB60 and one plant in CO 23B × IRBB60 combinations were identified. The identified lines were crossed with respective male sterile lines for conversion of improved B line into CMS line through back-crossing, in addition to selfing. The plants with high recurrent genome and phenotypically similar to parental lines and sterile are being used for the hybrid rice development program. Currently, using these lines (improved CMS line, test crosses were made to develop new rice hybrids. Hybrids combinations viz., CO 23A × AD08009R and CO 24A × IET20898R were found to be stable at different locations with high yield. The R line used in this study has been introgressed with xa5, xa13, and Xa21 genes in a separate breeding program. These new hybrids with resistance against bacterial blight

  13. O papel de Rhizoctonia spp. binucleadas na indução de resistência a mela da soja = The role of binucleate Rhizoctonia spp. inducing resistance to the soybean foliar blight

    Directory of Open Access Journals (Sweden)

    Marco Antonio Basseto

    2008-04-01

    Full Text Available O papel de Rhizoctonia spp. binucleadas (RBN, no biocontrole de doenças causadas por R. solani Kühn em várias culturas, tem sido relatado na literatura. No entanto, não há informação, no Brasil, sobre o potencial de RBN como agentes de biocontrole contradoenças causadas por Rhizoctonia na soja. A hipótese testada foi de que isolados de RBN podem induzir resistência na soja contra a mela, causada por R. solani do grupo de anastomose (AG 1 IA. Desta forma, o objetivo deste trabalho foi avaliar isolados de RBN, obtidos de amendoim, feijão e soja quanto à capacidade de induzir resistência na soja contra a mela, em condições de casa de vegetação. Esta pesquisa evidencia a ação de RBN na indução de resistência em plantas de soja contra a mela. Entretanto, a manifestação e a efetividade do fenômeno de indução de resistência são dependentes da época de cultivo da soja.The role of non-pathogenic binucleate Rhizoctonia spp. (BNR onthe biocontrol of diseases caused by R. solani on many crops has been reported in the literature. However, in Brazil, there is no information about the potential of BNR as biocontrol agents against Rhizoctonia diseases on soybean. On this research we tested thehypothesis that BNR can induce resistance on soybean against the foliar blight caused by R. solani anastomosis group (AG 1 IA. Thus, the objective of this research was to evaluate BNR isolates isolated from peanuts, snapbeans and soybean according to their ability forinducing resistance on soybean against the foliar blight disease, under greenhouse conditions. This research evidenced the role of BNR inducing resistance on soybeans against the foliar blight. However, both the occurrence and effectiveness of the phenomenon of induced resistance are dependent on the soybean cultivation season.

  14. Sharing a Host Plant (Wheat [Triticum aestivum]) Increases the Fitness of Fusarium graminearum and the Severity of Fusarium Head Blight but Reduces the Fitness of Grain Aphids (Sitobion avenae)

    Science.gov (United States)

    Drakulic, Jassy; Caulfield, John; Woodcock, Christine; Jones, Stephen P. T.; Linforth, Robert; Bruce, Toby J. A.

    2015-01-01

    We hypothesized that interactions between fusarium head blight-causing pathogens and herbivores are likely to occur because they share wheat as a host plant. Our aim was to investigate the interactions between the grain aphid, Sitobion avenae, and Fusarium graminearum on wheat ears and the role that host volatile chemicals play in mediating interactions. Wheat ears were treated with aphids and F. graminearum inoculum, together or separately, and disease progress was monitored by visual assessment and by quantification of pathogen DNA and mycotoxins. Plants exposed to both aphids and F. graminearum inoculum showed accelerated disease progression, with a 2-fold increase in disease severity and 5-fold increase in mycotoxin accumulation over those of plants treated only with F. graminearum. Furthermore, the longer the period of aphid colonization of the host prior to inoculation with F. graminearum, the greater the amount of pathogen DNA that accumulated. Headspace samples of plant volatiles were collected for use in aphid olfactometer assays and were analyzed by gas chromatography-mass spectrometry (GC-MS) and GC-coupled electroantennography. Disease-induced plant volatiles were repellent to aphids, and 2-pentadecanone was the key semiochemical underpinning the repellent effect. We measured aphid survival and fecundity on infected wheat ears and found that both were markedly reduced on infected ears. Thus, interactions between F. graminearum and grain aphids on wheat ears benefit the pathogen at the expense of the pest. Our findings have important consequences for disease epidemiology, because we show increased spread and development of host disease, together with greater disease severity and greater accumulation of pathogen DNA and mycotoxin, when aphids are present. PMID:25769834

  15. Relationship between soil cellulolytic activity and suppression of seedling blight of barley in arable soils

    DEFF Research Database (Denmark)

    Rasmussen, Peter Have; Knudsen, I.; Elmholt, S.

    2002-01-01

    the Hanes-Wolf transformation of the Michaelis-Menten equation. Soil samples from 6 to 13 cm depth were collected in the early spring as undisturbed blocks from 10 arable soils with different physico-chemical properties and cultivation history. Significant correlations were found between soil suppresiveness......The objective was to investigate the relationship between soil suppression of seedling blight of barley caused by Fusarium culmorum (W.G. Smith) Sacc. and the soil cellulolytic activity of beta-glucosidase, cellobiohydrolase and endocellulase. Disease suppression was investigated in bioassays...... with test soils mixed with sand, and barley seeds inoculated with F. culmorum. After 19 days, disease severity was evaluated on the barley seedlings. Soil cellulolytic activities were measured using 4-methylumbelliferyl-labelled fluorogenic substrates, and were expressed as V-max values obtained by using...

  16. Medicinal plants - a potent antibacterial source against bacterial leaf blight (BLB) of rice

    International Nuclear Information System (INIS)

    Jabeen, R.

    2011-01-01

    The antibacterial potential of indigenous medicinal plants as alternative chemical pesticides for controlling bacterial leaf blight (BLB) of rice was investigated. Twenty-five different species of medicinal plants were collected from various sites in Pakistan. Decoctions of all medicinal plant species were screened by the disc plate diffusion method for testing the susceptibility of an aggressive isolate of Xanthomonas oryzae pv. oryzae (Xoo 105). Out of twenty five medicinal plants, Thuja orientalis (cone + leaves), Azadirachta indica (seeds + fruits), Amomum subulatum (fruits), Terminalia chebula (fruits), Terminalia bellirica (fruits), Anethum graveolens (fruits) and Ferula assa-foetida (fruits) decoctions showed significant activity. The efficacy of decoctions from six promising plants were further tested through detached leaf, glasshouse and field assays. A decoction of Terminalia chebula demonstrated the highest effectiveness in terms of regulating BLB in the plants both under laboratory and field conditions. Bioactive fractions of Terminalia chebula were purified, characterized and tentatively identified as allegic acid. (author)

  17. Fusarium head blight resistance and mycotoxin profiles of four Triticum species genotypes

    Directory of Open Access Journals (Sweden)

    Tomasz GÓRAL

    2017-05-01

    Full Text Available Fusarium head blight (FHB resistance was evaluated for accessions of four Triticum species, including bread wheat (modern and old cultivars, spelt, emmer, and einkorn. Fusarium head infection, Fusarium kernel damage and accumulation of trichothecene toxins (deoxynivalenol, nivalenol in grains were analysed. Modern bread wheat cultivars were the most susceptible to head infection, and emmer and einkorn accessions were the most resistant. Kernel damage was the least for emmer and spelt and greatest for bread wheat. No significant differences between the four host species were observed for toxin accumulation. However, the greatest amounts of deoxynivalenol were detected in the grains of modern wheat cultivars and the least in old bread wheat cultivars. The greatest amount of nivalenol was detected in einkorn grains and the least in old bread wheat cultivars. Wide variability of resistance of all types in all four species was observed. Accessions resistant to FHB and toxin accumulation in grains were identified.

  18. Surface layers of Xanthomonas malvacearum, the cause of bacterial blight of cotton.

    Science.gov (United States)

    Verma, J P; Formanek, H

    1981-01-01

    Mureins were isolated from two strains of Xanthomonas malvacearum, a phytopathogenic bacterium causing bacterial blight of cotton. The purity of murein was 70-95 % and the amino acid and amino sugar components (glutamic acid, alanina, meso-disminopimelic acid, muramic acid and glucosamine) were present at the molar ratio of 1:1.9:1:l.12.0.85. The bacterium secreted a copious amount of slime which masked itd surface structure. The slime was composed of densley interwoven network of filamentous material originating from the cell surface and extended into the medium without and discernable boundary. The slime was secreted through surface layers pores by force, giving the effect of a spray or jet. Slime also played a role in chain formatin of baterial cells.

  19. Rice mutation breeding for resistance against leaf blight disease and brown planthopper

    International Nuclear Information System (INIS)

    Mugiono; Ismachin, M

    1981-01-01

    Seeds of Pelita 1/1 were treated variously with EMS 1%, 20, 30, 35, 40 and 50 krad doses gamma rays from a Co 60 source. The 1% EMS treatment, of presoaking for 36 hours in distilled water and stored for one week before sowing, yielded more mutants resistant against bacterial leaf blight compared to other treatments with EMS. Treatment with 20 krad of gamma rays gave an indication of a good probability for improving resistance. Screening for brown planthopper resistance among 350 M 4 lines yielded 4 moderate resistant (MR) lines. However, no resistant line was found. From 36 crosses between the mutants and IR-26 or mutants with Mudgo 86 promising lines were found. The promising lines, beside resistant against brown planthopper, were selected based on early maturity and short stem. (author)

  20. Genomic survey of pathogenicity determinants and VNTR markers in the cassava bacterial pathogen Xanthomonas axonopodis pv. Manihotis strain CIO151.

    Science.gov (United States)

    Arrieta-Ortiz, Mario L; Rodríguez-R, Luis M; Pérez-Quintero, Álvaro L; Poulin, Lucie; Díaz, Ana C; Arias Rojas, Nathalia; Trujillo, Cesar; Restrepo Benavides, Mariana; Bart, Rebecca; Boch, Jens; Boureau, Tristan; Darrasse, Armelle; David, Perrine; Dugé de Bernonville, Thomas; Fontanilla, Paula; Gagnevin, Lionel; Guérin, Fabien; Jacques, Marie-Agnès; Lauber, Emmanuelle; Lefeuvre, Pierre; Medina, Cesar; Medina, Edgar; Montenegro, Nathaly; Muñoz Bodnar, Alejandra; Noël, Laurent D; Ortiz Quiñones, Juan F; Osorio, Daniela; Pardo, Carolina; Patil, Prabhu B; Poussier, Stéphane; Pruvost, Olivier; Robène-Soustrade, Isabelle; Ryan, Robert P; Tabima, Javier; Urrego Morales, Oscar G; Vernière, Christian; Carrere, Sébastien; Verdier, Valérie; Szurek, Boris; Restrepo, Silvia; López, Camilo; Koebnik, Ralf; Bernal, Adriana

    2013-01-01

    Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in Africa and South America. Current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. Previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable tools for diagnostics and detection. Here we have generated the first manually annotated high-quality draft genome sequence of Xam strain CIO151. Its genomic structure is similar to that of other xanthomonads, especially Xanthomonas euvesicatoria and Xanthomonas citri pv. citri species. Several putative pathogenicity factors were identified, including type III effectors, cell wall-degrading enzymes and clusters encoding protein secretion systems. Specific characteristics in this genome include changes in the xanthomonadin cluster that could explain the lack of typical yellow color in all strains of this pathovar and the presence of 50 regions in the genome with atypical nucleotide composition. The genome sequence was used to predict and evaluate 22 variable number of tandem repeat (VNTR) loci that were subsequently demonstrated as polymorphic in representative Xam strains. Our results demonstrate that Xanthomonas axonopodis pv. manihotis strain CIO151 possesses ten clusters of pathogenicity factors conserved within the genus Xanthomonas. We report 126 genes that are potentially unique to Xam, as well as potential horizontal transfer events in the history of the genome. The relation of these regions with virulence and pathogenicity could explain several aspects of the biology of this pathogen, including its ability to colonize both vascular and non-vascular tissues of cassava plants. A set of 16 robust, polymorphic VNTR loci will be useful to develop a multi-locus VNTR analysis

  1. Genetic control of late blight, yield and some yield related traits in tomato (lycopersicon esculentum mill.)

    International Nuclear Information System (INIS)

    Saleem, M.Y.; Asghar, M.; Khan, A.R.; Iqbal, Q.

