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Sample records for characterize phytophthora capsici

  1. Comparison of expression, purification and characterization of a new pectate lyase from Phytophthora capsici using two different methods

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    Zhang Xiuguo

    2011-04-01

    Full Text Available Abstract Background Pectate lyases (PELs play an important role in the infection process of plant pathogens and also have a commercial significance in industrial applications. Most of the PELs were expressed as soluble recombinant proteins, while a few recombinant proteins were insoluble. The production of a large-scale soluble recombinant PEL would allow not only a more detailed structural and functional characterization of this enzyme but also may have important applications in the food industry. Results We cloned a new pectate lyase gene (Pcpel2 from Phytophthora capsici. Pcpel2 was constructed by pET system and pMAL system, and both constructs were used to express the PCPEL2 in Escherichia coli BL21 (DE3 pLysS. The expressed products were purified using affinity chromatography and gel filtration chromatography. The purity, specific activity and pathogenicity of the purified PCPEL2 expressed by the pMAL system were higher than the purified PCPEL2 expressed by the pET system. In addition, some other characteristics of the purified PCPEL2 differed from the two systems, such as crystallographic features. Purified PCPEL2 expressed by the pMAL system was crystallized by the hanging-drop vapour-diffusion method at 289 K, and initial crystals were grown. Conclusion The two different methods and comparison presented here would be highly valuable in obtaining an ideal enzyme for the downstream experiments, and supply an useful alternative to purify some insoluble recombinant proteins.

  2. Survival and spread of Phytophthora capsici in Coastal Peru.

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    Hurtado-Gonzáles, O; Aragon-Caballero, L; Apaza-Tapia, W; Donahoo, R; Lamour, K

    2008-06-01

    Phytophthora capsici is a soilborne pathogen that causes significant losses to pepper production in Peru. Our objective was to investigate the mechanisms by which P. capsici is able to survive and spread. During 2005 to 2007, 227 isolates of P. capsici were collected from four species of pepper (Capsicum annum, C. baccatum, C. chinense, and C. pubescens) and tomato (Solanum lycopersicum) at 33 field sites in 13 provinces across coastal Peru. All 227 isolates were of the A2 mating type and amplified fragment length polymorphism (AFLP) analysis indicates that 221 of the isolates had the same genotype. Analyses of six polymorphic single nucleotide polymorphism (SNP) loci showed fixed heterozygosity suggesting a single clonal lineage is widely dispersed. Members of the same clonal lineage were recovered during 2005 to 2007 from geographically separate locations from each of the host types sampled. Our results indicate that clonal reproduction drives the population structure of P. capsici in Peru. The impact of continuous cropping and irrigation from common river sources on the population structure in Barranca Valley are discussed. PMID:18944293

  3. BABA and Phytophthora nicotianae Induce Resistance to Phytophthora capsici in Chile Pepper (Capsicum annuum).

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    Stamler, Rio A; Holguin, Omar; Dungan, Barry; Schaub, Tanner; Sanogo, Soumaila; Goldberg, Natalie; Randall, Jennifer J

    2015-01-01

    Induced resistance in plants is a systemic response to certain microorganisms or chemicals that enhances basal defense responses during subsequent plant infection by pathogens. Inoculation of chile pepper with zoospores of non-host Phytophthora nicotianae or the chemical elicitor beta-aminobutyric acid (BABA) significantly inhibited foliar blight caused by Phytophthora capsici. Tissue extract analyses by GC/MS identified conserved change in certain metabolite concentrations following P. nicotianae or BABA treatment. Induced chile pepper plants had reduced concentrations of sucrose and TCA cycle intermediates and increased concentrations of specific hexose-phosphates, hexose-disaccharides and amino acids. Galactose, which increased significantly in induced chile pepper plants, was shown to inhibit growth of P. capsici in a plate assay. PMID:26020237

  4. Induced expression of defense-related genes in Arabidopsis upon infection with Phytophthora capsici

    NARCIS (Netherlands)

    Wang, Y.; Bouwmeester, K.; Mortel, van de J.E.; Shan, W.; Govers, F.

    2013-01-01

    Recognition of pathogens by plants initiates defense responses including activation of defense-related genes and production of antimicrobial compounds. Recently, we reported that Phytophthora capsici can successfully infect Arabidopsis and revealed interaction specificity among various accession-iso

  5. First Report of Insensitivity to Cyazofamid among Isolates of Phytophthora capsici from the Southeastern United States

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    Phytophthora capsici is rapidly becoming an important limiting factor in vegetable production in the southeastern United States, particularly on cucurbits as fruit rots. One of the primary strategies used to manage diseases caused by P. capsici is the regular application of fungicides. Recently th...

  6. Response of U.S. bottle gourd (Lagenaria siceraria) Plant Introductions to Phytophthora capsici

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    Phytophthora capsici causes severe damage to cucurbit crops grown in open fields in southeast U.S. Most cucurbit species are susceptible to damping-off, root and crown rot, and/or fruit rot caused by P. capsici. Bottle gourd plants (Lagenaria siceraria), which are resistant to Fusarium wilt, are b...

  7. Loss of heterozygosity drives clonal diversity of Phytophthora capsici in China.

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    Jian Hu

    Full Text Available Phytophthora capsici causes significant loss to pepper (Capsicum annum in China and our goal was to develop single nucleotide polymorphism (SNP markers for P. capsici and characterize genetic diversity nationwide. Eighteen isolates of P. capsici from locations worldwide were re-sequenced and candidate nuclear and mitochondrial SNPs identified. From 2006 to 2012, 276 isolates of P. capsici were recovered from 136 locations in 27 provinces and genotyped using 45 nuclear and 2 mitochondrial SNPs. There were two main mitochondrial haplotypes and 95 multi-locus genotypes (MLGs identified. Genetic diversity was geographically structured with a high level of genotypic diversity in the north and on Hainan Island in the south, suggesting outcrossing contributes to diversity in these areas. The remaining areas of China are dominated by four clonal lineages that share mitochondrial haplotypes, are almost exclusively the A1 or A2 mating type and appear to exhibit extensive diversity based on loss of heterozygosity (LOH. Analysis of SNPs directly from infected peppers confirmed LOH in field populations. One clonal lineage is dominant throughout much of the country. The overall implications for long-lived genetically diverse clonal lineages amidst a widely dispersed sexual population are discussed.

  8. Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici.

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    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 metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced 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. PMID:25288942

  9. Resistance in watermelon rootstocks to crown rot caused by Phytophthora capsici

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    Phytophthora crown and fruit rot caused by Phytophthora capsici is becoming an important and emerging disease of watermelon (Citrullus lanatus) in south eastern United States. In recent years, the practice of grafting seedless watermelons (triploids) onto rootstocks belonging to other Cucurbitaceae...

  10. Genetic Diversity of pathogenic and nonpathogenic populations of Phytophthora capsici from pepper plants and soil

    Science.gov (United States)

    Thirty-six Phytophthora capsici strains and one Phytophthora parasitica strain were evaluated for pathogenicity and disease severity on pepper (Capsicum annuum) plants. The strains represent a range of geographic locations and were collected primarily from pepper stems or roots of plants with sympto...

  11. Evaluation of Watermelon Germplasm for Resistance to Phytophthora Blight Caused by Phytophthora capsici

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    Min-Jeong Kim

    2013-03-01

    Full Text Available This study was conducted to determine the Phytophthora rot resistance of 514 accessions of watermelon germplasm, Citrullus lanatus var lanatus. About 46% of the 514 accessions tested were collections from Uzbekistan, Turkey, China, U.S.A., and Ukraine. Phytophthora capsici was inoculated to 45-day-old watermelon seedlings by drenching with 5 ml of sporangial suspension (10⁶ sporangia/ml. At 7 days after inoculation, 21 accessions showed no disease symptoms while 291 accessions of susceptible watermelon germplasm showed more than 60.1% disease severity. A total of 510 accessions of watermelon germplasm showed significant disease symptoms and were rated as susceptible to highly susceptible 35 days after inoculation. The highly susceptible watermelon germplasm exhibited white fungal hyphae on the lesion or damping off with water-soaked and browning symptoms. One accession (IT032840 showed moderate resistance and two accessions (IT185446 and IT187904 were resistant to P. capsici. Results suggest that these two resistant germplasm can be used as a rootstock and as a source of resistance in breeding resistant watermelon varieties against Phytophthora.

  12. Infection of Phytophthora capsici on pepper——Models and affecting factors

    Institute of Scientific and Technical Information of China (English)

    Xuemin LIU; Yanling ZHOU; Lijun LI

    2008-01-01

    Under controlled conditions in a growth chamber, we studied the mortality of pepper seedlings caused by Phytophthora capsici. The results showed that soil temperature and soil water content were important factors affecting their infection with P. capsici and the optimum condition for infection was found to be a soil temperature of 22℃-28℃ and a soil water content of 40%. The relationships of pepper seedling mortality caused by P. capsici along with soil temperature, soil water content and their interactions can be described by mathematical models. Field observations suggested that the Gompertz model was the best one for describing the epidemiological dynamics of the disease. The incidence of pepper phytophthora blight was significantly related to the initial incidence of pepper phytophthora blight, soil temperature, soil water content and air temperature. A forecasting model for pepper phytophthora blight in the field was developed.

  13. Biological characteristics and mating type distribution of Phytophthora capsici from China.

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    Du, Y; Gong, Z-H; Liu, G-Z; Chai, G-X; Li, C

    2014-01-01

    Phytophthora capsici from seven provinces of China were investigated for their mating type, hyphal growth, zoospore production, and virulence. All of the morphological characteristics and the results of polymerase chain reaction confirmed that these isolates were indeed Phytophthora capsici. The test of mating type showed that the mating types of 19 representative isolates from China varied. The hyphal growth and the amount of zoospores produced from these isolates differed and there was no evident relationship between them, which indicated the existence of genetic diversity among the isolates in China. Also, the isolates that were more virulent on the pepper cultivars that we checked produced more zoospores than other isolates. PMID:24535866

  14. Genome Sequencing and Mapping Reveal Loss of Heterozygosity as a Mechanism for Rapid Adaptation in the Vegetable Pathogen Phytophthora capsici

    Energy Technology Data Exchange (ETDEWEB)

    Lamour, Kurt H.; Mudge, Joann; Gobena, Daniel; Hurtado-Gonzales, Oscar P.; Schmutz, Jeremy; Kuo, Alan; Miller, Neil A.; Rice, Brandon J.; Raffaele, Sylvain; Cano, Liliana M.; Bharti, Arvind K.; Donahoo, Ryan S.; Finely, Sabra; Huitema, Edgar; Hulvey, Jon; Platt, Darren; Salamov, Asaf; Savidor, Alon; Sharma, Rahul; Stam, Remco; Sotrey, Dylan; Thines, Marco; Win, Joe; Haas, Brian J.; Dinwiddie, Darrell L.; Jenkins, Jerry; Knight, James R.; Affourtit, Jason P.; Han, Cliff S.; Chertkov, Olga; Lindquist, Erika A.; Detter, Chris; Grigoriev, Igor V.; Kamoun, Sophien; Kingsmore, Stephen F.

    2012-02-07

    The oomycete vegetable pathogen Phytophthora capsici has shown remarkable adaptation to fungicides and new hosts. Like other members of this destructive genus, P. capsici has an explosive epidemiology, rapidly producing massive numbers of asexual spores on infected hosts. In addition, P. capsici can remain dormant for years as sexually recombined oospores, making it difficult to produce crops at infested sites, and allowing outcrossing populations to maintain significant genetic variation. Genome sequencing, development of a high-density genetic map, and integrative genomic or genetic characterization of P. capsici field isolates and intercross progeny revealed significant mitotic loss of heterozygosity (LOH) in diverse isolates. LOH was detected in clonally propagated field isolates and sexual progeny, cumulatively affecting >30percent of the genome. LOH altered genotypes for more than 11,000 single-nucleotide variant sites and showed a strong association with changes in mating type and pathogenicity. Overall, it appears that LOH may provide a rapid mechanism for fixing alleles and may be an important component of adaptability for P. capsici.

  15. Effect of phytophthora capsici crown rot on watermelon rootstocks and grafts

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    Crown and fruit rot caused by Phytophthora capsici is becoming an important and emerging disease of watermelon in the southeastern United States. In recent years, the practice of grafting seedless watermelons onto rootstocks belonging to other Cucurbitaceae genera is also gaining acceptance in our l...

  16. Antifungal Activity and Biochemical Response of Cuminic Acid against Phytophthora capsici Leonian.

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    Wang, Yong; Sun, Yang; Zhang, Ying; Zhang, Xing; Feng, Juntao

    2016-01-01

    Phytophthora blight of pepper caused by Phytophthora capsici Leonian is a destructive disease throughout the world. Cuminic acid, extracted from the seed of Cuminum cyminum L., belongs to the benzoic acid chemical class. In this study, the sensitivity and biochemical response of P. capsici to cuminic acid was determined. The mean EC50 (50% effective concentration) values for cuminic acid in inhibiting mycelial growth and zoospore germination of the 54 studied P. capsici isolates were 14.54 ± 5.23 μg/mL and 6.97 ± 2.82 μg/mL, respectively. After treatment with cuminic acid, mycelial morphology, sporangium formation and mycelial respiration were significantly influenced; cell membrane permeability and DNA content increased markedly, but pyruvic acid content, adenosine triphosphate (ATP) content, and ATPase activity decreased compared with the untreated control. In pot experiments, cuminic acid exhibited both protective and curative activity. Importantly, POD and PAL activity of the pepper leaves increased after being treated with cuminic acid. These indicated that cuminic acid not only showed antifungal activity, but also could improve the defense capacity of the plants. All the results suggested that cuminic acid exhibits the potential to be developed as a new phytochemical fungicide, and this information increases our understanding of the mechanism of action of cuminic acid against Phytophthora capsici. PMID:27294911

  17. Study on the Resistance Induced by Salicylic Acid Against Phytophthora capsici in Pepper (Capsicum annuum)

    Institute of Scientific and Technical Information of China (English)

    MAO Ai-jun; WANG Yong-jian; FENG Lan-xiang; GENG San-sheng; XU Yong

    2005-01-01

    Pepper Phytophthora blight caused by Phytophthora capsici L. is the most destructive disease for reducing pepper yields in the world. Building up varietal resistance and induced resistance to the disease are of agricultural importance. In this paper, the disease resistance induced by salicylic acid (SA) against P. capsici were studied by using four hot pepper lines with different resistant abilities and one P. capsici strain with middle pathogenicity. Results show that SA could induce significantly the resistance of pepper seedlings to P. capsici, but CaC12, KH2PO4 and VAM couldn't. SA at a relative low concentration from 0.15 to 0.3 g L-1 had no antifungal activity in vitro against P. capsici. That means the disease resistant enhancement of the plants treated with SA is due to the induction effect, but not the antifungal effect of SA. About 1 to 5 days internal between SA-treatment and challenge inoculation was sufficient to induce the disease resistance of hot pepper. The resistance could remain more than 20 days after treatment with SA.

  18. Interactions of Phytophthora capsici with Resistant and Susceptible Pepper Roots and Stems.

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    Dunn, Amara R; Smart, Christine D

    2015-10-01

    Using host resistance is an important strategy for managing pepper root and crown rot caused by Phytophthora capsici. An isolate of P. capsici constitutively expressing a gene for green fluorescent protein was used to investigate pathogen interactions with roots, crowns, and stems of Phytophthora-susceptible bell pepper 'Red Knight', Phytophthora-resistant bell pepper 'Paladin', and Phytophthora-resistant landrace Criollos de Morelos 334 (CM-334). In this study, the same number of zoospores attached to and germinated on roots of all cultivars 30 and 120 min postinoculation (pi), respectively. At 3 days pi, significantly more secondary roots had necrotic lesions on Red Knight than on Paladin and CM-334 plants. By 4 days pi, necrotic lesions had formed on the taproot of Red Knight but not Paladin or CM-334 plants. Although hyphae were visible in the crowns and stems of all Red Knight plants observed at 4 days pi, hyphae were observed in crowns of only a few Paladin and in no CM-334 plants, and never in stems of either resistant cultivar at 4 days pi. These results improve our understanding of how P. capsici infects plants and may contribute to the use of resistant pepper cultivars for disease management and the development of new cultivars. PMID:26010399

  19. Determining Tolerance in Commercial Watermelon Rootstocks to Crown Rot caused by Phytophthora Capsici using Real-Time PCR

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    Phytophthora crown and fruit rot caused by Phytophthora capsici is becoming an important and emerging disease of watermelon (Citrullus lanatus) in southeastern United States. Various rootstocks have been used for grafting watermelon in Asia and Europe to manage soil-borne diseases such as Fusarium ...

  20. Chemical control trials against Phytophthora capsici (Leon on pepper cultivations in Morocco

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    Pussemier, L.

    1988-01-01

    Full Text Available Chemical control trials against Phytophthora capsici (Leon on pepper cultivations in Morocco. Pepper protection trials against collar and root rot have been undertaken under laboratory and culture conditions using Aliette (80 % of phosethylaluminium and Ridomil M 58 (10 % of metalaxyl associated to 48 % of maneb. It has been proved that, contrary to Ridomil M 58, Aliette does not protect the hostplant when the Phytophthora capsici (Leon zoospores are used as inoculum. But both fongicides are active when inoculating with a mycelian suspension. Trials undertaken under plastic glasshouses confirmed the laboratory results both with an artificial inoculation and with a natural one on contaminated soil. Only Ridomil M 58 provides satisfactory protection during the first weeks after the treatment. When disease propagation conditions are particularly favorable (permanent presence of an active inoculum source, the protection given by repeated Ridomil M 58 applications gradually disappears after a few weeks.

  1. Chemical control of pepper mildew Phytophthora capsici (Leon), on early peppers in Tunisia

    OpenAIRE

    Moens, M.; Ben Aïcha, B.; Ben Hamouda, M.

    1986-01-01

    Peper mildew, caused by Phytophthora capsici, is a serious problem in the intensive early cultures of the Tunisian Nebhana region. In experiments done in very severe conditions of contamination, the best control was obtained by a weekly soil drench (100 ml per plant) with the commercial metalaxyl + maneb mixture (40 g + 192g. hh1). The protection continued up to 5 weeks after the end of the treatment. The action of foliar sprayings was slower and not remanant. The effectiveness of captafol an...

  2. Phytophthora capsici Epidemic Dispersion on Commercial Pepper Fields in Aguascalientes, Mexico

    OpenAIRE

    Adrián Zapata-Vázquez; Mario Sánchez-Sánchez; Alicia del-Río-Robledo; Héctor Silos-Espino; Catarino Perales-Segovia; Silvia Flores-Benítez; Mario Martín González-Chavira; Luis Lorenzo Valera-Montero

    2012-01-01

    Chili pepper blight observed on pepper farms from north Aguascalientes was monitored for the presence of Phytophthora capsici during 2008–2010. Initially, ELISA tests were directed to plant samples from greenhouses and rustic nurseries, showing an 86% of positive samples. Later, samples of wilted plants from the farms during the first survey were tested with ELISA. The subsequent survey on soil samples included mycelia isolation and PCR amplification of a 560 bp fragment of ITS-specific DNA s...

  3. Phytophthora capsici epidemic dispersion on commercial pepper fields in Aguascalientes, Mexico.

    Science.gov (United States)

    Zapata-Vázquez, Adrián; Sánchez-Sánchez, Mario; del-Río-Robledo, Alicia; Silos-Espino, Héctor; Perales-Segovia, Catarino; Flores-Benítez, Silvia; González-Chavira, Mario Martín; Valera-Montero, Luis Lorenzo

    2012-01-01

    Chili pepper blight observed on pepper farms from north Aguascalientes was monitored for the presence of Phytophthora capsici during 2008-2010. Initially, ELISA tests were directed to plant samples from greenhouses and rustic nurseries, showing an 86% of positive samples. Later, samples of wilted plants from the farms during the first survey were tested with ELISA. The subsequent survey on soil samples included mycelia isolation and PCR amplification of a 560 bp fragment of ITS-specific DNA sequence of P. capsici. Data was analyzed according to four geographical areas defined by coordinates to ease the dispersal assessment. In general, one-third of the samples from surveyed fields contained P. capsici, inferring that this may be the pathogen responsible of the observed wilt. Nevertheless, only five sites from a total of 92 were consistently negative to P. capsici. The presence of this pathogen was detected through ELISA and confirmed through PCR. The other two-thirds of the negative samples may be attributable to Fusarium and Rhizoctonia, both isolated instead of Phytophthora in these areas. Due to these striking results, this information would be of interest for local plant protection committees and farmers to avoid further dispersal of pathogens to new lands. PMID:22629131

  4. Antifungal activity of the osthol derivative JS-B against Phytophthora capsici.

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    Wang, Chun-Mei; Guan, Wei; Fang, Shu; Chen, Hao; Li, You-Qin; Cai, Chun; Fan, Yong-Jian; Shi, Zhi-Qi

    2010-08-01

    JS-B (C(12)H(10)O(3)) is a derivative compound of osthol. The antifungal properties of JS-B were tested against 10 economically important plant pathogens. JS-B was effective in inhibiting the mycelial growth of Phytophthora capsici, and its inhibition on different stages of the life cycle of P. capsici was observed. The 50% effective concentration (EC(50)) of JS-B on mycelial dry weight and zoospore germination of P. capsici was 43.74 and 86.03 microg/ml, respectively. The rupture of released zoospores induced by JS-B was reduced by the addition of 100 mM glucose. The ultrastructural study showed that JS-B caused destruction of most of the mitochondrions, the concentration of cell nuclear, and the existing vesicles. When compared with dimethomorph, the activity of JS-B on P. capsici was determined under pot conditions. The result showed that JS-B has a curative effect on pepper blight. PMID:20706903

  5. Compatibilidad fisiológica y sensibilidad a fungicidas de aislamientos de phytophthora capsici Leo

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    Luis Pérez Moreno; Luisa Josefina Durán Ortiz; Rafael Ramírez Malagón; Jesús Ricardo Sánchez Pale; Víctor Olalde Portugal

    2003-01-01

    Para determinar el grupo de compatibilidad y sensibilidad a fungicidas de aislamientos de Phytophthora capsici presentes en el estado de Guanajuato, México, en 1999 se colectaron raíces de chile infectadas por este patógeno en cuatro localidades de los municipios de Salvatierra y Silao. De este material se obtuvieron ocho aislamientos, los cuales se cultivaron en medio de jugo de tomate-agar para la producción de oosporas, y en harina de maíz agar para la producción de esporangios. Del total ...

  6. Búsqueda de resistencia a Phytophthora capsici Leonian en germoplasma de Capsicum spp

    OpenAIRE

    Hurtado Tenorio, Ifigenia

    2010-01-01

    Las especies del género Capsicum son de gran importancia mundial debido a su valor y uso, alimenticio, medicinal e industrial. Phytophthora capsici es el agente causal de La secadera una enfermedad que produce la pudrición del cuello de la raíz y tallo en los cultivos de Capsicum generando pérdidas hasta del 100%. Por esta razón la obtención de materiales resistentes es la alternativa más deseable de manejo de esta enfermedad. El objetivo de la investigación es Identificar fuentes de resisten...

  7. Atividade antifúngica de óleos essenciais de espécies de Piper sobre Crinipellis perniciosa, Phytophthora palmivora e Phytophthora capsici Antifungal activity of essential oils of Piper species against Crinipellis perniciosa, Phytophthora palmivora and Phytophthora capsici

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    Danielle Mariana M.H. Silva

    2007-04-01

    Full Text Available Avaliou-se in vitro, a atividade fungitóxica do óleo essencial em diferentes concentrações extraído de 10 espécies de Piper coletadas na região Amazônica, sobre o crescimento micelial e a germinação de basidiósporos de Crinipellis perniciosa e sobre o crescimento micelial de Phytophthora palmivora e P. capsici. Os óleos mais efetivos que inibiram em 100% o crescimento dos três fungos foram os de P. callosum, P. marginatum var. anisatum e P. enckea, nas concentrações de 0,75µL/mL e 1µL/mL. Quanto à germinação de basidiósporos de C. perniciosa, o óleo de P. dilatatum foi o mais eficiente a 0,4µL/mL seguido pelos óleos de P. callosum e P. marginatum var. anisatum a 0,5µL/mL.Ten essential oils extracted from species of Piper collected in the Amazon region were evaluated in vitro according to their effectiveness in inhibiting mycelial growth and basidiospore germination of Crinipellis perniciosa and in inhibiting mycelial growth of Phytophthora palmivora and P. capsici. The essential oils of P. callosum, P. marginatum var. anisatum and P. enckea were most effective, causing 100% inhibition of the three fungi in concentrations of 0.75µL/mL and 1.0µl/mL. For basidiospore germination, the oil of P. dilatatum was the best at 0.4µL/mL concentration, followed by the oils of P. callosum and P. marginatum var. anisatum at 0.5µL/mL.

  8. Antifungal activity of salaceyin A against Colletotrichum orbiculare and Phytophthora capsici.

    Science.gov (United States)

    Park, C N; Lee, D; Kim, W; Hong, Y; Ahn, J S; Kim, B S

    2007-08-01

    The antifungal activities of novel salicylic acid derivatives, salaceyin A, 6-(9-methyldecyl) salicylic acid, and salaceyin B, 6-(9-methylundecyl) salicylic acid were evaluated against plant pathogenic fungi. Salaceyin A showed antifungal activity against Cladosporium cucumerinum, Colletotrichum orbiculare and Phytophthora capsici at 64 microg ml(-1) while salaceyin B was less effective. In vitro antifungal activities of the compounds were influenced by the experimental pH value of the MIC test medium wherein their antifungal activities were enhanced by increasingly acidic conditions. Salaceyin A showed potent in vivo control efficacy against Phytophthora blight in pepper plants. The disease was effectively suppressed at 500 microg ml(-1), which was comparable to the commercial fungicide, metalaxyl. Salaceyin A suppressed anthracnose development on cucumber leaves in a concentration dependent manner. The control efficacy of salaceyin A against C. orbiculare infection was similar to chlorothalonil when applied prior to pathogen inoculation. Since the salaceyins are derivatives of salicylic acid, a known important signal molecule critical to plant defenses against pathogen invasion, we investigated the possibility that exogenous application of the salaceyin A would activate a systemic acquired resistance against P. capsici infection and C. orbiculare development on pepper and cucumber plants respectively. The addition of 500 microg ml(-1) of salaceyin A to the plant root systems did not significantly decrease disease development in the hosts. We are led to conclude that the disease control efficacy of salaceyin A against the Phytophthora blight and anthracnose diseases, mainly originates from the direct interaction of the agent with the pathogens. PMID:17647212

  9. A Virulence Essential CRN Effector of Phytophthora capsici Suppresses Host Defense and Induces Cell Death in Plant Nucleus

    OpenAIRE

    Mafurah, Joseph Juma; Ma, Huifei; Zhang, Meixiang; Xu, Jing; HE Feng; Ye, Tingyue; Shen, Danyu; Yanyu CHEN; Rajput, Nasir Ahmed; Dou, Daolong

    2015-01-01

    Phytophthora capsici is a soil-borne plant pathogen with a wide range of hosts. The pathogen secretes a large array of effectors during infection of host plants, including Crinkler (CRN) effectors. However, it remains largely unknown on the roles of these effectors in virulence especially in P. capsici. In this study, we identified a cell death-inducing CRN effector PcCRN4 using agroinfiltration approach. Transient expression of PcCRN4 gene induced cell death in N. benthamiana, N. tabacum and...

  10. Chemical control of pepper mildew Phytophthora capsici (Leon, on early peppers in Tunisia

    Directory of Open Access Journals (Sweden)

    Moens, M.

    1986-01-01

    Full Text Available Peper mildew, caused by Phytophthora capsici, is a serious problem in the intensive early cultures of the Tunisian Nebhana region. In experiments done in very severe conditions of contamination, the best control was obtained by a weekly soil drench (100 ml per plant with the commercial metalaxyl + maneb mixture (40 g + 192g. hh1. The protection continued up to 5 weeks after the end of the treatment. The action of foliar sprayings was slower and not remanant. The effectiveness of captafol and phosethylaluminium soil drenches (0.2g and 0.4 g per plant was poor. An improvement of the control was obtained by diluting a dose of 0, 4g captafol per plant in a greater quantity of water (500 ml. Phytotoxic symptoms appeared on the leaves ofthe pepper plants after all metalaxyl + maneb treatments, but not after the other fungicide applications.

  11. Transcriptome- Assisted Label-Free Quantitative Proteomics Analysis Reveals Novel Insights into Piper nigrum-Phytophthora capsici Phytopathosystem.

    Science.gov (United States)

    Mahadevan, Chidambareswaren; Krishnan, Anu; Saraswathy, Gayathri G; Surendran, Arun; Jaleel, Abdul; Sakuntala, Manjula

    2016-01-01

    Black pepper (Piper nigrum L.), a tropical spice crop of global acclaim, is susceptible to Phytophthora capsici, an oomycete pathogen which causes the highly destructive foot rot disease. A systematic understanding of this phytopathosystem has not been possible owing to lack of genome or proteome information. In this study, we explain an integrated transcriptome-assisted label-free quantitative proteomics pipeline to study the basal immune components of black pepper when challenged with P. capsici. We report a global identification of 532 novel leaf proteins from black pepper, of which 518 proteins were functionally annotated using BLAST2GO tool. A label-free quantitation of the protein datasets revealed 194 proteins common to diseased and control protein datasets of which 22 proteins showed significant up-regulation and 134 showed significant down-regulation. Ninety-three proteins were identified exclusively on P. capsici infected leaf tissues and 245 were expressed only in mock (control) infected samples. In-depth analysis of our data gives novel insights into the regulatory pathways of black pepper which are compromised during the infection. Differential down-regulation was observed in a number of critical pathways like carbon fixation in photosynthetic organism, cyano-amino acid metabolism, fructose, and mannose metabolism, glutathione metabolism, and phenylpropanoid biosynthesis. The proteomics results were validated with real-time qRT-PCR analysis. We were also able to identify the complete coding sequences for all the proteins of which few selected genes were cloned and sequence characterized for further confirmation. Our study is the first report of a quantitative proteomics dataset in black pepper which provides convincing evidence on the effectiveness of a transcriptome-based label-free proteomics approach for elucidating the host response to biotic stress in a non-model spice crop like P. nigrum, for which genome information is unavailable. Our dataset

  12. Transcriptome- Assisted Label-Free Quantitative Proteomics Analysis Reveals Novel Insights into Piper nigrum—Phytophthora capsici Phytopathosystem

    Science.gov (United States)

    Mahadevan, Chidambareswaren; Krishnan, Anu; Saraswathy, Gayathri G.; Surendran, Arun; Jaleel, Abdul; Sakuntala, Manjula

    2016-01-01

    Black pepper (Piper nigrum L.), a tropical spice crop of global acclaim, is susceptible to Phytophthora capsici, an oomycete pathogen which causes the highly destructive foot rot disease. A systematic understanding of this phytopathosystem has not been possible owing to lack of genome or proteome information. In this study, we explain an integrated transcriptome-assisted label-free quantitative proteomics pipeline to study the basal immune components of black pepper when challenged with P. capsici. We report a global identification of 532 novel leaf proteins from black pepper, of which 518 proteins were functionally annotated using BLAST2GO tool. A label-free quantitation of the protein datasets revealed 194 proteins common to diseased and control protein datasets of which 22 proteins showed significant up-regulation and 134 showed significant down-regulation. Ninety-three proteins were identified exclusively on P. capsici infected leaf tissues and 245 were expressed only in mock (control) infected samples. In-depth analysis of our data gives novel insights into the regulatory pathways of black pepper which are compromised during the infection. Differential down-regulation was observed in a number of critical pathways like carbon fixation in photosynthetic organism, cyano-amino acid metabolism, fructose, and mannose metabolism, glutathione metabolism, and phenylpropanoid biosynthesis. The proteomics results were validated with real-time qRT-PCR analysis. We were also able to identify the complete coding sequences for all the proteins of which few selected genes were cloned and sequence characterized for further confirmation. Our study is the first report of a quantitative proteomics dataset in black pepper which provides convincing evidence on the effectiveness of a transcriptome-based label-free proteomics approach for elucidating the host response to biotic stress in a non-model spice crop like P. nigrum, for which genome information is unavailable. Our dataset

  13. Genetically diverse long-lived clonal lineages of Phytophthora capsici from pepper in Gansu, China.

    Science.gov (United States)

    Hu, Jian; Pang, Zhili; Bi, Yang; Shao, Jingpeng; Diao, Yongzhao; Guo, Jianguo; Liu, Yonggang; Lv, Heping; Lamour, Kurt; Liu, Xili

    2013-09-01

    Phytophthora capsici causes significant loss to pepper production in China, and our objective was to investigate the population structure in Gansu province. Between 2007 and 2011, 279 isolates were collected from pepper at 24 locations. Isolates (or subsets) were assessed for simple sequence repeat (SSR) genotype, metalaxyl resistance, mating type, and physiological race using cultivars from the World Vegetable Center (AVRDC) and New Mexico recombinant inbred lines (NMRILs). The A1 and A2 mating types were recovered from nine locations and metalaxyl-resistant isolates from three locations. A total of 104 isolates tested on the AVRDC panel resolved five physiological races. None of 42 isolates tested on the NMRIL panel caused visible infection. SSR genotyping of 127 isolates revealed 59 unique genotypes, with 42 present as singletons and 17 having 2 to 13 isolates. Isolates with identical genotypes were recovered from multiple sites across multiple years and, in many cases, had different race types or metalaxyl sensitivities. Isolates clustered into three groups with each group having almost exclusively the A1 or A2 mating type. Overall it appears long-lived genetically diverse clonal lineages are dispersed across Gansu, outcrossing is rare, and functionally important variation exists within a clonal framework. PMID:23550971

  14. Inhibition of Phytophthora parasitica and P. capsici by Silver Nanoparticles Synthesized Using Aqueous Extract of Artemisia absinthium.