    2011-01-01

    Genetic control of late blight (LB) and some economic traits was assessed to identify genotypes suitable for the hybrids were derived from crossing of 2 male sterile lines viz., development of late blight resistant hybrids in tomato. 10 F/sub 1/ hybrid were derived from crossing of 2 male sterile lines viz., TMS1 and TMS2 with 5 elite lines viz., Nagina, Riogrande, Roma, 88572 and Picdenato according to line x tester technique. Disease resistance was measured using detached leaf and whole plant assay techniques. Data were also recorded for days to maturity, number of fruit per plant, single fruit weight and yield per plant. The analysis of variance showed significant differences among crosses, lines, testers and line x tester interaction for almost all parameters. Estimate of genetic components indicated preponderance of additive type of gene action for detached leaf assay, whole plant assay, number of fruit per plant and yield per plant whereas non-additive type of gene action for days to maturity and single fruit weight. Among parents, TMS2, Nagina, Roma and Picdenato showed significant favorable general combing ability (GCA) effects for disease rating traits while TMS1 and Riogrande indicated desirable GCA effects for yield and some yield related traits. Among hybrids, TMS2 x Roma and TMS1 x Riogrande had significant specific combing ability (SCA) effects for detached and whole plant assays. However, hybrid TMS2 x Roma appeared as good combination of LB resistance as it had both parents with desirable GCA effects. All hybrids showed average type of SCA effects for yield and yield components. Genetic control of LB revealed that a multiple crossing program involving genotypes with high GCA effects would be rewarding to identify LB resistant genotypes in early generations. (author)

  2. Actinomycetes from Eucalyptus and their biological activities for controlling Eucalyptus leaf and shoot blight.

    Science.gov (United States)

    Himaman, Winanda; Thamchaipenet, Arinthip; Pathom-Aree, Wasu; Duangmal, Kannika

    2016-01-01

    In Thailand, Eucalyptus plantations rapidly expand across the country. Leaf and shoot blight caused by Cryptosporiopsis eucalypti, Cylindrocladium sp. and Teratosphaeria destructans is a serious disease in Eucalyptus plantations. In this study, a total of 477 actinomycete strains were successfully isolated from roots and rhizosphere soil of Eucalyptus. Four hundred and thirty nine isolates were classified as streptomycetes and 38 isolates were non-streptomycetes. Among these isolates, 272 (57.0%), 118 (24.7%) and 241 (50.5%) isolates were antagonistic to Cryptosporiopsis eucalypti, Cylindrocladium sp. and Teratosphaeria destructans, respectively. All isolates were tested for their abilities to produce siderophores, indole acetic acid (IAA) and solubilise phosphate. Most isolates (464, 97.3%) produced siderophores. The majority of isolates (345, 72.3%) solubilised phosphate. In addition, almost half of these isolates (237, 49.7%) produced indole acetic acid. Strain EUSKR2S82 which showed the strongest inhibitory effect against all tested fungi with plant growth promoting ability was selected to test with Eucalyptus. This strain could colonize plant roots and increase Eucalyptus roots length. In a detached leaves bioassay, the disease severity of EUSKR2S82-inoculated Eucalyptus leaves was only 30% compared to 95% in the control treatment. The 16S rRNA gene sequence analysis revealed that the strain EUSKR2S82 was related to Streptomyces ramulosus NRRL-B 2714(T) (99.44% similarity). Identification of non-streptomycete isolates using 16S rRNA gene sequences classified them into 9 genera: Actinoallomurus, Actinomadura, Amycolatopsis, Cryptosporangium, Microbispora, Micromonospora, Nocardia, Nonomuraea and Pseudonocardia. It is evident that Eucalyptus tree harbored several genera of actinomycetes. The selected isolate, EUSKR2S82 showed potential as a candidate for biocontrol agent of leaf and shoot blight of Eucalyptus and to promote growth. Copyright © 2016 Elsevier Gmb

  3. Simultaneous Detection of Brown Rot- and Soft Rot-Causing Bacterial Pathogens from Potato Tubers Through Multiplex PCR.

    Science.gov (United States)

    Ranjan, R K; Singh, Dinesh; Baranwal, V K

    2016-11-01

    Ralstonia solanacearum (Smith) Yabuuchi et al. and Erwinia carotovora subsp. carotovora (Jones) Bergey et al. (Pectobacterium carotovorum subsp. carotovorum) are the two major bacterial pathogens of potato causing brown rot (wilt) and soft rot diseases, respectively, in the field and during storage. Reliable and early detection of these pathogens are keys to avoid occurrence of these diseases in potato crops and reduce yield loss. In the present study, multiplex polymerase chain reaction (PCR) protocol was developed for simultaneous detection of R. solanacearum and E. carotovora subsp. carotovora from potato tubers. A set of oligos targeting the pectatelyase (pel) gene of E. carotovora subsp. carotovora and the universal primers based on 16S r RNA gene of R. solanacearum were used. The standardized multiplex PCR protocol could detect R. solanacearum and E. carotovora subsp. carotovora up to 0.01 and 1.0 ng of genomic DNA, respectively. The protocol was further validated on 96 stored potato tuber samples, collected from different potato-growing states of India, viz. Uttarakhand, Odisha, Meghalaya and Delhi. 53.1 % tuber samples were positive for R. solanacearum, and 15.1 % of samples were positive for E. carotovora subsp. carotovora, and both the pathogens were positive in 26.0 % samples when BIO-PCR was used. This method offers sensitive, specific, reliable and fast detection of two major bacterial pathogens from potato tubers simultaneously, particularly pathogen-free seed certification in large scale.

  4. AMPK in Pathogens

    OpenAIRE

    Mesquita, Inês Morais; Moreira, Diana; Marques, Belém Sampaio; Laforge, Mireille; Cordeiro-da-Silva, Anabela; Ludovico, Paula; Estaquier, Jérôme; Silvestre, Ricardo Jorge Leal

    2016-01-01

    During host–pathogen interactions, a complex web of events is crucial for the outcome of infection. Pathogen recognition triggers powerful cellular signaling events that is translated into the induction and maintenance of innate and adaptive host immunity against infection. In opposition, pathogens employ active mechanisms to manipulate host cell regulatory pathways toward their proliferation and survival. Among these, subversion of host cell energy metabolism by pathogens is currently recogn...

  5. The survival of pathogens in soil treated with wastewater sludge and in potatoes grown in such soil.

    Science.gov (United States)

    Chale-Matsau, J R B; Snyman, H G

    2006-01-01

    The prevalence of pathogens on potatoes (Solanum tuberosum) grown in soil amended with a pathogen rich wastewater sludge was investigated. Bacteria of the family Enterobacteriaceae are important pathogens causing intestinal and systemic illness of humans and other animals. Type B sludge was used. Sludges investigated are the high metal and the low metal sludges. Microorganisms in the sludge-amended soil were using culture-based technique. Salmonella and E. coli were observed in tested soil samples. No microorganisms were isolated from control samples taken throughout the process of the experiment. At harvest time, some of the potato samples from LMS soil were contaminated. These potatoes were subjected to further investigation using molecular techniques (polymerase chain reaction) with fD1 and rP2 as primers. Organisms identified from the sequenced potato peel samples with the BLAST search tool included Enterobacter agglomerans (Pantoea agglomerans), several Buttiauxella spp., Pectobacterium spp., Erwinia spp. and a few Pantoea spp. Other than the E. agglomerans, which is commonly found in the gut and upper respiratory tract of humans and in the environment, all the other species identified were found to be mainly either plant or soil pathogens. The E. agglomerans are not primary pathogens but secondary opportunistic pathogens particularly in immunocompromised individuals. These results suggest that growing high risk crops using wastewater sludge contaminated soil may lead to limited infestation of produce with primary pathogens. It appears that the use of HMS due to early pathogen die-off provides less risk of infection than the LMS. However, proper treatment of wastewater sludge to reduce pathogen load is essential prior to its use as soil conditioner.

  6. Carboxymethyl-cellulase from Erwinia chrysanthemi. II. Purification and partial characterization of an endo-. beta. -1,4-glucanase

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, M.H.; Chambost, J.P.; Magnan, M.; Cattaneo, J.

    1984-01-01

    The extracellular carboxymethyl-cellulase of Erwinia chrysanthemi, strain 3665, had a marked tendency to form aggregates when concentration and/or storage time of culture supernatant were increased. In submitting an unconcentrated glycerol culture supernatant to ion exchange chromatography, one major endo-..beta..-1,4,-glucanase could be isolated with a high degree of purity and partially characterized. The molecular size was 45 kd. The pI was 4.3. The enzyme rapidly decreased the viscosity of carboxymethyl-cellulose with a slow increase in the reducing sugars produced. It displayed its highest activity towards carboxymethyl-cellulose at a pH between 6.2 and 7.5. It had a significant capacity to hydrolyze amorphous cellulose such as phosphoric acid-swollen cellulose. The major products of this degradation were cellobiose and cellotriose. It exhibited a very low activity on microcrystalline cellulose. Glucose and cellobiose did not affect significantly its activity against carboxymethyl-cellulose. 21 references.

  7. Hyperspectral remote sensing for advanced detection of early blight (Alternaria solani) disease in potato (Solanum tuberosum) plants

    Science.gov (United States)

    Atherton, Daniel

    Early detection of disease and insect infestation within crops and precise application of pesticides can help reduce potential production losses, reduce environmental risk, and reduce the cost of farming. The goal of this study was the advanced detection of early blight (Alternaria solani) in potato (Solanum tuberosum) plants using hyperspectral remote sensing data captured with a handheld spectroradiometer. Hyperspectral reflectance spectra were captured 10 times over five weeks from plants grown to the vegetative and tuber bulking growth stages. The spectra were analyzed using principal component analysis (PCA), spectral change (ratio) analysis, partial least squares (PLS), cluster analysis, and vegetative indices. PCA successfully distinguished more heavily diseased plants from healthy and minimally diseased plants using two principal components. Spectral change (ratio) analysis provided wavelengths (490-510, 640, 665-670, 690, 740-750, and 935 nm) most sensitive to early blight infection followed by ANOVA results indicating a highly significant difference (p potato plants.

  8. Induction of bacterial blight resistance in elite Indian rice cultivars using gamma-rays and ethyl methanesulfonate

    International Nuclear Information System (INIS)

    Agrawal, P.K.; Gosal, S.S.; Sidhu, G.S.

    2001-01-01

    Rice is the most important cereal crop in the world feeding more than 50 percent of the human population. During the last 30 years, induced mutation breeding has played a significant role in rice breeding programmes. Rice mutants with higher yield, greater tolerance to diseases and pests and other agronomic qualities have been released for commercial cultivation in many countries. Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae is the second important disease in Southeast Asia. In the Basmati field sometime the yield loss is up to 100%. Moreover, there is no resistance source available. In Basmati rice, which is known for its quality and aroma. Induction of bacterial blight resistance in Basmati will help in developing high yielding Basmati type cultivars without compromising the quality

  9. Transfer of bacterial blight resistance from Oryza meyeriana to O.Sativa L.by asymmetric somatic hybridization

    Institute of Scientific and Technical Information of China (English)

    ZHU Yongsheng; CHEN Baotang; YU Shunwu; ZHANG Duanpin; ZHANG Xueqin; YAN Qiusheng

    2004-01-01

    Asymmetric somatic hybrid plants were produced between cultivated rice (Oryza sativa L.) and wild species [O. Meyeriana (Zoll. etMor, exSteud.)] with high resistance to rice bacterial blight. X-ray-irradiated protoplasts of the wild species were used as donor and chemically fused with iodoacetamide-inactivated protoplasts of rice cv. 02428to produce hybrids. Seventy-two plants were regenerated from 623 calli based on metabolic complementation. The morphological characters of the plants closely resembled that of the rice. Simple sequence repeats were employed to identify their hybridity. Cytological analysis of root-tips revealed that their chromosome number varied in the range of 27-38. The somatic hybrids were inoculated with strains of Xanthamonas oryzae pv. Oryzae at adult growth stage and demonstrated the resistance to bacterial blight introgression from the O. Meyeriana.

  10. Extracellular peptidases of the cereal pathogen Fusarium graminearum.

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    Rohan George Thomas Lowe

    2015-11-01

    Full Text Available The plant pathogenic fungus Fusarium graminearum (Fgr creates economic and health risks in cereals agriculture. Fgr causes head blight (or scab of wheat and stalk rot of corn, reducing yield, degrading grain quality and polluting downstream food products with mycotoxins. Fungal plant pathogens must secrete proteases to access nutrition and to breakdown the structural protein component of the plant cell wall. Research into the proteolytic activity of Fgr is hindered by the complex nature of the suite of proteases secreted. We used a systems biology approach comprising genome analysis, transcriptomics and label-free quantitative proteomics to characterise the peptidases deployed by Fgr during growth. A combined analysis of published microarray transcriptome datasets revealed seven transcriptional groupings of peptidases based on in vitro growth, in planta growth, and sporulation behaviours. An orbitrap MS/MS proteomics technique defined the extracellular proteases secreted by Fusarium graminearum. A meta-classification based on sequence characters and transcriptional/translational activity in planta and in vitro provides a platform to develop control strategies that target Fgr peptidases.

  11. Fungal endophytes of turmeric (Curcuma longa L.) and their biocontrol potential against pathogens Pythium aphanidermatum and Rhizoctonia solani.

    Science.gov (United States)

    Vinayarani, G; Prakash, H S

    2018-03-14

    Endophytic fungi have been isolated from the healthy turmeric (Curcuma longa L.) rhizomes from South India. Thirty-one endophytes were identified based on morphological and ITS-rDNA sequence analysis. The isolated endophytes were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric respectively. Results revealed that only six endophytes showed > 70% suppression of test pathogens in antagonistic dual culture assays. The endophyte T. harzianum TharDOB-31 showed significant in vitro mycelial growth inhibition of P. aphanidermatum (76.0%) and R. solani (76.9%) when tested by dual culture method. The SEM studies of interaction zone showed morphological abnormalities like parasitism, shriveling, breakage and lysis of hyphae of the pathogens by endophyte TharDOB-31. Selected endophytic isolates recorded multiple plant growth promoting traits in in vitro studies. The rhizome bacterization followed by soil application of endophyte TharDOB-31 showed lowest Percent Disease Incidence of rhizome rot and leaf blight, 13.8 and 11.6% respectively. The treatment of TharDOB-31 exhibited significant increase in plant height (85 cm) and fresh rhizome yield/plant (425 g) in comparison with untreated control under greenhouse condition. The confocal microscopy validates the colonization of the TharDOB-31 in turmeric rhizomes. The secondary metabolites in ethyl acetate extract of TharDOB-31 were found to contain higher number of antifungal compounds by high resolution liquid chromatograph mass spectrometer analysis. Thereby, endophyte T. harzianum isolate can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

  12. Efficacy of a copper-based bactericide in controlling bacterial blight of grapevines caused by Xylophilus ampelinus

    OpenAIRE

    Komatsu, Tsutomu; Kondo, Norio

    2015-01-01

    We investigated the efficacy of a microbial copper agent to protect against bacterial blight of grapevine caused by Xylophilus ampelinus from 2012 to 2014 in Hokkaido, Japan. A solution of the basic copper wettable powder sulfate was sprayed at 10-day intervals in two processing plots, using two application protocols: seven rounds of application immediately after leaf development and three or four applications at the initial onset of the disease. Due to the low disease incidence for the durat...

  13. Defense Response and Suppression of Phytophthora Blight Disease of Pepper by Water Extract from Spent Mushroom Substrate of Lentinula edodes

    Directory of Open Access Journals (Sweden)

    Dae-Sun Kang

    2017-06-01

    Full Text Available The spent mushroom substrate (SMS of Lentinula edodes that was derived from sawdust bag cultivation was used as materials for controlling Phytophthora blight disease of pepper. Water extract from SMS (WESMS of L. edodes inhibited mycelial growth of Phytophthora capsici, suppressed Phytophthora blight disease of pepper seedlings by 65% and promoted growth of the plant over 30%. In high performance liquid chromatography (HPLC analysis, oxalic acid was detected as the main organic acid compound in WESMS and inhibited the fungal mycelium at a minimum concentration of 200 mg/l. In quantitative real-time PCR, the transcriptional expression of CaBPR1 (PR protein 1, CaBGLU (β-1,3-glucanase, CaPR-4 (PR protein 4, and CaPR-10 (PR protein 10 were significantly enhanced on WESMS and DL-β-aminobutyric acid (BABA treated pepper leaves. In addition, the salicylic acid content was also increased 4 to 6 folds in the WESMS and BABA treated pepper leaves compared to water treated leaf sample. These findings suggest that WESMS of L. edodes suppress Phytophthora blight disease of pepper through multiple effects including antifungal activity, plant growth promotion, and defense gene induction.

  14. Data set from a comprehensive phosphoproteomic analysis of rice variety IRBB5 in response to bacterial blight

    Directory of Open Access Journals (Sweden)

    Yuxuan Hou

    2016-03-01

    Full Text Available Bacterial blight (BB caused by Xanthomonas oryzae pv. oryzae (Xoo has become one of the most devastating diseases for rice, a major food source for over half of the world populations. To investigate the roles of protein phosphorylation in rice bacterial blight resistance, a quantitative phosphoproteomic study was conducted in rice variety IRBB5 at 0 h and 24 h after Xoo infection. 2367 and 2223 phosphosites on 1334 and 1297 representative proteins were identified in 0 h and 24 h after Xoo infection, respectively, out of which 762 proteins were found to be differentially phosphorylated. In associated with the published article “A comprehensive quantitative phosphoproteome analysis of rice in response to bacterial blight” in BMC Plant Biology (Hou et al., 2015 [1], this dataset article provided the detailed information of experimental designing, methods, features as well as the raw data of mass spectrometry (MS identification. The MS proteomics data could be fully accessed from the ProteomeXchange Consortium with the dataset identifier http://www.ebi.ac.uk/pride/archive/projects/PXD002222. Keywords: Rice (Oryza sativa L., Bacterial blight, Phosphoproteome

  15. Application of Gamma Irradiation and Its Convergent Treatments on Several Varieties of Oriental Hybrid Lily to Control Leaf Blight

    Directory of Open Access Journals (Sweden)

    Ji-Hoon Kim

    2014-06-01

    Full Text Available In order to seek more eco-friend, economic and safer quarantine method than current methyl bromide fumigation, the convergent treatment with 200 Gy of gamma irradiation and several chemicals such as nano-siver particles (NSS, sodium dichloroisocyanurate (NaDCC was tried on the cuttings of lily in the packing of catonnage box for export. With 6 independent experiments of gamma irradiation on the three lily cultivars, cvs. Siberia, Le reve and Sorbonne, incidence and severity of lily leaf blight was investigated on leaves and petals at 8-d after infection. 200 Gy of gamma irradiation decreased at 13-25% of severity on the leaf of Sorbonne, but it increased at 2-5% of severity on the leaf of Siberia and Le reve. Chemical substitutes such as NSS and NaDCC were not effective to control of lily blight on cuttings. By 200 Gy of gamma irradiation treatment, chlorophyll contents were statistically significantly decreased at 12-d after irradiation and the longevities vaselife of fully open flower of Siberia and Sorbonne were increased at 0.4 to 1.2 days. In addition, the relative fresh weights of the gamma irradiated cuttings were severely dried compared to the non-irradiated control. On the other hands, the symptoms of phyto-toxicity of high dose gamma irradiation at 1 or 2 kGy on cv. Siberia were to be blight at the tip of bloom, bent necks of flower, and delayed the process of flowering.

  16. Transcriptome of Aphanomyces euteiches: new oomycete putative pathogenicity factors and metabolic pathways.

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    Elodie Gaulin

    Full Text Available Aphanomyces euteiches is an oomycete pathogen that causes seedling blight and root rot of legumes, such as alfalfa and pea. The genus Aphanomyces is phylogenically distinct from well-studied oomycetes such as Phytophthora sp., and contains species pathogenic on plants and aquatic animals. To provide the first foray into gene diversity of A. euteiches, two cDNA libraries were constructed using mRNA extracted from mycelium grown in an artificial liquid medium or in contact to plant roots. A unigene set of 7,977 sequences was obtained from 18,864 high-quality expressed sequenced tags (ESTs and characterized for potential functions. Comparisons with oomycete proteomes revealed major differences between the gene content of A. euteiches and those of Phytophthora species, leading to the identification of biosynthetic pathways absent in Phytophthora, of new putative pathogenicity genes and of expansion of gene families encoding extracellular proteins, notably different classes of proteases. Among the genes specific of A. euteiches are members of a new family of extracellular proteins putatively involved in adhesion, containing up to four protein domains similar to fungal cellulose binding domains. Comparison of A. euteiches sequences with proteomes of fully sequenced eukaryotic pathogens, including fungi, apicomplexa and trypanosomatids, allowed the identification of A. euteiches genes with close orthologs in these microorganisms but absent in other oomycetes sequenced so far, notably transporters and non-ribosomal peptide synthetases, and suggests the presence of a defense mechanism against oxidative stress which was initially characterized in the pathogenic trypanosomatids.

  17. The Effect of Salicylic Acid and Chelated Magnesium Sulfate on Matters Allocation in Vegetative and Reproductive Parts in Pear cv. Louise Bonne Infected to Fire Blight Disease

    Directory of Open Access Journals (Sweden)

    mahjabin adel

    2017-10-01

    Full Text Available Introduction: Distribution of photosynthetic substances between vegetative and reproductive parts is influenced by the environmental factors as well as plant nutrition status. Therefore, application of nutrient substances (such as chelated magnesium sulfate and salicylic acid combination can influence the distribution of photosynthetic substances which in turn result in changes in allocation of photo-assimilates between vegetative and reproductive parts. Since the investigation of partitioning of photo- assimilates is complex and the interpretation of treatments effects on partitioning of substances is difficult in garden plants, this examination has been focused on external application of nutritional treatments on different organs growth by comparing the effects of salicylic acid and chelated magnesium sulfate on the allocation of photo- assimilates. Materials and Methods: This experiment was performed in a commercial 10-year old orchard of Qazvin in 2013. Initially, 60 uniform pears (cv. Louise Bonne which were infected to fire blight disease were selected. Before treatment imposing, agronomic practices such as removing and pruning infected shoots were applied. Treatments were combination of salicylic acid and chelated magnesium sulfate at different levels, which were applied on foliage under the conditions of neutral pollution to fire blight. In the present research, vegetative parameters (current shoot growth, leaf weight, leaf area, relative water content and so on and reproductive parameters (length: diameter ratio and density of fruit and so on were measured. The fully expanded leaves were collected randomly from each replicate. After washing the samples were weighed and these values referred to as initial readings (fresh weight. Then, the leaf samples were placed in distilled water for 24 h in the dark at room temperature. The turgid leaves were blotted dry and weighed (saturation weight. After weighing, the material was oven-dried at 70

  18. Monitoring and Predicting the Long Distance Transport of Fusarium graminearum, Causal Agent of Fusarium Head Blight in Wheat and Barley

    Science.gov (United States)

    Prussin, Aaron Justin, II

    Fusarium head blight (FHB), caused by Fusarium graminearum , is a serious disease of wheat and barley that has caused several billion dollars in crop losses over the last decade in the United States. Spores of F. graminearum are released from corn and small grain residues left-over from the previous growing season and are transported long distances in the atmosphere before being deposited. Current risk assessment tools consider environmental conditions favorable for disease development, but do not include spore transport. Long distance transport models have been proposed for a number of plant pathogens, but many of these models have not been experimentally validated. In order to predict the atmospheric transport of F. graminearum, the potential source strength ( Qpot) of inoculum must be known. We conducted a series of laboratory and field experiments to estimate Qpot from a field-scale source of inoculum of F. graminearum. Perithecia were generated on artificial (carrot agar) and natural (corn stalk) substrates. Artificial substrate (carrot agar) produced 15+/-0.4 perithecia cm-2, and natural substrate (corn stalk) produced 44+/-2 perithecia cm-2. Individual perithecia were excised from both substrate types and allowed to release ascospores every 24 hours. Perithecia generated from artificial (carrot agar) and natural (corn stalk) substrates released a mean of 104+/-5 and 276+/-16 ascospores, respectively. A volumetric spore trap was placed inside a 3,716 m2 clonal source of inoculum in 2011 and 2012. Results indicated that ascospores were released under field conditions predominantly (>90%) during the night (1900 to 0700 hours). Estimates of Qpot for our field-scale sources of inoculum were approximately 4 billion ascospores per 3,716 m 2. Release-recapture studies were conducted from a clonal field-scale source of F. graminearum in 2011 and 2012. Microsatellites were used to identify the released clone of F. graminearum at distances up to 1 km from the source

  19. The Diaporthe sojae species complex: Phylogenetic re-assessment of pathogens associated with soybean, cucurbits and other field crops.

    Science.gov (United States)

    Udayanga, Dhanushka; Castlebury, Lisa A; Rossman, Amy Y; Chukeatirote, Ekachai; Hyde, Kevin D

    2015-05-01

    Phytopathogenic species of Diaporthe are associated with a number of soybean diseases including seed decay, pod and stem blight and stem canker and lead to considerable crop production losses worldwide. Accurate morphological identification of the species that cause these diseases has been difficult. In this study, we determined the phylogenetic relationships and species boundaries of Diaporthe longicolla, Diaporthe phaseolorum, Diaporthe sojae and closely related taxa. Species boundaries for this complex were determined based on combined phylogenetic analysis of five gene regions: partial sequences of calmodulin (CAL), beta-tubulin (TUB), histone-3 (HIS), translation elongation factor 1-α (EF1-α), and the nuclear ribosomal internal transcribed spacers (ITS). Phylogenetic analyses revealed that this large complex of taxa is comprised of soybean pathogens as well as species associated with herbaceous field crops and weeds. Diaporthe arctii, Diaporthe batatas, D. phaseolorum and D. sojae are epitypified. The seed decay pathogen D. longicolla was determined to be distinct from D. sojae. D. phaseolorum, originally associated with stem and leaf blight of Lima bean, was not found to be associated with soybean. A new species, Diaporthe ueckerae on Cucumis melo, is introduced with description and illustrations. Published by Elsevier Ltd.

  20. Severidade da mela da soja causada por Rhizoctonia solani AG-1 IA em função de doses de potássio Severity of hte foliar blight of the soylean caused by Rhizoctonia solani AG-1 IA infunction of doses of potassium

    Directory of Open Access Journals (Sweden)

    Marco Antonio Basseto

    2007-03-01

    Full Text Available O fungo Rhizoctonia solani pertencente ao grupo de anastomose 1 IA (AG-1 IA é um dos patógenos mais importantes afetando a cultura da soja no Brasil. Este fungo causa queima da folha e/ou mela em soja, para a qual medidas de manejo cultural são consideradas alternativas importantes para controle antes do estabelecimento da doença. Há evidências de que a adubação potássica diminui substancialmente a severidade dos sintomas de várias doenças da soja como a queima foliar (Cercospora kikuchii, a seca da haste e da vagem (Phomopsis phaseoli var. sojae e o cancro da haste (Diaporthe phaseolorum f. sp. meridionalis. Apesar das evidências do efeito do potássio no controle de várias doenças da soja, não há informação na literatura sobre o efeito desse nutriente no controle da mela. A hipótese testada foi que a mela da soja pode ser controlada através de incrementos na adubação potássica. De maneira geral, concluiu-se que, sob condições de casa de vegetação, o incremento de K no solo não resultou no controle da mela da soja. É necessário, entretanto, confirmar esta observação conduzindo-se experimentos sob condições de campo, podendo-se incluir a avaliação do efeito da doença sob aspectos da produção.The fungus Rhizoctonia solani, belonging to anastomosis group 1IA (AG-1 IA is one of the most important pathogens affecting soybean in Brazil. This fungus causes aerial or foliar blight of soybean, and cultural measures are thought as important choices for the control before the establishment of the disease. Based on evidences that potassium amendments can substantially reduce the severity of several soybean diseases such as Cercospora leaf blight (Cercospora kikuchii, pod and stem blight (Phomopsis phaseoli var. sojae and stem canker (Diaporthe phaseolorum f. sp. meridionalis. Despite all evidence, there is no information in the literature about the effect of potassium controlling the soybean foliar blight. The

  1. Regulation of expression of pectate lyase genes pelA, pelD, and pelE in Erwinia chrysanthemi.

    Science.gov (United States)

    Reverchon, S; Robert-Baudouy, J

    1987-06-01

    The regulation of pelA, pelD, and pelE genes encoding three of the five major pectate lyase isoenzymes (PLa, PLd, and PLe) in Erwinia chrysanthemi B374 was analyzed by using genetic fusions to lacZ. These three genes are clustered on a 5-kilobase DNA fragment in the order pelD-pelE-pelA and constitute three independent transcriptional units. We localized the pelDEA cluster near the pro-1 marker on the genetic map of B374 by chromosomal mobilization with RP4::mini-Mu plasmid pULB110. Three classes of regulatory mutations responsible for constitutive pectate lyase synthesis have been described (kdgR, gpiR, and cri). We studied the effects of each mutation on pelE, pelD, and pelA expression independently. The mutations kdgR and gpiR mainly affect the expression of pelE and pelD, although PLa synthesis is slightly increased. The cri mutation results in a low level of constitutive expression of the three pel genes, but it is a pleiotropic mutation since other genes not involved in pectinolysis are also affected. In addition, we demonstrated that exuR, a negative regulatory gene governing the catabolism of hexuronates, does not modify the expression of pel genes. The frequency of gpiR or cri mutations (about 10(-8)) and the resulting constitutivity of pectate lyase synthesis suggest that these genes act as negative regulatory genes in addition to kdgR, which is already known to encode a repressor. Moreover, we found that expression of pel-lac fusions carried on pBR322 derivatives was higher in E. chrysanthemi than in Escherichia coli; this fact suggests the existence of positive regulation of pectate lyase synthesis in E. chrysanthemi.