    Science.gov (United States)

    Ali, Mohammad; Kim, Bosung; Belfield, Kevin D; Norman, David; Brennan, Mary; Ali, Gul Shad

    2015-09-01

    Application of nanoparticles for controlling plant pathogens is a rapidly emerging area in plant disease management, and nanoparticles synthesis methods that are economical and ecofriendly are extensively investigated. In this project, we investigated the potential of silver nanoparticles (AgNPs) synthesized with aqueous extract of Artemisia absinthium against several Phytophthora spp., which cause many economically important crop diseases. In in vitro dose-response tests conducted in microtiter plates, 10 µg ml⁻¹ of AgNPs inhibited mycelial growth of P. parasitica, P. infestans, P. palmivora, P. cinnamomi, P. tropicalis, P. capsici, and P. katsurae. Detailed in vitro dose-response analyses conducted with P. parasitica and P. capsici revealed that AgNPs synthesized with A. absinthium extract were highly potent (IC50: 2.1 to 8.3 µg ml⁻¹) and efficacious (100%) in inhibiting mycelial growth, zoospore germination, germ tube elongation, and zoospore production. Interestingly, AgNP treatment accelerated encystment of zoospores. Consistent with in vitro results, in planta experiments conducted in a greenhouse revealed that AgNP treatments prevented Phytophthora infection and improved plant survival. Moreover, AgNP in in planta experiments did not produce any adverse effects on plant growth. These investigations provide a simple and economical method for controlling Phytophthora with AgNP without affecting normal plant physiology. PMID:25871856

  15. Phosphite effect on hot and sweet pepper reaction to Phytophthora capsici Efeito do fosfito na reação de pimentão e pimenteira a Phytophthora capsici

    Directory of Open Access Journals (Sweden)

    Fernando Cesar Sala

    2004-10-01

    Full Text Available Phosphite has been recommended to enhance plant resistance against Phytophthora. This work evaluated the response of hot and sweet pepper (Capsicum annuum L. to Phytophthora capsici from juvenile up to the adult stage following treatment with phosphite. Sweet pepper hybrids considered to be resistant to P. capsici, like Reinger, Nathalie and Athenas, were evaluated. The susceptible checks were hybrid Magali R and cvs. Myr 10 and Ikeda. Hot pepper Criollo de Morelos 328, CM 334, BGH 3756, BGH 5122, CNPH 294 and Locorte were used as referential resistant lines. Phosphite did not have an effect on the hot pepper resistant lines because of their genetic homozygozity, while no protection was observed for the Athenas hybrid claimed to be resistant. Heterozygous hybrids recognized as resistant, like Reinger and Nathalie, showed higher survival following phosphite treatment, and their reaction was equivalent to the resistant cvs. CM 328 and CM 334, except for the fruiting stage. Depending of the hybrid heterozygous genotype, phosphite possibly acts through indirect phytoalexin induction through the inhibited pathogen.Fosfito tem sido recomendado para aumentar o sistema de resistência de plantas atacadas por fitopatógenos. Este trabalho avaliou a ação do fosfito nas reações de pimentão e pimenteiras (Capsicum annuum L. a Phytophthora capsici na fase juvenil até a fase adulta, tratadas com fosfito. Os híbridos de pimentão considerados resistentes a P. capsici foram Reinger, Nathalie e Athenas, enquanto que o híbrido Magali R e as cvs. Myr 10 e Ikeda constituíram as referenciais suscetíveis. As linhagens de pimenta Criollo de Morelos 328, CM 334, BGH 3756, BGH 5122, CNPH 294 e Locorte, foram usadas como padrão referencial de resistência ao patógeno. O fosfito não afetou a reação das linhagens resistentes devido sua homozigosidade genética. Não houve ação protetora do fosfito nos hospedeiros suscetíveis, inclusive no híbrido Athenas

  16. PUDRICIÓN BASAL CAUSADA POR Phytophthora capsici EN PLANTAS DE CHILE TRATADAS CON VERMICOMPOST

    Directory of Open Access Journals (Sweden)

    Lidieth Uribe-Lor\\u00EDo

    2014-01-01

    Full Text Available Pudrición basal causada por Phytophthora capcisi en plantas de chile tratadas con vermicompost. El objetivo de este trabajo fue evaluar a nivel de invernadero el efecto de vermicompost sobre la incidencia y severidad de Phytophthora capcisi en plantas de chile (Capsicum annuum. Esta investigación se realizó entre febrero y marzo del 2012 en el Centro de Investigaciones Agronómicas, Sabanilla, San José, Costa Rica. Se utilizó un diseño completamente al azar con cuatro repeticiones y ocho plantas por unidad experimental en un arreglo factorial con los factores de dosis (0, 25% y 50% v/v vermicompost:suelo e inoculación (0 y 500 zoosporas por gramo de suelo. Se trasplantaron plántulas de 35 días, que fueron inoculadas dos semanas después del trasplante. La aplicación de vermicompost provocó un aumento significativo del peso fresco foliar y del peso seco foliar y radical; a mayor dosis, mayor fue el incremento. Las plantas de todos los tratamientos que incluyeron inoculación con P. capsici presentaron síntomas de la enfermedad en la raíz. Los valores de incidencia y severidad fueron mayores para el tratamiento con 50% de abono. En este tratamiento se presentaron síntomas de marchitez. La ausencia de diferencias en las variables de peso fresco y seco entre los tratamientos inoculados y sin inocular, a los que se adicionó abono al 25%, sugiere que esta dosis podría compensar el daño causado por el patógeno. Se observó una menor concentración de nutrimentos en los tejidos de las plantas inoculadas lo que indica que el daño causado a la raíz pudo haber afectado la adquisición de nutrimentos.

  17. 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...

  18. Antagonistic interaction betweenTrichoderma asperellum and Phytophthora capsici in vitro

    Institute of Scientific and Technical Information of China (English)

    Heng JIANG; Liang ZHANG; Jing-ze ZHANG; Mohammad Reza OJAGHIAN; Kevin D HYDE

    2016-01-01

    Phytophthora capsiciis a phytopathogen that causes a destructive pepper blight that is extremely difficult to control. Using a fungicide application against the disease is costly and relatively ineffective and there is also a huge environmental concern about the use of such chemicals. The genusTrichoderma has been known to have a potential biocontrol issue. In this paper we investigate the mechanism for causing the infection ofT. asperellum againstP. capsici.Trichodermasp. (isolate CGMCC 6422) was developed to have a strong antagonistic action against hyphae of P. capsici through screening tests. The strain was identified asT. asperelum through using a combination of mor-phological characteristics and molecular data.T. asperelum was able to colapse the mycelium of the colonies of the pathogen through dual culture tests by breaking down the pathogenic hyphae into fragments. The scanning electron microscope showed that the hyphae ofT. asperelumsurrounded and penetrated the pathogens hyphae, resulting in hyphal collapse. The results show that seven days after inoculation, the hyphae of the pathogen were completely degraded in a dual culture.T. asperellum was also able to enter theP. capsici oospores through using oogonia and then developed hyphae and produced conidia, leading to the disintegration of the oogonia and oospores. Seven days after inoculation, an average 10.8% of the oospores were infected, but at this stage, the structures of oospores were stil intact. Subsequently, the number of infected oospores increased and the oospores started to colapse. Forty-two days after inoculation, almost al the oospores were infected, with 9.3% of the structures of the oospores being intact and 90.7% of the oospores having colapsed.%题目:体外棘孢木霉与辣椒疫霉菌的拮抗互作目的:筛选出对辣椒疫霉菌具有高效拮抗作用的木霉生防菌株,研究其对辣椒菌菌丝体和卵孢子的作用机制,评价其应用于辣椒疫病的生防潜

  19. Inhibitory effect of Xenorhabdus nematophila TB on plant pathogens Phytophthora capsici and Botrytis cinerea in vitro and in planta.

    Science.gov (United States)

    Fang, Xiangling; Zhang, Manrang; Tang, Qian; Wang, Yonghong; Zhang, Xing

    2014-01-01

    Entomopathogenic bacteria Xenorhabdus spp. produce secondary metabolites with potential antimicrobial activity for use in agricultural productions. This study evaluated the inhibitory effect of X. nematophila TB culture on plant pathogens Botrytis cinerea and Phytophthora capsici. The cell-free filtrate of TB culture showed strong inhibitory effects (>90%) on mycelial growth of both pathogens. The methanol-extracted bioactive compounds (methanol extract) of TB culture also had strong inhibitory effects on mycelial growth and spore germinations of both pathogens. The methanol extract (1000 μg/mL) and cell-free filtrate both showed strong therapeutic and protective effects (>70%) on grey mold both in detached tomato fruits and plants, and leaf scorch in pepper plants. This study demonstrates X. nematophila TB produces antimicrobial metabolites of strong activity on plant pathogens, with great potential for controlling tomato grey mold and pepper leaf scorch and being used in integrated disease control to reduce chemical application. PMID:24599183

  20. The Effects of Arbuscular Mycorrhizal Fungus (AMF) and Humic Acid on the Growth of Pepper (Capsicum annuum L.) Plant and Root Rot Disease Caused by Phytophthora capsici Leonian

    OpenAIRE

    ASLANPAY, Burcu; Semra DEMİR

    2015-01-01

    In this study, the effects of singular and double combinations of Arbuscular Mycorrhizal Fungi (AMF) and humic acid (HA) were investigated on the growth of pepper (Capsicum annuum L.) and rot root disease caused by Phytophthora capsici Leonian which has been known as an important problem of pepper cultivation and leading yield losses. Under controlled conditions, four F1 pepper cultivars (Ergenekon, Bafra, Sirena and Yıldız) were inoculated with three different AMF strains (Glomus intraradice...

  1. QTL mapping of fruit rot resistance to the plant pathogen Phytophthora capsici in a recombinant inbred line Capsicum annuum population.

    Science.gov (United States)

    Naegele, R P; Ashrafi, H; Hill, T A; Chin-Wo, S Reyes; Van Deynze, A E; Hausbeck, M K

    2014-05-01

    Phytophthora capsici is an important pepper (Capsicum annuum) pathogen causing fruit and root rot, and foliar blight in field and greenhouse production. Previously, an F6 recombinant inbred line population was evaluated for fruit rot susceptibility. Continuous variation among lines and partial and isolate-specific resistance were found. In this study, Phytophthora fruit rot resistance was mapped in the same F6 population between Criollo del Morelos 334 (CM334), a landrace from Mexico, and 'Early Jalapeno' using a high-density genetic map. Isolate-specific resistance was mapped independently in 63 of the lines evaluated and the two parents. Heritability of the resistance for each isolate at 3 and 5 days postinoculation (dpi) was high (h(2) = 0.63 to 0.68 and 0.74 to 0.83, respectively). Significant additive and epistatic quantitative trait loci (QTL) were identified for resistance to isolates OP97 and 13709 (3 and 5 dpi) and 12889 (3 dpi only). Mapping of fruit traits showed potential linkage with few disease resistance QTL. The partial fruit rot resistance from CM334 suggests that this may not be an ideal source for fruit rot resistance in pepper. PMID:24168044

  2. Identification and Characterisation CRN Effectors in Phytophthora capsici Shows Modularity and Functional Diversity

    OpenAIRE

    Stam, Remco; Jupe, Julietta; Howden, Andrew J. M.; Morris, Jenny A.; Boevink, Petra C.; Hedley, Pete E; Huitema, Edgar

    2013-01-01

    Phytophthora species secrete a large array of effectors during infection of their host plants. The Crinkler (CRN) gene family encodes a ubiquitous but understudied class of effectors with possible but as of yet unknown roles in infection. To appreciate CRN effector function in Phytophthora, we devised a simple Crn gene identification and annotation pipeline to improve effector prediction rates. We predicted 84 full-length CRN coding genes and assessed CRN effector domain diversity in sequence...

  3. Two non-target recessive genes confer resistance to the anti-oomycete microtubule inhibitor zoxamide in Phytophthora capsici.

    Directory of Open Access Journals (Sweden)

    Yang Bi

    Full Text Available This study characterized isolates of P. capsici that had developed a novel mechanism of resistance to zoxamide, which altered the minimum inhibition concentration (MIC but not the EC50. Molecular analysis revealed that the β-tubulin gene of the resistant isolates contained no mutations and was expressed at the same level as in zoxamide-sensitive isolates. This suggested that P. capsici had developed a novel non-target-site-based resistance to zoxamide. Analysis of the segregation ratio of zoxamide-resistance in the sexual progeny of the sensitive isolates PCAS1 and PCAS2 indicated that the resistance to zoxamide was controlled by one or more recessive nuclear genes. Furthermore, the segregation of resistance in the F1, F2, and BC1 progeny was in accordance with the theoretical ratios of the χ(2 test (P>0.05, which suggested that the resistance to zoxamide was controlled by two recessive genes, and that resistance to zoxamide occurred when at least one pair of these alleles was homozygous. This implies that the risk of zoxamide-resistance in P. capsici is low to moderate. Nevertheless this potential for resistance should be monitored closely, especially if two compatible mating types co-exist in the same field.

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

    Directory of Open Access Journals (Sweden)

    Mao Sopheareth

    2013-03-01

    Full Text Available A chitinolytic bacterial strain having strong antifungal activity was isolated and identified as Burkholderia cepacia MPC-7 based on 16S rRNA gene analysis. MPC-7 solubilized insoluble phosphorous in hydroxyapatite agar media. It produced gluconic acid and 2-ketogluconic acid related to the decrease in pH of broth culture. The antagonist produced benzoic acid (BA and phenylacetic acid (PA. The authentic compounds, BA and PA, showed a broad spectrum of antimicrobial activity against yeast, several bacterial and fungal pathogens in vitro. To demonstrate the biocontrol efficiency of MPC-7 on late blight disease caused by Phytophthora capsici, pepper plants in pot trials were treated with modified medium only (M, M plus zoospore inoculation (MP, MPC-7 cultured broth (B and B plus zoospore inoculation (BP. With the sudden increase in root mortality, plants in MP wilted as early as five days after pathogen inoculation. However, plant in BP did not show any symptom of wilting until five days. Root mortality in BP was markedly reduced for as much as 50%. Plants in B had higher dry weight, P concentration in root, and larger leaf area compared to those in M and MP. These results suggested that B. cepacia MPC-7 should be considered as a candidate for the biological fertilizer as well as antimicrobial agent for pepper plants.

  5. Genetic Diversity, Population Structure, and Resistance to Phytophthora capsici of a Worldwide Collection of Eggplant Germplasm

    OpenAIRE

    Naegele, Rachel P.; Boyle, Samantha; Quesada-Ocampo, Lina M.; Hausbeck, Mary K.

    2014-01-01

    Eggplant (Solanum melongena L.) is an important solanaceous crop with high phenotypic diversity and moderate genotypic diversity. Ninety-nine genotypes of eggplant germplasm (species (S. melongena, S. incanum, S. linnaeanum and S. gilo), landraces and heirloom cultivars) from 32 countries and five continents were evaluated for genetic diversity, population structure, fruit shape, and disease resistance to Phytophthora fruit rot. Fruits from each line were measured for fruit shape and evaluate...

  6. Actividad de pal, acumulación de fenoles y flavonoides en el chile CM-334 infectado por Nacobbus aberrans e inoculado en el follaje con Phytophthora capsici.

    OpenAIRE

    Sandoval Luna, Ruth

    2012-01-01

    Se evaluó la respuesta del chile (Capsicum annuum) CM-334 infectado con Nacobbus aberrans (Na) y en el follaje inoculado con diferentes tipos de inoculación de Phytophthora capsici. En plantas completas o con el tallo decapitado se inoculo micelio, en el follaje zoosporas asperjadas, por inmersión en una suspensión de zoosporas y también en la raíz. Se tuvieron experimentos con plantas susceptibles (var. Joe E. Parker) y resistentes (CM-334), infectadas o sin infectar con N. aberrans y 21 día...

  7. Structure reveals regulatory mechanisms of a MaoC-like hydratase from Phytophthora capsici involved in biosynthesis of polyhydroxyalkanoates (PHAs.

    Directory of Open Access Journals (Sweden)

    Huizheng Wang

    Full Text Available BACKGROUND: Polyhydroxyalkanoates (PHAs have attracted increasing attention as "green plastic" due to their biodegradable, biocompatible, thermoplastic, and mechanical properties, and considerable research has been undertaken to develop low cost/high efficiency processes for the production of PHAs. MaoC-like hydratase (MaoC, which belongs to (R-hydratase involved in linking the β-oxidation and the PHA biosynthetic pathways, has been identified recently. Understanding the regulatory mechanisms of (R-hydratase catalysis is critical for efficient production of PHAs that promise synthesis an environment-friendly plastic. METHODOLOGY/PRINCIPAL FINDINGS: We have determined the crystal structure of a new MaoC recognized from Phytophthora capsici. The crystal structure of the enzyme was solved at 2.00 Å resolution. The structure shows that MaoC has a canonical (R-hydratase fold with an N-domain and a C-domain. Supporting its dimerization observed in structure, MaoC forms a stable homodimer in solution. Mutations that disrupt the dimeric MaoC result in a complete loss of activity toward crotonyl-CoA, indicating that dimerization is required for the enzymatic activity of MaoC. Importantly, structure comparison reveals that a loop unique to MaoC interacts with an α-helix that harbors the catalytic residues of MaoC. Deletion of the loop enhances the enzymatic activity of MaoC, suggesting its inhibitory role in regulating the activity of MaoC. CONCLUSIONS/SIGNIFICANCE: The data in our study reveal the regulatory mechanism of an (R-hydratase, providing information on enzyme engineering to produce low cost PHAs.

  8. Resistance Assessment for Oxathiapiprolin in Phytophthora capsici and the Detection of a Point Mutation (G769W) in PcORP1 that Confers Resistance.

    Science.gov (United States)

    Miao, Jianqiang; Cai, Meng; Dong, Xue; Liu, Li; Lin, Dong; Zhang, Can; Pang, Zhili; Liu, Xili

    2016-01-01

    The potential for oxathiapiprolin resistance in Phytophthora capsici was evaluated. The baseline sensitivities of 175 isolates to oxathiapiprolin were initially determinated and found to conform to a unimodal curve with a mean EC50 value of 5.61 × 10(-4) μg/ml. Twelve stable oxathiapiprolin-resistant mutants were generated by fungicide adaptation in two sensitive isolates, LP3 and HNJZ10. The fitness of the LP3-mutants was found to be similar to or better than that of the parental isolate LP3, while the HNJZ10-mutants were found to have lost the capacity to produce zoospores. Taken together these results suggest that the risk of P. capsici developing resistance to oxathiapiprolin is moderate. Comparison of the PcORP1 genes in the LP3-mutants and wild-type parental isolate, which encode the target protein of oxathiapiprolin, revealed that a heterozygous mutation caused the amino acid substitution G769W. Transformation and expression of the mutated PcORP1-769W allele in the sensitive wild-type isolate BYA5 confirmed that the mutation in PcORP1 was responsible for the observed oxathiapiprolin resistance. Finally diagnostic tests including As-PCR and CAPs were developed to detect the oxathiapiprolin resistance resulting from the G769W point mutation in field populations of P. capsici. PMID:27199944

  9. Transfer RNA Derived Small RNAs Targeting Defense Responsive Genes Are Induced during Phytophthora capsici Infection in Black Pepper (Piper nigrum L.).

    Science.gov (United States)

    Asha, Srinivasan; Soniya, Eppurath V

    2016-01-01

    Small RNAs derived from transfer RNAs were recently assigned as potential gene regulatory candidates for various stress responses in eukaryotes. In this study, we report on the cloning and identification of tRNA derived small RNAs from black pepper plants in response to the infection of the quick wilt pathogen, Phytophthora capsici. 5'tRFs cloned from black pepper were validated as highly expressed during P. capsici infection. A high-throughput systematic analysis of the small RNAome (sRNAome) revealed the predominance of 5'tRFs in the infected leaf and root. The abundance of 5'tRFs in the sRNAome and the defense responsive genes as their potential targets indicated their regulatory role during stress response in black pepper. The 5'Ala(CGC) tRF mediated cleavage was experimentally mapped at the tRF binding sites on the mRNA targets of Non-expresser of pathogenesis related protein (NPR1), which was down-regulated during pathogen infection. Comparative sRNAome further demonstrated sequence conservation of 5'Ala tRFs across the angiosperm plant groups, and many important genes in the defense response were identified in silico as their potential targets. Our findings uncovered the diversity, differential expression and stress responsive functional role of tRNA-derived small RNAs during Phytophthora infection in black pepper. PMID:27313593

  10. Assessing the efficacy of pre-harvest, chlorine-based sanitizers against human pathogen indicator microorganisms and Phytophthora capsici in non-recycled surface irrigation water.

    Science.gov (United States)

    Lewis Ivey, M L; Miller, S A

    2013-09-01

    Many factors must be considered in order to develop and implement treatment systems to improve the microbial quality of surface water and prevent the accidental introduction of plant and human pathogens into vegetable crops. The efficacy of chlorine gas (Cl2(g)) and chlorine dioxide (ClO2) injection systems in combination with rapid sand filtration (RSF) was evaluated in killing fecal indicator microorganisms in irrigation water in a vegetable-intensive production area. The efficacy of ClO2 and Cl2(g) was variable throughout the distribution systems and coliform bacteria never dropped below levels required by the United States Environmental Protection Agency for recreational waters. Sampling date and sampling point had a significant effect on the abundance of coliforms in Cl2(g)- and ClO2-treated water. Sampling date and sampling point also had a significant effect on the abundance of generic Escherichia coli in Cl2(g) treated water but only sampling point was significant in ClO2 treated water. Although the waterborne plant pathogen Phytophthora capsici was detected in five different sources of surface irrigation water using baiting and P. capsici-specific PCR, in vitro studies indicated that ClO2 at concentrations similar to those used to treat irrigation water did not reduce mycelial growth or direct germination of P. capsici sporangia and reduced zoospore populations by less than 50%. This study concludes that injection of ClO2 and Cl2(g) into surface water prior to rapid sand filtration is inadequate in reducing fecal indicator microorganism populations and ClO2 ineffectively kills infectious propagules of P. capsici. Additional research is needed to design a system that effectively targets and significantly reduces both plant and human pathogens that are present in surface irrigation water. A model for a multiple barrier approach to treating surface water for irrigation is proposed. PMID:23770479

  11. Characterisation of cell death inducing Phytophthora capsici CRN effectors suggests diverse activities in the host nucleus

    Directory of Open Access Journals (Sweden)

    Remco eStam

    2013-10-01

    Full Text Available Plant-Microbe interactions are complex associations that feature recognition of Pathogen Associated Molecular Patterns by the plant immune system and dampening of subsequent responses by pathogen encoded secreted effectors. With large effector repertoires now identified in a range of sequenced microbial genomes, much attention centres on understanding their roles in immunity or disease. These studies not only allow identification of pathogen virulence factors and strategies, they also provide an important molecular toolset suited for studying immunity in plants. The Phytophthora intracellular effector repertoire encodes a large class of proteins that translocate into host cells and exclusively target the host nucleus. Recent functional studies have implicated the CRN protein family as an important class of diverse effectors that target distinct subnuclear compartments and modify host cell signalling. Here, we characterised three necrosis inducing CRNs and show that there are differences in the levels of cell death. We show that only expression of CRN20_624 has an additive effect on PAMP induced cell death but not AVR3a induced ETI. Given their distinctive phenotypes, we assessed localisation of each CRN with a set of nuclear markers and found clear differences in CRN subnuclear distribution patterns. These assays also revealed that expression of CRN83_152 leads to a distinct change in nuclear chromatin organisation, suggesting a distinct series of events that leads to cell death upon over-expression. Taken together, our results suggest diverse functions carried by CRN C-termini, which can be exploited to identify novel processes that take place in the host nucleus and are required for immunity or susceptibility.

  12. Use of the vital stain FUN-1 indicates viability of Phytophthora capsici propagules and can be used to predict maximum zoospore production.

    Science.gov (United States)

    Lewis Ivey, Melanie L; Miller, Sally A

    2014-01-01

    The fluorescent vital dye FUN®-1 (2-chloro-4-[2,3-dihydro-3-methyl-{benzo-1,3-thiazol-2-yl}-methylidene]-1-phenylquinolinium iodide) was evaluated as a tool to assess Phytophthora capsici sporangia and zoospore metabolic activity and viability. Under aerobic conditions, mycelia, sporangia and zoospores cultured on agar medium and stained with FUN-1 exhibited red fluorescent cylindrical intravacuolar structures (CIVS) that were clearly visible at 100× magnification. Encysted zoospores did not exhibit CIVS after exposure to FUN-1 dye. Over 7 d there was a significant reduction in the percent of sporangia containing CIVS, which corresponded with a significant increase in zoospore formation and release. The decline in the percentage of metabolically active sporangia and increase in the number of zoospores fit both a linear and log regression model. The FUN-1 dye was suitable for distinguishing between live and dead sporangia and effective in monitoring the change in metabolic activity of sporangia over time. It will be useful in determining parameters, including P. capsici culture age, that maximize production of zoospores in vitro. PMID:24782503

  13. Gageopeptins A and B, new inhibitors of zoospore motility of the phytopathogen Phytophthora capsici from a marine-derived bacterium Bacillus sp. 109GGC020.

    Science.gov (United States)

    Tareq, Fakir Shahidullah; Hasan, Choudhury M; Lee, Hyi-Seung; Lee, Yeon-Ju; Lee, Jong Seok; Surovy, Musrat Zahan; Islam, Md Tofazzal; Shin, Hee Jae

    2015-08-15

    The motility of zoospores is critical in the disease cycles of the peronosporomycetes that cause devastating diseases in plants, fishes, vertebrates, and microbes. In the course of screening for secondary metabolites regulating the motility of zoospores of Phytophthora capsici, we discovered two new inhibitors from the ethyl acetate extract of the fermentation broth of a marine-derived strain Bacillus sp. 109GGC020. The structures of these novel metabolites were elucidated as new cyclic lipopeptides and named gageopeptins A (1) and B (2) by spectroscopic analyses including high resolution MS and extensive 1D and 2D NMR. The stereoconfigurations of 1 and 2 were assigned based on the chemical derivatization studies and reviews of the literature data. Although compounds 1 and 2 impaired the motility of zoospores of P. capsici in dose- and time-dependent manners, compound 1 (IC50 = 1 μg/ml) was an approximately 400-fold stronger motility inhibitor than 2 (IC50 = 400 μg/ml). Interestingly, the zoospores halted by compound 1 were subsequently lysed at higher concentrations (IC50 = 50 μg/ml). Compounds 1 and 2 were also tested against some bacteria and fungi by broth dilution assay, and exhibited moderate antibacterial and good antifungal activities. PMID:26071635

  14. A new ethylene-responsive factor CaPTI1 gene of pepper (Capsicum annuum L. involved in the regulation of defense response to Phytophthora capsici

    Directory of Open Access Journals (Sweden)

    Jing-Hao eJin

    2016-01-01

    Full Text Available Ethylene-responsive factors (ERF are usually considered to play diverse roles in plant response to biotic and abiotic stresses. In this study, an ERF gene CaPTI1 was isolated from pepper transcriptome database. CaPTI1 contains an open reading frame (ORF of 543bp, which encodes a putative polypeptide of 180 amino acids with a theoretical molecular weight of 20.30 kDa. Results of expression profile showed that CaPTI1 had a highest expression level in roots and this gene could not only response to the infection of Phytophthora capsici and the stresses of cold and drought, but also be induced by the signaling molecule (salicylic acid (SA, Methyl Jasmonate (MeJA, Ethephon (ETH and hydogen peroxide (H2O2. Furthermore, virus-induce gene silencing (VIGS of CaPTI1 in pepper weakened the defense response significantly by reducing the expression of defense related genes CaPR1, CaDEF1 and CaSAR82 and also the root activity. These results suggested that CaPTI1 is involved in the regulation of defense response to P. capsici in pepper.

  15. Crystallization and preliminary X-ray analysis of the MaoC-like dehydratase from Phytophthora capsici

    International Nuclear Information System (INIS)

    The MaoC-like dehydratase from P. capsici was cloned, expressed and purified to homogeneity. Crystals were obtained that diffracted to 1.93 Å resolution. MaoC-like dehydratase (MaoC) plays an important role in supplying (R)-3-hydroxyacyl-CoA from the fatty-acid oxidation pathway to polyhydroxyalkanoate (PHA) biosynthetic pathways. PHAs have been attracting much attention as they can be used in the biosynthesis of synthetic plastics. Crystals of MaoC from Phytophora capsici were grown by the hanging-drop vapour-diffusion method at 289 K in a number of screening conditions. An MaoC crystal diffracted to 1.93 Å resolution using X-ray radiation and belonged to the orthorhombic space group P212121, with unit-cell parameters a = 81.458, b = 82.614, c = 124.228 Å, α = β = γ = 90°

  16. Diversidade genética de isolados de Phytophthora capsici de diferentes hospedeiros com base em marcadores RAPD, patogenicidade e morfologia

    Directory of Open Access Journals (Sweden)

    Luz Edna Dora M. Newman

    2003-01-01

    Full Text Available Phytophthora capsici é uma espécie onívora com vários hospedeiros cultivados na Bahia. Variações morfológicas ocorrem entre isolados de cacaueiro (Theobromae cacao, seringueira (Hevea brasiliensis e pimenta-do-reino (Piper nigrum, todos classificados como P. capsici. Utilizaram-se marcadores RAPD e reações de patogenicidade para estudar a diversidade genética dentro desta espécie. Foram analisados 22 isolados sendo, oito de cacau, oito de seringueira, três de pimentão (Capsicum annuum (dois antigos e um recente, um de abóbora (Cucurbita moschata, um de tomate (Lycopersicon esculentum e um de pimenta-do-reino. Os isolados de pimentão, abóbora e tomate foram obtidos em Minas Gerais, o de pimenta-do-reino no Pará e, os demais, na Bahia e Espírito Santo. O DNA genômico de cada isolado foi extraído e amplificado utilizando-se oito primers decâmeros, os quais geraram 123 marcadores RAPD. Distâncias genéticas e análises de agrupamento permitiram a diferenciação de três grupos: o primeiro formado por isolados de cacaueiro, o segundo por sete dos oito isolados de seringueira e o terceiro por dois isolados de pimentão (antigos. Os isolados de tomate, pimenta-do-reino, pimentão (recente, o de abóbora e um de seringueira mostraram-se distantes geneticamente dos demais. Inoculações em frutos de cacau, seringueira, tomate e pimentão, com e sem ferimento, mostraram que o isolado de seringueira que não agrupou com os demais foi o menos virulento dos isolados testados, não causando lesões em frutos de seringueira sem ferimento. Frutos de pimentão só foram infetados por isolados de tomate e pimentão, enquanto os frutos de cacau foram infetados por todos os isolados testados. A manutenção de todos os grupos dentro de P. capsici é discutida.

  17. Down-regulation of osmotin (PR5) gene by virus-induced gene silencing (VIGS) leads to susceptibility of resistant Piper colubrinum Link. to the oomycete pathogen Phytophthora capsici Leonian.