  2. Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent

    Directory of Open Access Journals (Sweden)

    Petti Carloalberto

    2012-11-01

    Full Text Available Abstract Background Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA and abscisic acid (ABA, are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens –mediated control of Fusarium head blight (FHB disease of barley and to determine if biocontrol-associated hormones directly affect disease development. Results A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Conclusions Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced

  3. Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent.

    Science.gov (United States)

    Petti, Carloalberto; Reiber, Kathrin; Ali, Shahin S; Berney, Margaret; Doohan, Fiona M

    2012-11-22

    Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA) and abscisic acid (ABA), are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens -mediated control of Fusarium head blight (FHB) disease of barley and to determine if biocontrol-associated hormones directly affect disease development. A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced both symptoms and yield loss asssociated with the disease

  4. Leaf blight and defoliation of Eugenia spp. caused by Cylindrocladium candelabrum and C. spathiphylli in Brazil

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    Luiz Sebastião Poltronieri

    2011-06-01

    Full Text Available Leaf blight and defoliation of Eugenia stipitata Mc Vaugh and Eugenia patrisii Vahl, caused respectively by Cylindrocladium candelabrum (Calonectria scoparia and C. spathiphylli (Calonectria spathiphylli are reported in the state of Pará, Brazil. On both host species, the disease is characterized by dark brown lesions of different sizes and shapes. A whitish bright sporulation, resembling Cylindrocladium is observed on the necrotic lesions by using a stereomycroscope or a pocket lense (10-20 X. Under favorable conditions and depending on the level of infection, intense premature tree defoliation may also be found.Although the conidial germination and mycelial growth were higher at 25ºC for both species, C. candelabrum was more sensitive to the variation of temperature (10, 20, 30 and 40 ºC than C. spathiphylli. This is the first report of C. candelabrum and C. spathiphylli on Eugenia stipitata (araçá-boi and on Eugenia patrisii (ubaia-da-amazônia, respectively in Brazil.

  5. Botanicals and Phosphonate Show Potential to Replace Copper for Control of Potato Late Blight

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    Hans-Rudolf Forrer

    2017-11-01

    Full Text Available Potato late blight (PLB caused by Phytophthora infestans (Pi is the most harmful disease in potato production worldwide. In organic farming, copper is used despite its persistence in soil and toxicity to soil organisms. To replace copper, suspensions of powders from three promising botanicals, including bark of buckthorn (Frangula alnus, FA, roots of medicinal rhubarb (Rheum palmatum and galls of the nutgall tree (Galla chinensis, were tested in multi-year field experiments. The current study shows for the first time that botanicals could replace copper under field conditions and best PLB reduction on leaves was achieved with FA, reaching a level close to that of 2 to 3 kg copper per hectare and year. Better results than with copper were achieved with Phosfik® (Ph, a phosphonate-based product. For both FA and Ph, the mode of action is based on induced resistance, for Ph also on direct fungicidal effects. A disadvantage of Ph is the accumulation of residues in potato tubers. Nevertheless, two to three applications with 2 to 3 L/ha of Ph would be feasible to not exceed a minimal risk level (MLR of 20 mg/kg of phosphorous acid as proposed by the European Food Safety Authority. Due to an excellent environmental profile and a complex mode of action counteracting Pi resistance, phosphonate-based products would be most suitable for sustainable PLB management in integrated pest management (IPM programmes.

  6. Genetic analysis of the induced mutants of rice resistant to bacterial leaf blight

    International Nuclear Information System (INIS)

    Nakai, H.

    1990-01-01

    Full text: Seeds of the rice cultivar 'Harebare', which is susceptible to bacterial leaf blight (BLB), were treated with thermal neutrons, gamma-rays, ethyleneimine and ethylmethane-sulfonate. In the M2, plants with better resistance to BLB were identified through inoculation at the seedling and the flag leaf stages with an isolate (T7174) of the Japanese differential race I. Several mutant lines resistant to BLB were selected through tests of the M 3 or M 4 lines derived from selected resistant M 2 plants. The frequency of resistant mutants was significantly higher after the thermal neutron treatment than after treatments with other mutagens. Two mutants, which originated from the neutron treatment, showing a highly quantitative resistance to multiple BLB races were analysed for gene(s) for resistance. The resistance of one of them (M41) to the Japanese races I, II, III, IV, and V was found to be conditioned by a single recessive gene. Three other recessive genes for resistance are known, but their reaction to differential races is different. Therefore, this gene was thought to be new and was tentatively designated as xa-nm(t). The resistance of another mutant (M57) was found to be polygenically inherited. (author)

  7. Correspondence of Charles Darwin on James Torbitt's project to breed blight-resistance potatoes.

    Science.gov (United States)

    DeArce, M

    2008-01-01

    The most prolific of Darwin's correspondents from Ireland was James Torbitt, an enterprising grocer and wine merchant of 58 North Street, Belfast. Between February 1876 and March 1882, 141 letters were exchanged on the feasibility and ways of supporting one of Torbitt's commercial projects, the large-scale production and distribution of true potato seeds (Solan um tuberosum) to produce plants resistant to the late blight fungus Phytophthora infestans, the cause of repeated potato crop failures and thus the Irish famines in the nineteenth century. Ninety-three of these letters were exchanged between Torbitt and Darwin, and 48 between Darwin and third parties, seeking or offering help and advice on the project. Torbitt's project required selecting the small proportion of plants in an infested field that survived the infection, and using those as parents to produce seeds. This was a direct application of Darwin's principle of selection. Darwin cautiously lobbied high-ranking civil servants in London to obtain government funding for the project, and also provided his own personal financial support to Torbit.

  8. An Endophytic Bacterial Strain Isolated from Eucommia ulmoides Inhibits Southern Corn Leaf Blight

    Directory of Open Access Journals (Sweden)

    Ting Ding

    2017-05-01

    Full Text Available Bacillus subtilis DZSY21 isolated from the leaves of Eucommia ulmoides oliv. was labeled by antibiotic marker and found to effectively colonize the leaves of maize plant. Agar diffusion assays and biocontrol effect experiments showed that strain DZSY21 and its lipopeptides had antagonistic activity against Bipolaris maydis, as well as high biocontrol effects on southern corn leaf blight caused by B. maydis. Using MALDI-TOF-MS analysis, we detected the presence of antimicrobial surfactin A, surfactin B, and fengycin in the strain DZSY21. Signaling pathways mediated by DZSY21 were analyzed by testing the expression of key plant genes involved in regulation of salicylic acid (SA or JA/ET pathways, the defense-related genes PR1 and LOX were concurrently expressed in the leaves of DZSY21-treated plants; this corresponded to slight increase in the expression level of PDF1.2 and decreases in ERF gene transcription levels. The results indicated an induced systemic response that is dependent on the SA and jasmonic acid (JA pathways. Thus, we hypothesized that the strain DZSY21 inhibits B. maydis by producing antifungal lipopeptides and activating an induced systemic response through SA- and JA-dependent signaling pathways. This work describes a mechanism behind reduced disease severity in plants inoculated with the endophytic bacteria DZSY21.

  9. Salicylic acid regulates basal resistance to Fusarium head blight in wheat.

    Science.gov (United States)

    Makandar, Ragiba; Nalam, Vamsi J; Lee, Hyeonju; Trick, Harold N; Dong, Yanhong; Shah, Jyoti

    2012-03-01

    Fusarium head blight (FHB) is a destructive disease of cereal crops such as wheat and barley. Previously, expression in wheat of the Arabidopsis NPR1 gene (AtNPR1), which encodes a key regulator of salicylic acid (SA) signaling, was shown to reduce severity of FHB caused by Fusarium graminearum. It was hypothesized that SA signaling contributes to wheat defense against F. graminearum. Here, we show that increased accumulation of SA in fungus-infected spikes correlated with elevated expression of the SA-inducible pathogenesis-related 1 (PR1) gene and FHB resistance. In addition, FHB severity and mycotoxin accumulation were curtailed in wheat plants treated with SA and in AtNPR1 wheat, which is hyper-responsive to SA. In support of a critical role for SA in basal resistance to FHB, disease severity was higher in wheat expressing the NahG-encoded salicylate hydroxylase, which metabolizes SA. The FHB-promoting effect of NahG was overcome by application of benzo (1,2,3), thiadiazole-7 carbothioic acid S-methyl ester, a synthetic functional analog of SA, thus confirming an important role for SA signaling in basal resistance to FHB. We further demonstrate that jasmonate signaling has a dichotomous role in wheat interaction with F. graminearum, constraining activation of SA signaling during early stages of infection and promoting resistance during the later stages of infection.

  10. Identification of molecular markers linked to rice bacterial blight resistance genes from Oryza meyeriana

    Directory of Open Access Journals (Sweden)

    Jing WANG,Chen CHENG,Yanru ZHOU,Yong YANG,Qiong MEI,Junmin LI,Ye CHENG,Chengqi YAN,Jianping CHEN

    2015-09-01

    Full Text Available Y73 is a progeny of asymmetric somatic hybridization between Oryza sativa cv. Dalixiang and the wild rice species Oryza meyeriana. Inoculation with a range of strains of Xanthomonas oryzae pv. oryzae showed that Y73 had inherited a high level of resistance to rice bacterial blight (BB from its wild parent. An F2 population of 7125 individuals was constructed from the cross between Y73 and a BB-susceptible cultivar IR24. After testing 615 SSR and STS markers covering the 12 rice chromosomes, 186 markers were selected that showed polymorphism between Y73 and IR24. Molecular markers linked to the BB resistance genes in Y73 were scanned using the F2 population and the polymorphic markers. The SSR marker RM128 on chromosome 1, the STS marker R03D159 on chromosome 3 and the STS marker R05D104 on chromosome 5 were found to be linked to the rice BB resistance genes in Y73.

  11. Development of late blight resistance and heat tolerance through gamma irradiation of shoot cultures in potato

    International Nuclear Information System (INIS)

    Gosal, S.S.; Jitender Kaur, Adas; Minocha, J.L.

    2001-01-01

    In vitro shoot cultures of two potato varieties viz., Kufri jyoti and Kufri Chandramukhi were gamma irradiated at 20 Gy and 40 Gy. Micro tubers were induced in micro propagated M1V3 generation. For heat tolerance micro tubers were induced at elevated (28 C ) incubation temperature (optimum being 20 1C ) and were characterized by early sowing, chlorophyll persistence and harvest index. The number of micro tubers/plant was highly reduced at elevated temperature and the resulting tubers exhibited distorted shapes and growth of apical buds. Thus obtained micro tubers exhibited better germination (62.3%) even in early sowing at relatively higher temperature. The progenies from putative heat tolerant plants were grown in the field by sowing at higher temperature for four subsequent generations. Heat tolerant plants segregated in each generation but the frequency of heat tolerant plants increased in the advanced generation. For developing late blight resistance micro tubers produced from irradiated shoot cultures were sown in pots and resulting plants were screened using detached leaf method. The progenies of putative resistant plants grown in the field were artificially inoculated with sporangial inoculum of Phytophthora infection's. Field grown plants exhibited segregation with respect to disease reaction and about 56 per cent plants showed resistance. Segregation was reduced during following generation and the frequency of resistant plants was increased up to 72.3 per cent. Thus, repeated selections has helped in developing stable mutants in both the varieties

  12. Transcriptome Analysis Reveals Candidate Genes involved in Blister Blight defense in Tea (Camellia sinensis (L) Kuntze)

    Science.gov (United States)

    Jayaswall, Kuldip; Mahajan, Pallavi; Singh, Gagandeep; Parmar, Rajni; Seth, Romit; Raina, Aparnashree; Swarnkar, Mohit Kumar; Singh, Anil Kumar; Shankar, Ravi; Sharma, Ram Kumar

    2016-07-01

    To unravel the molecular mechanism of defense against blister blight (BB) disease caused by an obligate biotrophic fungus, Exobasidium vexans, transcriptome of BB interaction with resistance and susceptible tea genotypes was analysed through RNA-seq using Illumina GAIIx at four different stages during ~20-day disease cycle. Approximately 69 million high quality reads were assembled de novo, yielding 37,790 unique transcripts with more than 55% being functionally annotated. Differentially expressed, 149 defense related transcripts/genes, namely defense related enzymes, resistance genes, multidrug resistant transporters, transcription factors, retrotransposons, metacaspases and chaperons were observed in RG, suggesting their role in defending against BB. Being present in the major hub, putative master regulators among these candidates were identified from predetermined protein-protein interaction network of Arabidopsis thaliana. Further, confirmation of abundant expression of well-known RPM1, RPS2 and RPP13 in quantitative Real Time PCR indicates salicylic acid and jasmonic acid, possibly induce synthesis of antimicrobial compounds, required to overcome the virulence of E. vexans. Compendiously, the current study provides a comprehensive gene expression and insights into the molecular mechanism of tea defense against BB to serve as a resource for unravelling the possible regulatory mechanism of immunity against various biotic stresses in tea and other crops.

  13. Potential effects of diurnal temperature oscillations on potato late blight with special reference to climate change.

    Science.gov (United States)

    Shakya, S K; Goss, E M; Dufault, N S; van Bruggen, A H C

    2015-02-01

    Global climate change will have effects on diurnal temperature oscillations as well as on average temperatures. Studies on potato late blight (Phytophthora infestans) development have not considered daily temperature oscillations. We hypothesize that growth and development rates of P. infestans would be less influenced by change in average temperature as the magnitude of fluctuations in daily temperatures increases. We investigated the effects of seven constant (10, 12, 15, 17, 20, 23, and 27°C) and diurnally oscillating (±5 and ±10°C) temperatures around the same means on number of lesions, incubation period, latent period, radial lesion growth rate, and sporulation intensity on detached potato leaves inoculated with two P. infestans isolates from clonal lineages US-8 and US-23. A four-parameter thermodynamic model was used to describe relationships between temperature and disease development measurements. Incubation and latency progression accelerated with increasing oscillations at low mean temperatures but slowed down with increasing oscillations at high mean temperatures (P effects of global climate change on disease development.

  14. A proteomics survey on wheat susceptibility to Fusarium head blight during grain development.

    Science.gov (United States)

    Chetouhi, Cherif; Bonhomme, Ludovic; Lecomte, Philippe; Cambon, Florence; Merlino, Marielle; Biron, David Georges; Langin, Thierry

    2015-02-01

    The mycotoxigenic fungal species Fusarium graminearum is able to attack several important cereal crops, such as wheat and barley. By causing Fusarium Head Blight (FHB) disease, F. graminearum induces yield and quality losses and poses a public health concern due to in planta mycotoxin production. The molecular and physiological plant responses to FHB, and the cellular biochemical pathways used by F. graminearum to complete its infectious process remain still unknown. In this study, a proteomics approach, combining 2D-gel approach and mass spectrometry, has been used to determine the specific protein patterns associated with the development of the fungal infection during grain growth on susceptible wheat. Our results reveal that F. graminearum infection does not deeply alter the grain proteome and does not significantly disturb the first steps of grain ontogeny but impacts molecular changes during the grain filling stage (impact on starch synthesis and storage proteins). The differentially regulated proteins identified were mainly involved in stress and defence mechanisms, primary metabolism, and main cellular processes such as signalling and transport. Our survey suggests that F. graminearum could take advantage of putative susceptibility factors closely related to grain development processes and thus provide new insights into key molecular events controlling the susceptible response to FHB in wheat grains.

  15. Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici.

    Science.gov (United States)

    Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

    2013-06-01

    We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

  16. The Effect of Freezing Temperatures on Microdochium majus and M. nivale Seedling Blight of Winter Wheat

    Directory of Open Access Journals (Sweden)

    Ian M. Haigh

    2012-01-01

    Full Text Available Exposure to pre-emergent freezing temperatures significantly delayed the rate of seedling emergence (P<0.05 from an infected and a non-infected winter wheat cv. Equinox seed lot, but significant effects for timing of freezing and duration of freezing on final emergence were only seen for the Microdochium-infested seed lot. Freezing temperatures of −5∘C at post-emergence caused most disease on emerged seedlings. Duration of freezing (12 hours or 24 hours had little effect on disease index but exposure to pre-emergent freezing for 24 hours significantly delayed rate of seedling emergence and reduced final emergence from the infected seed lot. In plate experiments, the calculated base temperature for growth of M. nivale and M. majus was −6.3∘C and −2.2∘C, respectively. These are the first set of experiments to demonstrate the effects of pre-emergent and post-emergent freezing on the severity of Microdochium seedling blight.

  17. In vitro induction of variation through radiation for late blight resistance and heat tolerance in potato

    Energy Technology Data Exchange (ETDEWEB)

    Minocha, J L; Das, A; Gopal, J; Gosal, S S [Biotechnology Centre, Punjab Agricultural Univ., Ludhiana, Punjab (India)

    1997-07-01

    In vitro plants were obtained from nodal sections of sprouts of cvs. `Kufri Jyoti` and `Kufri Chandramukhi` of potato cultured on MS medium with 3% sucrose. Callus from leaves of in vitro cultured plantlets was induced on modified Linsmaier and Skoog medium supplemented with 5 mg/1 NAA. The obtained shoots and calli were irradiated with 20 and 40 Gy gamma rays. Irradiatied shoots were transferred to MS medium with 8% sucrose for multiplication, and then to MS medium with 8% sucrose and 10 mg/1 BAP to induce microtuber formation, which gave on average 1.3 microtubers per plant. The microtubers were planted in pots and variation was observed in plant morphology and tuber characters. To study variation for late blight resistance, irradiated calli were kept on Gamborg B-5 medium with culture filtrate of Phytophthora infestans. To induce variation for heat tolerance, in vitro shoots from irradiated material were mass-propagated and allowed to produce microtubers at high temperature. (author). 3 refs, 3 tabs.

  18. Genomics-enabled analysis of the emergent disease cotton bacterial blight.

    Directory of Open Access Journals (Sweden)

    Anne Z Phillips

    2017-09-01

    Full Text Available Cotton bacterial blight (CBB, an important disease of (Gossypium hirsutum in the early 20th century, had been controlled by resistant germplasm for over half a century. Recently, CBB re-emerged as an agronomic problem in the United States. Here, we report analysis of cotton variety planting statistics that indicate a steady increase in the percentage of susceptible cotton varieties grown each year since 2009. Phylogenetic analysis revealed that strains from the current outbreak cluster with race 18 Xanthomonas citri pv. malvacearum (Xcm strains. Illumina based draft genomes were generated for thirteen Xcm isolates and analyzed along with 4 previously published Xcm genomes. These genomes encode 24 conserved and nine variable type three effectors. Strains in the race 18 clade contain 3 to 5 more effectors than other Xcm strains. SMRT sequencing of two geographically and temporally diverse strains of Xcm yielded circular chromosomes and accompanying plasmids. These genomes encode eight and thirteen distinct transcription activator-like effector genes. RNA-sequencing revealed 52 genes induced within two cotton cultivars by both tested Xcm strains. This gene list includes a homeologous pair of genes, with homology to the known susceptibility gene, MLO. In contrast, the two strains of Xcm induce different clade III SWEET sugar transporters. Subsequent genome wide analysis revealed patterns in the overall expression of homeologous gene pairs in cotton after inoculation by Xcm. These data reveal important insights into the Xcm-G. hirsutum disease complex and strategies for future development of resistant cultivars.

  19. Screening of bacterial antagonists for biological control of Phytophthora blight of pepper.

    Science.gov (United States)

    Rajkumar, M; Lee, Wang Hyu; Lee, Kui Jae

    2005-01-01

    The aim of this study was to assess the potential of bacterial antagonists to control Phytophthora blight of pepper caused by P. capsici using different screening methods. Among a collection of fluorescent pseudomonas isolated from the rhizosphere of pepper, twelve isolates were initially selected based on dual culture assay on potato dextrose agar and corn meal agar. Further, these twelve isolates were screened for the reduction of disease severity caused by P. capsici using detached leaves and seedling assay. Most of the antagonists showed varying levels of antagonism against P. capsici in both detached leaves and seedlings assay. In addition, few isolates increased shoot and root length of pepper in seedling assays. Among them, isolate PS119 showing highest ability to reduce the disease severity in the in vitro seedling assay was found to be the most efficient antagonists against P. capsici in the in vivo biological control tests. These results indicate that the in vitro seedling assay can be used as a rapid and more accurate technique for the selection of promising biocontrol agents against P. capsici. ((c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

  20. In vitro induction of variation through radiation for late blight resistance and heat tolerance in potato

    International Nuclear Information System (INIS)

    Minocha, J.L.; Das, A.; Gopal, J.; Gosal, S.S.

    1997-01-01

    In vitro plants were obtained from nodal sections of sprouts of cvs. 'Kufri Jyoti' and 'Kufri Chandramukhi' of potato cultured on MS medium with 3% sucrose. Callus from leaves of in vitro cultured plantlets was induced on modified Linsmaier and Skoog medium supplemented with 5 mg/1 NAA. The obtained shoots and calli were irradiated with 20 and 40 Gy gamma rays. Irradiatied shoots were transferred to MS medium with 8% sucrose for multiplication, and then to MS medium with 8% sucrose and 10 mg/1 BAP to induce microtuber formation, which gave on average 1.3 microtubers per plant. The microtubers were planted in pots and variation was observed in plant morphology and tuber characters. To study variation for late blight resistance, irradiated calli were kept on Gamborg B-5 medium with culture filtrate of Phytophthora infestans. To induce variation for heat tolerance, in vitro shoots from irradiated material were mass-propagated and allowed to produce microtubers at high temperature. (author). 3 refs, 3 tabs

  1. Comparative vesicle proteomics reveals selective regulation of protein expression in chestnut blight fungus by a hypovirus.

    Science.gov (United States)

    Wang, Jinzi; Wang, Fangzhen; Feng, Youjun; Mi, Ke; Chen, Qi; Shang, Jinjie; Chen, Baoshan

    2013-01-14

    The chestnut blight fungus (Cryphonectria parasitica) and hypovirus constitute a model system to study fungal pathogenesis and mycovirus-host interaction. Knowledge in this field has been gained largely from investigations at gene transcription level so far. Here we report a systematic analysis of the vesicle proteins of the host fungus with/without hypovirus infection. Thirty-three differentially expressed protein spots were identified in the purified vesicle protein samples by two-dimensional electrophoresis and mass spectrometry. Down-regulated proteins were mostly cargo proteins involved in primary metabolism and energy generation and up-regulated proteins were mostly vesicle associated proteins and ABC transporter. A virus-encoded protein p48 was found to have four forms with different molecular mass in vesicles from the virus-infected strain. While a few of the randomly selected differentially expressed proteins were in accordance with their transcription profiles, majority were not in agreement with their mRNA accumulation patterns, suggesting that an extensive post-transcriptional regulation may have occurred in the host fungus upon a hypovirus infection. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Metabolite profiles of rice cultivars containing bacterial blight-resistant genes are distinctive from susceptible rice

    Institute of Scientific and Technical Information of China (English)

    Jiao Wu; Haichuan Yu; Haofu Dai; Wenli Mei; Xin Huang; Shuifang Zhu; Ming Peng

    2012-01-01

    The metabolic changes of bacterial blight-resistant line C418/Xa23 generated by molecular marker-assisted selection (n =12),transgenic variety C418-Xa21 generated by using the Agrobacterium-mediated system (n =12),and progenitor cultivar C418 (n =12) were monitored using gas chromatography/mass spectrometry.The validation,discrimination,and establishment of correlative relationships between metabolite signals were performed by cluster analysis,principal component analysis,and partial least squares-discriminant analysis.Significant and unintended changes were observed in 154 components in C418/Xa23 and 48 components in C418-Xa21 compared with C418 (P < 0.05,Fold change > 2.0).The most significant decreases detected (P< 0.001) in both C418/Xa23 and C418-Xa21 were in three amino acids: glycine,tyrosine,and alanine,and four identified metabolites: malic acid,ferulic acid,succinic acid,and glycerol.Linoleic acid was increased specifically in C418/Xa23 which was derived from traditional breeding.This line,possessing a distinctive metabolite profile as a positive control,shows more differences vs.the parental than the transgenic line.Only succinic acid that falls outside the boundaries of natural variability between the two non-transgenic varieties C418 and C418/Xa23 should be further investigated with respect to safety or nutritional impact.

  3. Screening of ten advanced chickpea lines for blight and wilt resistance

    International Nuclear Information System (INIS)

    Jamil, F.F.; Haq, I.; Sarwar, N.; Alam, S.S.; Khan, J.A.; Hanif, M.; Khan, I.A.; Sarwar, M.; Haq, M.A.

    2002-01-01

    Ten advanced chickpea lines developed at NIAB were screened for resistance to Ascochyta blight and Fusarium wilt diseases in different sets of experiments conducted under controlled environment. Inoculation of plants by spore suspension of virulent strains of Ascochyta rabiei revealed that one line (97313) was resistant tolerant, two lines (97305, 97392) were tolerant, six lines (97306, 97310, 97311, 97303, 97302, 97393) were tolerant/susceptible and one line (97301) was susceptible. Screening of the same lines against Fusarium wilt by water culture method showed that two lines (97301, 97313) were moderately resistant, four lines (97302, 97303, 97306, 97393) were tolerant and the remaining four lines were susceptible. Screening through phytotoxic culture filtrates revealed that two lines (97302, 97313) were less sensitive to culture filtrates of Ascochyta rabiei and Fusarium oxysporum than the resistant check (CM88). These lines were also analyzed spectrophotometrically for peroxidase enzyme activity. Maximum enzyme activity was detected after 48 hours of inoculation with A. rabiei in three lines (97305, 97311, 97313) and resistant check (CM88) while enzyme activity in the remaining lines reached its maximum after 72 hours of inoculation which was comparable to the susceptible check (Pb-1). These studies lead to the conclusion that one line (97313) exhibited resistance against both the diseases and can be used as a source of resistance for further improvement of chickpea germplasm. (author)

  4. Genetic architecture of fusarium head blight resistance in four winter triticale populations.

    Science.gov (United States)

    Kalih, R; Maurer, H P; Miedaner, T

    2015-03-01

    Fusarium head blight (FHB) is a devastating disease that causes significant reductions in yield and quality in wheat, rye, and triticale. In triticale, knowledge of the genetic architecture of FHB resistance is missing but essential due to modern breeding requirements. In our study, four doubled-haploid triticale populations (N=120 to 200) were evaluated for resistance to FHB caused by artificial inoculation with Fusarium culmorum in four environments. DArT markers were used to genotype triticale populations. Seventeen quantitative trait loci (QTL) for FHB resistance were detected across all populations; six of them were derived from rye genome and located on chromosomes 4R, 5R, and 7R, which are here reported for the first time. The total cross-validated ratio of the explained phenotypic variance for all detected QTL in each population was 41 to 68%. In all, 17 QTL for plant height and 18 QTL for heading stage were also detected across all populations; 3 and 5 of them, respectively, were overlapping with QTL for FHB. In conclusion, FHB resistance in triticale is caused by a multitude of QTL, and pyramiding them contributes to higher resistance.