    Science.gov (United States)

    Anu, K; Jessymol, K K; Chidambareswaren, M; Gayathri, G S; Manjula, S

    2015-06-01

    Piper colubrinum Link., a distant relative of Piper nigrum L., is immune to the oomycete pathogen Phytophthora capsici Leonian that causes 'quick wilt' in cultivated black pepper (P. nigrum). The osmotin, PR5 gene homologue, earlier identified from P. colubrinum, showed significant overexpression in response to pathogen and defense signalling molecules. The present study focuses on the functional validation of P. colubrinum osmotin (PcOSM) by virus induced gene silencing (VIGS) using Tobacco Rattle Virus (TRV)-based vector. P. colubrinum plants maintained under controlled growth conditions in a growth chamber were infiltrated with Agrobacterium carrying TRV empty vector (control) and TRV vector carrying PcOSM. Three weeks post infiltration, viral movement was confirmed in newly emerged leaves of infiltrated plants by RT-PCR using TRV RNA1 and TRV RNA2 primers. Semi-quantitative RT-PCR confirmed significant down-regulation of PcOSM gene in TRV-PcOSM infiltrated plant compared with the control plants. The control and silenced plants were challenged with Phytophthora capsici which demonstrated that knock-down of PcOSM in P. colubrinum leads to increased fungal mycelial growth in silenced plants compared to control plants, which was accompanied by decreased accumulation of H2O2 as indicated by 3,3'-diaminobenzidine (DAB) staining. Thus, in this study, we demonstrated that Piper colubrinum osmotin gene is required for resisting P. capsici infection and has possible role in hypersensitive cell death response and oxidative burst signaling during infection. PMID:26155671

  18. Draft Genome Sequence of Lysobacter capsici AZ78, a Bacterium Antagonistic to Plant-Pathogenic Oomycetes.

    Science.gov (United States)

    Puopolo, Gerardo; Sonego, Paolo; Engelen, Kristof; Pertot, Ilaria

    2014-01-01

    Lysobacter capsici AZ78, isolated from tobacco rhizosphere, effectively controls Phytophthora infestans and Plasmopara viticola on tomato and grapevine plants, respectively. We report the first draft genome sequence of the L. capsici species. PMID:24762937

  19. Recombinant inbred line differential identifies race-specific resistance to phytophthora root rot in Capsicum annuum.

    Science.gov (United States)

    Sy, O; Steiner, R; Bosland, P W

    2008-08-01

    A differential series is the normal method for identification of races within a plant pathogen and a host interaction. A host differential is extremely useful for phytopathological as well as breeding purposes. A set of recombinant inbred lines (RILs) were developed and characterized for race differentiation of Phytophthora root rot caused by Phytophthora capsici. The highly resistant Capsicum annuum accession Criollo de Morelos-334 was hybridized to a susceptible cultivar, Early Jalapeno, to generate the RIL population. The host differential characterized 17 isolates of P. capsici into 13 races. The establishment of a stable host differential for the P. capsici and C. annuum interaction will assist researchers in understanding the complex inheritance of resistance to Phytophthora root rot and to develop resistant cultivars. PMID:18943204

  20. Reducción de la incidencia de Phytophthora capsici Leo en el sistema radical de plántulas de chile pre-micorrizadas con Glomus intraradices

    Directory of Open Access Journals (Sweden)

    D. Espinosa-Victoria

    2004-01-01

    Full Text Available El presente trabajo tuvo como objetivo estudiar el efecto de la pre-micorrización con el hongo Glomus intraradices en el sistema radical de plántulas de chile (Capsicum annuum L. var. "Tres Lomos" infectadas con el patógeno Phytophthora capsici. Se realizaron ensayos a escala de microcosmos para determinar los cambios en arquitectura radical, variación en el número de lesiones producidas por el patógeno, así como en la actividad de las enzimas antioxidantes peroxidasa (PO y catalasa (CAT. Las plántulas pre-micorrizadas presentaron menor número de raíces de 2°, 3er y 4° orden, así como disminución en el número de lesiones producidas por P. capsici a partir del tercer día de contacto con el patógeno, alcanzando el valor máximo de 70.2 lesiones y 23% de necrosis radical al doceavo día de la interacción. En contraste, las plántulas inoculadas sólo con P. capsici presentaron mayor número de raíces de 2°, 3er y 4° orden, así como mayor número de lesiones, que aumentó a partir del tercer día de contacto con el patógeno, alcanzando el valor máximo de 269.5 lesiones y 80% de necrosis radical al doceavo día de la interacción. Las plántulas pre-micorrizadas presentaron los valores más altos de actividad de la PO a lo largo del experimento, con un valor máximo de 4.62 U mg-1 de tejido radical a 12 días de contacto con P. capsici. Por otro lado, la enzima CAT presentó los valores más altos de actividad en las plantas pre-micorrizadas a partir de seis días de contacto con el patógeno, alcanzando el valor máximo de 2.79 U mg-1 tejido radical a nueve días de la interacción con el patógeno. La modificación de la arquitectura radical, junto con el aumento de la actividad de las enzimas PO y CAT inducida por la pre-colonización de G. intraradices, resultaron en una menor severidad de la enfermedad así como en 100% de supervivencia de las plántulas de chile. Debido a que los resultados se obtuvieron a nivel de

  1. Reação de híbridos, linhagens e progênies de pimentão à requeima causada por Phytophthora capsici e ao mosaico amarelo causado por Pepper yellow mosaic vírus (PepYMV Reaction of hybrids, lines and progenies of sweet pepper the blight caused by Phytophthora capsici and to Pepper yellow mosaic virus (PepYMV

    Directory of Open Access Journals (Sweden)

    Ildon Rodrigues do Nascimento

    2007-02-01

    Full Text Available A requeima do pimentão (Capsicum annuum L. causada por Phytophthora capsici e o mosaico amarelo causado por PepYMV são prioridades nos programas de melhoramento de pimentão em andamento no Brasil. Foram avaliados três híbridos comerciais (Magali R, Atenas F1 e Fortuna Super F1, cinco linhagens, 20 híbridos experimentais e duas progênies F2:4 do programa de melhoramento da Universidade Federal de Lavras/HortiAgro Sementes quanto à reação a P. capsici e a PepYMV. Os experimentos foram montados independentemente em blocos casualizados, com quatro e duas repetições, respectivamente. Cada parcela foi constituída de oito plantas instaladas em bandejas de 128 células, que foram mantidas em estufa com cobertura plástica e laterais teladas. As avaliações foram feitas do 4º ao 14º e do 15º ao 40º dias após a inoculação (DAI para P. capsici e PepYMV, respectivamente. A inoculação com P. capsici foi feita pormeio da distribuição de 5 mL de suspensão com 10(4 zoósporos/mL no solo ao redor do colo de cada planta. A inoculação mecânica de PepYMV foi feita a partir de macerados de folhas de Nicotiana tabacum cv. TNN, previamente infectadas. Os híbridos Magali R e Fortuna Super, foram suscetíveis a P. capsici, enquanto que o acesso Criollo de Morellos 334, a linhagem PIM-013 e as progênies PIX-03 pl#03-2 e PIX-030 pl#06-3 (ambas originadas do cruzamento com Criollo de Morellos, foram resistentes. Reação de resistência a P. capsici foi também observada para os híbridos experimentais que tiveram PIM-013 como uma das linhagens parentais. Criollo de Morellos 334, as progênies PIX-03 pl#03-2 e PIX-030 pl#06-3, o híbrido comercial Magali R e outros 6 híbridos experimentais que tinham como um dos genitores a linhagem MYR-29 forma ressitentes ao PepYMV. As progênies PIX-03 pl#03-2 e PIX-030 pl#06-3 são fontes promissoras de resistência a ambos os patógenos para serem desenvolvidas e exploradas em programas de melhoramento

  2. 贵州辣椒疫霉种群的组成与分布%Composition and Distribution of Phytophthora capsici Population in Guizhou

    Institute of Scientific and Technical Information of China (English)

    陈小均; 吴石平; 谭清群; 何海永; 杨学辉

    2014-01-01

    In order to provide a theoretical basis for pepper phytophthora blight control and resistance cultivars breeding, artificial inoculation in seedling stage was used and 49 representative strains of P .capsici from 12 counties of six districts in Guizhou were selected to identify physiological race according to a subset of identification hosts of pepper in different years.The results showed that four races were identified,which were race 1,race 2,race 3 and race 0.Race 0 was a new one.The composition, distribution and types of dominant race of P.capsici were different in different year and region in Guizhou. The ratio of each race was almost the same from 2004 to 2007,but in 2009 and 2012,the predominant race was race 1 and race 3 with a incidence frequency of 50.00% and 71.43%,respectively.Among different regions,Guiyang had four physiological races,next were Zunyi and Liupanshui with three races and two for Anshun,Qiannan and Bijie.Race 1 was the dominant population in Zunyi and race 3 was the dominant one in Guiyang,Anshun,Qiannan.%为了对贵州辣椒疫病的防治与抗病品种的选育提供理论依据,采用苗期人工接种技术,对不同年度分离自贵州省遵义、贵阳、六盘水、黔南、毕节和安顺等6个地区(州、市)12县(市、区)的49个辣椒疫霉单孢菌株进行了生理小种鉴定。鉴定出 race 0、race 1、race 2和 race 3共4个生理小种,race 0为新小种。贵州辣椒疫霉生理小种的组成、分布以及优势小种的种类因时间和空间不同而有所差异,2004-2007年4个小种组成相对均衡,2009年优势小种为 race 1、出现频率50.00%,2012年优势小种为 race 3、出现频率高达71.43%。不同地区间生理小种数以贵阳最多,有4个小种;其次是遵义和六盘水,均有3个小种;安顺、黔南和毕节只有2个生理小种。贵阳、安顺和黔南的优势小种为 race3,遵义是 race1,毕节和六盘水的小种分布较为平均。

  3. 大蒜素对辣椒炭疽病和辣椒疫病病菌的室内抑制活性测定及田间防效研究%A study on fungicidal activity of allicin against Colletotrichum capsici and Phytophthora capsici in the laboratory and its efficacy in the field

    Institute of Scientific and Technical Information of China (English)

    周清; 李保同; 汤丽梅

    2014-01-01

    Allicin is a botanical antibiotic extracted from garlic.To explore fungicidal activity of allicin against Colletotrichum capsici and Phytophthora capsici in the laboratory its inhibitory effects against mycelial growth and conidial production were assayed by measuring mycelial growth rate and conidial germination.Its efficacy in the field was tested by foliar spraying.Allicin showed inhibitory effects against mycelia growth,conidial production and germination of both fungi and its activity increased with increased concentrations.The EC50 was 130.15,142.60 and 127.21μg/mL against mycelial growth,conidial production and conidial germination re-spectively of C.capsici,and 128.11,123.64 and 139.68μg/mL respectively against P.capsici.Field tests showed that the efficacies of allicin 6% EW (emulsion in water)at 600 and at 1200μg/mL against C.capsici were 83.54%-88.25% respectively and 82.85%-85.88% against P.capsici.On the third day after the third spray they were 74.59%-79.16% and 74.59%-78.01% respectively but at the fourteenth day after the third spray,they were not significantly different from that of the control [carbendazim 50% WP (wettalbe powders) at 1000μg/mL].The efficacies of allicin 6% EW at 200-600μg/mL against C.capsici and P.capsici were less than 7 6% on the third to fourteenth day after the third spray,and were significantly lower than that of the control.The recommended dosage of allicin 6% EW against C.capsici and P.capsici is 600-1200μg/mL on pepper seedlings and during the fruiting period,spraying was done 3 times at 10 d intervals.%大蒜素是从大蒜中提取的植物源抗生素。为探明大蒜素对辣椒炭疽病和辣椒疫病病菌的抑制活性及田间防治效果,采用生长速率法和孢子萌发法分别测定了大蒜素对辣椒炭疽病菌和辣椒疫病菌菌丝生长、孢子产生和孢子萌发的抑制作用,采用叶面喷雾法研究了大蒜素对2种病害的田间防治效果。结果表明,大蒜素可抑

  4. Primary inoculum sources and characterization of Norwegian Phytophthora infestans

    OpenAIRE

    Sharma, Shiva Shankar

    2013-01-01

    Late blight caused by Phytophthora infestans (Mont.) de Barry is a major constrain to potato production in Norway. To characterize present populations of P. infestans and to find potential inoculum sources for early epidemics of late blight in Norway, P. infestans infected samples were collected from 10 different farms of Norway. 237 plant samples were collected in early epidemic. At least 68 recovered isolates from leaf samples were used for testing of their mating type, metalaxyl and propam...

  5. Characterization of cell death inducing Phytophthora capsici CRN effectors suggests diverse activities in the host nucleus

    OpenAIRE

    Stam, Remco; Howden, Andrew J. M.; Delgado-Cerezo, Magdalena; M. M. Amaro, Tiago M.; Motion, Graham B.; Pham, Jasmine; Huitema, Edgar

    2013-01-01

    Plant-Microbe interactions are complex associations that feature recognition of Pathogen Associated Molecular Patterns by the plant immune system and dampening of subsequent responses by pathogen encoded secreted effectors. With large effector repertoires now identified in a range of sequenced microbial genomes, much attention centers on understanding their roles in immunity or disease. These studies not only allow identification of pathogen virulence factors and strategies, they also provide...

  6. Host resistance to phytophthora fruit rot in U.S. watermelon plant introductions

    Science.gov (United States)

    Phytophthora capsici, distributed worldwide, is an aggressive pathogen with a broad host range, infecting solanaceous, leguminaceous, and cucurbitaceous crops. Phytophthora fruit rot of watermelon (Citrullus lanatus) caused by P. capsici was first reported in the U.S. in 1940. Since then, the dise...

  7. Targeted gene mutation in Phytophthora spp.

    NARCIS (Netherlands)

    Lamour, K.H.; Finley, L.; Hurtado-Gonzales, O.; Gobena, D.; Tierney, M.; Meijer, H.J.G.

    2006-01-01

    The genus Phytophthora belongs to the oomycetes and is composed of plant pathogens. Currently, there are no strategies to mutate specific genes for members of this genus. Whole genome sequences are available or being prepared for Phytophthora sojae, P. ramorum, P. infestans, and P. capsici and the d

  8. Tolerance to Phytophthora Fruit Rot in Watermelon Plant Introductions

    Science.gov (United States)

    Phytophthora capsici is distributed worldwide, and is an aggressive pathogen with a broad host range infecting solanaceous, leguminaceous, and cucurbitaceous crops. Fruit rot, caused by P. capsici is an emerging disease in most watermelon producing regions of Southeast US. Resistance to fruit rot o...

  9. Effect of Cultural Practices and Fungicides on Phytophthora Fruit Rot of Watermelon in the Carolinas

    Science.gov (United States)

    Phytophthora fruit rot, caused by Phytophthora capsici, is an important and emerging disease of watermelon (Citrullus lanatus) in the Southeastern U.S. To develop strategies to manage Phytophthora fruit rot, we evaluated the effects of two cultural practices (raised bare ground and plastic mulched ...

  10. Functional, genetic and chemical characterization of biosurfactants produced by plant growth-promoting Pseudomonas putida 267

    NARCIS (Netherlands)

    Kruijt, M.; Tran, H.; Raaijmakers, J.M.

    2009-01-01

    Aims: Plant growth-promoting Pseudomonas putida strain 267, originally isolated from the rhizosphere of black pepper, produces biosurfactants that cause lysis of zoospores of the oomycete pathogen Phytophthora capsici. The biosurfactants were characterized, the biosynthesis gene(s) partially identif

  11. 利用辣椒疫霉培养滤液体外筛选胡椒抗瘟病无性系研究%In vitro Selection of Black Pepper (Piper nigrum Linn.) Somaclones Resistant to Foot Rot Using Culture Filtrate of Phytophthora capsici

    Institute of Scientific and Technical Information of China (English)

    刘进平; 郑成木

    2004-01-01

    Based on shoot-tip multiplication technique, the application of in vitro selection of black pepper somaclones resistant to foot rot disease caused by fungus Phytophthora capsici was carried out using a large-leaf variety Daye (Lampong Type) which is widely cultivated in Hainan but highly susceptible to P. capsici as explant resources. The results demonstrated that sterilization methods significantly influenced on the toxicity of the culture filtrate of P. capsici. The fungal filtrate toxicity could be maintained using filtrate sterilization by addition of the fungal filtrate into selective medium instead of autoclave sterilization. The survival rate of shoot tips and multiple shoots decreased with the increasing concentrations of the fungal culture filtrate. Some cultures blackened and died finally, and some formed calli or remained dormant. After 2 subcultures onto the same selective medium,microshoots were rooted in vitro and transferred to the greenhouse conditions for screening the resistance to fungus P. capsici. The plants exhibited no external symptoms of the disease during three successive times of resistance assay once two weeks were considered to be resistant. As the concentrations of fungal culture filtrate increased, the total number of regenerated plants obtained declined but the frequencies of plants resistant to P. capsici increased. 1 (1.54%), 4 (20.00%) and 3 (42.86%) disease resistant somaclonal variants were obtained at concentration of 25%, 50% and 75% fungal culture filtrate as selective agents, respectively, with the total number of 8 plants resistant to P. capsici.%在胡椒(Piper nigrum Linn.)茎尖丛生增殖技术的基础上,以印尼大叶种"Lampong Type"无菌实生苗作外植体源,利用辣椒疫霉(Phytophthora capsici)培养滤液对胡椒茎尖及其增殖形成的丛生芽进行体外选择.辣椒疫霉培养滤液的不同灭菌方法对辣椒疫霉培养滤液的毒性影响显著,过滤灭菌方式可以保持辣椒疫霉

  12. Evaluation of Commercial Watermelon Rootstocks for Tolerance to Phytophthora Blight and Watermelon Vine Decline

    Science.gov (United States)

    Phytophthora blight and fruit rot caused by Phytophthora capsici, and watermelon vine decline (WVD) caused by Squash vein yellowing virus (SqVYV), are two important and emerging diseases of watermelons (Citrullus lanatus). Recently, the practice of grafting seedless watermelons (triploids) onto roo...

  13. Phytophthora fruit rot-resistant watermelon germplasm lines: USVL489-PFR, USVL782-PFR, USVL203-PFR, and USVL020-PFR

    Science.gov (United States)

    USVL489-PFR, USVL782-PFR, USVL203-PFR, and USVL020-PFR are watermelon (Citrullus lanatus var. lanatus (Thunb.) Matsum. & Nakai) germplasm lines that exhibit high levels of resistance to Phytophthora fruit rot caused by the plant pathogen Phytophthora capsici. Resistance in these germplasm lines is ...

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

    OpenAIRE

    Sung Chul Yun; Sung Taek Kim

    2011-01-01

    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 c...

  15. Characterization of Phytophthora infestans populations in Colombia: first report of the A2 mating type.

    Science.gov (United States)

    Vargas, Angela M; Quesada Ocampo, Lina M; Céspedes, Maria Catalina; Carreño, Natalia; González, Adriana; Rojas, Alejandro; Zuluaga, A Paola; Myers, Kevin; Fry, William E; Jiménez, Pedro; Bernal, Adriana J; Restrepo, Silvia

    2009-01-01

    Phytophthora infestans, the causal agent of late blight in crops of the Solanaceae family, is one of the most important plant pathogens in Colombia. Not only are Solanum lycopersicum, and S. tuberosum at risk, but also several other solanaceous hosts (Physalis peruviana, S. betaceum, S. phureja, and S. quitoense) that have recently gained importance as new crops in Colombia may be at risk. Because little is known about the population structure of Phytophthora infestans in Colombia, we report here the phenotypic and molecular characterization of 97 isolates collected from these six different solanaceous plants in Colombia. All the isolates were analyzed for mating type, mitochondrial haplotypes, genotype for several microsatellites, and sequence of the internal transcribed spacer (ITS) region. This characterization identified a single individual of A2 mating type (from Physalis peruviana) for the first time in Colombia. All isolates had an ITS sequence that was at least 97% identical to the consensus sequence. Of the 97 isolates, 96 were mitochondrial haplotype IIa, with the single A2 isolate being Ia. All isolates were invariant for the microsatellites. Additionally, isolates collected from S. tuberosum and P. peruviana (64 isolates) were tested for: aggressiveness on both hosts, genotype for the isozymes (glucose-6-phosphate isomerase and peptidase), and restriction fragment length polymorphism fingerprint pattern as detected by RG57. Isolates from S. tuberosum were preferentially pathogenic on S. tuberosum, and isolates from P. peruviana were preferentially pathogenic on P. peruviana. The population from these two hosts was dominated by a single clonal lineage (59 of 64 individuals assayed), previously identified from Ecuador and Peru as EC-1. This lineage was mating type A1, IIa for mitochondrial DNA, invariant for two microsatellites, and invariant for both isozymes. The remaining four A1 isolates were in lineages very closely related to EC-1 (named EC-1.1, CO

  16. Evaluation of fungicide rotations and MELCAST for management of Phytophthora fruit rot of watermelon, 2014

    Science.gov (United States)

    The experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC. The soil was Yonges loamy fine sand, and for the past 5 years, the field has been infested with Phytophthora capsici. The experimental design was a randomized complete block with four replications. Four-week-old...

  17. Effect of actigard and other new fungicides on phytophthora fruit rot of watermelon

    Science.gov (United States)

    Fruit rot, caused by Phytophthora capsici is an emerging disease in most watermelon producing regions of Southeast U.S. Between 2003 and 2008, we observed many watermelon farms in Georgia, South Carolina, and North Carolina, where growers did not harvest the crop due to severe fruit rot. The Natio...

  18. Evaluation of Actigard and fungicides for management of Phytophthora fruit rot of watermelon, 2011.

    Science.gov (United States)

    The experiment was conducted at the U.S. Vegetable Laboratory, Charleston, SC. The soil was Yonges loamy fine sand. The field has been infested with Phytophthora capsici for the previous 2 years. The experimental design was a randomized complete block with 4 replications. Four-week old seedlings...

  19. Evaluation of fungicide rotations for management of Phytophthora fruit rot of watermelon, 2013

    Science.gov (United States)

    The experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC in summer of 2013. The soil was Yonges loamy fine sand and the field has been infested with Phytophthora capsici for the previous 2 years. Five-week-old seedlings of the seedless watermelon cultivar Vanessa growin...

  20. Evaluation of Actigard and fungicides for management of Phytophthora fruit rot of watermelon, 2013

    Science.gov (United States)

    The experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC, in summer of 2013. The soil was Yonges loamy fine sand and the field has been infested with Phytophthora capsici for the previous 2 years. Five-week-old seedlings of the seedless watermelon cultivar Vanessa growi...

  1. Antifungal Effect of Plant Essential Oils on Controlling Phytophthora Species

    OpenAIRE

    Amini, Jahanshir; Farhang, Vahid; Javadi, Taimoor; Nazemi, Javad

    2016-01-01

    In this study, antifungal activity of essential oils of Cymbopogon citratus and Ocimum basilicum and two fungicides Mancozeb and Metalaxyl-Mancozeb in six different concentrations were investigated for controlling three species of Phytophthora, including P. capsici, P. drechsleri and P. melonis on pepper, cucumber and melon under in vitro and greenhouse conditions, respectively. Under the in vitro condition, the median effective concen- tration (EC50) values (ppm) of plant essential oils and ...

  2. Occurrence and characterization of a Phytophthora sp. pathogenic to asparagus (Asparagus officinalis) in Michigan.

    Science.gov (United States)

    Saude, C; Hurtado-Gonzales, O P; Lamour, K H; Hausbeck, M K

    2008-10-01

    A homothallic Phytophthora sp. was recovered from asparagus (Asparagus officinalis) spears, storage roots, crowns, and stems in northwest and central Michigan in 2004 and 2005. Isolates (n = 131) produced ovoid, nonpapillate, noncaducous sporangia 45 microm long x 26 microm wide and amphigynous oospores of 25 to 30 microm diameter. Mycelial growth was optimum at 25 degrees C with no growth at 5 and 30 degrees C. All isolates were sensitive to 100 ppm mefenoxam. Pathogenicity studies confirmed the ability of the isolates to infect asparagus as well as cucurbits. Amplified fragment length polymorphism analysis of 99 isolates revealed identical fingerprints, with 12 clearly resolved fragments present and no clearly resolved polymorphic fragments, suggesting a single clonal lineage. The internal transcribed spacer regions of representative isolates were homologous with a Phytophthora sp. isolated from diseased asparagus in France and a Phytophthora sp. from agave in Australia. Phylogenetic analysis supports the conclusion that the Phytophthora sp. isolated from asparagus in Michigan is a distinct species, and has been named Phytophthora asparagi. PMID:18943453

  3. Inhibiton of Phytophthora capsici by a novel pesticide

    Science.gov (United States)

    A potential new pesticide, referred to as ‘SPK’, is currently being investigated under a cooperative project between the University of Florida and the USDA, ARS. In vitro studies have been conducted on multiple plant pathogenic fungi and oomycetes. Preliminary laboratory studies were conducted usin...

  4. Microbiota Characterization of Compost Using Omics Approaches Opens New Perspectives for Phytophthora Root Rot Control

    Science.gov (United States)

    Blaya, Josefa; Marhuenda, Frutos C.; Pascual, Jose A.; Ros, Margarita

    2016-01-01

    Phytophthora root rot caused by Phytophthora nicotianae is an economically important disease in pepper crops. The use of suppressive composts is a low environmental impact method for its control. Although attempts have been made to reveal the relationship between microbiota and compost suppressiveness, little is known about the microorganisms associated with disease suppression. Here, an Ion Torrent platform was used to assess the microbial composition of composts made of different agro-industrial waste and with different levels of suppressiveness against P. nicotianae. Both bacterial and fungal populations responded differently depending on the chemical heterogeneity of materials used during the composting process. High proportions (67–75%) of vineyard pruning waste were used in the most suppressive composts, COM-A and COM-B. This material may have promoted the presence of higher relative abundance of Ascomycota as well as higher microbial activity, which have proved to be essential for controlling the disease. Although no unique fungi or bacteria have been detected in neither suppressive nor conducive composts, relatively high abundance of Fusarium and Zopfiella were found in compost COM-B and COM-A, respectively. To the best of our knowledge, this is the first work that studies compost metabolome. Surprisingly, composts and peat clustered together in principal component analysis of the metabolic data according to their levels of suppressiveness achieved. This study demonstrated the need for combining the information provided by different techniques, including metagenomics and metametabolomics, to better understand the ability of compost to control plant diseases. PMID:27490955

  5. Microbiota Characterization of Compost Using Omics Approaches Opens New Perspectives for Phytophthora Root Rot Control.

    Science.gov (United States)

    Blaya, Josefa; Marhuenda, Frutos C; Pascual, Jose A; Ros, Margarita

    2016-01-01

    Phytophthora root rot caused by Phytophthora nicotianae is an economically important disease in pepper crops. The use of suppressive composts is a low environmental impact method for its control. Although attempts have been made to reveal the relationship between microbiota and compost suppressiveness, little is known about the microorganisms associated with disease suppression. Here, an Ion Torrent platform was used to assess the microbial composition of composts made of different agro-industrial waste and with different levels of suppressiveness against P. nicotianae. Both bacterial and fungal populations responded differently depending on the chemical heterogeneity of materials used during the composting process. High proportions (67-75%) of vineyard pruning waste were used in the most suppressive composts, COM-A and COM-B. This material may have promoted the presence of higher relative abundance of Ascomycota as well as higher microbial activity, which have proved to be essential for controlling the disease. Although no unique fungi or bacteria have been detected in neither suppressive nor conducive composts, relatively high abundance of Fusarium and Zopfiella were found in compost COM-B and COM-A, respectively. To the best of our knowledge, this is the first work that studies compost metabolome. Surprisingly, composts and peat clustered together in principal component analysis of the metabolic data according to their levels of suppressiveness achieved. This study demonstrated the need for combining the information provided by different techniques, including metagenomics and metametabolomics, to better understand the ability of compost to control plant diseases. PMID:27490955

  6. Caracterização de isolados de Phytophthora drechsleri, agente causal da podridão mole de raízes de mandioca Characterization of Phytophthora drechsleri, the causal agent of cassava soft root rot

    Directory of Open Access Journals (Sweden)

    Maria de Fátima S. Muniz

    2006-04-01

    Full Text Available O presente trabalho teve como objetivo caracterizar nove isolados de Phytophthora sp. obtidos de mandioca (Manihot esculenta, através da morfologia e morfometria das estruturas propagativas e crescimento micelial em diferentes temperaturas e avaliar sua patogenicidade. Os esporângios produzidos em extrato de solo não esterilizado mostraram-se ovóides, não papilados, persistentes, formados em esporangióforos não ramificados ou em simpódio, com dimensões de 24,6 - 57,4 µ x 14,8 - 37,7 µm e relação comprimento/largura de 1,0 - 2,6. Os clamidósporos foram raros. Os oósporos obtidos em cultura monospórica em V8 ágar eram apleuróticos, com 13,1 - 34,4 µm de diâmetro. Oogônios mostraram-se esféricos e mediram 19,7 - 41,0 µm de diâmetro; anterídios anfígenos, com dimensões de 8,2 - 24,6 µm x 8,2 - 19,7 µm. O maior diâmetro das colônias ocorreu a 25 ºC em V8 ágar. Os isolados patogênicos às plantas e raízes destacadas de mandioca inoculados foram identificados como Phytophthora drechsleri.Nine Phytophthora isolates from cassava (Manihot esculenta were characterized based on morphology and morphometry of propagative structures, growth at 10, 15, 20, 25, 30 and 35 ºC, and by evaluating its pathogenicity. Sporangia produced on nonsterile soil extract were ovoid, nonpapillate and persistent, formed in a sympodium or unbranched sporangiophores, 24.6 to 57.4 µm long x 14.8 to 37.7 µm wide, and length-breadth ratio was 1.0 - 2.6. Chlamydospores were rarely observed. Oospores produced in single spore culture on V8 agar medium were aplerotic, and 13.1 to 34.4 µm in diameter. Antheridia were amphigynous, measuring 8.2 - 24.6 µ x 8.2 - 19.7 µ ; oogonia ranged from 19.7 to 41.0 µm in diameter. Culture growth was greatest at 25 ºC in V8 agar medium. The isolates that were pathogenic to plants and detached roots of cassava were identified as Phytophthora drechsleri Tucker.

  7. Enhanced biological control of phytophthora blight of pepper by biosurfactant-producing pseudomonas.

    Science.gov (United States)

    Ozyilmaz, Umit; Benlioglu, Kemal

    2013-12-01

    Pseudomonas isolates from different crop plants were screened for in vitro growth inhibition of Phytophthora capsici and production of biosurfactant. Two in vivo experiments were performed to determine the efficacy of selected Pseudomonas strains against Phytophthora blight of pepper by comparing two fungicide treatments [acibenzolar-S-methyl (ASM) and ASM + mefenoxam]. Bacterial isolates were applied by soil drenching (1 × 10(9) cells/ml), ASM (0.1 μg a.i./ml) and ASM + mefenoxam (0.2 mg product/ml) were applied by foliar spraying, and P. capsici inoculum was incorporated into the pot soil three days after treatments. In the first experiment, four Pseudomonas strains resulted in significant reduction from 48.4 to 61.3% in Phytophthora blight severity. In the second experiment, bacterial treatments combining with olive oil (5 mL per plant) significantly enhanced biological control activity, resulting in a reduction of disease level ranging from 56.8 to 81.1%. ASM + mefenoxam was the most effective treatment while ASM alone was less effective in both bioassays. These results indicate that our Pseudomonas fluorescens strains (6L10, 6ba6 and 3ss9) that have biosurfactant-producing abilities are effective against P. capsici on pepper, and enhanced disease suppression could be achieved when they were used in combination with olive oil. PMID:25288970

  8. Effect of Inoculum Density,Soil Water Matric Potential and Soil Temperature on Mortality of Pepper Caused by Phytophthora capsici%接种体密度、土壤水分基质势和土壤温度对辣椒疫病死苗率的影响

    Institute of Scientific and Technical Information of China (English)

    刘学敏; 周艳玲; 李立军; 潘争艳

    2004-01-01

    在生长箱内控制条件下分析测定了接种体密度、土壤水分基质势和土壤温度对辣椒疫病死苗率的影响.结果表明,在每克干土中接种1个辣椒疫霉菌孢子囊就能造成侵染,引致辣椒死苗,随着接种体密度升高死苗率增大,直至接种体孢子囊密度达到50~80个/g干土时死苗率达到最高.土壤温度和土壤水分状况是决定辣椒疫病死苗率的重要因子,病菌侵染的最适土温是22~28℃,土壤水分接近饱和,即土壤水分基质势(ψm值)为0时最容易侵染发病,土壤过于干燥和过饱和都不利于侵染发病.辣椒疫病死苗率与土壤温度、土壤水分基质势及其互作之间可用数学模式描述.%In control condition of the growth chamber analyzing the influence of inoculum density,soil water matric potential and soil temperature on mortality of pepper caused by P.capsici,results showed that so long as one sporangium existed in 1 g dry soil,the pepper plant could be infected and dead,the percentage of diseased plant increased with increasing inoculum density up to about 50-80 sporangia in per gram dry soil,and then declined.Soil temperature and soil water status were important factors affecting mortality of pepper blight,and the optimum infection temperature of P.capsici was in range from 22 to 28℃,ψm value approached 0,soil water content approached the saturation,as optimum for the infection of the pathogen sporangia,while soil over-saturation and over-dry were unfavorable for infection of pathogen.The relationship among mortality percentage,soil temperature,ψm value and their interactions were described by mathematical function.