  5. Automated Identification of Northern Leaf Blight-Infected Maize Plants from Field Imagery Using Deep Learning.

    Science.gov (United States)

    DeChant, Chad; Wiesner-Hanks, Tyr; Chen, Siyuan; Stewart, Ethan L; Yosinski, Jason; Gore, Michael A; Nelson, Rebecca J; Lipson, Hod

    2017-11-01

    Northern leaf blight (NLB) can cause severe yield loss in maize; however, scouting large areas to accurately diagnose the disease is time consuming and difficult. We demonstrate a system capable of automatically identifying NLB lesions in field-acquired images of maize plants with high reliability. This approach uses a computational pipeline of convolutional neural networks (CNNs) that addresses the challenges of limited data and the myriad irregularities that appear in images of field-grown plants. Several CNNs were trained to classify small regions of images as containing NLB lesions or not; their predictions were combined into separate heat maps, then fed into a final CNN trained to classify the entire image as containing diseased plants or not. The system achieved 96.7% accuracy on test set images not used in training. We suggest that such systems mounted on aerial- or ground-based vehicles can help in automated high-throughput plant phenotyping, precision breeding for disease resistance, and reduced pesticide use through targeted application across a variety of plant and disease categories.

  6. Pathogenicity of Diaporthe spp. on two blueberry cultivars (Vaccinium corymbosum)

    NARCIS (Netherlands)

    Cardinaals, J.; Wenneker, M.; Voogd, J.G.B.; Leeuwen, van G.C.M.

    2018-01-01

    Diaporthe vaccinii causes twig blight and fruit rot and is currently listed as a quarantine organism for the European Union. In the Netherlands, two species from the same genus, Diaporthe eres and Diaporthe rudis, are regularly isolated from blighted twigs of Vaccinium corymbosum. This study

  7. Derivation of Mutants of Erwinia carotovora subsp. betavasculorum Deficient in Export of Pectolytic Enzymes with Potential for Biological Control of Potato Soft Rot

    Science.gov (United States)

    Costa, José M.; Loper, Joyce E.

    1994-01-01

    Erwinia carotovora subsp. betavasculorum Ecb168 produces an antibiotic(s) that suppresses growth of the related bacterium Erwinia carotovora subsp. carotovora in culture and in wounds of potato tubers. Strain Ecb168 also produces and secretes pectolytic enzymes and causes a vascular necrosis and root rot of sugar beet. Genes (out) involved in secretion of pectolytic enzymes by Ecb168 were localized to two HindIII fragments (8.5 and 10.5 kb) of Ecb168 genomic DNA by hybridization to the cloned out region of E. carotovora subsp. carotovora and by complementation of Out- mutants of E. carotovora subsp. carotovora. Out- mutants of Ecb168, which did not secrete pectate lyase into the culture medium, were obtained when deletions internal to either HindIII fragment were introduced into the genome of Ecb168 through marker exchange mutagenesis. Out- mutants of Ecb168 were complemented to the Out+ phenotype by introduction of the corresponding cloned HindIII fragment. Out- mutants of Ecb168 were less virulent than the Out+ parental strain on potato tubers. Strain Ecb168 and Out- derivatives inhibited the growth of E. carotovora subsp. carotovora in culture, indicating that the uncharacterized antibiotic(s) responsible for antagonism was exported through an out-independent mechanism. Strain Ecb168 and Out- derivatives reduced the establishment of large populations of E. carotovora subsp. carotovora in wounds of potato tubers and suppressed tuber soft rot caused by E. carotovora subsp. carotovora. PMID:16349316

  8. AMPK in Pathogens.

    Science.gov (United States)

    Mesquita, Inês; Moreira, Diana; Sampaio-Marques, Belém; Laforge, Mireille; Cordeiro-da-Silva, Anabela; Ludovico, Paula; Estaquier, Jérôme; Silvestre, Ricardo

    2016-01-01

    During host-pathogen interactions, a complex web of events is crucial for the outcome of infection. Pathogen recognition triggers powerful cellular signaling events that is translated into the induction and maintenance of innate and adaptive host immunity against infection. In opposition, pathogens employ active mechanisms to manipulate host cell regulatory pathways toward their proliferation and survival. Among these, subversion of host cell energy metabolism by pathogens is currently recognized to play an important role in microbial growth and persistence. Extensive studies have documented the role of AMP-activated protein kinase (AMPK) signaling, a central cellular hub involved in the regulation of energy homeostasis, in host-pathogen interactions. Here, we highlight the most recent advances detailing how pathogens hijack cellular metabolism by suppressing or increasing the activity of the host energy sensor AMPK. We also address the role of lower eukaryote AMPK orthologues in the adaptive process to the host microenvironment and their contribution for pathogen survival, differentiation, and growth. Finally, we review the effects of pharmacological or genetic AMPK modulation on pathogen growth and persistence.

  9. Food-borne pathogens

    International Nuclear Information System (INIS)

    Niemand, J.G.

    1985-01-01

    The Salmonella scare reinforced the importance of never taking chances when it comes to controlling pathogens. The issue has been resolved by radurisation. The article deals with the various pathogens that can effect food and argues the case for radurisation in dealing with them. It also looks at some of the other food products that can be treated using this process

  10. Reação de genótipos de melancia ao crestamento gomoso do caule Response of watermelon cultivars to gummy stem blight

    Directory of Open Access Journals (Sweden)

    Gil Rodrigues dos Santos

    2005-12-01

    Full Text Available Face à importância do crestamento gomoso do caule e à escassez de relatos da reação de genótipos de melancia na literatura nacional e internacional, este trabalho teve por objetivo avaliar a resposta de genótipos comerciais de melancia ao crestamento gomoso. No campo, estudou-se o nível de infecção nas folhas em delineamento de blocos ao acaso com nove cultivares de melancia e quatro repetições, com inoculação de duas plantas por parcela aos 43 dias após o plantio (DAP. Foram avaliadas as cultivares Crimson Sweet, Onix, Rubi, Safira, Eureka, Georgia, Sheila, Savana e Riviera. Em casa de vegetação, estudou-se a infecção no caule em vasos, com delineamento inteiramente casualizado, com três repetições, em esquema fatorial de 9 x 3, sendo o fator "a" = cultivares e o fator "b" = isolados. Foram avaliadas as mesmas cultivares do ensaio de campo, com inoculação artificial com disco de micélio aos 15 dias após a semeadura, quando do surgimento da primeira folha definitiva. Os isolados de D. bryoniae utilizados na inoculação das plântulas foram: UnB 76 (Melão-DF, UnB 75 (Melancia-PE e UnB 81 (Abóbora-DF. Dentre as cultivares avaliadas no campo, Riviera mostrou-se mais resistente e apresentou menores (PGummy stem blight, caused by Didymella bryoniae, is one of the most important watermelon diseases. Nevertheless, there are relatively few published studies on the response of watermelon genotypes to the disease. This paper reports results of studies on the response of commercially available watermelon cultivars to gummy stem blight. Leaf infection was studied in a randomized complete block field experiment with nine watermelon genotypes and four replicates. Two plants per experimental plot were inoculated 43 days after planting. Cultivars Crimson Sweet, Onix, Rubi, Safira, Eureka, Georgia, Sheila, Savana and Riviera were evaluated. Stem infection was studied in the greenhouse, in a completely randomized design, with three

  11. Pathogen inactivation techniques.

    Science.gov (United States)

    Pelletier, J P R; Transue, S; Snyder, E L

    2006-01-01

    The desire to rid the blood supply of pathogens of all types has led to the development of many technologies aimed at the same goal--eradication of the pathogen(s) without harming the blood cells or generating toxic chemical agents. This is a very ambitious goal, and one that has yet to be achieved. One approach is to shun the 'one size fits all' concept and to target pathogen-reduction agents at the Individual component types. This permits the development of technologies that might be compatible with, for example, plasma products but that would be cytocidal and thus incompatible with platelet concentrates or red blood cell units. The technologies to be discussed include solvent detergent and methylene blue treatments--designed to inactivate plasma components and derivatives; psoralens (S-59--amotosalen) designed to pathogen-reduce units of platelets; and two products aimed at red blood cells, S-303 (a Frale--frangible anchor-linker effector compound) and Inactine (a binary ethyleneimine). A final pathogen-reduction material that might actually allow one material to inactivate all three blood components--riboflavin (vitamin B2)--is also under development. The sites of action of the amotosalen (S-59), the S-303 Frale, Inactine, and riboflavin are all localized in the nucleic acid part of the pathogen. Solvent detergent materials act by dissolving the plasma envelope, thus compromising the integrity of the pathogen membrane and rendering it non-infectious. By disrupting the pathogen's ability to replicate or survive, its infectivity is removed. The degree to which bacteria and viruses are affected by a particular pathogen-reducing technology relates to its Gram-positive or Gram-negative status, to the sporulation characteristics for bacteria, and the presence of lipid or protein envelopes for viruses. Concerns related to photoproducts and other breakdown products of these technologies remain, and the toxicology of pathogen-reduction treatments is a major ongoing area

  12. Biological and epidemiological aspects of the quarantine pathogen Phytophthora ramorum

    Directory of Open Access Journals (Sweden)

    Beatrice Ginetti

    2015-12-01

    Full Text Available Phytophthora ramorum is a quarantine pathogen that causes leaf blight and shoot dieback of the crown, bark cankers and death on a number of both ornamental and forest trees, especially in North America and northern Europe, where it has produced severe outbreaks.In Italy it was first reported in 2002, on Rhodondendron yakushimanum in a Piedmont nursery; after that it seemed to have disappeared, only to re-emerge in 2013 when numerous isolates were detected on batches of Viburnum tinus plants growing in some nurseries in the Pistoia area (Tuscany, which is an important district in the trade of nursery plants world-wide. This work reports on a number of laboratory tests that were carried out on isolates from infected plant samples. The micromorphological and macromorphological characteristics of the pathogen growing on carrot agar (CA, corn meal agar (CMA, malt extract agar (MEA potato dextrose agar, and V8 agar with added PARPNH (see text were determined, as was the growth rate at 10º, 15º, 20º, 25°, 30º, 32º and 35ºC. Molecular analysis was employed to identify the isolates more precisely. Inoculation trials under the bark were also carried out to ascertain the isolate virulence and the Koch’s Postulates.The Plant Protection Service of the Tuscan Region (SFR, Servizio Fitosanitario Regionale was alerted as soon as the pathogen infection was detected and it took the prescribed steps to eradicate the infection in the field and prevent the recurrence of an epidemic.

  13. Processes for managing pathogens.

    Science.gov (United States)

    Godfree, Alan; Farrell, Joseph

    2005-01-01

    Wastewater contains human, animal, and plant pathogens capable of causing viral, bacterial, or parasitic infections. There are several routes whereby sewage pathogens may affect human health, including direct contact, contamination of food crops, zoonoses, and vectors. The range and numbers of pathogens in municipal wastewater vary with the level of endemic disease in the community, discharges from commercial activities, and seasonal factors. Regulations to control pathogen risk in the United States and Europe arising from land application of biosolids are based on the concept of multiple barriers to the prevention of transmission. The barriers are (i) treatment to reduce pathogen content and vector attraction, (ii) restrictions on crops grown on land to which biosolids have been applied, and (iii) minimum intervals following application and grazing or harvesting. Wastewater treatment reduces number of pathogens in the wastewater by concentrating them with the solids in the sludge. Although some treatment processes are designed specifically to inactivate pathogens, many are not, and the actual mechanisms of microbial inactivation are not fully understood for all processes. Vector attraction is reduced by stabilization (reduction of readily biodegradable material) and/or incorporation immediately following application. Concerns about health risks have renewed interest in the effects of treatment (on pathogens) and advanced treatment methods, and work performed in the United States suggests that Class A pathogen reduction can be achieved less expensively than previously thought. Effective pathogen risk management requires control to the complete chain of sludge treatment, biosolids handling and application, and post-application activities. This may be achieved by adherence to quality management systems based on hazard analysis critical control point (HACCP) principles.

  14. In vitro antimicrobial activity of plant extracts of Avicennia alba against some important pathogens

    Directory of Open Access Journals (Sweden)

    Varahalarao Vadlapudi

    2012-05-01

    Full Text Available Objective: In this present study antimicrobial activity of aerial parts of Avicennia alba were evaluated against the resistant pathogens belong to aquatic, human and plant origin. Methods: Soxhlet extraction method was used to get the corresponding extracts of hexane, chloroform and methanol. The antimicrobial activities of the organic solvent extracts on the various test microorganisms, including bacteria and fungi investigated using agar well diffusion technique. The length of inhibition zone was measured in millimeters from the edge of the well to the edge of the inhibition zone. Methanol and chloroform extracts exhibited promising antimicrobial activity than hexane extracts. Results: The zone of inhibition of chloroform varies from (9 to 17 mm where as with methanol (11 to 28 mm at 100 mg/ml concentration. Among all microorganisms studied Erwinia caratovara and Pseudomonas syringae showed the considerable growth inhibition with chloroform and methanolic extracts. Conclusions: A. alba can be used in the treatment of infectious diseases caused by resistant pathogenic microorganisms. Further studies are being carried out in order to separate the individual components that are present in plant extracts of A. alba using column chromatography.

  15. COMPLEX OF PATHOGENES ON VEGETABLE CROPS IN CONDITION OF CENTRAL REGION OF RUSSIA

    Directory of Open Access Journals (Sweden)

    L. T. Timina

    2015-01-01

    Full Text Available As a result of monitoring of causative agents of diseases of vegetable crops and studying of its species specification, the genus and species of fungi and bacteria, were found. Previously unknown in the Central region of Russia pathogens of carrot were identified: Sclerotinia nevales, Gleocladium roseum, Verticillium spp, Trichotecium roseum, Streptomyces scabies, F. nivale, F. chlamidosporum, F. equiseti, F. proliferatum, Chaetomium spp., Erysiphe umbelliferum, Erwinia carotovora. Main causative agents of diseases  of carrot during storage were also described: Alternaria infectoria, A. alternatа, A. arborescens, A. radicina, A. cheiranthi, A. corotiincultae, A. cinerariae, Embellisia spp., Nimbia spp., Cladosporium spp. It was found new pathogen for onion (Aspergillus niger, garlic (Fusarium semitectum, F. subglutinans, F. proliferatum, F.avenacium, red beet (Typhula ishikariensis, and radish (Drechslera Bondartseva.