  9. Antifungal Effect of Plant Essential Oils on Controlling Phytophthora Species.

    Science.gov (United States)

    Amini, Jahanshir; Farhang, Vahid; Javadi, Taimoor; Nazemi, Javad

    2016-02-01

    In this study, antifungal activity of essential oils of Cymbopogon citratus and Ocimum basilicum and two fungicides Mancozeb and Metalaxyl-Mancozeb in six different concentrations were investigated for controlling three species of Phytophthora, including P. capsici, P. drechsleri and P. melonis on pepper, cucumber and melon under in vitro and greenhouse conditions, respectively. Under the in vitro condition, the median effective concen- tration (EC50) values (ppm) of plant essential oils and fungicides were measured. In greenhouse, soil infested with Phytophthora species was treated by adding 50 ml of essential oils and fungicides (100 ppm). Disease severity was determined after 28 days. Among two tested plant essential oils, C. citratus had the lowest EC50 values for inhibition of the mycelial growth of P. capsici (31.473), P. melonis (33.097) and P. drechsleri (69.112), respectively. The mean EC50 values for Metalaxyl-Mancozeb on these pathogens were 20.87, 20.06 and 17.70, respectively. Chemical analysis of plant essential oils by GC-MS showed that, among 42 compounds identified from C. citratus, two compounds β-geranial (α-citral) (39.16%) and z-citral (30.95%) were the most abundant. Under the greenhouse condition, Metalaxyl-Mancozeb caused the greatest reduction in disease severity, 84.2%, 86.8% and 92.1% on melon, cucumber, and pepper, respectively. The C. citratus essential oil reduced disease severity from 47.4% to 60.5% compared to the untreated control (p≤0.05). Essential oils of O. basilicum had the lowest effects on the pathogens under in vitro and greenhouse conditions. These results show that essential oils may contribute to the development of new antifungal agents to protect the crops from Phytophthora diseases. PMID:26889111

  10. Antifungal Activity of Turkish Propolis Against Phytophthora Species

    OpenAIRE

    Yanar Yusuf; Yanar Durdane; Arslan Servet

    2005-01-01

    The antifungal effects of 10 different concentrations (10, 7, 5, 3, 1, 0.1, 0.07, 0.05, 0.03 and 0.01 �g mL 1) of propolis methanol extract (PME) on Phytophthora infestans, P. capsici and P. parasitica were evaluated in vitro. PME was mixed with steril Corn Meal Agar medium (CMA) at various concentrations. Aceton of 4% and recommended dose of Metalaxyl (1.8 mg a.i. mL 1) were used as control. Mycelial discs (5 mm in diameter), taken from actively growing margin of five-day-old culture of each...

  11. [Morphological and molecular characterization of the antagonistic interaction between the endophyte Diaporthe sp. isolated from frailejón (Espeletia sp.) and the plant pathogen Phytophthora infestans].

    Science.gov (United States)

    Prada, Harold; Avila, Laura; Sierra, Roberto; Bernal, Adriana; Restrepo, Silvia

    2009-09-30

    Endophytic fungi produce a great variety of secondary metabolites both in vivo and in vitro. In this study, we characterized the ability of a sterile-mycelium endophytic fungus isolated from Espeletia sp. to control the growth of Phytophthora infestans in Petri dishes. Sequence from the ITS regions (internal transcribed spacer) of the endophyte showed 94% similarity to Diaporthe phaseolorum's. The antagonistic interaction between Diaporthe sp. and P. infestans was evaluated in three different culture media. Diaporthe sp. showed an antagonistic effect towards P. infestans, with some variation depending on which medium was used. In an attempt to identify possible genes involved in this antagonism, we detected a gene from the endophyte encoding an amylase, which was differentially expressed during this biotic interaction. PMID:19635440

  12. Caracterização de isolados de Phytophthora infestans do Distrito Federal e de Goiás Characterization of Phytophthora infestans isolates from Distrito Federal and Goiás, Brazil

    Directory of Open Access Journals (Sweden)

    Ailton Reis

    2006-06-01

    Full Text Available Foram caracterizados 123 isolados de Phytophthora infestans obtidos de 21 lavouras de tomateiro e oito de batateira, em municípios do Estado de Goiás e Cidades Satélites de Brasília, no período de abril de 2001 a setembro de 2003. Os isolados foram caracterizados para os marcadores grupo de compatibilidade (123 isolados; isoenzima glucose 6-fosfato-isomerase (Gpi (34 isolados e resistência aos fungicidas mefenoxam (77 isolados e metalaxyl (32 isolados de batateira, usando o método de disco de folhas. Todos os 78 isolados de tomateiro foram classificados no grupo de compatibilidade A1, enquanto os 45 de batateira foram do grupo A2. Os fenótipos para Gpi dos isolados de tomateiro (19 e de batateira (15 foram 86/100, típico da linhagem clonal US-1, e 100/100, típico da linhagen clonal BR-1, respectivamente. Quanto à resistência a mefenoxam, constataram-se isolados de tomateiro resistentes (36%, intermediários (48% e sensíveis (16%. A maioria dos isolados de batateira foi classificada como sensível (82% e apenas 9% de intermediários e resistentes. Dos isolados de batateira avaliados para resistência ao metalaxyl, 25% foram resistentes, 62% intermediários e 13% sensíveis. A população de P. infestans no Distrito Federal e no Estado de Goiás é constituída de duas linhagens clonais, com especificidade por hospedeiro.From April 2001 to September 2003, 123 isolates of Phytophthora infestans were collected in 21 tomato and eight potato fields of Distrito Federal (DF and Goiás State (GO, Brazil. Isolates were characterized for mating type (123 isolates, glucose 6-phosphate-isomerase alloenzyme (Gpi (34 isolates, and for resistance to mefenoxam (77 isolates and metalaxyl (32 potato isolates, using the leaf disc method. All the tomato isolates (78 were of the A1 mating type and all the potato isolates (45 were of the A2 mating type. Nineteen tomato and 15 potato isolates were tested for Gpi and were classified as 86/100 phenotype

  13. Caracterização de isolados de Phytophthora infestans do Distrito Federal e de Goiás Characterization of Phytophthora infestans isolates from Distrito Federal and Goiás, Brazil

    OpenAIRE

    Ailton Reis; Fabiana H. S. Ribeiro; EDUARDO S. G. MIZUBUTI

    2006-01-01

    Foram caracterizados 123 isolados de Phytophthora infestans obtidos de 21 lavouras de tomateiro e oito de batateira, em municípios do Estado de Goiás e Cidades Satélites de Brasília, no período de abril de 2001 a setembro de 2003. Os isolados foram caracterizados para os marcadores grupo de compatibilidade (123 isolados); isoenzima glucose 6-fosfato-isomerase (Gpi) (34 isolados) e resistência aos fungicidas mefenoxam (77 isolados) e metalaxyl (32 isolados de batateira), usando o método de dis...

  14. Isolation and characterization of soil Streptomyces species as potential biological control agents against fungal plant pathogens.

    Science.gov (United States)

    Evangelista-Martínez, Zahaed

    2014-05-01

    The use of antagonist microorganisms against fungal plant pathogens is an attractive and ecologically alternative to the use of chemical pesticides. Streptomyces are beneficial soil bacteria and potential candidates for biocontrol agents. This study reports the isolation, characterization and antagonist activity of soil streptomycetes from the Los Petenes Biosphere Reserve, a Natural protected area in Campeche, Mexico. The results showed morphological, physiological and biochemical characterization of six actinomycetes and their inhibitory activity against Curvularia sp., Aspergillus niger, Helminthosporium sp. and Fusarium sp. One isolate, identified as Streptomyces sp. CACIS-1.16CA showed the potential to inhibit additional pathogens as Alternaria sp., Phytophthora capsici, Colletotrichum sp. and Rhizoctonia sp. with percentages ranging from 47 to 90 %. This study identified a streptomycete strain with a broad antagonist activity that could be used for biocontrol of plant pathogenic fungi. PMID:24310522

  15. Phytophthora genomics: the plant destroyers' genome decoded

    NARCIS (Netherlands)

    Govers, F.; Gijzen, M.

    2006-01-01

    The year 2004 was an exciting one for the Phytophthora research community. The United States Department of Energy Joint Genome Institute (JGI) completed the draft genome sequence of two Phytophthora species, Phytophthora sojae and Phytophthora ramorum. In August of that year over 50 people gathered

  16. Evaluation of a Diverse, Worldwide Collection of Wild, Cultivated, and Landrace Pepper (Capsicum annuum) for Resistance to Phytophthora Fruit Rot, Genetic Diversity, and Population Structure.

    Science.gov (United States)

    Naegele, R P; Tomlinson, A J; Hausbeck, M K

    2015-01-01

    Pepper is the third most important solanaceous crop in the United States and fourth most important worldwide. To identify sources of resistance for commercial breeding, 170 pepper genotypes from five continents and 45 countries were evaluated for Phytophthora fruit rot resistance using two isolates of Phytophthora capsici. Genetic diversity and population structure were assessed on a subset of 157 genotypes using 23 polymorphic simple sequence repeats. Partial resistance and isolate-specific interactions were identified in the population at both 3 and 5 days postinoculation (dpi). Plant introductions (PIs) 640833 and 566811 were the most resistant lines evaluated at 5 dpi to isolates 12889 and OP97, with mean lesion areas less than Criollo de Morelos. Genetic diversity was moderate (0.44) in the population. The program STRUCTURE inferred four genetic clusters with moderate to very great differentiation among clusters. Most lines evaluated were susceptible or moderately susceptible at 5 dpi, and no lines evaluated were completely resistant to Phytophthora fruit rot. Significant population structure was detected when pepper varieties were grouped by predefined categories of disease resistance, continent, and country of origin. Moderately resistant or resistant PIs to both isolates of P. capsici at 5 dpi were in genetic clusters one and two. PMID:25054617

  17. Molecular Characterization of Resistant Accessions of Cocoa (Theobroma cocoa L.) to Phytophthora Pod Rot Selected on-Farm in Côte-d’Ivoire.

    Science.gov (United States)

    Cocoa is (Theobroma cacao L.) is a significant agricultural commodity in Côted’Ivoire which ranks 1st in the world cocoa export. Phytophthora pod rot (Ppr)also call Black pod is the most widespread disease of cocoa. Lost due to this disease depends on the species of the pathogen and vary globally fr...

  18. Activity and characterization of secondary metabolites produced by a new microorganism for control of plant diseases.

    Science.gov (United States)

    Ko, Wen-Hsiung; Tsou, Yi-Jung; Lin, Mei-Ju; Chern, Lih-Ling

    2010-09-30

    Microorganisms capable of utilizing vegetable tissues for growth in soils were isolated and their vegetable broth cultures were individually sprayed directly on leaves to test their ability to control Phytophthora blight of bell pepper caused by Phytophthora capsici. Liquid culture of Streptomyces strain TKA-5, a previously undescribed species obtained in this study, displayed several desirable disease control characteristics in nature, including high potency, long lasting and ability to control also black leaf spot of spoon cabbage caused by Alternaria brassicicolca. The extract was fungicidal to P. capsici but fungistatic to A. brassicicola. It was stable at high temperature and high pH. However, after exposure to pH 2 for 24h, the extract was no longer inhibitory to P. capsici although it was still strongly inhibitory to A. brassicicola. After treatment with cation or anion exchange resins, the extract lost its inhibitory effect against P. capsici but not A. brassicicola. The results suggest that the extract contained two different kinds of inhibitory metabolites, one against P. capsici with both positive and negative charges on its molecule and another against A. brassicicola with no charges on its molecule. The inhibitory metabolites were soluble in ethanol or methanol but not in water, ether or chloroform. They were dialyzable in the membrane tubing with molecular weight cut-off of 10,000, 1000 or 500 but not 100, indicating that the inhibitors have a molecular weight between 500 and 100. Results also showed that both inhibitors are not proteins. PMID:20580869

  19. Isolation and Characterization of a Novel Pathogenesis-Related Protein Gene (GmPRP) with Induced Expression in Soybean (Glycine max) during Infection with Phytophthora sojae

    OpenAIRE

    Jiang, Liangyu; Wu, Junjiang; Fan, Sujie; Li, Wenbin; Dong, Lidong; Cheng, Qun; Xu, Pengfei; Zhang, Shuzhen

    2015-01-01

    Pathogenesis-related proteins (PR proteins) play crucial roles in the plant defense system. A novel PRP gene was isolated from highly resistant soybean infected with Phytophthora sojae (P. sojae) and was named GmPRP (GenBank accession number: KM506762). The amino acid sequences of GmPRP showed identities of 74%, 73%, 72% and 69% with PRP proteins from Vitis vinifera, Populus trichocarpa, Citrus sinensis and Theobroma cacao, respectively. Quantitative real-time reverse transcription PCR (qRT-P...

  20. Characterization and efficacy of bacterial strains for biological control of soil-borne diseases caused by Phytophthora cactorum and Meloidogyne javanica on Rosaceous plants

    OpenAIRE

    Agustí Alcals, Lourdes

    2008-01-01

    S'avaluaren 58 soques de Pseudomonas fluorescens i Pantoea agglomerans per la seva eficàcia en el biocontrol de la malaltia causada per l'oomicet Phytophthora cactorum en maduixera i pel nematode formador de gal·les Meloidogyne javanica en el portaempelt GF-677.Es desenvolupà un mètode ex vivo d'inoculació de fulla amb l'objectiu de seleccionar soques bacterianes com a agents de control biològic de P. cactorum en maduixera. Tres soques de P. fluorescens es seleccionaren com a soques eficaces ...

  1. Zoospore interspecific signaling promotes plant infection by Phytophthora

    Directory of Open Access Journals (Sweden)

    Zhou Zhaohui S

    2010-12-01

    Full Text Available Abstract Background Oomycetes attack a huge variety of economically and ecologically important plants. These pathogens release, detect and respond to signal molecules to coordinate their communal behaviors including the infection process. When signal molecules are present at or above threshold level, single zoospores can infect plants. However, at the beginning of a growing season population densities of individual species are likely below those required to reach a quorum and produce threshold levels of signal molecules to trigger infection. It is unclear whether these molecules are shared among related species and what their chemistries are. Results Zoospore-free fluids (ZFF from Phytophthora capsici, P. hydropathica, P. nicotianae (ZFFnic, P. sojae (ZFFsoj and Pythium aphanidermatum were cross tested for stimulating plant infection in three pathosystems. All ZFFs tested significantly increased infection of Catharanthus roseus by P. nicotianae. Similar cross activities were observed in infection of Lupinus polyphyllus and Glycine max by P. sojae. Only ZFFnic and ZFFsoj cross induced zoospore aggregation at a density of 2 × 103 ml-1. Pure autoinducer-2 (AI-2, a component in ZFF, caused zoospore lysis of P. nicotianae before encystment and did not stimulate plant infection at concentrations from 0.01 to 1000 μM. P. capsici transformants with a transiently silenced AI-2 synthase gene, ribose phosphate isomerase (RPI, infected Capsicum annuum seedlings at the same inoculum concentration as the wild type. Acyl-homoserine lactones (AHLs were not detected in any ZFFs. After freeze-thaw treatments, ZFF remained active in promoting plant infection but not zoospore aggregation. Heat treatment by boiling for 5 min also did not affect the infection-stimulating property of ZFFnic. Conclusion Oomycetes produce and use different molecules to regulate zoospore aggregation and plant infection. We found that some of these signal molecules could act in an inter

  2. Enxertia em plantas de pimentão no controle da murcha de fitóftora em ambiente protegido Sweet pepper grafting to control phytophthora blight under protected cultivation

    OpenAIRE

    Haydée S. Santos; Rumy Goto

    2004-01-01

    Avaliou-se a viabilidade de utilização da enxertia em plantas de pimentão (Capsicum annuum, L.), visando o controle da murcha de fitóftora. A pesquisa foi conduzida de setembro de 2000 a julho de 2001, na UNESP, Botucatu, em ambiente protegido. Adotou-se o delineamento experimental de blocos ao acaso, com 4 repetições e 5 plantas por parcela. Foram utilizados dois porta-enxertos resistentes a Phytophthora capsici, híbridos F1 de Capsicum annuum, e três híbridos comerciais suscetíveis (Elisa, ...

  3. Citrus phytophthora diseases: Management challenges and successes

    OpenAIRE

    Graham, J; Feichtenberger, E.

    2015-01-01

    Phytophthora spp. are present in nearly all citrus groves in Florida and Brazil and phytophthora-induced diseases, especially foot and root rot, have the potential to cause economically important crop losses. Disease-related losses due to root rot are difficult to estimate because fibrous root damage and yield loss are not always directly proportional. Challenges from phytophthora diseases have been addressed in both countries by enacting phytosanitary requirements for production of pathogen-...

  4. A Phytophthora sojae effector PsCRN63 forms homo-/hetero-dimers to suppress plant immunity via an inverted association manner.

    Science.gov (United States)

    Li, Qi; Zhang, Meixiang; Shen, Danyu; Liu, Tingli; Chen, Yanyu; Zhou, Jian-Min; Dou, Daolong

    2016-01-01

    Oomycete pathogens produce a large number of effectors to promote infection. Their mode of action are largely unknown. Here we show that a Phytophthora sojae effector, PsCRN63, suppresses flg22-induced expression of FRK1 gene, a molecular marker in pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI). However, PsCRN63 does not suppress upstream signaling events including flg22-induced MAPK activation and BIK1 phosphorylation, indicating that it acts downstream of MAPK cascades. The PsCRN63-transgenic Arabidopsis plants showed increased susceptibility to bacterial pathogen Pseudomonas syringae pathovar tomato (Pst) DC3000 and oomycete pathogen Phytophthora capsici. The callose deposition were suppressed in PsCRN63-transgenic plants compared with the wild-type control plants. Genes involved in PTI were also down-regulated in PsCRN63-transgenic plants. Interestingly, we found that PsCRN63 forms an dimer that is mediated by inter-molecular interactions between N-terminal and C-terminal domains in an inverted association manner. Furthermore, the N-terminal and C-terminal domains required for the dimerization are widely conserved among CRN effectors, suggesting that homo-/hetero-dimerization of Phytophthora CRN effectors is required to exert biological functions. Indeed, the dimerization was required for PTI suppression and cell death-induction activities of PsCRN63. PMID:27243217

  5. Lysobacter capsici AZ78 can be combined with copper to effectively control Plasmopara viticola on grapevine.

    Science.gov (United States)

    Puopolo, Gerardo; Giovannini, Oscar; Pertot, Ilaria

    2014-01-01

    The bacterial genus Lysobacter represents a still underdeveloped source of biocontrol agents able to protect plants against pathogenic oomycetes. In this work the L. capsici strain AZ78 was evaluated with regard to the biological control of Plasmopara viticola, the causal agent of grapevine downy mildew. L. capsici AZ78 is able to resist copper ions and its resistance to this metal is probably due to the presence of genes coding for copper oxidase (copA) and copper exporting PIB-type ATPases (ctpA). The presence of both genes was also detected in other members of the Lysobacter genus. Resistance to copper allowed L. capsici AZ78 to be combined with a low-dose of a copper-based fungicide, leading to more effective control of grapevine downy mildew. Notably, prophylactic application of L. capsici AZ78 alone to grapevine leaves reduced downy mildew disease to the same degree as a copper-based fungicide. Furthermore, L. capsici AZ78 persists in the phyllosphere of grapevine plants and tolerates environmental stresses such as starvation, freezing, mild heat shock and UV light irradiation. These traits suggest that L. capsici AZ78 could be a suitable candidate for developing a new biofungicide to be used in combination with copper to control grapevine downy mildew. PMID:24140153

  6. Uso de marcadores RAPD na classificação de isolados de Phytophthora spp. causadores da podridão parda do cacaueiro no Brasil

    Directory of Open Access Journals (Sweden)

    Faleiro Fábio G.

    2003-01-01

    Full Text Available Objetivou-se neste trabalho propor uma metodologia para a utilização de marcadores RAPD como uma ferramenta auxiliar na classificação de isolados de Phytophthora spp. causadores da podridão-parda do cacaueiro (Theobroma cacao no Brasil. Existe uma necessidade constante de monitorar populações de Phytophthora spp. nas regiões cacaueiras do Brasil e a tarefa de classificação dos isolados é difícil e demorada. Com base em estudos de diversidade genética de isolados de Phytophthora capsici, P. palmivora e P. citrophthora por meio de marcadores RAPD, foram escolhidos três isolados de cada espécie como padrões e dois "primers" decâmeros mais informativos na diferenciação das espécies (OPA 13 e OPH 18. O DNA genômico dos isolados padrões e de três isolados não classificados foi extraído e amplificado, utilizando-se os dois "primers" decâmeros mais informativos. Os padrões de marcadores RAPD obtidos permitiram uma diferenciação visual clara dos isolados de cada espécie e mostraram-se úteis na classificação de isolados de Phytophthora spp. A metodologia proposta já está sendo utilizada no Centro de Pesquisas do Cacau, solucionando eventuais dúvidas resultantes da caracterização morfológica dos isolados.

  7. Phytophthora Database: A forensic database supporting the identification and monitoring of Phytophthora

    Science.gov (United States)

    Due to their high virulence and ability to spread rapidly, Phytophthora species represent a serious threat to agricultural production and ecological systems. Many novel Phytophthora species have been reported in recent years, indicative of our limited understanding of the ecology and diversity of Ph...

  8. Phytophthora infestans population structure: A worldwide scale

    International Nuclear Information System (INIS)

    Phytophthora infestans, the causal agent of late blight disease in potato and other members of the Solanaceae family, is responsible for causing the Irish potato famine and, even today, it causes enormous economic losses all over the world. For the establishment of an adequate pest management strategy, the determination of the pathogen's population structure is required. To characterize P. infestans populations worldwide two allozymes, Gpi (Glucose-6-phospate isomerase) and Pep (Pep tidase), the RG57 DNA RFLP fingerprinting probe, as well as resistance to the fungicide metalaxyl and mating type, have been used as markers. P. infestans populations in Mexico have been one of the main focuses of research in the population biology of this pathogen because this country has been considered as one of the possible centers of origin of this oomycete. In this review we present the population structure of P. infestans in Mexico, Europe, Africa, Asia, North America, and South America, expanding it on the present situation of P. infestans in Colombia. Finally, we will discuss different lines of research that are being carried out today with respect to P. infestans in Colombia, which have shown the importance of continuing the study of this devastating plant pathogen in our country.

  9. Phytophthora infestans population structure: a worldwide scale

    Directory of Open Access Journals (Sweden)

    Cárdenas Toquica Martha

    2012-08-01

    Full Text Available Phytophthora infestans, the causal agent of late blight disease in potato and other members of the Solanaceae family, is responsible for causing the Irish potato famine and, even today, it causes enormous economic losses all over the world. For the establishment of an adequate pest management strategy, the determination of population structure is required. To characterize P. infestans populations worldwide two allozymes, Gpi (Glucose-6-phospate isomerase and Pep (Peptidase, the RG57 DNA RFLP fingerprinting probe, as well as resistance to the fungicide metalaxyl and the mating type, have been used as markers. P. infestans populations in Mexico have been one of the main focuses of research in the population biology of this pathogen because this country has been considered as one of the possible centers of origin of this oomycete. In this review we present the population structure of P. infestans in Mexico, Europe, Africa, Asia, North America, and South America expanding on the present situation of P. infestans in Colombia. Finally, we will discuss different lines of research that are being carried out today with respect to P. infestans in Colombia, which have shown the importance of continuing the study of this devastating plant pathogen in our country.

  10. A species-specific polymerase chain reaction assay for rapid and sensitive detection of Colletotrichum capsici.

    Science.gov (United States)

    Torres-Calzada, C; Tapia-Tussell, R; Quijano-Ramayo, A; Martin-Mex, R; Rojas-Herrera, R; Higuera-Ciapara, I; Perez-Brito, D

    2011-09-01

    Colletotrichum capsici is an important fungal species that causes anthracnose in many genera of plants causing severe economic losses worldwide. A primer set was designed based on the sequences of the ribosomal internal transcribed spacer (ITS1 and ITS2) regions for use in a conventional PCR assay. The primer set (CcapF/CcapR) amplified a single product of 394 bp with DNA extracted from 20 Mexican isolates of C. capsici. The specificity of primers was confirmed by the absence of amplified product with DNA of four other Colletotrichum species and eleven different fungal genera. This primer set is capable of amplifying only C. capsici from different contaminated tissues or fungal structures, thereby facilitating rapid diagnoses as there is no need to isolate and cultivate the fungus in order to identify it. The sensitivity of detection with this PCR method was 10 pg of genomic DNA from the pathogen. This is the first report of a C. capsici-specific primer set. It allows rapid pathogen detection and provides growers with a powerful tool for a rational selection of fungicides to control anthracnose in different crops and in the post-harvest stage. PMID:21253896

  11. Species from within the Phytophthora cryptogea complex and related species, P. erythroseptica and P. sansomeana, readily hybridize.

    Science.gov (United States)

    Safaiefarahani, Banafsheh; Mostowfizadeh-Ghalamfarsa, Reza; Hardy, Giles E St J; Burgess, Treena I

    2016-08-01

    During a study on the phylogenetic relationships between species in the Phytophthora cryptogea complex and related species, Phytophthora erythroseptica and Phytophthora sansomeana, 19 hybrid isolates with multiple polymorphisms in the nuclear sequences were observed. Molecular characterization of hybrids was achieved by sequencing three nuclear (internal transcribed spacers, β-tubulin (TUB), heat shock protein 90) and two mitochondrial (cytochrome c oxidase subunit I (coxI), NADH dehydrogenase subunit I (NADH)) gene regions and cloning of the single-copy nuclear gene, TUB. Based on the molecular studies the hybrid isolates belonged to six distinct groups between P. cryptogea, P. erythroseptica, Phytophthora pseudocryptogea, P. sansomeana, and Phytophthora sp. kelmania. In all cases, only a single coxI and NADH allele was detected and nuclear genes were biparentally inherited, suggesting that the hybrids arose from sexual recombination events. Colony morphology, growth rate, cardinal temperatures, breeding system, and morphology of sporangia, oogonia, oospores, and antheridia were also determined. Some morphological differences between the hybrids and the parental species were noted; however, they were not sufficient to reliably distinguish the taxa and DNA markers from nuclear and mitochondrial genes will to be necessary for their identification. The parental species are all important pathogens of agricultural fields that have been transported globally. With the apparent ease of hybridization within this group there is ample opportunity for virulent hybrids to form, perhaps with extended host ranges. PMID:27521629

  12. Sporulation on plant roots by Phytophthora ramorum

    Science.gov (United States)

    Phytophthora ramorum has been shown to infect the roots of many of the pathogen’s foliar hosts. Methods of detecting inoculum in runoff and of quantifying root colonization were tested using Viburnum tinus, Camellia oleifera, Quercus prinus, Umbellularia californica, and Epilobium ciliatum. Plants...

  13. Overexpression of a Phytophthora Cytoplasmic CRN Effector Confers Resistance to Disease, Salinity and Drought in Nicotiana benthamiana.

    Science.gov (United States)

    Rajput, Nasir Ahmed; Zhang, Meixiang; Shen, Danyu; Liu, Tingli; Zhang, Qimeng; Ru, Yanyan; Sun, Peng; Dou, Daolong

    2015-12-01

    The Crinkler (CRN) effector family is produced by oomycete pathogens and may manipulate host physiological and biochemical events inside host cells. Here, PsCRN161 was identified from Phytophthora sojae based on its broad and strong cell death suppression activities. The effector protein contains two predicted nuclear localization signals and localized to nuclei of plant cells, indicating that it may target plant nuclei to modify host cell physiology and function. The chimeric gene GFP:PsCRN161 driven by the Cauliflower mosaic virus (CaMV) 35S promoter was introduced into Nicotiana benthamiana. The four independent PsCRN161-transgenic lines exhibited increased resistance to two oomycete pathogens (P. parasitica and P. capsici) and showed enhanced tolerance to salinity and drought stresses. Digital gene expression profiling analysis showed that defense-related genes, including ABC transporters, Cyt P450 and receptor-like kinases (RLKs), were significantly up-regulated in PsCRN161-transgenic plants compared with GFP (green fluorescent protein) lines, implying that PsCRN161 expression may protect plants from biotic and abiotic stresses by up-regulation of many defense-related genes. The results reveal previously unknown functions of the oomycete effectors, suggesting that the pathogen effectors could be directly used as functional genes for plant molecular breeding for enhancement of tolerance to biotic and abiotic stresses. PMID:26546319

  14. Phytophthora Genome Sequences Uncover Evolutionary Origins and Mechanisms of Pathogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Tyler, Brett M.; Tripathy, Sucheta; Zhang, Xuemin; Dehal, Paramvir; Jiang, Rays H. Y.; Aerts, Andrea; Arredondo, Felipe D.; Baxter, Laura; Bensasson, Douda; Beynon, JIm L.; Chapman, Jarrod; Damasceno, Cynthia M. B.; Dorrance, Anne E.; Dou, Daolong; Dickerman, Allan W.; Dubchak, Inna L.; Garbelotto, Matteo; Gijzen, Mark; Gordon, Stuart G.; Govers, Francine; Grunwald, NIklaus J.; Huang, Wayne; Ivors, Kelly L.; Jones, Richard W.; Kamoun, Sophien; Krampis, Konstantinos; Lamour, Kurt H.; Lee, Mi-Kyung; McDonald, W. Hayes; Medina, Monica; Meijer, Harold J. G.; Nordberg, Erik K.; Maclean, Donald J.; Ospina-Giraldo, Manuel D.; Morris, Paul F.; Phuntumart, Vipaporn; Putnam, Nicholas J.; Rash, Sam; Rose, Jocelyn K. C.; Sakihama, Yasuko; Salamov, Asaf A.; Savidor, Alon; Scheuring, Chantel F.; Smith, Brian M.; Sobral, Bruno W. S.; Terry, Astrid; Torto-Alalibo, Trudy A.; Win, Joe; Xu, Zhanyou; Zhang, Hongbin; Grigoriev, Igor V.; Rokhsar, Daniel S.; Boore, Jeffrey L.

    2006-04-17

    Draft genome sequences have been determined for the soybean pathogen Phytophthora sojae and the sudden oak death pathogen Phytophthora ramorum. Oömycetes such as these Phytophthora species share the kingdom Stramenopila with photosynthetic algae such as diatoms, and the presence of many Phytophthora genes of probable phototroph origin supports a photosynthetic ancestry for the stramenopiles. Comparison of the two species' genomes reveals a rapid expansion and diversification of many protein families associated with plant infection such as hydrolases, ABC transporters, protein toxins, proteinase inhibitors, and, in particular, a superfamily of 700 proteins with similarity to known oömycete avirulence genes.

  15. Susceptibility of common alder (Alnus glutinosa) seeds and seedlings to Phytophthora alni and other Phytophthora species

    Energy Technology Data Exchange (ETDEWEB)

    Haque, M. M.; Diez, J. J.

    2012-11-01

    Phytophthora alni is a highly destructive host specific pathogen to alders (Alnus spp.) spreading all over Europe. Recently this pathogen has been reported to cause diseases in common alder (Alnus glutinosa) in Spain. Seeds and seedlings of A. glutinosa were tested in vitro for their susceptibility to alder Phytophthora and other Phytophthora species. Isolates of P. alni ssp. alni, P. cinnamomi, P. citrophthora, P. nicotianae and P. palmivora were used in the experiments. Seeds and seedlings were inoculated with a zoospore suspension and uniform mycelial blocks of agar of the Phytophthora species. Susceptibility was calculated in terms of pathogen virulence on seed germination and seedling mortality 42 and 67 days after inoculation respectively. Seed germination and seedling mortality rates varied differently among the isolates used. Results implied that common alder and its seeds and seedlings are at risk to be infected by P. alni. In addition, other Phytophthora species are able to infect this kind of material showing their relative host non-specificity. This is one important finding concerning alder regeneration in infected areas, and the possibility of disease spread on this plant material. (Author) 42 refs.

  16. Overexpression of Soybean Isoflavone Reductase (GmIFR) Enhances Resistance to Phytophthora sojae in Soybean

    OpenAIRE

    Cheng, Qun; Li, Ninghui; Dong, Lidong; Zhang, Dayong; Fan, Sujie; Jiang, Liangyu; Wang, Xin; Xu, Pengfei; Zhang, Shuzhen

    2015-01-01

    Isoflavone reductase (IFR) is an enzyme involved in the biosynthetic pathway of isoflavonoid phytoalexin in plants. IFRs are unique to the plant kingdom and are considered to have crucial roles in plant response to various biotic and abiotic environmental stresses. Here, we report the characterization of a novel member of the soybean isoflavone reductase gene family GmIFR. Overexpression of GmIFR transgenic soybean exhibited enhanced resistance to Phytophthora sojae. Following stress treatmen...

  17. Phytophthora sojae Effector PsCRN70 Suppresses Plant Defenses in Nicotiana benthamiana

    OpenAIRE

    Rajput, Nasir Ahmed; Zhang, Meixiang; Ru, Yanyan; Liu, Tingli; Xu, Jing; Li LIU; Mafurah, Joseph Juma; Dou, Daolong

    2014-01-01

    Phytophthora sojae, an oomycete pathogen, produces a large number of effector proteins that enter into host cells. The Crinklers (Crinkling and Necrosis, CRN) are cytoplasmic effectors that are conserved in oomycete pathogens and their encoding genes are highly expressed at the infective stages in P. sojae. However, their roles in pathogenesis are largely unknown. Here, we functionally characterized an effector PsCRN70 by transiently and stably overexpressing it in Nicotiana benthamiana. We d...

  18. Genes for and molecular markers linked with resistance to Phytophthora fragariae in strawberry

    OpenAIRE

    Weg, van de, W.E.; Henken, B.; Haymes, K M; den Nijs, A.P.M.

    1998-01-01

    A gene-for-gene model is presented which explains interactions between cultivars of strawberry and races of Phytophthora fragariae var. fragariae, the causal agent of red core (red stele) root rot. The model allows the constitution of a universal differential set of strawberry genotypes and the characterizing of fungal isolates into races, the genotyping of strawberry cultivars and selections in a breeding programme, and facilitates the search for linked molecular markers for more efficient s...

  19. Screening of strawberry resistance to Phytophthora cactorum

    OpenAIRE

    Parikka, Päivi

    2007-01-01

    Crown rot of strawberry, Phytophthora cactorum, has been a problem in Finnish strawberry production since 1990. Susceptible cultivars can suffer from severe plant losses without fungicide treatment. Resistance of cultivars to crown rot has been tested in Finland since 1993. The method used during the first years was the crown test where mycelium of P. cactorum is placed in a small wound in the crowns of strawberry plants. Zoospores are now used in the NFT system to inoculate small plants. The...

  20. Phytophthora parasitica: a model oomycete plant pathogen

    OpenAIRE

    Meng, Yuling; Qiang ZHANG; Ding, Wei; Shan, Weixing

    2014-01-01

    Oomycetes are eukaryotic microorganisms morphologically similar to but phylogenetically distant from true fungi. Most species in the genus Phytophthora of oomycetes are devastating plant pathogens, causing damages to both agricultural production and natural ecosystems. Tremendous progress has been achieved in recent years in diversity, evolution and lifestyles of oomycete plant pathogens, as well as on the understanding of genetic and molecular basis of oomycete-plant interactions. Phytophtho...

  1. Comparing New Zealand and United Kingdom isolates of Phytophthora kernoviae

    Science.gov (United States)

    Phytophthora kernoviae was discovered in the United Kingdom in 2003, and identified as a new species in 2005. Recent DNA sequence studies identified two unknown Phytophthora isolates collected in the 1950s and 2002 in New Zealand as P. kernoviae. The purpose of this study was to compare two isolat...

  2. Phytophthora rotråte i juletrefelt

    DEFF Research Database (Denmark)

    Talgø, Venche; Thomsen, Iben Margrete

    2015-01-01

    Phytophthora rotråte forårsaket av ulike arter av Phytophthora er et stort problem i juletreproduksjonen iUSA. I Norge er det også rapportert om flere tilfeller av skade på grunn av Phytophthora både i juletrær og klippegrønt, men så langt ikke i Danmark. I begge landene er flere arter av...... Phytophthora funnet på treaktige vekster i grøntanlegg. Vi har også sett en urovekkende spredning av Phytophthora til løvtrær i bynære skoger, vassdrag og naturområder det siste tiåret, spesielt i Norge. Både i Norge og Danmark har vi undersøkt vann i eller like ved juletreplantinger og funnet flere...

  3. Phytophthora infestans POPULATION STRUCTURE: A WORLDWIDE SCALE Estructura poblacional de Phytophthora infestans: una escala global

    Directory of Open Access Journals (Sweden)

    MARTHA CÁRDENAS

    2012-05-01

    Full Text Available Phytophthora infestans, the causal agent of late blight disease in potato and other members of the Solanaceae family, is responsible for causing the Irish potato famine and, even today, it causes enormous economic losses all over the world. For the establishment of an adequate pest management strategy, the determination of the pathogen's population structure is required. To characterize P. infestans populations worldwide two allozymes, Gpi (Glucose-6-phospate isomerase and Pep ( Pep tidase, the RG57 DNA RFLP fingerprinting probe, as well as resistance to the fungicide metalaxyl and mating type, have been used as markers. P. infestans populations in Mexico have been one of the main focuses of research in the population biology of this pathogen because this country has been considered as one of the possible centers of origin of this oomycete. In this review we present the population structure of P. infestans in Mexico, Europe, Africa, Asia, North America, and South America, expanding it on the present situation of P. infestans in Colombia. Finally, we will discuss different lines of research that are being carried out today with respect to P. infestans in Colombia, which have shown the importance of continuing the study of this devastating plant pathogen in our country.Phytophthora infestans, el agente causal del tizón tardío de la papa y otros miembros de la familia de las Solanáceas, es el responsable de la gran hambruna irlandesa y aún hoy sigue causando grandes pérdidas económicas alrededor del planeta. Para establecer estrategias de control adecuadas contra este patógeno se requiere comprender la estructura poblacional del mismo. Mundialmente se han utilizado como marcadores las aloenzimas, Gpi (Glucosa-6-fosfato isomerasa y Pep (Peptidasa y la sonda de fingerprinting de RFLP (Polimorfismos de la Longitud de los Fragmentos de Restricción, RG57. De igual forma, la resistencia al fungicida metalaxyl y el tipo de apareamiento, han sido

  4. Phytophthora parasitica transcriptome, a new concept in the understanding of the citrus gummosis

    Directory of Open Access Journals (Sweden)

    Daniel D. Rosa

    2007-01-01

    Full Text Available Due to the economic importance of gummosis disease for the citriculture, studies on P. parasitica-Citrus interaction comprise a significant part in the Brazilian Citrus genome data bank (CitEST. Among them, two cDNA libraries constructed from two different growth conditions of the P. parasitica pathogen are included which has generated the PP/CitEST database (CitEST - Center APTA Citros Sylvio Moreira/IAC- Millennium Institute. Through this genomic approach and clustering analyses the following has been observed: out of a total of 13,285 available in the Phytophthora parasitica database, a group of 4,567 clusters was formed, comprising 2,649 singlets and 1,918 contigs. Out of a total of 4,567 possible genes, only 2,651 clusters were categorized; among them, only 4.3% shared sequence similarities with pathogenicity factors and defense. Some of these possible genes (103 corresponding to 421 ESTs, were characterized by phylogenetic analysis and discussed. A comparison made with the COGEME database has shown homology which may be part of an evolutionary pathogenicity pathway present in Phytophthora and also in other fungi. Many of the genes which were identified here, which may encode proteins associated to mechanisms of citrus gummosis pathogenicity, represent only one facet of the pathogen-host Phytophthora - Citrus interaction.

  5. A Phytophthora infestans Cystatin-Like Protein Targets a Novel Tomato Papain-Like Apoplastic Protease1[W][OA

    Science.gov (United States)

    Tian, Miaoying; Win, Joe; Song, Jing; van der Hoorn, Renier; van der Knaap, Esther; Kamoun, Sophien

    2007-01-01

    There is emerging evidence that the proteolytic machinery of plants plays important roles in defense against pathogens. The oomycete pathogen Phytophthora infestans, the agent of the devastating late blight disease of tomato (Lycopersicon esculentum) and potato (Solanum tuberosum), has evolved an arsenal of protease inhibitors to overcome the action of host proteases. Previously, we described a family of 14 Kazal-like extracellular serine protease inhibitors from P. infestans. Among these, EPI1 and EPI10 bind and inhibit the pathogenesis-related (PR) P69B subtilisin-like serine protease of tomato. Here, we describe EPIC1 to EPIC4, a new family of P. infestans secreted proteins with similarity to cystatin-like protease inhibitor domains. Among these, the epiC1 and epiC2 genes lacked orthologs in Phytophthora sojae and Phytophthora ramorum, were relatively fast-evolving within P. infestans, and were up-regulated during infection of tomato, suggesting a role during P. infestans-host interactions. Biochemical functional analyses revealed that EPIC2B interacts with and inhibits a novel papain-like extracellular cysteine protease, termed Phytophthora Inhibited Protease 1 (PIP1). Characterization of PIP1 revealed that it is a PR protein closely related to Rcr3, a tomato apoplastic cysteine protease that functions in fungal resistance. Altogether, this and earlier studies suggest that interplay between host proteases of diverse catalytic families and pathogen inhibitors is a general defense-counterdefense process in plant-pathogen interactions. PMID:17085509

  6. The Lysobacter capsici AZ78 Genome Has a Gene Pool Enabling it to Interact Successfully with Phytopathogenic Microorganisms and Environmental Factors.

    Science.gov (United States)

    Puopolo, Gerardo; Tomada, Selena; Sonego, Paolo; Moretto, Marco; Engelen, Kristof; Perazzolli, Michele; Pertot, Ilaria

    2016-01-01

    Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC 33913. Whole genome comparison, supported by functional analysis, indicated that L. capsici AZ78 has a larger number of genes responsible for interaction with phytopathogens and environmental stress than S. malthophilia K729a and X. c. pv. campestris ATCC 33913. Genes involved in the production of antibiotics, lytic enzymes and siderophores were specific for L. capsici AZ78, as well as genes involved in resistance to antibiotics, environmental stressors, fungicides and heavy metals. The L. capsici AZ78 genome did not encompass genes involved in infection of humans and plants included in the S. malthophilia K729a and X. c. pv. campestris ATCC 33913 genomes, respectively. The L. capsici AZ78 genome provides a genetic framework for detailed analysis of other L. capsici members and the development of novel biofungicides based on this bacterial strain. PMID:26903975

  7. The Lysobacter capsici AZ78 genome has a gene pool enabling it to interact successfully with phytopathogenic microorganisms and environmental factors

    Directory of Open Access Journals (Sweden)

    Gerardo ePuopolo

    2016-02-01

    Full Text Available Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC 33913. Whole genome comparison, supported by functional analysis, indicated that L. capsici AZ78 has a larger number of genes responsible for interaction with phytopathogens and environmental stress than S. malthophilia K729a and X. c. pv. campestris ATCC 33913. Genes involved in the production of antibiotics, lytic enzymes and siderophores were specific for L. capsici AZ78, as well as genes involved in resistance to antibiotics, environmental stressors, fungicides and heavy metals. The L. capsici AZ78 genome did not encompass genes involved in infection of humans and plants included in the S. malthophilia K729a and X. c. pv. campestris ATCC 33913 genomes respectively. The L. capsici AZ78 genome provides a genetic framework for detailed analysis of other L. capsici members and the development of novel biofungicides based on this bacterial strain.

  8. Phytophthora species, new pathogens in landscape and gardens

    OpenAIRE

    Leszek B. Orlikowski; Ptaszek, Magdalena; Orlikowska, Teresa; Trzewik, Aleksandra

    2010-01-01

    The open of Polish borders on Western Europe in 1990 caused the very fast increase of ornamental plants import, especially seedlings or young cuttings. During the twenty years Phytophthora alni, P. cambivora, P. cinnamomi, P. citricola, P. citrophthora, P. nicotianae var. nicotianae and P. ramorum were found on diseased plants in hardy ornamental nursery stocks. Among them ericaceous and coniferous plants were attacked the most often. Since 2005 Phytophthora root and stem rot was also observe...

  9. Phytophthora Species, New Threats to the Plant Health in Korea

    Directory of Open Access Journals (Sweden)

    Ik-Hwa Hyun

    2014-12-01

    Full Text Available Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries into Korea from 1900 to 2010. The genus Phytophthora, classified in oomycetes, includes more than 120 species that are mostly recognized worldwide as highly invasive plant pathogens. After 2000, over 50 new species of Phytophthora were identified internationally as plant pathogens occurring in crops and forest trees. In Korea, Phytophthora is also one of the most serious plant pathogens. To date, 22 species (about one-fifth of known species of the genus have been identified and reported as plant pathogens in the country. The likelihood of new exotic Phytophthora species being introduced into Korea continues to increase, thus necessitating intensive plant quarantine inspections. As new potential threats to plant health in Korea, six Phytophthora species, namely, P. alni, P. inundata, P. kernoviae, P. pinifolia, P. quercina, and P. ramorum, are discussed in this review with focus on history, disease, biology, management, and plant quarantine issues.

  10. Biosynthesis of Antibiotic Leucinostatins in Bio-control Fungus Purpureocillium lilacinum and Their Inhibition on Phytophthora Revealed by Genome Mining

    Science.gov (United States)

    Li, Erfeng; Mao, Zhenchuan; Ling, Jian; Yang, Yuhong; Yin, Wen-Bing; Xie, Bingyan

    2016-01-01

    Purpureocillium lilacinum of Ophiocordycipitaceae is one of the most promising and commercialized agents for controlling plant parasitic nematodes, as well as other insects and plant pathogens. However, how the fungus functions at the molecular level remains unknown. Here, we sequenced two isolates (PLBJ-1 and PLFJ-1) of P. lilacinum from different places Beijing and Fujian. Genomic analysis showed high synteny of the two isolates, and the phylogenetic analysis indicated they were most related to the insect pathogen Tolypocladium inflatum. A comparison with other species revealed that this fungus was enriched in carbohydrate-active enzymes (CAZymes), proteases and pathogenesis related genes. Whole genome search revealed a rich repertoire of secondary metabolites (SMs) encoding genes. The non-ribosomal peptide synthetase LcsA, which is comprised of ten C-A-PCP modules, was identified as the core biosynthetic gene of lipopeptide leucinostatins, which was specific to P. lilacinum and T. ophioglossoides, as confirmed by phylogenetic analysis. Furthermore, gene expression level was analyzed when PLBJ-1 was grown in leucinostatin-inducing and non-inducing medium, and 20 genes involved in the biosynthesis of leucionostatins were identified. Disruption mutants allowed us to propose a putative biosynthetic pathway of leucinostatin A. Moreover, overexpression of the transcription factor lcsF increased the production (1.5-fold) of leucinostatins A and B compared to wild type. Bioassays explored a new bioactivity of leucinostatins and P. lilacinum: inhibiting the growth of Phytophthora infestans and P. capsici. These results contribute to our understanding of the biosynthetic mechanism of leucinostatins and may allow us to utilize P. lilacinum better as bio-control agent. PMID:27416025

  11. Comparing necrosis of Rhododendron leaf tissue inoculated with Phytophthora ramorum sporangia or zoospores

    Science.gov (United States)

    Phytophthora species produce sporangia that either germinate directly or release zoospores depending upon environmental conditions. Phytophthora ramorum is no exception producing abundant sporangia that are disseminated by wind and rain. Past research involving inoculation trials or screening host...

  12. Endophytic Trichoderma isolates from tropical environments delay disease onset and induce resistance against Phytophthora capsici in hot pepper using multiple mechanisms

    Science.gov (United States)

    Isolates of several Trichoderma spp., were collected from tropical environments as potential biocontrol agents for cacao (Theobroma cacao) diseases. The diversity of isolates collected, including new species, and there endophytic nature on their host plants, led us to consider if these isolates have...

  13. The Lysobacter capsici AZ78 Genome Has a Gene Pool Enabling it to Interact Successfully with Phytopathogenic Microorganisms and Environmental Factors

    OpenAIRE

    Puopolo, Gerardo; Tomada, Selena; Sonego, Paolo; Moretto, Marco; Engelen, Kristof; Perazzolli, Michele; Pertot, Ilaria

    2016-01-01

    Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC ...

  14. Penggunaan Jamur Endofit Dari Terong Belanda (Solanum betacea) untuk Mengendalikan Fusarium oxysporum f.sp.capsici dan Alternari solani Secara In Vitro

    OpenAIRE

    Kurnia, Amalia Tri

    2015-01-01

    Amalia Tri Kurnia. Using of endophytic fungi from Solanum betacea to control Fusarium oxysporum f.sp. capsici and Alternaria solani in vitro, supervised by Mukhtar Iskandar Pinem dan Syahrial Oemry. This research aimed to know efectivity of endophytic fungi from Solanum betacea to control Fusarium oxysporum f.sp. capsici and Alternaria solani in vitro. This research was conducted on Plant Disease Laboratory of Fakultas Pertanian USU on May 2013 until January 2014, us...

  15. Risico voor resistente rassen, Phytophthora doorbreekt resisten tiegen (interview met Geert Kessel)

    NARCIS (Netherlands)

    Engwerda, J.; Kessel, G.J.T.

    2009-01-01

    In phytophthora-resistente aardappelrassen Bionica en Toluca kan alsnog phytoph-thora ontstaan. Wageningen UR waarschuwt telers hiervoor. Bij laboratoriumexperimenten zijn drie phytophthora-isolaten gevonden die het resistentiegen Blb2 hebben doorbroken. Het is voor het eerst dat de aardappelziekte

  16. Mapping the Progression of Phytophthora Ramorum

    Science.gov (United States)

    Banh, T.; Li, J.; El-Askary, H. M.

    2013-12-01

    There has been a plant pathogen, Phytophthora Ramorum that has been causing trouble for the plant species in the forests of California and Oregon. Phytophthora is essentially a water mold that infects oak species like California black oak, coast live oak as well as California bay laurel (Lamsal). What this project aims to accomplish is to observe any changes in NDVI values between the years of 2002 and 1994. What the project hopes to observe is a decline of NDVI values between the two years because the infection of Phytophtora Ramorum will cause stress to the plant or kill the plant, which will lower the values of NDVI. The project will utilizes satellite data to create NDVI images over the study area and two types of change detection methods to observe the differences between the NDVI values of the two years. Preliminary results for the project, data obtained from Landsat 7 ETM+ with a resolution of 240 meters, was not able to observe any significant changes. A finer resolution to differentiate the NDVI values would be needed. In addition the best way to keep the pathogen from getting out of control is with ground level management, or complete eradication of the pathogen. These eradication methods include burning the infected host plants and spreading herbicide (Alexander). With that in mind it would be ideal to have an early detection of the pathogen infestation. Therefore another goal of the project is to continue to research if remote sensing could play a role in an early detection method for the presence of Phytophtora Ramorum.

  17. Phytophthora palmivora, agente da podridão de raiz e frutos de mamoeiro no Estado de Alagoas Phytophthora palmivora, causal agent of root and fruit rots of papaya in the State of Alagoas, Brazil

    Directory of Open Access Journals (Sweden)

    Juliana Paiva Carnaúba

    2006-04-01

    Full Text Available O mamoeiro (Carica papaya é uma das mais importantes fruteiras tropicais, e seus frutos contribuem com uma produção de 1,65 milhão de toneladas por ano para o Brasil. Um isolado de Phytophthora sp. obtido de frutos de mamoeiro da cultivar Havaí, em Alagoas, foi caracterizado morfologicamente e sua patogenicidade foi confirmada em frutos e mudas deste hospedeiro. Em meio suco V-8, os esporangióforos apresentaram-se delgados, simples ou pouco ramificados, enquanto os esporângios se apresentaram ovóides a elipsóides, proeminentemente papilados e um pedicelo curto na porção basal, medindo em média 37,68 x 27,52 mm. Através das características apresentadas pelo isolado e os sintomas induzidos, o agente causal foi identificado como Phytophthora palmivora. Apesar de essa doença já ocorrer em outros estados, como Bahia, Espírito Santo, São Paulo, Pernambuco e Pará, este é o primeiro relato de Phytophthora palmivora em mamoeiro no Estado de Alagoas.The papaya (Carica papaya is one of the most important tropical fruit crops and its fruit contribute with a production of 1.65 millions tons/year in Brazil. An isolated of Phytophthora sp. gotten from papaya fruits cv. Hawaii, in the state of Alagoas, was characterized morphologically and its pathogenicity to this fruits and seedling was confirmed. In a V-8 medium, the sporangiophores presented to be slim, simple or little ramified, while the sporangia presented ovoid to ellipsoid, prominently papillae and one short pedicel in the basal portion, measuring in average 37,68 x 27,52 (m. Through the characteristics presented by the isolated and the induced symptoms, the causal agent was identified as Phytophthora palmivora. Despite of this disease already occurring in other states like in Bahia, Espirito Santo, São Paulo, Pernambuco and Pará, this is the first report of Phytophthora palmivora on papaya in the state of Alagoas, Brazil.

  18. The aspartic proteinase family of three Phytophthora species

    Directory of Open Access Journals (Sweden)

    ten Have Arjen

    2011-05-01

    Full Text Available Abstract Background Phytophthora species are oomycete plant pathogens with such major social and economic impact that genome sequences have been determined for Phytophthora infestans, P. sojae and P. ramorum. Pepsin-like aspartic proteinases (APs are produced in a wide variety of species (from bacteria to humans and contain conserved motifs and landmark residues. APs fulfil critical roles in infectious organisms and their host cells. Annotation of Phytophthora APs would provide invaluable information for studies into their roles in the physiology of Phytophthora species and interactions with their hosts. Results Genomes of Phytophthora infestans, P. sojae and P. ramorum contain 11-12 genes encoding APs. Nine of the original gene models in the P. infestans database and several in P. sojae and P. ramorum (three and four, respectively were erroneous. Gene models were corrected on the basis of EST data, consistent positioning of introns between orthologues and conservation of hallmark motifs. Phylogenetic analysis resolved the Phytophthora APs into 5 clades. Of the 12 sub-families, several contained an unconventional architecture, as they either lacked a signal peptide or a propart region. Remarkably, almost all APs are predicted to be membrane-bound. Conclusions One of the twelve Phytophthora APs is an unprecedented fusion protein with a putative G-protein coupled receptor as the C-terminal partner. The others appear to be related to well-documented enzymes from other species, including a vacuolar enzyme that is encoded in every fungal genome sequenced to date. Unexpectedly, however, the oomycetes were found to have both active and probably-inactive forms of an AP similar to vertebrate BACE, the enzyme responsible for initiating the processing cascade that generates the Aβ peptide central to Alzheimer's Disease. The oomycetes also encode enzymes similar to plasmepsin V, a membrane-bound AP that cleaves effector proteins of the malaria parasite

  19. Monitoring Lysobacter capsici AZ78 using strain specific qPCR reveals the importance of the formulation for its survival in vineyards.

    Science.gov (United States)

    Segarra, Guillem; Puopolo, Gerardo; Porcel-Rodríguez, Elena; Giovannini, Oscar; Pertot, Ilaria

    2016-02-01

    Survival in the phyllosphere is a critical feature for biofungicides based on non-spore forming bacteria. Moreover, knowledge of their persistence on plants is important to design effective formulations and application techniques. With this scope, the aim of this work was to develop a specific method to monitor the fate in the environment of Lysobacter capsici AZ78, a biocontrol agent of Plasmopara viticola, and to evaluate the contribution of formulation in its persistence on grapevine leaves. A strain-specific primer pair derived from REP-PCR fingerprinting was used in quantitative PCR experiments to track the evolution of L. capsici AZ78 population in vineyards. The population reached between 5 and 6 log10 cells gram of leaf(-1) after application and decreased by more than 100 times in one week. Multiple regression analysis showed that unfavourable temperature was the main environmental factor correlating with the decrease of L. capsici AZ78 persistence on grapevine leaves. Importantly, the use of formulation additives protected L. capsici AZ78 against environmental factors and improved its persistence on the leaves by more than 10 times compared to nude cells. Formulation and the knowledge about the persistence of L. capsici AZ78 in vineyards will be useful to develop commercial biofungicides for foliar application. PMID:26691736

  20. Genetic diversity of Phytophthora infestans in the Northern Andean region

    Directory of Open Access Journals (Sweden)

    Grünwald Niklaus J

    2011-02-01

    Full Text Available Abstract Background Phytophthora infestans (Mont. de Bary, the causal agent of potato late blight, is responsible for tremendous crop losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato, and more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana and tree tomato (Solanum betaceum, all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly understood in Colombia and Venezuela. To understand the P. infestans population structure in the Northern part of the Andes, four nuclear regions (ITS, Ras, β-tubulin and Avr3a and one mitochondrial (Cox1 region were analyzed in isolates of P. infestans sampled from different hosts in Colombia and Venezuela. Results Low genetic diversity was found within this sample of P. infestans isolates from crops within several regions of Colombia and Venezuela, revealing the presence of clonal populations of the pathogen in this region. We detected low frequency heterozygotes, and their distribution patterns might be a consequence of a high migration rate among populations with poor effective gene flow. Consistent genetic differentiation exists among isolates from different regions. Conclusions The results here suggest that in the Northern Andean region P. infestans is a clonal population with some within-clone variation. P. infestans populations in Venezuela reflect historic isolation that is being reinforced by a recent self-sufficiency of potato seeds. In summary, the P. infestans population is mainly shaped by migration and probably by the appearance of variants of key effectors such as Avr3a.

  1. Susceptibility of sprouted oak acorns to Phytophthora ramorum zoospores

    Science.gov (United States)

    Phytophthora ramorum is a recently emerged pathogen, having established in Europe and several western U.S. states, including California and Oregon. It has a wide host range and is a threat to forest ecology and the nursery industry. In California, coast live oak (Quercus agrifolia) is a major host...

  2. A Surface Plasmon Resonance Immunobiosensor for Detection of Phytophthora infestans

    DEFF Research Database (Denmark)

    Skottrup, Peter; Frøkiær, Hanne; Hejgaard, Jørn;

    In this study we focused on the development of a Surface Plasmon Resonance (SPR) immunosensor for Phytophthora infestans detection. The fungus-like organism is the cause of potato late blight and is a major problem in potato growing regions of the world. Efficient control is dependent on early...

  3. Interactions between biosurfactant-producing Pseudomonas and Phytophthora species

    NARCIS (Netherlands)

    Tran, H.

    2007-01-01

    Fluorescent Pseudomonas bacteria produce a wide variety of antimicrobial metabolites, including soap-like compounds referred to as biosurfactants. The results of this thesis showed that biosurfactant-producing Pseudomonas bacteria are effective in controlling Phytophthora foot rot disease of black p

  4. Elicitin recognition confers enhanced resistance to Phytophthora infestans in potato

    NARCIS (Netherlands)

    Du, J.; Verzaux, E.C.; Chaparro-Garcia, A.; Bijsterbosch, G.; Keizer, L.C.P.; Zhou, J.; Liebrand, T.W.H.; Xie, C.; Govers, F.; Robatzek, S.; Vossen, van der E.A.G.; Jacobsen, E.; Visser, R.G.F.; Kamoun, S.; Vleeshouwers, V.G.A.A.

    2015-01-01

    Potato late blight, caused by the destructive Irish famine pathogen Phytophthora infestans, is a major threat to global food security1,2. All late blight resistance genes identified to date belong to the coiled-coil, nucleotide-binding, leucine-rich repeat class of intracellular immune receptors3. H

  5. Antifungal Activity of Extractable Conifer Heartwood Compounds Toward Phytophthora ramorum

    Science.gov (United States)

    Individual compounds and ethyl acetate extracts from heartwood of seven conifer species were tested for fungicidal activity against Phytophthora ramorum. Extracts from incense and western redcedar exhibited the strongest activity (EC50 589 and 646 ppm, respectively), yellow-cedar, western juniper, ...

  6. Management of Fusarium oxysporum f. sp. capsici by leaf extract of Eucalyptus citriodora

    International Nuclear Information System (INIS)

    Fusarium wilt of chili (Capsicum annum L.) is an important disease in Pakistan that causes significant yield losses. In the present study, pathogenicity test was conducted using four strains of Fusarium oxysporum f.sp. capsici and ten chili varieties. It revealed that strain B was the most pathogenic strain and variety sky red was the most susceptible while variety Anchal was the most resistant against F. oxysporum strain B. Antifungal bioassays were conducted to find out antimycotic effect of extracts of fruit, bark and leaves of Eucalyptus citriodora (Hook.) against F. oxysporum. Ten concentrations (0, 1.0, 1.5, 2.0, 2.5 and 5%) of methanolic extracts of each plant part were employed against the target pathogen. Leaf extract imparted the maximum (up to 98%) and significant suppression in fungal growth while fruit and bark extracts proved less effective exhibiting only 50-60% reduction in fungal mycelial growth. The work concludes that methanolic extract of leaves of E. citriodora have potential to restrain the disastrous effects of the pathogenic fungus as the plant extracts of Eucalyptus conferred about 85% disease control in chilli plants with significantly high intensity of defense related enzymes under pathogenic stress. (author)

  7. Molecular mapping and construction of SCAR markers of the strawberry Rpf 1 resistance gene to Phytophthora fragariae and their use in breeding programs

    OpenAIRE

    Haymes, K.M.; Weg, van de, H; Arens, P; Vosman, B.; Nijs, den, J.C.M.

    1997-01-01

    The commercial strawberry (Fragaria x ananassa) resistance gene Rpfl conferring resistance to various isolates of Phytophthora fragariae, was mapped using 7 RAPD markers. A DNA fragment representing a RAPD marker linked to susceptibility was cloned, sequenced and converted into a sequence characterized amplified region (SCAR) marker. Next, SCAR primers to the resistant allele (SCAR-R) were developed based upon a deletion region between susceptible and resistant plants. The SCAR-R primers were...

  8. Molecular mapping and construction of SCAR markers of the strawberry Rpf1 resistance gene to Phytophthora fragariae and their use in breeding programmes

    OpenAIRE

    Haymes, K.M.; Weg, van de, H; Arens, P; Vosman, B.; den Nijs, A.P.M.

    1998-01-01

    The commercial strawberry (Fragaria x ananassa) resistance gene Rpfl conferring resistance to various isolates of Phytophthora fragariae, was mapped using 7 RAPD markers. A DNA fragment representing a RAPD marker linked to susceptibility was cloned, sequenced and converted into a sequence characterized amplified region (SCAR) marker. Next, SCAR primers to the resistant allele (SCAR-R) were developed based upon a deletion region between susceptible and resistant plants. The SCAR-R primers were...

  9. The incompatible interaction between Phytophthora parasitica var. nicotianae race 0 and tobacco is suppressed in transgenic plants expressing antisense lipoxygenase sequences

    OpenAIRE

    Rancé, Iann; Fournier, Joëlle; Esquerré-Tugayé, Marie-Thérèse

    1998-01-01

    Nicotiana tabacum 46-8 cultivar displays an incompatible interaction with race 0 of Phytophthora parasitica var. nicotianae (Ppn), a fungal pathogen of most tobacco cultivars. At the plant level, incompatibility is characterized by the induction of lipoxygenase (LOX, EC = 1.13.11.12) activity and localized hypersensitive cell death before defense gene activation. To evaluate the involvement of LOX in the onset of plant defense, tobacco 46-8 plants were genetically engineered using full-length...