  16. A Natural Mutation Involving both Pathogenicity and Perithecium Formation in the Fusarium graminearum Species Complex

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    Haruhisha Suga

    2016-12-01

    Full Text Available Members of the Fusarium graminearum species complex (Fg complex or FGSC are the primary pathogens causing Fusarium head blight in wheat and barley worldwide. A natural pathogenicity mutant (strain 0225022 was found in a sample of the Fg complex collected in Japan. The mutant strain did not induce symptoms in wheat spikes beyond the point of inoculation, and did not form perithecia. No segregation of phenotypic deficiencies occurred in the progenies of a cross between the mutant and a fully pathogenic wild-type strain, which suggested that a single genetic locus controlled both traits. The locus was mapped to chromosome 2 by using sequence-tagged markers; and a deletion of ∼3 kb was detected in the mapped region of the mutant strain. The wild-type strain contains the FGSG_02810 gene, encoding a putative glycosylphosphatidylinositol anchor protein, in this region. The contribution of FGSG_02810 to pathogenicity and perithecium formation was confirmed by complementation in the mutant strain using gene transfer, and by gene disruption in the wild-type strain.

  17. Genetics of Resistance and Pathogenicity in the Maize/Setosphaeria turcica Pathosystem and Implications for Breeding

    Directory of Open Access Journals (Sweden)

    Ana L. Galiano-Carneiro

    2017-08-01

    Full Text Available Northern corn leaf blight (NCLB, the most devastating leaf pathogen in maize (Zea mays L., is caused by the heterothallic ascomycete Setosphaeria turcica. The pathogen population shows an extremely high genetic diversity in tropical and subtropical regions. Varietal resistance is the most efficient technique to control NCLB. Host resistance can be qualitative based on race-specific Ht genes or quantitative controlled by many genes with small effects. Quantitative resistance is moderately to highly effective and should be more durable combatting all races of the pathogen. Quantitative resistance must, however, be analyzed in many environments (= location × year combinations to select stable resistances. In the tropical and subtropical environments, quantitative resistance is the preferred option to manage NCLB epidemics. Resistance level can be increased in practical breeding programs by several recurrent selection cycles based on disease severity rating and/or by genomic selection. This review aims to address two important aspects of the NCLB pathosystem: the genetics of the fungus S. turcica and the modes of inheritance of the host plant maize, including successful breeding strategies regarding NCLB resistance. Both drivers of this pathosystem, pathogen, and host, must be taken into account to result in more durable resistance.

  18. Toxicity of twenty-two plant essential oils against pathogenic bacteria of vegetables and mushrooms.

    Science.gov (United States)

    Todorović, Biljana; Potočnik, Ivana; Rekanović, Emil; Stepanović, Miloš; Kostić, Miroslav; Ristić, Mihajlo; Milijašević-Marčić, Svetlana

    2016-12-01

    ASBTRACT Toxicity of twenty-two essential oils to three bacterial pathogens in different horticultural systems: Xanthomonas campestris pv. phaseoli (causing blight of bean), Clavibacter michiganensis subsp. michiganensis (bacterial wilt and canker of tomato), and Pseudomonas tolaasii (causal agent of bacterial brown blotch on cultivated mushrooms) was tested. Control of bacterial diseases is very difficult due to antibiotic resistance and ineffectiveness of chemical products, to that essential oils offer a promising alternative. Minimal inhibitory and bactericidal concentrations are determined by applying a single drop of oil onto the inner side of each plate cover in macrodilution assays. Among all tested substances, the strongest and broadest activity was shown by the oils of wintergreen (Gaultheria procumbens), oregano (Origanum vulgare), and lemongrass (Cymbopogon flexuosus. Carvacrol (64.0-75.8%) was the dominant component of oregano oils, while geranial (40.7%) and neral (26.7%) were the major constituents of lemongrass oil. Xanthomonas campestris pv. phaseoli was the most sensitive to plant essential oils, being susceptible to 19 oils, while 11 oils were bactericidal to the pathogen. Sixteen oils inhibited the growth of Clavibacter michiganensis subsp. michiganensis and seven oils showed bactericidal effects to the pathogen. The least sensitive species was Pseudomonas tolaasii as five oils inhibited bacterial growth and two oils were bactericidal. Wintergreen, oregano, and lemongrass oils should be formulated as potential biochemical bactericides against different horticultural pathogens.

  19. The plant pathogen Phytophthora andina emerged via hybridization of an unknown Phytophthora species and the Irish potato famine pathogen, P. infestans.

    Directory of Open Access Journals (Sweden)

    Erica M Goss

    Full Text Available Emerging plant pathogens have largely been a consequence of the movement of pathogens to new geographic regions. Another documented mechanism for the emergence of plant pathogens is hybridization between individuals of different species or subspecies, which may allow rapid evolution and adaptation to new hosts or environments. Hybrid plant pathogens have traditionally been difficult to detect or confirm, but the increasing ease of cloning and sequencing PCR products now makes the identification of species that consistently have genes or alleles with phylogenetically divergent origins relatively straightforward. We investigated the genetic origin of Phytophthora andina, an increasingly common pathogen of Andean crops Solanum betaceum, S. muricatum, S. quitoense, and several wild Solanum spp. It has been hypothesized that P. andina is a hybrid between the potato late blight pathogen P. infestans and another Phytophthora species. We tested this hypothesis by cloning four nuclear loci to obtain haplotypes and using these loci to infer the phylogenetic relationships of P. andina to P. infestans and other related species. Sequencing of cloned PCR products in every case revealed two distinct haplotypes for each locus in P. andina, such that each isolate had one allele derived from a P. infestans parent and a second divergent allele derived from an unknown species that is closely related but distinct from P. infestans, P. mirabilis, and P. ipomoeae. To the best of our knowledge, the unknown parent has not yet been collected. We also observed sequence polymorphism among P. andina isolates at three of the four loci, many of which segregate between previously described P. andina clonal lineages. These results provide strong support that P. andina emerged via hybridization between P. infestans and another unknown Phytophthora species also belonging to Phytophthora clade 1c.

  20. A Rice CPYC-Type Glutaredoxin OsGRX20 in Protection against Bacterial Blight, Methyl Viologen and Salt Stresses

    Directory of Open Access Journals (Sweden)

    Xi Ning

    2018-02-01

    Full Text Available Glutaredoxins (GRXs belong to the antioxidants involved in the cellular stress responses. In spite of the identification 48 GRX genes in rice genomes, the biological functions of most of them remain unknown. Especially, the biological roles of members of GRX family in disease resistance are still lacking. Our proteomic analysis found that OsGRX20 increased by 2.7-fold after infection by bacterial blight. In this study, we isolated and characterized the full-length nucleotide sequences of the rice OsGRX20 gene, which encodes a GRX family protein with CPFC active site of CPYC-type class. OsGRX20 protein was localized in nucleus and cytosol, and its transcripts were expressed predominantly in leaves. Several stress- and hormone-related motifs putatively acting as regulatory elements were found in the OsGRX20 promoter. Real-time quantitative PCR analysis indicated that OsGRX20 was expressed at a significantly higher level in leaves of a resistant or tolerant rice genotype, Yongjing 50A, than in a sensitive genotype, Xiushui 11, exposed to bacterial blight, methyl viologen, heat, and cold. Its expression could be induced by salt, PEG-6000, 2,4-D, salicylic acid, jasmonic acid, and abscisic acid treatments in Yongjing 50A. Overexpression of OsGRX20 in rice Xiushui 11 significantly enhanced its resistance to bacterial blight attack, and tolerance to methyl viologen and salt stresses. In contrast, interference of OsGRX20 in Yongjing 50A led to increased susceptibility to bacterial blight, methyl viologen and salt stresses. OsGRX20 restrained accumulation of superoxide radicals in aerial tissue during methyl viologen treatment. Consistently, alterations in OsGRX20 expression affect the ascorbate/dehydroascorbate ratio and the abundance of transcripts encoding four reactive oxygen species scavenging enzymes after methyl viologen-induced stress. Our results demonstrate that OsGRX20 functioned as a positive regulator in rice tolerance to multiple stresses

  1. Chlorophyll Fluorescence and Reflectance-Based Non-Invasive Quantification of Blast, Bacterial Blight and Drought Stresses in Rice

    Czech Academy of Sciences Publication Activity Database

    Šebela, David; Quiňones, C.; Cruz, C.; Ona, I.; Olejníčková, Julie; Jagadish, K. S. V.

    2018-01-01

    Roč. 59, č. 1 (2018), s. 30-43 ISSN 0032-0781 R&D Projects: GA MŠk(CZ) LO1415 EU Projects: European Commission(XE) 284443 - EPPN Institutional support: RVO:86652079 Keywords : marker-assisted selection * oryza-sativa l. * water -stress * magnaporthe-grisea * disease resistance * photosynthetic efficiency * spectral reflectance * carotenoid content * eucalyptus leaves * diurnal changes * Bacterial blight * Chlorophyll fluorescence * Drought stress * Reflectance * Rice bast Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 4.760, year: 2016

  2. Recombinant deamidated mutants of Erwinia chrysanthemi L-asparaginase have similar or increased activity compared to wild-type enzyme.

    Science.gov (United States)

    Gervais, David; Foote, Nicholas

    2014-10-01

    The enzyme Erwinia chrysanthemi L-asparaginase (ErA) is an important biopharmaceutical product used in the treatment of acute lymphoblastic leukaemia. Like all proteins, certain asparagine (Asn) residues of ErA are susceptible to deamidation to aspartic acid (Asp), which may be a concern with respect to enzyme activity and potentially to pharmaceutical efficacy. Recombinant ErA mutants containing Asn to Asp changes were expressed, purified and characterised. Two mutants with single deamidation sites (N41D and N281D) were found to have approximately the same specific activity (1,062 and 924 U/mg, respectively) as the wild-type (908 U/mg). However, a double mutant (N41D N281D) had an increased specific activity (1261 U/mg). The N41D mutation conferred a slight increase in the catalytic constant (k cat 657 s(-1)) when compared to the WT (k cat 565 s(-1)), which was further increased in the double mutant, with a k cat of 798 s(-1). Structural analyses showed that the slight changes caused by point mutation of Asn41 to Asp may have reduced the number of hydrogen bonds in this α-helical part of the protein structure, resulting in subtle changes in enzyme turnover, both structurally and catalytically. The increased α-helical content observed with the N41D mutation by circular dichroism spectroscopy correlates with the difference in k cat, but not K m. The N281D mutation resulted in a lower glutaminase activity compared with WT and the N41D mutant, however the N281D mutation also imparted less stability to the enzyme at elevated temperatures. Taken as a whole, these data suggest that ErA deamidation at the Asn41 and Asn281 sites does not affect enzyme activity and should not be a concern during processing, storage or clinical use. The production of recombinant deamidated variants has proven an effective and powerful means of studying the effect of these changes and may be a useful strategy for other biopharmaceutical products.

  3. Genomic Selection for Predicting Fusarium Head Blight Resistance in a Wheat Breeding Program

    Directory of Open Access Journals (Sweden)

    Marcio P. Arruda

    2015-11-01

    Full Text Available Genomic selection (GS is a breeding method that uses marker–trait models to predict unobserved phenotypes. This study developed GS models for predicting traits associated with resistance to head blight (FHB in wheat ( L.. We used genotyping-by-sequencing (GBS to identify 5054 single-nucleotide polymorphisms (SNPs, which were then treated as predictor variables in GS analysis. We compared how the prediction accuracy of the genomic-estimated breeding values (GEBVs was affected by (i five genotypic imputation methods (random forest imputation [RFI], expectation maximization imputation [EMI], -nearest neighbor imputation [kNNI], singular value decomposition imputation [SVDI], and the mean imputation [MNI]; (ii three statistical models (ridge-regression best linear unbiased predictor [RR-BLUP], least absolute shrinkage and operator selector [LASSO], and elastic net; (iii marker density ( = 500, 1500, 3000, and 4500 SNPs; (iv training population (TP size ( = 96, 144, 192, and 218; (v marker-based and pedigree-based relationship matrices; and (vi control for relatedness in TPs and validation populations (VPs. No discernable differences in prediction accuracy were observed among imputation methods. The RR-BLUP outperformed other models in nearly all scenarios. Accuracies decreased substantially when marker number decreased to 3000 or 1500 SNPs, depending on the trait; when sample size of the training set was less than 192; when using pedigree-based instead of marker-based matrix; or when no control for relatedness was implemented. Overall, moderate to high prediction accuracies were observed in this study, suggesting that GS is a very promising breeding strategy for FHB resistance in wheat.

  4. Assessment of Bacterial Blight Tolerance of Persian Walnut Based on Immature Nut Test

    Directory of Open Access Journals (Sweden)

    Attila BANDI

    2015-06-01

    Full Text Available Bacterial blight is one of the most serious diseases affecting Persian walnut (Juglans regia L.. Susceptibility to this disease was evaluated by artificial inoculation in an in vitro experiment for cultivars developed in Hungary and for selections from Transylvania. Thirty pieces of immature fruit of 11 walnut cultivars and 10 selections were inoculated by punction using a suspension containing a mixture of Xaj-isolates of controlled virulence. As control, a moderate resistant (mR ‘Pedro’ and a highly susceptible (hS ‘Milotai intenzív’ cultivars were used. After ten days the diameter of the necrotic area around the inoculation points was measured and the disease rate (DR was noted. For the calculation of indexes it was taken the structure of the lesions (diffuse or defined margin into consideration. None of the 21 cultivars/selections analysed were found to be hardly resistant, although all of them showed a higher degree of resistance than the susceptible control (‘Milotai intenzív’. The majority of the analysed cultivars fit into the moderate susceptible (mS and moderate resistant (mR group. ‘Milotai kései’ and SZEN-10, had a notable reaction as considered to be moderate resistant (mR, showed a similar degree of resistance compared to the control cultivar ‘Pedro’. It was concluded that these cultivars, based on their resistance to Xanthomonas arboricola pv. juglandis, could be proposed as resistance gene sources, as well as for production purposes in the environmental conditions of the Carpathian Basin.