  10. Phytophthora Root and Crown Rot on Apples in Bulgaria

    Directory of Open Access Journals (Sweden)

    Mariana Nakova

    2010-01-01

    Full Text Available Phytophthora is a genus of Oomycota responsible for some of the most serious diseases with great economic impact (Judelson and Blanco, 2005. While 54 species were found in the 20th century (Erwin and Ribeiro, 1996 another 51-54 new species have been identified(Brasier, 2008 since the year 2000. They are spread worldwide and have broad range of host plants – fruit trees, citrus, forest and park species. Phytophthora can cause serious damages in orchards and nurseries of apples, cherries, etc. In Bulgaria they have been found first on young apples and cherries (1998-1999 in Plovdiv region (Nakova, 2003. Surveys have been done for discovering disease symptoms in Plovdiv and Kjustendil regions. Isolates have been obtained from infected plant material (roots and stem bases applying baiting bioassay (green apples, variety Granny Smith and/or PARP 10 selective media. Phytophthora strains were identified based on standard morphology methods – types of colonies on PDA, CMA, V 8, type and size of sporangia, oogonia and antheridia, andoospores. Cardial temperatures for their growth were tested on CMA and PDA.For molecular studies, DNA was extracted from mycelium using the DNA extraction kit.DNA was amplified using universal primers ITS 6 and ITS 4. Amplification products concentrations were estimated by comparison with the standard DNA. Sequencing was done at the Scottish Crop Research Institute (SCRI, Dundee, Scotland. Phytophthora root and crown rot symptoms first appear in early spring. Infected trees show bud break delay, have small chlorotic leaves, and branches die all of a sudden. Later symptoms are found in August-September. Leaves of the infected trees show reddish discoloration and drop down. Both symptoms are connected with lesions (wet, necrotic in appearance at stem bases of the trees.Disease spread was 2-3% in most gardens, only in an apple orchard in Bjaga (Plovdiv region it was up to 8-10%. Morphologically, the isolates acquired from

  11. Enxertia em plantas de pimentão no controle da murcha de fitóftora em ambiente protegido Sweet pepper grafting to control phytophthora blight under protected cultivation

    Directory of Open Access Journals (Sweden)

    Haydée S. Santos

    2004-03-01

    Full Text Available Avaliou-se a viabilidade de utilização da enxertia em plantas de pimentão (Capsicum annuum, L., visando o controle da murcha de fitóftora. A pesquisa foi conduzida de setembro de 2000 a julho de 2001, na UNESP, Botucatu, em ambiente protegido. Adotou-se o delineamento experimental de blocos ao acaso, com 4 repetições e 5 plantas por parcela. Foram utilizados dois porta-enxertos resistentes a Phytophthora capsici, híbridos F1 de Capsicum annuum, e três híbridos comerciais suscetíveis (Elisa, Margarita e Magali-R. A enxertia foi realizada quando porta-enxertos e enxertos apresentavam respectivamente sete e três folhas verdadeiras, pelo método de garfagem fenda simples. Aos 14 dias após o transplante das mudas foi feita a inoculação do fungo, utilizando sementes de trigo infestadas pelo patógeno, depositadas ao redor do colo da planta. Quatro dias após a inoculação, e a partir daí a cada 15 dias, foram feitas avaliações que confirmaram a resistência dos porta-enxertos e a suscetibilidade das plantas não enxertadas. Observou-se bom nível de compatibilidade de enxertia em todas as combinações, precocidade de florescimento das plantas não enxertadas, manutenção de resistência à doença pelas plantas enxertadas durante todo o período e variações na altura das plantas em algumas combinações. Com relação à produção, verificou-se que os frutos mantiveram as características fenotípicas de cada híbrido, revelando que não houve interferência dos porta-enxertos neste aspecto. Concluiu-se haver viabilidade técnica de utilização da enxertia no controle da murcha de fitóftora em ambiente protegido.The viability of grafting was evaluated in sweet pepper (Capsicum annuum, L plants to control phytophthora blight. The research was carried out during the period of September 2000 to July 2001, in Botucatu (Brazil, under protected cultivation. The experimental design was of randomized blocks with four replication and

  12. Sensitivity of Progeny of Phytophthora infestans to Fungicides

    OpenAIRE

    Diana M. Earnshaw; Richard C. Shattock

    2012-01-01

    This study investigated fungicide sensitivity of progeny of Phytophthora infestans at the University of Wales, Bangor. Sexual progeny were derived from an A2 parent that was Metalaxyl Sensitive (MS) with three A1 parents that were: MS, MS and MR (metalaxyl resistant). Sporangial and zoosporangial progeny from the parent and from some sexual progeny were also assessed. The different isolates were grown on Rye B Agar amended with different concentrations of one of five different fungicides: Met...

  13. Phytophthora Species, New Threats to the Plant Health in Korea

    OpenAIRE

    Hyun, Ik-Hwa; Choi, Woobong

    2014-01-01

    Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries ...

  14. Development of a screening method for resistance to Phytophthora cactorum

    OpenAIRE

    Rijbroek, van, P.C.L.; Meulenbroek, E.J.; Lindeloof, van de, C.P.J.

    1997-01-01

    In The Netherlands the fungus Phytophthora cactorum, which causes crown rot in strawberry plants, has become a problem. Because of high losses of plants and the difficulty of chemical control, resistant cultivars are wanted. Therefore we wish to develop an efficient, reliable and fast screening method, which can be used for breeding and for determining the Value for Cultivation and Use (VCU) with regard to Plant Variety Rights. In previous research cultivars were screened by a "crown-test", w...

  15. Effects of hydrostatic pressure, agitation and CO2 stress on Phytophthora nicotianae zoospore survival

    Science.gov (United States)

    Phytophthora nicotianae Breda de Haan was used as a model pathogen to investigate the effects of hydrostatic pressure, agitation, and aeration with CO2 or breathable air on the survival of Phytophthora zoospores in water. Injecting CO2 into 2 liters of zoospore-infested water for 5 min at 110.4 ml ...

  16. Toluca nog steeds resistent tegen phytophthora (interview met o.a. Geert Kessel)

    NARCIS (Netherlands)

    Engwerda, J.; Kessel, G.J.T.

    2009-01-01

    Het biologische aardappelras Toluca is nog steeds volledig resistent tegen phytophthora. Dat in een laboratorium drie isolaten van phytophthora de resistentie hebben omzeild, is een theoretisch gegeven, vindt commercieel directeur Jan van Hoogen van Agrico. Toluca is gekweekt door Agrico en in 2007

  17. An overview of Australia's Phytophthora species assemblage in natural ecosystems recovered from a survey in Victoria.

    Science.gov (United States)

    Dunstan, William A; Howard, Kay; StJ Hardy, Giles E; Burgess, Treena I

    2016-06-01

    Although Phytophthora species cause serious diseases worldwide, until recently the main focus on disease in natural ecosystems in southern Australia has been on the distribution and impact of P. cinnamomi. However, new Phytophthora pathogens have emerged from natural ecosystems, and there is a need to better understand the diversity and distribution of these species in our natural forests, woodlands and heathlands. From a survey along a 70 km pipeline easement in Victoria, Phytophthora species were isolated from 249 rhizosphere samples and 25 bait bags deployed in 21 stream, river, or wetland locations. Of the 186 Phytophthora isolates recovered, 130 were identified to species based on ITS sequence data. Ninety-five isolates corresponded to 13 described Phytophthora species while additionally 35 isolates were identified as Clade 6 hybrids. Phytophthora cinnamomi was the most common species isolated (31 %), followed by P. elongata (6 %), both species were only recovered from soil. Samples from sites with the highest soil moisture at the time of sampling had the highest yield of isolates. Consistent with other studies throughout the world, Clade 6 species and their hybrids dominated water samples, although many of these species were also recovered less frequently from soil samples. Many of the species recovered in this study have not previously been reported from eastern Australia, reinforcing that Phytophthora species are widespread, abundant and diverse in natural ecosystems. We have probably been underestimating Phytophthora diversity in Australia. PMID:27433440

  18. Effect of CO2 enhancement on beech (Fagus sylvatica L. seedling root rot due to Phytophthora plurivora and Phytophthora cactorum

    Directory of Open Access Journals (Sweden)

    Tkaczyk Miłosz

    2014-09-01

    Full Text Available Global climate change is associated with higher concentrations of atmospheric carbon dioxide (CO2. The ongoing changes are likely to have significant, direct or indirect effects on plant diseases caused by many biotic agents such as phytopathogenic fungi. This study results showed that increased CO2 concentration did not stimulate the growth of 1-year-old beech Fagus sylvatica L seedlings but it activated pathogenic Phytophthora species (P. plurivora and P. cactorum which caused significant reduction in the total number of fine roots as well as their length and area. The results of the greenhouse experiment indicated that pathogens once introduced into soil survived in pot soil, became periodically active (in sufficient water conditions and were able to damage beech fine roots. However, the trees mortality was not observed during the first year of experiment. DNA analyses performed on soil and beech tissue proved persistence of introduced Phytophthora isolates.

  19. Spatial analysis of the incidence of Phytophthora infestans (Mont. De Bary and Phytophthora nicotianae Breda de Haan on potato

    Directory of Open Access Journals (Sweden)

    Leónides Castellanos González

    2016-03-01

    Full Text Available The objective of this research was to conduct a spatial analysis of the incidence of Phytophthora nicotianae Breda de Haan and Phytophthora infestans (Mont. De Bary, during five seasons of potato in Fields Company Miscellaneous Crops in Horquita, Cienfuegos (2003-2004 to 2007-2008. Information about pathogens, collected by the Plant Protection Station of Yaguaramas, was used in order to do so. An alpha numerical database was made, oriented to a group of areas under center pivot irrigation machines (Kubans and Bayamón and its quadrants. Parallel to this, mapping of center pivot machines and quadrants was generated in MapInfo GIS 8.5. Several automatic geo codifications were made in order to relate the alphanumeric database and the mapping, and thematic maps were generated in the presence or absence of pathogens. The two study agents have presented high spatial variability during the five planting seasons. Both have influenced the same geographical area with similar appearance date. P. infestans has not expressed a defined dispersion pattern and it has spread at random from the primary source of incidence, while Phytophthora nicotianae has become an endemic agent which shows a dispersion pattern towards neighboring areas or areas connected by the road network from the primary sources, which have been associated with poor land leveling and late or intermediate planting seasons.

  20. Changes in susceptibility of beech (Fagus sylvatica) seedlings towards Phytophthora citricola under the influence of elevated atmospheric CO2 and nitrogen fertilization

    International Nuclear Information System (INIS)

    The growth-differentiation balance hypothesis (GDBH) predicts changes in susceptibility of plants against herbivores with changing resource availability. In the presented study we tested the validity of the GDBH for trees infected with a root pathogen. For this purpose Fagus sylvatica seedlings grown under different atmospheric CO2- and soil nitrogen regimes were infected with the root pathogen Phytophthora citricola. High nitrogen supply increased total biomass of beech regardless of the CO2-treatment, whereas elevated CO2 enhanced biomass only in the high nitrogen treatment. The responses of beech under the different growing regimes to the Phytophthora root infection were not in line with the predictions of the GDBH. Enhanced susceptibility of beech against P. citricola was found in seedlings grown under elevated CO2 and low nitrogen supply. Fifteen months after inoculation these plants were characterized by enhanced water use efficiency, by altered root-shoot ratios, and by enhanced specific root tip densities. - Susceptibility of Fagus sylvatica to the root pathogen Phytophthora citricola increased under elevated CO2

  1. Changes in susceptibility of beech (Fagus sylvatica) seedlings towards Phytophthora citricola under the influence of elevated atmospheric CO{sub 2} and nitrogen fertilization

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmann, F., E-mail: fleischmann@wzw.tum.d [Phytopathology of Woody Plants, Technische Universitaet Muenchen, Am Hochanger 13, 85354 Freising (Germany); Raidl, S. [Department Biology I and GeoBioCenterLMU, Systematic Mycology, Ludwig Maximilians Universitaet Muenchen, Menzinger Strasse 67, 80638 Muenchen (Germany); Osswald, W.F. [Phytopathology of Woody Plants, Technische Universitaet Muenchen, Am Hochanger 13, 85354 Freising (Germany)

    2010-04-15

    The growth-differentiation balance hypothesis (GDBH) predicts changes in susceptibility of plants against herbivores with changing resource availability. In the presented study we tested the validity of the GDBH for trees infected with a root pathogen. For this purpose Fagus sylvatica seedlings grown under different atmospheric CO{sub 2}- and soil nitrogen regimes were infected with the root pathogen Phytophthora citricola. High nitrogen supply increased total biomass of beech regardless of the CO{sub 2}-treatment, whereas elevated CO{sub 2} enhanced biomass only in the high nitrogen treatment. The responses of beech under the different growing regimes to the Phytophthora root infection were not in line with the predictions of the GDBH. Enhanced susceptibility of beech against P. citricola was found in seedlings grown under elevated CO{sub 2} and low nitrogen supply. Fifteen months after inoculation these plants were characterized by enhanced water use efficiency, by altered root-shoot ratios, and by enhanced specific root tip densities. - Susceptibility of Fagus sylvatica to the root pathogen Phytophthora citricola increased under elevated CO{sub 2}

  2. Elemental variations in the germinating fungus Phytophthora palmivora

    Energy Technology Data Exchange (ETDEWEB)

    Mazzolini, A.P.; Sealock, R.M.; Legge, G.J.F. (Micro Analytical Research Centre, Univ. of Melbourne, Parkville (Australia)); Grant, B.R. (Biochemistry Dept., Univ. of Melbourne, Parkville (Australia))

    1991-03-01

    We have measured the elemental variations between zoospores and germinating cystospores of the fungus Phytophthora palmivora, using a scanning proton microprobe. Averaged over a number of individual cells, our results indicate that the level of Ca is much lower in germinating cystospores than in zoospores. The levels of S, Cl, and Zn also appear to be lower, and the level of K appears to be higher. The spatial distribution of elements within the germinating cystospore is very similar for P, S, Cl, K, Mn, Fe, and Cu, but significantly different for Ca and Zn. (orig.).

  3. Elemental variations in the germinating fungus Phytophthora palmivora

    Science.gov (United States)

    Mazzolini, A. P.; Grant, B. R.; Sealock, R. M.; Legge, G. J. F.

    1991-03-01

    We have measured the elemental variations between zoospores and germinating cystospores of the fungus Phytophthora palmivora, using a scanning proton microprobe. Averaged over a number of individual cells, our results indicate that the level of Ca is much lower in germinating cystospores than in zoospores. The levels of S, Cl, and Zn also appear to be lower, and the level of K appears to be higher. The spatial distribution of elements within the germinating cystospore is very similar for P, S, Cl, K, Mn, Fe, and Cu, but significantly different for Ca and Zn.

  4. Elemental variations in the germinating fungus Phytophthora palmivora

    International Nuclear Information System (INIS)

    We have measured the elemental variations between zoospores and germinating cystospores of the fungus Phytophthora palmivora, using a scanning proton microprobe. Averaged over a number of individual cells, our results indicate that the level of Ca is much lower in germinating cystospores than in zoospores. The levels of S, Cl, and Zn also appear to be lower, and the level of K appears to be higher. The spatial distribution of elements within the germinating cystospore is very similar for P, S, Cl, K, Mn, Fe, and Cu, but significantly different for Ca and Zn. (orig.)

  5. Uji Antagonis Trichoderma spp. Terhadap Penyakit Layu (Fusarium oxysforum f.sp.capsici) Pada Tanaman Cabai (Capsicum annum L) Di Lapangan

    OpenAIRE

    Hasibuan, Martuani

    2012-01-01

    This experiment was conduct on Tandem Hilir, Hamparan Perak Distric, Tiga Kota Datar Village and Plant Disease Laboratory, agriculture faculty, University Of North Sumatra, Medan. From Oktober to March 2005. This experiment is to see the effectiveness of Trichoderma koningi, Thricoderma viridae, Trichoderma harzianum to control Fusarium oxysporum f.sp. capsici wilt disease on chili (Capsicum annum L.) on field It use randomize block design nonfactorial which 4 treatment and 6 repetition...

  6. Gene Duplication and Fragment Recombination Drive Functional Diversification of a Superfamily of Cytoplasmic Effectors in Phytophthora sojae

    OpenAIRE

    Shen, Danyu; Liu, Tingli; Ye, Wenwu; Li LIU; Liu, Peihan; Wu, Yuren; Wang, Yuanchao; Dou, Daolong

    2013-01-01

    Phytophthora and other oomycetes secrete a large number of putative host cytoplasmic effectors with conserved FLAK motifs following signal peptides, termed crinkling and necrosis inducing proteins (CRN), or Crinkler. Here, we first investigated the evolutionary patterns and mechanisms of CRN effectors in Phytophthora sojae and compared them to two other Phytophthora species. The genes encoding CRN effectors could be divided into 45 orthologous gene groups (OGG), and most OGGs unequally distri...

  7. EST sequencing and gene expression profiling of defence-related genes from Persea americana infected with Phytophthora cinnamomi

    OpenAIRE

    Mahomed Waheed; van den Berg Noëlani

    2011-01-01

    Abstract Background Avocado (Persea americana) belongs to the Lauraceae family and is an important commercial fruit crop in over 50 countries. The most serious pathogen affecting avocado production is Phytophthora cinnamomi which causes Phytophthora root rot (PRR). Root pathogens such as P. cinnamomi and their interactions with hosts are poorly understood and despite the importance of both the avocado crop and the effect Phytophthora has on its cultivation, there is a lack of molecular knowle...

  8. EFFECTS OF PHYTOPHTHORA ROOT ROT AND METALAXYL TREATMENT ON THE YIELD OF SOME FORAGE BRASSICA SPECIES

    OpenAIRE

    Karakaya, Aziz; KOCH, D.W.; Gray, F. A.

    1995-01-01

    Three forage Brassica species were evaluated for their growth and adaptability to the Rocky Mountain region. Brassicas were grown in fields infested with a Phytophthora disease previoıısly observed on kale (Brassica oleracea var. Acephala) Metalaxyl treatmıent did not affect Brassica yields signifıcantly. Although pest problems were detected, Brassica crops tolerated low temperatures and produced excellent yields ( up to 9.90 Mg/ha). The Phytophthora isolates from Brassica, which were identif...

  9. Investigation on the Biocontrol of Phytophthora diseases on strawberry based on antagonism

    OpenAIRE

    Anandhakumar, J.; Zeller, W.

    2004-01-01

    After screening of several rhizosphere bacteria against the soilborne pathogens of red core and crown rot disease of strawberry Phytophthora fragariae var. fragariae and Phytophthora cactorum under in vitro conditions, three of the most active isolates which produced up to 63% of reduction in mycelium growth, such as Raoultella terrigena (G-584), Bacillus amyloliquefaciens (G-V1) and Pseudomonas fluorescens (2R1-7) were selected for further studies under in vivo conditions. In ...

  10. 'Cisgenese kan handje helpen in bestrijding phytophthora' (interview met Geert Kessel)

    OpenAIRE

    Engwerda, J.; Kessel, G.J.T.

    2009-01-01

    Toluca en Bionica zijn prima biologische aardappelrassen. Maar WUR vindt een waarschuwing nodig omdat in het lab de resistentie tegen phytophthora omzeild kan worden. "Cisgenese kan helpen om resistentie tegen te gaan." Toluca en Bionica zijn prima rassen voor de biologische aardappelteelt. Ondanks dat Wageningen Universiteit en Researchcentrum (WUR) in het laboratorium drie phytophthora-isolaten heeft gevonden die in staat zijn het resistentiegen Blb2 te omzeilen. Beide rassen bezitten dit g...

  11. APPLICATION OF AGERATUM CONYZOIDES TO CONTROLING PHYTOPHTHORA POD ROT DISEASE, PHYTOPHORA PALMIVORA ON CACAO FIELD

    OpenAIRE

    Sjam, Sylvia; Surapati, Untung; Rosmana, Ade; Rahim, Muhammad Danial; Dewi, Vien Sartika; Limbongan, Amelia; Kartika, Rini

    2014-01-01

    ABSTRACT Phytophthora pod rot (PPR), caused by Phytophthora palmivora Bult is one of the most important diseases on cocoa in the world. In Indonesia, yield losses due to the diseases were estimated in the range of 33 ??? 99 %. The disease could be controlled by plant extracts, Ageratum conyzoides. This study aimed to evaluate the application of A. Conyzoides to controlling PPR in the cocoa field. The research was conducted at the Plant Pathology Laboratory, Faculty of Agriculture, Hasanu...

  12. Diverse Evolutionary Trajectories for Small RNA Biogenesis Genes in the Oomycete Genus Phytophthora

    OpenAIRE

    Stephanie R Bollmann; Fang, Yufeng; Press, Caroline M.; Tyler, Brett M.; Niklaus J Grünwald

    2016-01-01

    Gene regulation by small RNA pathways is ubiquitous among eukaryotes, but little is known about small RNA pathways in the Stramenopile kingdom. Phytophthora, a genus of filamentous oomycetes, contains many devastating plant pathogens, causing multibillion-dollar damage to crops, ornamental plants, and natural environments. The genomes of several oomycetes including Phytophthora species such as the soybean pathogen P. sojae, have been sequenced, allowing evolutionary analysis of small RNA-proc...

  13. The kinome of Phytophthora infestans reveals oomycete-specific innovations and links to other taxonomic groups

    Directory of Open Access Journals (Sweden)

    Ah-Fong Audrey MV

    2010-12-01

    Full Text Available Abstract Background Oomycetes are a large group of economically and ecologically important species. Its most notorious member is Phytophthora infestans, the cause of the devastating potato late blight disease. The life cycle of P. infestans involves hyphae which differentiate into spores used for dispersal and host infection. Protein phosphorylation likely plays crucial roles in these stages, and to help understand this we present here a genome-wide analysis of the protein kinases of P. infestans and several relatives. The study also provides new insight into kinase evolution since oomycetes are taxonomically distant from organisms with well-characterized kinomes. Results Bioinformatic searches of the genomes of P. infestans, P. ramorum, and P. sojae reveal they have similar kinomes, which for P. infestans contains 354 eukaryotic protein kinases (ePKs and 18 atypical kinases (aPKs, equaling 2% of total genes. After refining gene models, most were classifiable into families seen in other eukaryotes. Some ePK families are nevertheless unusual, especially the tyrosine kinase-like (TKL group which includes large oomycete-specific subfamilies. Also identified were two tyrosine kinases, which are rare in non-metazoans. Several ePKs bear accessory domains not identified previously on kinases, such as cyclin-dependent kinases with integral cyclin domains. Most ePKs lack accessory domains, implying that many are regulated transcriptionally. This was confirmed by mRNA expression-profiling studies that showed that two-thirds vary significantly between hyphae, sporangia, and zoospores. Comparisons to neighboring taxa (apicomplexans, ciliates, diatoms revealed both clade-specific and conserved features, and multiple connections to plant kinases were observed. The kinome of Hyaloperonospora arabidopsidis, an oomycete with a simpler life cycle than P. infestans, was found to be one-third smaller. Some differences may be attributable to gene clustering, which

  14. Phytophthora cactorum and Colletotrichum acutatum: Survival and Detection

    Directory of Open Access Journals (Sweden)

    Arja T. Lilja

    2006-12-01

    Full Text Available Phytophthora cactorum and Colletotrichum acutatum are pathogens which are transported with plant material as latent infections and can also survive in soil and plant debris. Since the beginning of 1990’s P. cactorum caused losses in strawberries in Finland and increased culling of silver birch seedlings in forest nurseries because of stem lesions. In this study primers specific for the pathogen were designed, and in a simple PCR they gave an amplification product from pure cultures only when P. cactorum was used as a template. No cross reactions were found with other Phytophthoras in group I or other microbes. Inoculated strawberry plants gave also a clear band in PCR-analyses when the template concentration was diluted. However, amplification was not always reproducible with birch seedlings. With soil samples the best result was gained by a combination of baiting and isolation. C. acutatum is a quarantine pathogen on strawberry in the European Union and thus the infected plants are destroyed in Finland to avoid further spread of the pathogen. The pathogen has earlier been found to survive over one winter in infected plant debris and soil. In the survival test (2003-2005 done in this study, specific amplification products were obtained from test plants inoculated with artificially infected plant residues after 20 months of storage outdoors on soil surface. More positive results were achieved from bait plants grown in soil collected from the field where infected plants had been destroyed two years before, than from samples collected a year after the plant destruction.

  15. Overexpression of Soybean Isoflavone Reductase (GmIFR) Enhances Resistance to Phytophthora sojae in Soybean.

    Science.gov (United States)

    Cheng, Qun; Li, Ninghui; Dong, Lidong; Zhang, Dayong; Fan, Sujie; Jiang, Liangyu; Wang, Xin; Xu, Pengfei; Zhang, Shuzhen

    2015-01-01

    Isoflavone reductase (IFR) is an enzyme involved in the biosynthetic pathway of isoflavonoid phytoalexin in plants. IFRs are unique to the plant kingdom and are considered to have crucial roles in plant response to various biotic and abiotic environmental stresses. Here, we report the characterization of a novel member of the soybean isoflavone reductase gene family GmIFR. Overexpression of GmIFR transgenic soybean exhibited enhanced resistance to Phytophthora sojae. Following stress treatments, GmIFR was significantly induced by P. sojae, ethephon (ET), abscisic acid (placeCityABA), salicylic acid (SA). It is located in the cytoplasm when transiently expressed in soybean protoplasts. The daidzein levels reduced greatly for the seeds of transgenic plants, while the relative content of glyceollins in transgenic plants was significantly higher than that of non-transgenic plants. Furthermore, we found that the relative expression levels of reactive oxygen species (ROS) of transgenic soybean plants were significantly lower than those of non-transgenic plants after incubation with P. sojae, suggesting an important role of GmIFR might function as an antioxidant to reduce ROS in soybean. The enzyme activity assay suggested that GmIFR has isoflavone reductase activity. PMID:26635848

  16. The hidden duplication past of the plant pathogen Phytophthora and its consequences for infection

    Directory of Open Access Journals (Sweden)

    Martens Cindy

    2010-06-01

    Full Text Available Abstract Background Oomycetes of the genus Phytophthora are pathogens that infect a wide range of plant species. For dicot hosts such as tomato, potato and soybean, Phytophthora is even the most important pathogen. Previous analyses of Phytophthora genomes uncovered many genes, large gene families and large genome sizes that can partially be explained by significant repeat expansion patterns. Results Analysis of the complete genomes of three different Phytophthora species, using a newly developed approach, unveiled a large number of small duplicated blocks, mainly consisting of two or three consecutive genes. Further analysis of these duplicated genes and comparison with the known gene and genome duplication history of ten other eukaryotes including parasites, algae, plants, fungi, vertebrates and invertebrates, suggests that the ancestor of P. infestans, P. sojae and P. ramorum most likely underwent a whole genome duplication (WGD. Genes that have survived in duplicate are mainly genes that are known to be preferentially retained following WGDs, but also genes important for pathogenicity and infection of the different hosts seem to have been retained in excess. As a result, the WGD might have contributed to the evolutionary and pathogenic success of Phytophthora. Conclusions The fact that we find many small blocks of duplicated genes indicates that the genomes of Phytophthora species have been heavily rearranged following the WGD. Most likely, the high repeat content in these genomes have played an important role in this rearrangement process. As a consequence, the paucity of retained larger duplicated blocks has greatly complicated previous attempts to detect remnants of a large-scale duplication event in Phytophthora. However, as we show here, our newly developed strategy to identify very small duplicated blocks might be a useful approach to uncover ancient polyploidy events, in particular for heavily rearranged genomes.

  17. EST sequencing and gene expression profiling of defence-related genes from Persea americana infected with Phytophthora cinnamomi

    Directory of Open Access Journals (Sweden)

    Mahomed Waheed

    2011-11-01

    Full Text Available Abstract Background Avocado (Persea americana belongs to the Lauraceae family and is an important commercial fruit crop in over 50 countries. The most serious pathogen affecting avocado production is Phytophthora cinnamomi which causes Phytophthora root rot (PRR. Root pathogens such as P. cinnamomi and their interactions with hosts are poorly understood and despite the importance of both the avocado crop and the effect Phytophthora has on its cultivation, there is a lack of molecular knowledge underpinning our understanding of defence strategies against the pathogen. In order to initiate a better understanding of host-specific defence we have generated EST data using 454 pyrosequencing and profiled nine defence-related genes from Pc-infected avocado roots. Results 2.0 Mb of data was generated consisting of ~10,000 reads on a single lane of the GS FLX platform. Using the Newbler assembler 371 contigs were assembled, of which 367 are novel for Persea americana. Genes were classified according to Gene Ontology terms. In addition to identifying root-specific ESTs we were also able to identify and quantify the expression of nine defence-related genes that were differentially regulated in response to P. cinnamomi. Genes such as metallothionein, thaumatin and the pathogenesis related PsemI, mlo and profilin were found to be differentially regulated. Conclusions This is the first study in elucidating the avocado root transcriptome as well as identifying defence responses of avocado roots to the root pathogen P. cinnamomi. Our data is currently the only EST data that has been generated for avocado rootstocks, and the ESTs identified in this study have already been useful in identifying defence-related genes as well as providing gene information for other studies looking at processes such as ROS regulation as well as hypoxia in avocado roots. Our EST data will aid in the elucidation of the avocado transcriptome and identification of markers for improved

  18. Stepwise flow diagram for the development of formulations of non spore-forming bacteria against foliar pathogens: The case of Lysobacter capsici AZ78.

    Science.gov (United States)

    Segarra, Guillem; Puopolo, Gerardo; Giovannini, Oscar; Pertot, Ilaria

    2015-12-20

    The formulation is a significant step in biopesticide development and is an efficient way to obtain consistency in terms of biological control under field conditions. Nonetheless, there is still a lack of information regarding the processes needed to achieve efficient formulation of non spore-forming bacterial biological control agents. In response to this, we propose a flow diagram made up of six steps including selection of growth parameters, checking of minimum shelf life, selection of protective additives, checking that the additives have no adverse effects, validation of the additive mix under field conditions and choosing whether to use additives as co-formulants or tank mix additives. This diagram is intended to provide guidance and decision-making criteria for the formulation of non spore-forming bacterial biological control agents against foliar pathogens. The diagram was then validated by designing an efficient formulation for a Gram-negative bacterium, Lysobacter capsici AZ78, to control grapevine downy mildew caused by Plasmopara viticola. A harvest of 10(10)L. capsici AZ78cellsml(-1) was obtained in a bench top fermenter. The viability of cells decreased by only one order of magnitude after one year of storage at 4°C. The use of a combination of corn steep liquor, lignosulfonate, and polyethyleneglycol in the formulation improved the survival of L. capsici AZ78 cells living on grapevine leaves under field conditions by one order of magnitude. Furthermore, the use of these additives also guaranteed a reduction of 71% in P. viticola attacks. In conclusion, this work presents a straightforward stepwise flow diagram to help researchers develop formulations for biological control agents that are easy to prepare, stable, not phytotoxic and able to protect the microorganims under field conditions. PMID:26467716

  19. 蛇床子素结构修饰物JS-B对辣椒疫霉病菌的抑制作用%Antifungal activity of osthol derivate JS-B against Phytophthora capsici

    Institute of Scientific and Technical Information of China (English)

    王春梅; 蔡春; 李优琴; 石志琦

    2007-01-01

    在室内离体条件下测试了蛇床子素结构修饰物JS-B对7种常见病原真菌的抑菌活性,结果显示:辣椒疫霉病菌菌丝生长对JS-B最敏感,其EC50值为41.78μg/ml.以蛇床子素为对照,测定了JS-B对辣椒疫霉病菌菌丝生长、孢子囊形成和释放游动孢子三种不同生长发育阶段的抑制作用.显微观察发现:JS-B能够引起辣椒疫霉菌丝形态发生异常,而蛇床子素处理的菌丝形态则无明显变化.不同酸度对JS-B和蛇床子素抑菌活性测定结果表明:两者在pH值为5~9时抑菌活性稳定.