  5. Yield loss assessment due to Alternaria blight and its management in linseed.

    Science.gov (United States)

    Singh, R B; Singh, H K; Parmar, Arpita

    2014-04-01

    Field experiments were conducted during 2010-11 and 2011-12 to assess the yield losses due to Alternaria blight disease caused by Alternaria lini and A. linicola in recently released cultivars and their management with the integration of Trichoderma viride, fungicides and plant extract. Disease severity on leaves varied from 41.07% (Parvati) to 65.01% (Chambal) while bud damage per cent ranged between 23.56% (Shekhar) to 46.12% (T-397), respectively in different cultivars. Maximum yield loss of 58.44% was recorded in cultivar Neelum followed by Parvati (55.56%), Meera (55.56%) and Chambal (51.72%), respectively while minimum loss was recorded in Kiran (19.99%) and Jeevan (22.22%). Minimum mean disease severity (19.47%) with maximum disease control (69.74%) was recorded with the treatment: seed treatment (ST) with vitavax power (2 g kg(-1) seed) + 2 foliar sprays (FS) of Saaf (a mixture of carbendazim+mancozeb) 0.2% followed by ST with Trichoderma viride (4g kg(-1) seed) + 2 FS of Saaf (0.2%). Minimum bud damage (13.75%) with maximum control (60.94%) was recorded with treatment of ST with vitavax power+2 FS of propiconazole (0.2%). Maximum mean seed yield (1440 kg ha(-1)) with maximum net return (Rs. 15352/ha) and benefit cost ratio (1:11.04) was obtained with treatment ST with vitavax power + 2 FS of Neem leaf extract followed by treatment ST with vitavax power+2 FS of Saaf (1378 kg ha(-1)).

  6. Evaluating Sheath Blight Resistance in Rice Using Detached Tiller and Field Screening Method

    Directory of Open Access Journals (Sweden)

    Bedanand Chaudhary

    2015-12-01

    Full Text Available In present study physical resistance test on 12 rice varieties against sheath blight (ShB caused by Rhizoctonia solani was examined. A detached tiller test was used to measure components of ShB physiological resistance at Regional Agricultural Research Station (RARS, Tarahara, Nepal. The varieties were evaluated in a randomized complete block design (RCBD with 3 replications in year 2010-12. A sclerotium was inserted below the leaf collar of individual tillers maintained in tubes filled with water. Only the 56-day old susceptible plants were inoculated. After 7 days of inoculation, number of lesions, dead leaves, vertical sheath colonization and disease severity were measured. In 2011, field experiments were conducted with three replications to address morphological resistance in 28 rice genotypes. Disease incidence was recorded on 14, 21 and 28 days after inoculation. The number of dead leaves differed only numerically while disease variables significantly (P=0.004 varied among varieties. The other variables were highly correlated with each other. Cluster analysis of variables formed three varietal groups; Sabitri with lowest, and Jasmine-85 and Betichikon having highest values. Rice genotypes differed significantly (P=0.05 for disease incidence and area Under Disease Progress Curve (AUDPC. Tetep and IAC-165 had the lowest and highest terminal disease incidences and AUDPC, respectively. Sabitri, MTU-1010 and IR-26 recorded lower AUDPC values. Hence, Tetep and Sabitri could be used as donors in hybridization and their plant morphology could be considered as selection guide for improving ShB resistance in rice.

  7. Extracts against Various Pathogens

    Directory of Open Access Journals (Sweden)

    Ritika Chauhan

    2013-07-01

    The present study shows that tested lichen Parmotrema sp. extracts demonstrated a strong antimicrobial effect. That suggests the active components from methanol extracts of the investigated lichen Parmotrema sp. can be used as natural antimicrobial agent against pathogens.

  8. Evolution of microbial pathogens

    National Research Council Canada - National Science Library

    DiRita, Victor J; Seifert, H. Steven

    2006-01-01

    ... A. Hogan vvi ■ CONTENTS 8. Evolution of Pathogens in Soil Rachel Muir and Man-Wah Tan / 131 9. Experimental Models of Symbiotic Host-Microbial Relationships: Understanding the Underpinnings of ...

  9. Indicators for waterborne pathogens

    National Research Council Canada - National Science Library

    Committee on Indicators for Waterborne Pathogens, National Research Council

    2004-01-01

    ... not practical or feasible to monitor for the complete spectrum of microorganisms that may occur in water, and many known pathogens are difficult to detect directly and reliably in water samples.Â...

  10. Host–Pathogen Interactions

    NARCIS (Netherlands)

    Smits, M.A.; Schokker, D.J.

    2011-01-01

    The outcome of an infection is determined by numerous interactions between hosts and pathogens occurring at many different biological levels, ranging from molecule to population. To develop new control strategies for infectious diseases in livestock species, appropriate methodologies are needed

  11. Effect of four growth-promoting rhizobacteria on crown blight caused by Phytophthora capsici in sweet pepper (Capsicum annuum

    Directory of Open Access Journals (Sweden)

    Carlos Ramírez

    2015-11-01

    Full Text Available Crown blight, caused by Phytophthora capsici, is the most important disease of pepper (Capsicum annuum in the world and causes great economic losses in Costa Rica. Alternatives to chemical control against this disease are crucial to prevent damage to human health and the environment. The antagonism of Plant-Growth-Promoting Rhizobacteria (PGPR on P. capsici, and its ability to reduce wilt in pepper plants were evaluated. PGPR strains previously isolated from sugarcane and rice were identified, using 16S RNA gene sequence, as Pseudomonas fluorescens PC4, Stenotrophomonas rhizophila PC9, Pseudomonas fragi PC11 and Azospirillum lipoferum PCJ2. The inhibition of P. capcisi growth was evaluated in vitro, in the presence of the PGPR. The effect of the four bacterial strains on pepper plants inoculated with P. capsici (100 zoospores.plant-1 was evaluated in the greenhouse. P. fluorescens PC4, S. rhizophila PC9 and A. lipoferum PCJ2, inhibited in vitro growth of the oomycete by 54%, 30% and 50 % respectively, while S. rhizophila PC9 increased by 14% shoot fresh weight of pepper plants at the greenhouse. Furthermore, PCJ2 and PC9 strains reduced the shoot and root severity of the disease, and PCJ2-inoculated plants showed no symptoms at all, indicating that PC9 and PCJ2 are promising rizobacteria for the control of crown blight in pepper.

  12. Genetic analysis of the pelA-pelE cluster encoding the acidic and basic pectate lyases in Erwinia chrysanthemi EC16.

    Science.gov (United States)

    Barras, F; Chatterjee, A K

    1987-10-01

    In Erwinia chrysanthemi (EC16) the clustered pelA and pelE genes encode an acidic (pI 4.2) and a basic (pI 10.0) pectate lyase (Pel), respectively. The pelA gene has been isolated on a 1.2 kb restriction fragment and the direction of transcription determined. DNA hybridization analysis showed that the pelE sequence shares DNA homology with pelA but not with pelB or pelC, two genes encoding other Pel species in EC16. Since Pel A and Pel E enzymes showed little similarity in terms of catalytic properties, it is proposed that pelA and pelE are duplicates which have highly diverged.

  13. Novel mutants of Erwinia carotovora subsp. carotovora defective in the production of plant cell wall degrading enzymes generated by Mu transpososome-mediated insertion mutagenesis.

    Science.gov (United States)

    Laasik, Eve; Ojarand, Merli; Pajunen, Maria; Savilahti, Harri; Mäe, Andres

    2005-02-01

    As in Erwinia carotovora subsp. carotovora the regulation details of the main virulence factors, encoding extracellular enzymes that degrade the plant cell wall, is only rudimentally understood, we performed a genetic screen to identify novel candidate genes involved in the process. Initially, we used Mu transpososome-mediated mutagenesis approach to generate a comprehensive transposon insertion mutant library of ca. 10000 clones and screened the clones for the loss of extracellular enzyme production. Extracellular enzymes production was abolished by mutations in the chromosomal helEcc, trkAEcc yheLEcc, glsEcc, igaAEcc and cysQEcc genes. The findings reported here demonstrate that we have isolated six new representatives that belong to the pool of genes modulating the production of virulence factors in E. carotovora.

  14. Potato pathogens in Northern and Western Europe

    NARCIS (Netherlands)

    Schepers, H.T.A.M.; Cooke, L.R.

    2015-01-01

    The climatic conditions in Northern and Western (NW) Europe, which are very suitable for the cultivation of potatoes, are also very favourable for a range of diseases of which late blight, caused by Phytophthora infestans, is by far the most important with the potential to cause total crop loss. It

  15. Identification and pathogenicity assessment of Fusarium spp ...

    African Journals Online (AJOL)

    Durum wheat is the major cereal crop cultivated in Tunisia; covering over 40% of the cereal growing areas. Durum wheat production remains below expectation due to its low productivity that is attributed to the chronically abiotic and biotic stresses. Fusarium head blight (FHB) caused by Fusarium spp. has become an ...

  16. Comparative study on the effect of chemicals on Alternaria blight in Indian mustard--a multi-location study in India.

    Science.gov (United States)

    Meena, P D; Chattopadhyay, C; Kumar, A; Awasthi, R P; Singh, R; Kaur, S; Thomas, L; Goyal, P; Chand, P

    2011-05-01

    High severity of Altemaria blight disease is a major constraint in production of rapeseed-mustard in India. The aim of this study was to investigate the suppressive potential of chemicals viz., zinc sulphate, borax, sulphur, potash and calcium sulphate, aqueous extracts viz., Eucalyptus globosus (50 g l-1) leaf extract and garlic (Allium sativum) bulb (20 g l-1) extract, cow urine and bio-agents Trichoderma harzianum, Pseudomonas fluorescence in comparison with the recommended chemical fungicide (mancozeb), against foliar disease Alternaria blight of Indian mustard [Brassica juncea (L.) Czern. and Coss] under five different geographical locations of India. Mancozeb recorded the lowest mean severity (leaf: 33.1%; pod: 26.3%) of Alternaria blight with efficacy of garlic bulb extract alone (leaf = 34.4%; pod = 27.3%) or in combination with cow urine (leaf = 34.2%; pod = 28.6%) being statistically at par with the recommended chemical fungicide. Chemicals also proved effective in reducing Alternaria blight severity on leaves and pods of Indian mustard (leaf = 36.3-37.9%; pod = 27.5-30.1%). The effective treatments besides providing significant reduction in disease severity also enabled increase in dry seed yield of the crop (mancozeb = 2052 kg ha-1; garlic = 2006 kg ha-1; control = 1561 kg ha-1).

  17. Biological control of Fusarium graminearum sensu stricto, causal agent of Fusarium head blight of wheat, using formulated antagonists under field conditions in Argentina

    NARCIS (Netherlands)

    Palazzini, Juan M.; Alberione, Enrique; Torres, Adriana; Donat, Christina; Kohl, Jurgen; Chulze, Sofia

    2016-01-01

    Fusarium head blight (FHB) mainly caused by Fusarium graminearum is a devastating disease that causes extensive yield and quality losses to wheat in humid and semi-humid regions of the world. The biocontrol effect of two bacterial strains on FHB incidence, severity and deoxynivalenol (DON)

  18. Role of hydroperoxide lyase in white-backed planthopper (Sogatella furcifera Horváth)-induced resistance to bacterial blight in rice, Oryza sativa L.

    Science.gov (United States)

    Gomi, Kenji; Satoh, Masaru; Ozawa, Rika; Shinonaga, Yumi; Sanada, Sachiyo; Sasaki, Katsutomo; Matsumura, Masaya; Ohashi, Yuko; Kanno, Hiroo; Akimitsu, Kazuya; Takabayashi, Junji

    2010-01-01

    A pre-infestation of the white-backed planthopper (WBPH), Sogatella furcifera Horváth, conferred resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) in rice (Oryza sativa L.) under both laboratory and field conditions. The infestation of another planthopper species, the brown planthopper (BPH) Nilaparvata lugens Stål, did not significantly reduce the incidence of bacterial blight symptoms. A large-scale screening using a rice DNA microarray and quantitative RT-PCR revealed that WBPH infestation caused the upregulation of more defence-related genes than did BPH infestation. Hydroperoxide lyase 2 (OsHPL2), an enzyme for producing C(6) volatiles, was upregulated by WBPH infestation, but not by BPH infestation. One C(6) volatile, (E)-2-hexenal, accumulated in rice after WBPH infestation, but not after BPH infestation. A direct application of (E)-2-hexenal to a liquid culture of Xoo inhibited the growth of the bacterium. Furthermore, a vapour treatment of rice plants with (E)-2-hexenal induced resistance to bacterial blight. OsHPL2-overexpressing transgenic rice plants exhibited increased resistance to bacterial blight. Based on these data, we conclude that OsHPL2 and its derived (E)-2-hexenal play some role in WBPH-induced resistance in rice.

  19. Comparison of two strategies for use of translaminar and contact fungicide in the control of potato late blight in the highland tropics of Ecuador

    DEFF Research Database (Denmark)

    Kromann, Peter; Leon, D.; Andrade-Piedra, J.L.

    2008-01-01

    Strategies based on using the translaminar fungicide cymoxanil for control of potato late blight, caused by Phytophthora infestans, were compared in the highland tropics of Ecuador in three separate field experiments. In one strategy, a commercial formulation of cymoxanil mixed with mancozeb was ...

  20. Detection of gene expression changes in Capsicum annuum L. leaf foliar blight caused by Phytophthora capsici Leon. using qRT-PCR and leaf discs

    Science.gov (United States)

    Phytophthora capsici is responsible for multiple disease syndromes of Capsicum annuum but the resistance mechanism is still unknown. Evaluating gene expression during foliar blight can be used to identify expression patterns associated with resistance in Capsicum species. This study reports a direct...