  20. Use of genome sequence data in the design and testing of SSR markers for Phytophthora species

    Directory of Open Access Journals (Sweden)

    Cardle Linda

    2008-12-01

    Full Text Available Abstract Background Microsatellites or single sequence repeats (SSRs are a powerful choice of marker in the study of Phytophthora population biology, epidemiology, ecology, genetics and evolution. A strategy was tested in which the publicly available unigene datasets extracted from genome sequences of P. infestans, P. sojae and P. ramorum were mined for candidate SSR markers that could be applied to a wide range of Phytophthora species. Results A first approach, aimed at the identification of polymorphic SSR loci common to many Phytophthora species, yielded 171 reliable sequences containing 211 SSRs. Microsatellites were identified from 16 target species representing the breadth of diversity across the genus. Repeat number ranged from 3 to 16 with most having seven repeats or less and four being the most commonly found. Trinucleotide repeats such as (AAGn, (AGGn and (AGCn were the most common followed by pentanucleotide, tetranucleotide and dinucleotide repeats. A second approach was aimed at the identification of useful loci common to a restricted number of species more closely related to P. sojae (P. alni, P. cambivora, P. europaea and P. fragariae. This analysis yielded 10 trinucleotide and 2 tetranucleotide SSRs which were repeated 4, 5 or 6 times. Conclusion Key studies on inter- and intra-specific variation of selected microsatellites remain. Despite the screening of conserved gene coding regions, the sequence diversity between species was high and the identification of useful SSR loci applicable to anything other than the most closely related pairs of Phytophthora species was challenging. That said, many novel SSR loci for species other than the three 'source species' (P. infestans, P. sojae and P. ramorum are reported, offering great potential for the investigation of Phytophthora populations. In addition to the presence of microsatellites, many of the amplified regions may represent useful molecular marker regions for other studies as

  1. Pathogenicity of Swedish isolates of Phytophthora quercina to Quercus robur in two different soils

    OpenAIRE

    Jönsson Belyazid, Ulrika; Jung, T.; Rosengren, Ulrika; Nihlgård, Bengt; Sonesson, Kerstin

    2003-01-01

    Several studies have demonstrated the involvement of soil-borne Phytophthora species, especially Phytophthora quercina , in European oak decline. However, knowledge about the pathogenicity of P. quercina in natural forest soils is limited. The short-term effects of two south-Swedish isolates of P. quercina on root vitality of Quercus robur seedlings grown in two different soils, one high pH, nutrient-rich peat-sand mixture and one acid, nitrogen-rich but otherwise nutrient-poor forest soil ar...

  2. CHITOSAN AND ITS HYDROLYSATE AT TOBACCO-Phytophthora parasitica INTERACTION

    Directory of Open Access Journals (Sweden)

    A. B. Falcón

    2002-01-01

    Full Text Available La quitosana es el derivado desacetilado de la quitina, un polimero de N-acetil-glucosamina que se extrae del exoesqueleto de los crustaceos. Ambos polimeros asi como sus oligomeros protegen varias especies de plantas contra enfermedades fungosas, mediante la induccion de mecanismos defensivos histologicos y bioquimicos que detienen el avance del patogeno en el vegetal. En nuestro trabajo se realizo la preparacion de quitosana mediante desacetilacion basica de quitina de calidad farmaceutica. La quitosana, a su vez, fue hidrolizada exhaustivamente con un preparado enzimatico comercial (celluclast para obtener oligomeros de pequeno tamano. Tanto al polimero como a su hidrolizado enzimatico se les estudiaron sus potencialidades para inducir resistencia sistemica en plantas de tabaco mediante bioensayos en condiciones controladas, donde se determino la capacidad de ambos elicitores para la induccion de marcadores de resistencia (actividad quitinasa, glucanasa y PAL y en el caso del hidrolizado, la proteccion del tabaco contra la invasion del patogeno Phytophthora parasitica var. nicotianae. Los resultados demostraron una induccion de actividad quitinasa y glucanasa por quitosana a concentraciones de 50 y 500 mg.L-1 mucho mas elevada en el caso de la mas alta concentracion del elicitor. Se observo ademas proteccion contra Ppn cuando se trataron plantas de tabaco via raiz con el hidrolizado enzimatico a concentraciones entre 5 y 500 mg.L-1 con una induccion de respuesta PAL y ¿À 1-3 glucanasa diferenciada en el tiempo de exposicion de las plantas al patogeno.

  3. Phytophthora infestans specific phosphorylation patterns and new putative control targets.

    Science.gov (United States)

    Frades, Itziar; Andreasson, Erik

    2016-04-01

    In this study we applied biomathematical searches of gene regulatory mechanisms to learn more about oomycete biology and to identify new putative targets for pesticides or biological control against Phytophthora infestans. First, oomycete phylum-specific phosphorylation motifs were found by discriminative n-gram analysis. We found 11.600 P. infestans specific n-grams, mapping 642 phosphoproteins. The most abundant group among these related to phosphatidylinositol metabolism. Due to the large number of possible targets found and our hypothesis that multi-level control is a sign of usefulness as targets for intervention, we identified overlapping targets with a second screen. This was performed to identify proteins dually regulated by small RNA and phosphorylation. We found 164 proteins to be regulated by both sRNA and phosphorylation and the dominating functions where phosphatidylinositol signalling/metabolism, endocytosis, and autophagy. Furthermore we performed a similar regulatory study and discriminative n-gram analysis of proteins with no clear orthologs in other species and proteins that are known to be unique to P. infestans such as the RxLR effectors, Crinkler (CRN) proteins and elicitins. We identified CRN proteins with specific phospho-motifs present in all life stages. PITG_12626, PITG_14042 and PITG_23175 are CRN proteins that have species-specific phosphorylation motifs and are subject to dual regulation. PMID:27020162

  4. Aluminum induces cross-resistance of potato to Phytophthora infestans.

    Science.gov (United States)

    Arasimowicz-Jelonek, Magdalena; Floryszak-Wieczorek, Jolanta; Drzewiecka, Kinga; Chmielowska-Bąk, Jagna; Abramowski, Dariusz; Izbiańska, Karolina

    2014-03-01

    The phenomenon of cross-resistance allows plants to acquire resistance to a broad range of stresses after previous exposure to one specific factor. Although this stress-response relationship has been known for decades, the sequence of events that underpin cross-resistance remains unknown. Our experiments revealed that susceptible potato (Solanum tuberosum L. cv. Bintje) undergoing aluminum (Al) stress at the root level showed enhanced defense responses correlated with reduced disease symptoms after leaf inoculation with Phytophthora infestans. The protection capacity of Al to subsequent stress was associated with the local accumulation of H2O2 in roots and systemic activation of salicylic acid (SA) and nitric oxide (NO) dependent pathways. The most crucial Al-mediated changes involved coding of NO message in an enhanced S-nitrosothiol formation in leaves tuned with an abundant SNOs accumulation in the main vein of leaves. Al-induced distal NO generation was correlated with the overexpression of PR-2 and PR-3 at both mRNA and protein activity levels. In turn, after contact with a pathogen we observed early up-regulation of SA-mediated defense genes, e.g. PR1, PR-2, PR-3 and PAL, and subsequent disease limitation. Taken together Al exposure induced distal changes in the biochemical stress imprint, facilitating more effective responses to a subsequent pathogen attack. PMID:24346311

  5. Identification of Phytophthora sojae genes involved in asexual sporogenesis

    Indian Academy of Sciences (India)

    Ziying Wang; Xhaoxia Wang; Jie Shen; Guangyue Wang; Xiaoxi Zhu; Hongxia Lu

    2009-08-01

    To explore the molecular mechanisms involved in asexual spore development in Phytophthora sojae, the zoospores of strain PS26 were treated with ultraviolet (UV) irradiation. After selection, a mutant progeny, termed PS26-U03, was obtained and demonstrated to exhibit no oospore production. A suppression subtractive hybridization (SSH) approach was developed to investigate differences in gene expression between PS26 and PS26-U03 during asexual sporogenesis. Of the 126 sequences chosen for examination, 39 putative unigenes were identified that exhibit high expression in PS26. These sequences are predicted to encode proteins involved in metabolism, cell cycle, protein biosynthesis, cell signalling, cell defence, and transcription regulation. Seven clones were selected for temporal expression analysis using RT-PCR based on the results of the dot-blot screens. Three of the selected genes, developmental protein DG1037 (UB88), glycoside hydrolase (UB149) and a hypothetical protein (UB145), were expressed only in PS26, whereas the transcripts of phosphatidylinositol-4-phosphate 5-kinase (UB36), FAD-dependent pyridine nucleotide-disulphide oxidoreductase (UB226) and sugar transporter (UB256) were expressed at very low levels in PS26-U03 but at high levels in PS26.

  6. Detection, Diversity, and Population Dynamics of Waterborne Phytophthora ramorum Populations.

    Science.gov (United States)

    Eyre, C A; Garbelotto, M

    2015-01-01

    Sudden oak death, the tree disease caused by Phytophthora ramorum, has significant environmental and economic impacts on natural forests on the U.S. west coast, plantations in the United Kingdom, and in the worldwide nursery trade. Stream baiting is vital for monitoring and early detection of the pathogen in high-risk areas and is performed routinely; however, little is known about the nature of water-borne P. ramorum populations. Two drainages in an infested California forest were monitored intensively using stream-baiting for 2 years between 2009 and 2011. Pathogen presence was determined both by isolation and polymerase chain reaction (PCR) from symptomatic bait leaves. Isolates were analyzed using simple sequence repeats to study population dynamics and genetic structure through time. Isolation was successful primarily only during spring conditions, while PCR extended the period of pathogen detection to most of the year. Water populations were extremely diverse, and changed between seasons and years. A few abundant genotypes dominated the water during conditions considered optimal for aerial populations, and matched those dominant in aerial populations. Temporal patterns of genotypic diversification and evenness were identical among aerial, soil, and water populations, indicating that all three substrates are part of the same epidemiological cycle, strongly influenced by rainfall and sporulation on leaves. However, there was structuring between substrates, likely arising due to reduced selection pressure in the water. Additionally, water populations showed wholesale mixing of genotypes without the evident spatial autocorrelation present in leaf and soil populations. PMID:25026455

  7. Monitoring of Soft Fruit Mother Plantings Aimed at Control of Phytophthora fragariae, Causal Agent of Root Rot

    Directory of Open Access Journals (Sweden)

    Slobodan Milenković

    2006-12-01

    Full Text Available Phytophthora fragariae was first detected in the Republic of Serbia in 2002, and it has been included in A2 quarantine list of damaging organisms since 2003. The project titled ‘Monitoring of soft fruit mother plantings aimed at the control of Phytophthora fragariae, causal agent of root rot’ was realized over 2004 – 2005 aiming at determination of population rate of the pathogen and the control of raspberry planting material. Over that period, the total 388 samples were tested. Collected samples were analyzed by PCR. The presence of Phytophthora fragariae was detected in 156 samples.

  8. Monitoring of Soft Fruit Mother Plantings Aimed at Control of Phytophthora fragariae, Causal Agent of Root Rot

    Directory of Open Access Journals (Sweden)

    Slobodan Milenković

    2006-01-01

    Full Text Available Phytophthora fragariae was first detected in the Republic of Serbia in 2002, and it has been included in A2 quarantine list of damaging organisms since 2003. The project titled ‘Monitoring of soft fruit mother plantings aimed at the control of Phytophthora fragariae, causal agent of root rot’ was realized over 2004 – 2005 aiming at determination of population rate of the pathogen and the control of raspberry planting material. Over that period, the total 388 samples were tested. Collected samples were analyzed by PCR. The presence of Phytophthora fragariae was detected in 156 samples.

  9. Early-screening for resistance to Phytophthora sp.p. in wild cherry clones (Prunus avium L.

    Directory of Open Access Journals (Sweden)

    Guerri S

    2004-01-01

    Full Text Available A new method for early selection of wild cherry clones for resistance to Phytophthora sp. is presented. Four Phytophthora species (P. cinnamomi, P. citrophthora, P. megasperma, P. alni were tested in vitro on four micropropagated cherry (Prunus avium clones, obtaining reliable and reproducible results. Variability in clones susceptibilities and in parasite virulence has been evidenced. Phytophthora citrophthora is confirmed to be a dangerous parasite, due to its capability to produce symptoms rapidly and its fitness to Mediterranean environments. On the contrary P. alni does not seem a dangerous parasite for wild cherry.

  10. Probing the Functions of Carbohydrate Binding Modules in the CBEL Protein from the Oomycete Phytophthora parasitica.

    Directory of Open Access Journals (Sweden)

    Thomas Martinez

    Full Text Available Oomycetes are microorganisms that are distantly related to true fungi and many members of this phylum are major plant pathogens. Oomycetes express proteins that are able to interact with plant cell wall polysaccharides, such as cellulose. This interaction is thought to be mediated by carbohydrate-binding modules that are classified into CBM family 1 in the CAZy database. In this study, the two CBMs (1-1 and 1-2 that form part of the cell wall glycoprotein, CBEL, from Phytophthora parasitica have been submitted to detailed characterization, first to better quantify their interaction with cellulose and second to determine whether these CBMs can be useful for biotechnological applications, such as biomass hydrolysis. A variety of biophysical techniques were used to study the interaction of the CBMs with various substrates and the data obtained indicate that CBEL's CBM1-1 exhibits much greater cellulose binding ability than CBM1-2. Engineering of the family 11 xylanase from Talaromyces versatilis (TvXynB, an enzyme that naturally bears a fungal family 1 CBM, has produced two variants. The first one lacks its native CBM, whereas the second contains the CBEL CBM1-1. The study of these enzymes has revealed that wild type TvXynB binds to cellulose, via its CBM1, and that the substitution of its CBM by oomycetal CBM1-1 does not affect its activity on wheat straw. However, intriguingly the addition of CBEL during the hydrolysis of wheat straw actually potentiates the action of TvXynB variant lacking a CBM1. This suggests that the potentiating effect of CBM1-1 might not require the formation of a covalent linkage to TvXynB.

  11. Probing the Functions of Carbohydrate Binding Modules in the CBEL Protein from the Oomycete Phytophthora parasitica.

    Science.gov (United States)

    Martinez, Thomas; Texier, Hélène; Nahoum, Virginie; Lafitte, Claude; Cioci, Gianluca; Heux, Laurent; Dumas, Bernard; O'Donohue, Michael; Gaulin, Elodie; Dumon, Claire

    2015-01-01

    Oomycetes are microorganisms that are distantly related to true fungi and many members of this phylum are major plant pathogens. Oomycetes express proteins that are able to interact with plant cell wall polysaccharides, such as cellulose. This interaction is thought to be mediated by carbohydrate-binding modules that are classified into CBM family 1 in the CAZy database. In this study, the two CBMs (1-1 and 1-2) that form part of the cell wall glycoprotein, CBEL, from Phytophthora parasitica have been submitted to detailed characterization, first to better quantify their interaction with cellulose and second to determine whether these CBMs can be useful for biotechnological applications, such as biomass hydrolysis. A variety of biophysical techniques were used to study the interaction of the CBMs with various substrates and the data obtained indicate that CBEL's CBM1-1 exhibits much greater cellulose binding ability than CBM1-2. Engineering of the family 11 xylanase from Talaromyces versatilis (TvXynB), an enzyme that naturally bears a fungal family 1 CBM, has produced two variants. The first one lacks its native CBM, whereas the second contains the CBEL CBM1-1. The study of these enzymes has revealed that wild type TvXynB binds to cellulose, via its CBM1, and that the substitution of its CBM by oomycetal CBM1-1 does not affect its activity on wheat straw. However, intriguingly the addition of CBEL during the hydrolysis of wheat straw actually potentiates the action of TvXynB variant lacking a CBM1. This suggests that the potentiating effect of CBM1-1 might not require the formation of a covalent linkage to TvXynB. PMID:26390127

  12. The Plant Pathogen Phytophthora andina Emerged via Hybridization of an Unknown Phytophthora Species and the Irish Potato Famine Pathogen, P. infestans

    Science.gov (United States)

    Goss, Erica M.; Cardenas, Martha E.; Myers, Kevin; Forbes, Gregory A.; Fry, William E.; Restrepo, Silvia; Grünwald, Niklaus J.

    2011-01-01

    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. PMID:21949727

  13. 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.

  14. Durable cisgenic resistance to Phytophthora infestans in potato and perspectives for applications in Africa

    NARCIS (Netherlands)

    Gheysen, G.; Heremans, B.; Droogenbroeck, van B.; Custers, R.; Vossen, J.H.; Visser, R.G.F.; Jacobsen, E.; Hutten, R.C.B.; Haverkort, A.J.

    2015-01-01

    Late blight caused by Phytophthora infestans is a major constraint in potato production. A promising strategy to combat late blight in potato is to combine different resistance genes to achieve durable resistance. Resistance genes from wild relatives can be introduced by breeding or by transformatio

  15. Bioassay conditions for infection of Pinus radiata seedlings with Phytophthora pinifolia zoospores

    Science.gov (United States)

    Phytophthora pinifolia is known to cause a devastating disease on Monterey pines in Chile. Although this pathogen is not yet present in the U.S., there is reason for concern. The main source of Monterey pine genetic material is found in California and there is potential for other important tree sp...

  16. Root susceptibility and inoculum production from roots of eastern oak species to Phytophthora ramorum

    Science.gov (United States)

    Little is known about root susceptibility of eastern tree species to Phytophthora ramorum. In this study, we examined root susceptibility and inoculum production from roots. Oak radicles of several eastern oak species were exposed to zoospore suspensions of 1, 10, 100, or 1000 zoospores per ml at ...

  17. Clonal Expansion of the Belgian Phytophthora ramorum Populations Based on New Microsatellite Markers

    Science.gov (United States)

    Coexistence of both mating types A1 and A2 within the EU1 lineage of Phytophthora ramorum has only been observed in Belgium, begging the question whether sexual reproduction is occurring. A collection of 411 Belgian P. ramorum isolates was established during a seven year survey. Our main objective w...

  18. Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation

    Science.gov (United States)

    The acquisition of plant sterols, mediated via elicitins, is required for growth and sporulation of Phytophthora spp. In this paper, we looked at the interaction between elicitins, sterols, and tannins. When ground leaf tissue was added to growth media, P. ramorum growth and sporulation was greates...

  19. Temperature effects on the onset of sporulation by Phytophthora ramorum on rhododendron Cunningham’s White

    Science.gov (United States)

    The effect of temperature and moist period on the onset of sporangia production by Phytophthora ramorum on Rhododendron ‘Cunningham’s White’ was examined with misted detached leaves held in humid chambers. Following wound-inoculation with sporangia, leaves were preincubated at 20°C for either 24 or...

  20. Infectivity and sporulation of Phytophthora ramorum on northern red oak and chestnut oak

    Science.gov (United States)

    Branches from northern red and chestnut oak seedlings were dip-inoculated with 5,000 sporangia per milliliter of Phytophthora ramorum and incubated at 100 percent relative humidity in dew chambers for 6 days. Three plants were then used to assess sporangia production, while the other three plants w...

  1. 'Cisgenese kan handje helpen in bestrijding phytophthora' (interview met Geert Kessel)

    NARCIS (Netherlands)

    Engwerda, J.; Kessel, G.J.T.

    2009-01-01

    Toluca en Bionica zijn prima biologische aardappelrassen. Maar WUR vindt een waarschuwing nodig omdat in het lab de resistentie tegen phytophthora omzeild kan worden. "Cisgenese kan helpen om resistentie tegen te gaan." Toluca en Bionica zijn prima rassen voor de biologische aardappelteelt. Ondanks

  2. Agrobacterium tumefaciens mediated transformation of the oomycete plant pathogen Phytophthora infestans

    NARCIS (Netherlands)

    Vijn, I.; Govers, F.

    2003-01-01

    Agrobacterium tumefaciens is widely used for plant DNA transformation and, more recently, has also been used to transform yeast and filamentous fungi. Here we present a protocol for Agrobacterium-mediated DNA transformation of the oomycete Phytophthora infestans, the causal agent of potato late blig

  3. Rapid Determination of Phytophthora infestans sporangia Using a Surface Plasmon Resonance Immunosensor

    DEFF Research Database (Denmark)

    Skottrup, Peter; Nicolaisen, Mogens; Justesen, Annemarie Fejer

    2007-01-01

    Phytophthora infestans is the cause of late blight disease in potato and is an economically important pathogen worldwide. Early disease detection is important to implement disease control measures. In this study a surface plasmon resonance (SPR) immunosensor for detection of P. infestans sporangia...

  4. Genes for and molecular markers linked with resistance to Phytophthora fragariae in strawberry

    NARCIS (Netherlands)

    Weg, van de W.E.; Henken, B.; Haymes, K.M.; den Nijs, A.P.M.

    1998-01-01

    A gene-for-gene model is presented which explains interactions between cultivars of strawberry and races of Phytophthora fragariae var. fragariae, the causal agent of red core (red stele) root rot. The model allows the constitution of a universal differential set of strawberry genotypes and the char

  5. Genetic variation between Phytophthora cactorum isolates differing in their ability to cause crown rot in strawberry

    NARCIS (Netherlands)

    Eikemo, H.; Klemsdal, S.S.; Riisberg, I.; Bonants, P.J.M.; Stensvand, A.; Tronsmo, A.M.

    2004-01-01

    Analysis of 44 isolates of Phytophthora cactorum, isolated from strawberry and other hosts, by AFLP showed that the crown rot pathotype is different from leather rot isolates and from P. cactorum isolated from other hosts. 16 of 23 crown rot isolates, including isolates from Europe, Japan, Australia

  6. Computational models in plant-pathogen interactions: the case of Phytophthora infestans

    OpenAIRE

    Pinzón, Andrés; Barreto, Emiliano; Bernal, Adriana; Achenie, Luke; González Barrios, Andres F; Isea, Raúl; Restrepo, Silvia

    2009-01-01

    Abstract Background Phytophthora infestans is a devastating oomycete pathogen of potato production worldwide. This review explores the use of computational models for studying the molecular interactions between P. infestans and one of its hosts, Solanum tuberosum. Modeling and conclusion Deterministic logistics models have been widely used to study pathogenicity me...

  7. Genetic analysis of Phytophthora infestans populations in the Nordic European countries reveals high genetic variability

    DEFF Research Database (Denmark)

    Brurberg, May Bente; Elameen, Abdelhameed; Le, Ving Hong;

    2011-01-01

    Late blight, caused by the oomycete Phytophthora infestans, is the most important disease of potato (Solanum tuberosum). The pathogen is highly adaptable and to get an overview of the genetic variation in the Nordic countries, Denmark, Finland, Norway and Sweden we have analyzed 200 isolates from...

  8. Stage-specific gene expression during sexual development in Phytophthora infestans

    DEFF Research Database (Denmark)

    Fabritius, Anna-Liisa; Cvitanich, Cristina; Judelson, Howard S.

    2002-01-01

    revealed that the predicted products of three of the genes had similarity to proteins that influence RNA stability, namely a ribonuclease activator, the pumilio family of RNA-binding proteins and RNase H. The products of two other mating-induced genes resembled two types of Phytophthora proteins previously...

  9. Phytophthora infestans has a plethora of phospholipase D enzymes including a subclass that has extracellular activity

    NARCIS (Netherlands)

    Meijer, H.J.G.; Hassen, H.H.; Govers, F.

    2011-01-01

    In eukaryotes phospholipase D (PLD) is involved in many cellular processes. Currently little is known about PLDs in oomycetes. Here we report that the oomycete plant pathogen Phytophthora infestans has a large repertoire of PLDs divided over six subfamilies: PXPH-PLD, PXTM-PLD, TM-PLD, PLD-likes, an

  10. Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems.

    Science.gov (United States)

    Govers, Laura L; Man In 't Veld, Willem A; Meffert, Johan P; Bouma, Tjeerd J; van Rijswick, Patricia C J; Heusinkveld, Jannes H T; Orth, Robert J; van Katwijk, Marieke M; van der Heide, Tjisse

    2016-08-31

    Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp. Zostera, P. gemini, or both, strongly affected sexual reproduction by reducing seed germination sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts. PMID:27559058

  11. Sensitivity of Progeny of Phytophthora infestans to Fungicides

    Directory of Open Access Journals (Sweden)

    Diana M. Earnshaw

    2012-05-01

    Full Text Available This study investigated fungicide sensitivity of progeny of Phytophthora infestans at the University of Wales, Bangor. Sexual progeny were derived from an A2 parent that was Metalaxyl Sensitive (MS with three A1 parents that were: MS, MS and MR (metalaxyl resistant. Sporangial and zoosporangial progeny from the parent and from some sexual progeny were also assessed. The different isolates were grown on Rye B Agar amended with different concentrations of one of five different fungicides: Metalaxyl, Propamocarb hydrochloride, Cymoxanil, Fluazinam and Azoxystrobin. The results indicated that in metalaxyl, the sensitivity of sporangial progeny was similar to that of the parent isolates, however that of zoosporangial progeny ranged from being Intermediate (MI to being Resistant (MR if the parents were Resistant (MR or from Sensitive (MS to being Intermediate (MI if the parents were Sensitive (MS. No resistance was observed among progeny that were exposed to Azoxystrobin. With the other fungicides, there was a variation in the sensitivity of sporangial and zoosporangial progeny e.g. some sensitive sporangia gave rise to highly resistant zoospores. The results showed that resistance to the most commonly used fungicides against late blight is possible. Although no resistance to the new fungicide azoxystrobin was observed, the appearance of resistance to it among other fungal pathogens has been reported. Therefore, breeders are faced with a challenge of coming up with cultivars with reduced susceptibility to late blight and plant pathologists are to come up with a wide range of fungicides so that their use can be rotated to avoid build-up of resistance isolates.

  12. Monitoring of Soft Fruit Mother Plantings Aimed at Control of Phytophthora fragariae, Causal Agent of Root Rot

    OpenAIRE

    Slobodan Milenković; Dušica Sretenović

    2007-01-01

    Phytophthora fragariae was first detected in the Republic of Serbia in 2002, and it has been included in A2 quarantine list of damaging organisms since 2003. The project titled ‘Monitoring of soft fruit mother plantings aimed at the control of Phytophthora fragariae, causal agent of root rot’ was realized over 2004 – 2005 aiming at determination of population rate of the pathogen and the control of raspberry planting material. Over that period, the total 388 samples were tested. Collected sam...

  13. Dual RNA-Sequencing of Eucalyptus nitens during Phytophthora cinnamomi Challenge Reveals Pathogen and Host Factors Influencing Compatibility

    OpenAIRE

    Meyer, Febé E.; Louise S Shuey; Naidoo, Sitha; Mamni, Thandekile; Berger, Dave K.; Myburg, Alexander A.; van den Berg, Noëlani; Naidoo, Sanushka

    2016-01-01

    Damage caused by Phytophthora cinnamomi Rands remains an important concern on forest tree species. The pathogen causes root and collar rot, stem cankers, and dieback of various economically important Eucalyptus spp. In South Africa, susceptible cold tolerant Eucalyptus plantations have been affected by various Phytophthora spp. with P. cinnamomi considered one of the most virulent. The molecular basis of this compatible interaction is poorly understood. In this study, susceptible Eucalyptus n...

  14. Monitoring of Soft Fruit Mother Plantings Aimed at Control of Phytophthora fragariae, Causal Agent of Root Rot

    OpenAIRE

    Slobodan Milenković; Dušica Sretenović

    2006-01-01

    Phytophthora fragariae was first detected in the Republic of Serbia in 2002, and it has been included in A2 quarantine list of damaging organisms since 2003. The project titled ‘Monitoring of soft fruit mother plantings aimed at the control of Phytophthora fragariae, causal agent of root rot’ was realized over 2004 – 2005 aiming at determination of population rate of the pathogen and the control of raspberry planting material. Over that period, the total 388 samples were tested. Collected sam...

  15. Alteração na atividade de peroxidase e concentração de fenóis em microtangerinas (Citrus spp. infectadas por Phytophthora parasitica

    Directory of Open Access Journals (Sweden)

    José Ribamar Gusmão Araújo

    2008-02-01

    Full Text Available The present research aimed to characterize and evaluate species and varieties of small-fruited mandarins of Tanaka’s group (Citrus spp. with potential use as rootstocks, in relation to infection to the Phytophthora parasitica, by means of foliar determination of peroxidase activity and total phenolics content. It was used the following species: C. reshni Hort. ex Tan., C. sunki Hort. ex Tan., C. pectinifera Tan., C. crenatifolia Lush., C. amblycarpa Ochese, C. aurantium L, C. reticulata Blanco and C. limonia Osb. The Center of Citrus Germoplasm of Botucatu and Cordeirópolis provide all plant material. Four resistant varieties to the stem rot and root rot infections: Pectinifera, Crenatifolia, Sun Chu Shu (clone Kat 1004 and Cleopatra (clone 1 were evaluated. Susceptible plants infected by P. parasitica presented higher activity of peroxidase, while phenolics contents were lower in susceptible group.

  16. Agro-transformation and evaluation of resistance to Phytophthora infestansin Solanum tuberosumL. variety Désirée

    Directory of Open Access Journals (Sweden)

    Jeanette Orbegozo

    2014-03-01

    Full Text Available The Oomycete Phytophthora infestans (Mont. de Bary, the causal agent of the disease known as late blight, is primarily responsible for the decreased in production performance and potato crops worldwide. The integration of the complete Rgenes sequences in the potato genome using Agro-transformation appears an alternative to be considered in the fight against this pathogen. The Rpi-blb2 gene (Rgene from the wild species Solanum bulbocastanumDunal shows a broad resistance to isolates ofP. infestans,making it an important candidate for plant breeding studies. This paper reports the integration of the Rpi-blb2gene into potato var. Désirée genome by Agrobacterium tumefaciens- mediated transformation system, the molecular characterization of 29 events transformed and whole plant infection with isolate POX67 of P. infestansfrom Peru. Désirée events [Rpi-blb2] 4 and Désirée [Rpi-blb2] 30, showed a substantial resistance to P. infestansinfection confirming complete transfer of the Rpi-blb2gene from a wild species to a cultivated species by genetic transformation.

  17. NBS Proifling Identiifes Potential Novel Locus from Solanum demissum That Confers Broad-Spectrum Resistance to Phytophthora infestans

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kun; XU Jian-fei; DUAN Shao-guang; PANG Wan-fu; BIAN Chun-song; LIU Jie; JIN Li-ping

    2014-01-01

    Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is the most serious disease of potato worldwide. The adoption of varieties with resistance genes, especially broad-spectrum resistance genes, is the most efifcient approach to control late blight. Solanum demissum is a well-known wild potato species from which 11 race-speciifc resistance genes have been identiifed, however, no broad-spectrum resistance genes like RB have been reported in this species. Here, we report a novel reisistance locus from S. demissum that potentially confer broad-spectrum resistance to late blight. A small segregating population of S. demissum were assessed for resistance to aggressive P. infestans isolates (race 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11). This coupled with nucleotide binding site (NBS) proifling analyses, led to the identiifcation of three fragments that linked to the potential candidate resistance gene(s). Cloning and sequence analysis of these fragments suggested that the identiifed resistance gene locus is located in the region containing R2 resistance gene at chromosome 4. Based on the sequences of the cloned fragments, a co-segregating sequence characterized ampliifed region (SCAR) marker, RDSP, was developed. The newly identiifed marker RDSP will be useful for marker assisted breeding and further cloning of this potential resistance gene locus.

  18. Production of antioomycete compounds active against the phytopathogens Phytophthora sojae and Aphanomyces cochlioides by clavicipitoid entomopathogenic fungi.

    Science.gov (United States)

    Putri, Sastia Prama; Ishido, Kei-Ichi; Kinoshita, Hiroshi; Kitani, Shigeru; Ihara, Fumio; Sakihama, Yasuko; Igarashi, Yasuhiro; Nihira, Takuya

    2014-05-01

    A total of 412 strains belonging to 14 genera of clavicipitoid entomopathogenic fungi (EPF) were screened for activities against two economically important plant pathogenic oomycetes, Phytophthora sojae and Aphanomyces cochlioides. To identify the antioomycete compounds produced by EPF, the extracts of 13 highly active EPF strains were characterized in detail by high performance liquid chromatography with diode array detection and high-resolution mass spectrometric detection and antioomycete assay. The antioomycete activity of several Metarhizium extracts was associated with previously isolated aurovertins, fungerin, N-(methyl-3-oxodec-6-enoyl)-2-pyrroline, and N-(methyl-3-oxodecanoyl)-2-pyrroline. The depsipeptide beauvericin was confirmed to be one of the active principles of three strains of Isaria tenuipes, which strongly inhibited mycelial growth of both P. sojae and A. cochlioides. Two known bioactive metabolites, paecilosetin and aranorosinol A, together with a novel and potent antioomycete compound, farinomalein, were isolated from the extracts of Isaria farinosa and all compounds were confirmed to have antioomycete activity. Identification of 8 antioomycete compounds from 13 clavicipitioid EPF demonstrated a new potential use of EPF as a source of compounds for the control of soil-borne plant pathogenic oomycetes. PMID:24268864

  19. Phenazine-1-carboxylic acid mediated anti-oomycete activity of the endophytic Alcaligenes sp. EIL-2 against Phytophthora meadii.

    Science.gov (United States)

    Abraham, Amith; Philip, Shaji; Jacob, Manoj Kurian; Narayanan, Sunilkumar Puthenpurackel; Jacob, C Kuruvilla; Kochupurackal, Jayachandran

    2015-01-01

    The oomycete pathogen, Phytophthora meadii, causes various diseases in Hevea brasiliensis at different stages of its life cycle. The study reports the structural characterization of the active principle from the culture filtrate of Alcaligenes sp. EIL-2 (GenBank ID: HQ641257) offering antagonistic activity against P. meadii. Gas Chromatography Mass Spectroscopy (GC-MS) analysis showed the similarity of the compound with phenazine derivatives. The specific representations of FT-IR spectrum such as 3200 cm(-1) (OH stretching, NH stretching and presence of aromatic ring), 1737 cm(-1) (carboxylic acid), 2200-2400 cm(-1) (conjugated dienes) and 1467 cm(-1), and 1422 cm(-1) (CN bonds) were an indicative of phenazine-1-carboxylic acid (PCA). The structure of the compound was further confirmed by (1)H NMR/(13)C NMR spectroscopy, DEPT experiments, and two-dimensional NMR spectral studies, including (1)H-(1)H COSY and (1)H-(13)C HSQC as PCA with the molecular formula of C₁₃H₈N₂O₂. P. meadii was sensitive to purified PCA extract from the endophyte and a concentration of 5 μg/ml completely inhibited the mycelia growth. PCA also showed zoosporicidal activity against P. meadii zoospores. This is the first study of this kind where PCA from an endophyte of H. brasiliensis is being confirmed to carry antagonistic activity against P. meadii. PMID:24985092

  20. PsVPS1, a dynamin-related protein, is involved in cyst germination and soybean infection of Phytophthora sojae.

    Directory of Open Access Journals (Sweden)

    Delong Li

    Full Text Available Plant pathogens secrete effector proteins to suppress plant immunity. However, the mechanism by which oomycete pathogens deliver effector proteins during plant infection remains unknown. In this report, we characterized a Phytophthora sojae vps1 gene. This gene encodes a homolog of the Saccharomyces cerevisiae vacuolar protein sorting gene vps1 that mediates budding of clathrin-coated vesicles from the late Golgi, which are diverted from the general secretory pathway to the vacuole. PsVPS1-silenced mutants were generated using polyethylene glycol-mediated protoplast stable transformation and were viable but had reduced extracellular protein activity. The PsVPS1-silenced mutants showed impaired hyphal growth, and the shapes of the vacuoles were highly fragmented. Silencing of PsVPS1 affected cyst germination as well as the polarized growth of germinated cysts. Silenced mutants showed impaired invasion of susceptible soybean plants regardless of wounding. These results suggest that PsVPS1 is involved in vacuole morphology and cyst development. Moreover, it is essential for the virulence of P. sojae and extracellular protein secretion.

  1. Efeito do lodo de esgoto na indução de supressividade in vitro a Phytophthora nicotianae Effect of sewage sludge in vitro to suppress Phytophthora nicotianae

    OpenAIRE

    Carolina Leoni; Raquel Ghini

    2003-01-01

    Uma alternativa de manejo das doenças causadas por Phytophthora spp. é o uso de matéria orgânica. No presente trabalho foi avaliada a potencialidade do lodo de esgoto na indução de supressividade in vitro a P. nicotianae. O efeito do lodo de esgoto incorporado ao solo na sobrevivência de P. nicotianae foi avaliado mediante um experimento fatorial com dois fatores: doses de lodo de esgoto (0, 10, 20 e 40% p/p) e concentrações de inóculo [0, 10 ou 20 g de grãos de trigo (Triticum aestivum) colo...

  2. Evaluation of Soybean Germplasm from Provinces in Northeast China for Resistance to Phytophthora sojae

    Institute of Scientific and Technical Information of China (English)

    XU Xiu-hong; PAN Jun-bo; QU Juan-juan; YANG Qing-kai

    2004-01-01

    Soybean Phytophthora root rot (Phytophthora sojae) is a severe disease all over the world. Soybean germplasm from central and southern China for resistance has been evaluated by American researchers on a large scale. P. sojae has been found frequently in northeast of China in recent years, but not systematic evaluation of soybean germplasm for resistance has occurred there. By means of hypocotyl inoculation, 922 cultivars/lines from northeast of China were screened and evaluated for their response to race 1, and 25 of P. sojae. Generally resistance was less frequent in northeast of China than in central and southern China. Five cultivars/lines were identified that confer resistant responses to race 1, 3, 8, 25 and four additional isolates of P. sojae. These cultivars/lines may provide valuable sources of resistance for future breeding programs.

  3. E-beam irradiation for the control of Phytophthora nicotianae var. nicotianae in stonewool cubes

    Directory of Open Access Journals (Sweden)

    Ptaszek Magdalena

    2015-09-01

    Full Text Available Effectiveness of electron beam irradiation was evaluated against Phytophthora nicotianae var. nicotianae, the causal agent of stem base and root rot of tomato. In laboratory trials, irradiation of 7-day-old Phytophthora cultures growing on potato-dextrose-agar (PDA medium with 1 kGy resulted in the disintegration of the pathogen’s hyphae. Increasing the irradiation dose to 3 kGy caused decay of the hyphae. Irradiation of infested stonewool with 5 kGy caused decrease of the pathogen population about 5 times. Application of 20 kGy completely eliminated the pathogen from stonewool. Irradiation of substratum resulted in significant increase of tomato seedlings healthiness, especially when the dose 20 kGy was applied.

  4. Applied Biotechnology to combat the late blight in potato caused by Phytophthora infestans

    OpenAIRE

    Haverkort, A.J.; Struik, P. C.; Visser, R. G. F.; Jacobsen, E.

    2009-01-01

    Potato is an important crop, grown worldwide. It suffers from many pests and diseases among which late blight, caused by the oomycete Phytophthora infestans, is the worst. The disease is still causing major damage in many potato production areas and control is only possible by applying fungicides frequently. The knowledge on the molecular biology and genetics of the interaction between the plant and the oomycete is developing rapidly. These are relevant fields of study, currently dominated by...

  5. Dimethomorph and metalaxyl sensitivity in somatic hybrids of Phytophthora parasitica obtained by protoplast fusion

    OpenAIRE

    Chabanne, Kamel; Leroux, P; Bompeix, G.; Maia, N.

    1996-01-01

    Protoplasts were successfully isolated from wild-type and mutant strains of #Phytophthora nicotianae$ var. #parasitica$ using Novozym 234. Putative somatic hybrids were recovered following protoplast fusions from the first time to dimethomorph resistant strain P 310 (Dim r) or metalaxyl P 26 (Met r) by selection on agar amended with dimethomorph and metalaxyl. Fusion products from this cross were resistant to dimethomorph and metalaxyl. Zoospore progeny from the fusion products retained this ...

  6. Population studies on Phytophthora infestans on potatoes and tomatoes in southern Germany

    OpenAIRE

    Moller, K.; Dilger, M.; Habermeyer, J.; Zinkernagel, V.; Flier, W.G.; Hausladen, H.

    2009-01-01

    Fifty-seven isolates of Phytophthora infestans from blighted potato foliage were collected in 1995 in southern Germany and analysed for mating type and sensitivity to metalaxyl. Fifty-six of them were characterised as A1 and one as A2 mating types. Resistance to metalaxyl was observed frequently: 53 isolates were resistant, three were partially sensitive, and one was sensitive. In a subsequent field study in 1999, 84 isolates collected from blighted potato and tomato foliage were analysed for...

  7. Stable transformation of the oomycete, Phytophthora infestans, using microprojectile bombardment

    DEFF Research Database (Denmark)

    Cvitanich, Cristina; Judelson, Howard S.

    2003-01-01

    Germinated asexual sporangia, zoospores, and mycelia of Phytophthora infestans were transformed to G418-resistance by microprojectile bombardment. After optimization, an average of 14 transformants/shot were obtained, using 10(6) germinated sporangia and gold particles coated with 1 microg of...... from primary transformants through G418 selection of zoospores. To facilitate the optimization of transformation, experiments were performed using a vector containing neomycin phosphotransferase (npt) and beta-glucuronidase (GUS) genes fused to oomycete transcriptional regulatory sequences. To indicate...

  8. Nature of vegetative cycle in Phytophthora parasitica Dastur and palmivora (BUTLER) BUTLER

    International Nuclear Information System (INIS)

    Up to now, neither cytological nor genetical studies have clearly demonstrated the 'ploidy' degree of somatic nuclei in different species of Phytophthora. Two complementary studies, using biological effect of γ rays upon zoospores, and microspectrophotometric techniques measuring relative amount of DNA by nucleus in zoospores or in hyphae, allowed to demonstrate diploid nature of the vegetative phase in P. palmivora (BUTLER) BUTLER and P. parasitica DASTUR cycles

  9. Biological control of Phytophthora nicotianae and organic media standardization in citrus nurseries.

    OpenAIRE

    SALEM, Assem

    2005-01-01

    Investigations were carried out for the biological control of Phytophthora nicotianae (citrus root rot) on two citrus rootstocks (Sour orange and Troyer citrange) transplanted in organic and conventional substrates, treated with the semi-commercial product Clonotri (Trichoderma harzianum and Clonostachys rosea) and Metalaxyl-M as a chemical control. Clonotri was more efficient than the chemical treatment increasing plant high and weight. Organic products (Chitosan, Quillaia, Equiseto and Clon...

  10. Assessing zoospore Phytophthora activity to enhance disease management and promote ecological surveillance of chestnut ink disease

    OpenAIRE

    Gouveia, Eugénia; Nunes, Luís

    2013-01-01

    Phytophthora cinnamomi and P. cambivora are soil borne Oomycetes that cause Chestnut Ink Disease, a lethal and widespread disease of the European chestnut (Castanea saliva Mill. Zoospores are the main infective propagules that actively swimming in liquid environments, reach the roots, encyst and infect the host. Gathering these biological characteristics we studied, on potting mix previously infested with P. cinnamomi, zoospore re lease and environmental conditions that prom...

  11. Genetic variation between Phytophthora cactorum isolates differing in their ability to cause crown rot in strawberry

    OpenAIRE

    Eikemo, H; Klemsdal, S.S.; Riisberg, I.; Bonants, P.J.M.; Stensvand, A.; Tronsmo, A.M.

    2004-01-01

    Analysis of 44 isolates of Phytophthora cactorum, isolated from strawberry and other hosts, by AFLP showed that the crown rot pathotype is different from leather rot isolates and from P. cactorum isolated from other hosts. 16 of 23 crown rot isolates, including isolates from Europe, Japan, Australia, and New Zealand, were identical in an analysis based on 96 polymorphic bands from seven primer combinations. Leather rot isolates of strawberry could not be distinguished from isolates from other...

  12. Biochemical contents of pepper seedlings inoculated with phytophthora infestans and arbuscular mycorrhiza

    OpenAIRE

    Odebode A.C.; Salami A.O.

    2004-01-01

    The effect of interactions between Arbuscular Glomus etunicatum and fungus Phytophthora infestans on biochemical contents of pepper plants was investigated in a greenhouse experiment. The sugar contents (i.e. Glucose fructose and sucrose) were higher in the control and mycorrhizal inoculated pepper seedlings and the lowest in pathogen inoculated seedlings. Free amino acids were the highest in the simultaneously inoculated pepper seedlings while total phenol was found to be the highest in pepp...

  13. Computational models in plant-pathogen interactions: the case of Phytophthora infestans

    OpenAIRE

    González Barrios Andres F; Achenie Luke; Bernal Adriana; Barreto Emiliano; Pinzón Andrés; Isea Raúl; Restrepo Silvia

    2009-01-01

    Abstract Background Phytophthora infestans is a devastating oomycete pathogen of potato production worldwide. This review explores the use of computational models for studying the molecular interactions between P. infestans and one of its hosts, Solanum tuberosum. Modeling and conclusion Deterministic logistics models have been widely used to study pathogenicity mechanisms since the early 1950s, and have focused on processes at higher biological resolution levels. In recent years, owing to th...

  14. Quantitative proteomics and transcriptomics of potato in response to Phytophthora infestans in compatible and incompatible interactions

    OpenAIRE

    Ali, Ashfaq; Alexandersson, Erik; Sandin, Marianne; Resjö, Svante; Lenman, Marit; Hedley, Pete; Levander, Fredrik; Andreasson, Erik

    2014-01-01

    Background In order to get global molecular understanding of one of the most important crop diseases worldwide, we investigated compatible and incompatible interactions between Phytophthora infestans and potato (Solanum tuberosum). We used the two most field-resistant potato clones under Swedish growing conditions, which have the greatest known local diversity of P. infestans populations, and a reference compatible cultivar. Results Quantitative label-free proteomics of 51 apoplastic secretom...

  15. Patogenicidad de "Phytophthora spp." causantes de podredumbre radical de "Quercus ilex ssp." "ballota" en viveros forestales

    OpenAIRE

    Andicoberry de los Reyes, Sergio; M. E. Sánchez; Trapero Casas, Antonio

    2004-01-01

    Within a research project on quality of plants for forestation of agricultural lands, we studied the etiology of a root rot affecting holm oak (Quercus ilex ssp. ballota) seedlings in two forest nurseries in southern Spain. Major disease symptoms were foliar wilting and necrosis of feeder roots. Three fungal species, Phytophthora cinnamomi, P. cryptogea and P. drechsleri, were isolated from necrotic roots of holm oak. Isolates of the three species showed similar growth patterns at different t...

  16. Mitochondrial DNA assessment of Phytophthora infestans isolates from potato and tomato in Ethiopia reveals unexpected diversity.

    Science.gov (United States)

    Shimelash, Daniel; Hussien, Temam; Fininsa, Chemeda; Forbes, Greg; Yuen, Jonathan

    2016-08-01

    Mitochondrial DNA (mtDNA) haplotypes were determined using restriction fragment length polymorphism (RFLP) for P. infestans sampled from 513 foliar lesions of late blight found on potato and tomato in different regions of Ethiopia. Among the four reported mitochondrial haplotypes of Phytophthora infestans, Ia, Ib and IIb were detected in 93 % of the samples analyzed but the vast majority of these were Ia. The remaining 7 % represented a previously unreported haplotype. DNA sequencing of this new haplotype also confirmed a single base nucleotide substitution that resulted in loss of EcoRI restriction site and gain of two additional MspI sites in cox1 and atp1 genes, respectively. There were 28 polymorphic sites among all nucleotide sequences including five reference isolates. Sites with alignment gaps were observed in P4 with one nucleotide deletion in 11 Ethiopian isolates. None of the reference sequence produced frame-shifts, with the exception of the 3-nucleotide deletion in the P4 region by Phytophthora andina, a feature that can be used to distinguish the new Ethiopian isolates from P. andina. While a distinguishing molecular data presented here clearly separated them from P. infestans, 7 % of the isolates that share this feature formed an important component of the late blight pathogen causing disease on Solanum tuberosum in Ethiopia. Thus, these Ethiopian isolates could represent a novel Phytophthora species reported for the first time here. PMID:26873223

  17. Mutation breeding against black pod (Phytophthora pod rot) disease of cacao (Theobroma cacao)

    International Nuclear Information System (INIS)

    Black pod rot disease, caused by Phytophthora palmivora, is an important disease of cacao (Theobroma cacao L.) in Nigeria and other cacao producing countries of West Africa and Latin America. A naturally occurring source of genetic resistance to the disease has not been found. This paper completes the report, the first part of which was published in Induced Mutations in Vegetatively Propagated Plants, IAEA, Vienna (1973). The survivors of the irradiated seedlings reported on in this publication were transplanted to the field along with their controls. When the Phytophthora pod disease season began in 1973, all experimental plants along with the controls were sprayed with active and freshly prepared dense sporangial suspension of P. palmivora. Observations on Phytophthora infection were recorded at two-weekly intervals for three months. Results were pooled for each set of experimental plants, after having confirmed that no marked difference appeared among individual plants of each group. Contrary to the observations recorded at the nursery stage, all experimental plants that showed no infection indicated disease infection levels normally characteristic of the F3 Amazon cultivar of Cacao in Nigeria. Although the nursery and the field data are difficult to reconcile and interpret, it is suggested that probably temporary disease tolerance/resistance, which some irradiated plants showed at the nursery (seedling) stage, was lost as the plants matured, thus suggesting different resistance factor systems for juvenile and mature cacao trees. (author)

  18. Mitochondrial genome sequences reveal evolutionary relationships of the Phytophthora Ic clade species

    Science.gov (United States)

    Lassiter, Erica S.; Russ, Carsten; Nusbaum, Chad; Zeng, Qiandong; Saville, Amanda; Olarte, Rodrigo; Carbone, Ignazio; Hu, Chia-Hui; Seguin-Orlando, Andaine; Samaniego, Jose A; Thorne, Jeffrey L.; Ristaino, Jean B.

    2015-01-01

    Phytophthora infestans is one of the most destructive plant pathogens of potato and tomato globally. The pathogen is closely related to four other Phytophthora species including P. phaseoli, P. ipomoeae, P. mirabilis, and P. andina that are important pathogens of other wild and domesticated hosts. P. andina is an interspecific hybrid between P. infestans and an unknown Phytophthora species. We have sequenced mitochondrial genomes of the sister species of P. infestans in order to resolve the evolutionary relationships within the clade. Phylogenetic analysis indicates that the P. phaseoli mitochondrial lineage is basal within the clade. P. mirabilis and P. ipomoeae are sister lineages and share a common ancestor with the Ic mitochondrial lineage of P. andina. These lineages in turn are sister to the P. infestans and P. andina Ia mitochondrial lineages. The P. andina Ic lineage diverged much earlier than the P. andina Ia mitochondrial lineage and P. infestans. The presence of two mitochondrial lineages in P. andina supports the hybrid nature of this species. The ancestral state of the P. andina Ic lineage in the tree and its occurrence only in the Andean regions of Ecuador, Colombia and Peru suggests further sampling in the Americasis warranted to understand the distribution of this species hybrid in nature. PMID:25754775

  19. Phytophthora parsiana sp. nov., a new high-temperature tolerant species.

    Science.gov (United States)

    Mostowfizadeh-Ghalamfarsa, R; Cooke, D E L; Banihashemi, Z

    2008-07-01

    As part of a study to examine the phylogenetic history of the taxonomically challenging species Phytophthora cryptogea and P. drechsleri, a distinct monophyletic group of isolates, previously described as P. drechsleri or P. cryptogea, were characterised. Analysis of their rDNA ITS sequences indicated that these isolates were distinct from P. drechsleri, P. cryptogea, and all members of Phytophthora ITS clades 1-8, clustering instead alongside basal groups previously described as clades 9 and 10. This group comprised six isolates all of which were isolated from woody plants, such as pistachio (Pistacia vera, Iran and USA), fig (Ficus carica, Iran), and almond (Prunus dulcis, Greece). Analysis of sequence data from nuclear (beta-tubulin and translation elongation factor 1alpha) and mitochondrial (cytochrome c oxidase subunit I) genes confirmed the ITS-based analysis as these isolates formed a distinct monophyletic group in all NJ trees. The isolates were fast growing with a relatively high optimum growth temperature of 30 degrees C and, in most cases, rapid colony growth even at 37 degrees C. The isolates produced complex colony patterns on almost all media, especially corn meal agar (CMA). Phylogenetic analysis and examination of all the other morphological and physiological data lead us to infer that this taxon has not been described previously. As this taxon was first isolated and described from Iran we propose that this taxon be formally designated as Phytophthora parsiana. PMID:18501580

  20. A novel elicitor protein from Phytophthora parasitica induces plant basal immunity and systemic acquired resistance.

    Science.gov (United States)

    Chang, Yi-Hsuan; Yan, Hao-Zhi; Liou, Ruey-Fen

    2015-02-01

    The interaction between Phytophthora pathogens and host plants involves the exchange of complex molecular signals from both sides. Recent studies of Phytophthora have led to the identification of various apoplastic elicitors known to trigger plant immunity. Here, we provide evidence that the protein encoded by OPEL of Phytophthora parasitica is a novel elicitor. Homologues of OPEL were identified only in oomycetes, but not in fungi and other organisms. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) revealed that OPEL is expressed throughout the development of P. parasitica and is especially highly induced after plant infection. Infiltration of OPEL recombinant protein from Escherichia coli into leaves of Nicotiana tabacum (cv. Samsun NN) resulted in cell death, callose deposition, the production of reactive oxygen species and induced expression of pathogen-associated molecular pattern (PAMP)-triggered immunity markers and salicylic acid-responsive defence genes. Moreover, the infiltration conferred systemic resistance against a broad spectrum of pathogens, including Tobacco mosaic virus, the bacteria wilt pathogen Ralstonia solanacearum and P. parasitica. In addition to the signal peptide, OPEL contains three conserved domains: a thaumatin-like domain, a glycine-rich protein domain and a glycosyl hydrolase (GH) domain. Intriguingly, mutation of a putative laminarinase active site motif in the predicted GH domain abolished its elicitor activity, which suggests enzymatic activity of OPEL in triggering the defence response. PMID:24965864

  1. The CAZyome of Phytophthora spp.: A comprehensive analysis of the gene complement coding for carbohydrate-active enzymes in species of the genus Phytophthora

    Directory of Open Access Journals (Sweden)

    Laird Emma W

    2010-09-01

    Full Text Available Abstract Background Enzymes involved in carbohydrate metabolism include Carbohydrate esterases (CE, Glycoside hydrolases (GH, Glycosyl transferases (GT, and Polysaccharide lyases (PL, commonly referred to as carbohydrate-active enzymes (CAZymes. The CE, GH, and PL superfamilies are also known as cell wall degrading enzymes (CWDE due to their role in the disintegration of the plant cell wall by bacterial and fungal pathogens. In Phytophthora infestans, penetration of the plant cells occurs through a specialized hyphal structure called appressorium; however, it is likely that members of the genus Phytophthora also use CWDE for invasive growth because hyphal forces are below the level of tensile strength exhibited by the plant cell wall. Because information regarding the frequency and distribution of CAZyme coding genes in Phytophthora is currently unknown, we have scanned the genomes of P. infestans, P. sojae, and P. ramorum for the presence of CAZyme-coding genes using a homology-based approach and compared the gene collinearity in the three genomes. In addition, we have tested the expression of several genes coding for CE in cultures grown in vitro. Results We have found that P. infestans, P. sojae and P. ramorum contain a total of 435, 379, and 310 CAZy homologs; in each genome, most homologs belong to the GH superfamily. Most GH and PL homologs code for enzymes that hydrolyze substances present in the pectin layer forming the middle lamella of the plant cells. In addition, a significant number of CE homologs catalyzing the deacetylation of compounds characteristic of the plant cell cuticle were found. In general, a high degree of gene location conservation was observed, as indicated by the presence of sequential orthologous pairs in the three genomes. Such collinearity was frequently observed among members of the GH superfamily. On the other hand, the CE and PL superfamilies showed less collinearity for some of their putative members

  2. The Transcriptome of Compatible and Incompatible Interactions of Potato (Solanum tuberosum) with Phytophthora infestans Revealed by DeepSAGE Analysis

    DEFF Research Database (Denmark)

    Gyetvai, Gabor; Sønderkær, Mads; Göbel, Ulrike;

    2012-01-01

    Late blight, caused by the oomycete Phytophthora infestans, is the most important disease of potato (Solanum tuberosum). Understanding the molecular basis of resistance and susceptibility to late blight is therefore highly relevant for developing resistant cultivars, either by marker-assissted s......Late blight, caused by the oomycete Phytophthora infestans, is the most important disease of potato (Solanum tuberosum). Understanding the molecular basis of resistance and susceptibility to late blight is therefore highly relevant for developing resistant cultivars, either by marker...

  3. Resistance to Phytophthora in mutant lines of currant tomato and in their original forms

    International Nuclear Information System (INIS)

    Information on the production of currant tomato mutants is contained in a previous report. Evaluation of fruit resistance against Phytophthora infestans (Mont.) de Bary was carried out with pathotypes T0 and T1. For artificial infection we used mainly a culture of T1 (isolate 275), supplied by the Byelorussian Scientific Research Institute of Potato, Fruit and Vegetable Growing at Samokhvalovich. As inoculum for T0, a local population of the potato pathotype from the village of Shebantsevo, Moscow province was used. The standard variety 'Gruntovyj gribovskij 1180' was used as the control. Green fruits were taken from the first or second raceme of 20 plants. They were inoculated by spraying in plastic cuvettes with moist filter paper. The cuvettes were covered with glass and maintained at temperature of 18-20 deg. C. The results were checked 5, 9 and 12 days after inoculation. Under natural conditions, each of the 20 plants was also evaluated. As result, three lines with increased resistance to Phytophthora were selected from the original wild-type of currant tomato. Induced mutant forms were tested in the same way for resistance to Phytophthora. Data is presented from 4 years study. Of 26 mutant lines studied, we identified seven whose fruit displayed a stable and enhanced resistance to Phytophthora under both laboratory and field conditions. With regard to leaf infection of these lines, positive results were not obtained. There appears to be no direct relationship between resistance to Phytophthora of the fruit and the leaves. The mutant lines are of determinate type with early and medium ripening time. The average fruit weight is 5-33 g; in the case of the original specimen, it is only 0.9-1.7 g. The fruits have a pleasant sour-sweet taste and a thick skin. It is noteworthy that the mutant lines selected on the basis of their suitability for cultivation not only showed the resistance selected from the wild-type, but in a number of cases even turned out to be more

  4. The inclusion of downy mildews in a multi-locus-dataset and its reanalysis reveals a high degree of paraphyly in Phytophthora.

    Science.gov (United States)

    Runge, Fabian; Telle, Sabine; Ploch, Sebastian; Savory, Elizabeth; Day, Brad; Sharma, Rahul; Thines, Marco

    2011-12-01

    Pathogens belonging to the Oomycota, a group of heterokont, fungal-like organisms, are amongst the most notorious pathogens in agriculture. In particular, the obligate biotrophic downy mildews and the hemibiotrophic members of the genus Phytophthora are responsible for a huge variety of destructive diseases, including sudden oak death caused by P. ramorum, potato late blight caused by P. infestans, cucurbit downy mildew caused by Pseudoperonospora cubensis, and grape downy mildew caused by Plasmopara viticola. About 800 species of downy mildews and roughly 100 species of Phytophthora are currently accepted, and recent studies have revealed that these groups are closely related. However, the degree to which Phytophthora is paraphyletic and where exactly the downy mildews insert into this genus in relation to other clades could not be inferred with certainty to date. Here we present a molecular phylogeny encompassing all clades of Phytophthora as represented in a multi-locus dataset and two representatives of the monophyletic downy mildews from divergent genera. Our results demonstrate that Phytophthora is at least six times paraphyletic with respect to the downy mildews. The downy mildew representatives are consistently nested within clade 4 (contains Phytophthora palmivora), which is placed sister to clade 1 (contains Phytophthora infestans). This finding would either necessitate placing all downy mildews and Phytopthora species in a single genus, either under the oldest generic name Peronospora or by conservation the later name Phytophthora, or the description of at least six new genera within Phytophthora. The complications of both options are discussed, and it is concluded that the latter is preferable, as it warrants fewer name changes and is more practical. PMID:22679601

  5. Influence of electron beam irradiation on growth of Phytophthora cinnamomi and its control in substrates

    International Nuclear Information System (INIS)

    Very extensive production procedure, especially in plants growing under covering, require methods, which would allow quick elimination or substantial reduction of populations of specific pathogens without affecting the growth and development of the cultivated plants. Among soil-borne pathogens, the Phytophthora species are especially dangerous for horticultural plants. In this study, irradiation with electron beam was applied to control Phytophthora cinnamomi. The influence of irradiation dose on the reduction of in vitro growth and the population density of the pathogen in treated peat and its mixture with composted pine bark (1:1), as well as the health of Chamaecyparis lawsoniana and Lavandula angustifolia plants were evaluated. Application of irradiation at a dose of 1.5 kGy completely inhibited the in vitro development of P. cinnamomi. This irradiation effect was connected with the disintegration of the hyphae and spores of the species. Irradiation of peat and its mixture with composted pine bark with 10 kGy resulted in the inhibition of stem base rot development in Ch. lawsoniana. Symptoms of the disease were not observed when the substrates were treated with 15 kGy. In the case of L. angustifolia, stem root rot was not observed on cuttings transplanted to infected peat irradiated at a dose of 10 kGy. Irradiation of the horticultural substrates did not affect plant growth. - Highlights: ► Electron beam irradiation is effective against soil-borne pathogens. Application of irradiation at dose 1.5 kGy completely inhibited in vitro development of Phytophthora cinnamomi. ► Irradiation of horticultural substrata did not influence the growth of plants.

  6. Phytophthora root and stem rot – new disease of Ilex aquifolium "Myrtifolia” in Poland

    Directory of Open Access Journals (Sweden)

    Leszek B. Orlikowski

    2014-08-01

    Full Text Available Phytophthora cinnamomi was often isolated from rotted roots and stems of English holly "Myrtifolia" together with Alternaria alternata, Cylindrocarpon destructanss, Fusarium avenaceum and other fungal species. Inoculation of leaf blades and stem parts of 4 species and 12 holly cultivars with P. cinnamomi showed the spread of rot symptoms on the most of them. On Ilex crenata tissues necrosis did not develop or spread slowly. Isolation of P. cinnamomi only from one holly cultivar in surveyed nursery indicate on transmission of the pathogen with imported young plants.

  7. New record of Phytophthora root and stem rot of Lavandula angustifolia

    Directory of Open Access Journals (Sweden)

    Leszek B. Orlikowski

    2013-12-01

    Full Text Available Phytophthora cinnamomi was isolated from rotted root and stem parts of lavender as well as from soil taken from containers with diseased plants. Additionally Botrytis cinerea, Fusarium spp. and Sclerotinia sclerotiorum were often isolated from diseased tissues. P. cinnamomi colonised leaves and stem parts of 4 lavender species in laboratory trials and caused stem rot of plants in greenhouse experiments. Cardinal temperature for in vitro growth were about 7,5 and 32°C with optimum 25-27,5°C. The species colonised stem tissues at temperature ranged from 10° to 32°C.

  8. Resistance to fungicides and streptomycin in Phytophthora parasitica : genetic determinism and use in hybrid determination

    OpenAIRE

    Chabanne, Kamel; Leroux, P; Bompeix, G.

    1996-01-01

    Progeny of #Phytophthora parasitica$ derived from the pairings between metalaxyl-resistant MET.1 (A2) carrying homozygous dominant resistance and S1 (A1) wild-type consisted of selfs from each parent and hybrids carrying heterozygous dominant resistance. Similar results were obtained when dimetomorph-resistant DT.1 (A1) carrying homozygous dominant resistance was paired with wild-type S2 (A2). Progeny from the pairing between homozygous Str resistant (A1) to streptomycin and A2 resistant to m...

  9. Mating Types of Phytophthora infestans Isolates and Their Responses to Metalaxyl and Dimethomorph in Korea

    OpenAIRE

    Jeom-Soon Kim; Young-Gyu Lee; Min Kwon; Ju-Il Kim; Samnyu Jee; Kyeong-Hun Park

    2014-01-01

    Phytophthora infestans was isolated from potato leaves collected from main potato producing areas in Korea during 2009-2011. In 2009, 99 isolates tested were all A1 mating type. Two of 64 isolates in 2010 and two of 78 isolates in 2011 were A2 mating type and they were found only in Miryang area. Among 99 isolates examined in 2009, 13.1% was resistant to metalaxyl, 3.1% was intermediate resistant and 83.8% was sensitive. In 2010, 19.4% of 62 isolates was resistant, 4.8% was interm...

  10. The Irish potato famine pathogen Phytophthora infestans translocates the CRN8 kinase into host plant cells

    OpenAIRE

    Damme, van, DA Dick; Bozkurt, T.O.; Cakir, C.; Schornack, S.; Sklenar, J.; Jones, A.M.E.; Kamoun, S

    2012-01-01

    Phytopathogenic oomycetes, such as Phytophthora infestans, secrete an arsenal of effector proteins that modulate plant innate immunity to enable infection. We describe CRN8, a host-translocated effector of P. infestans that has kinase activity in planta. CRN8 is a modular protein of the CRN effector family. The C-terminus of CRN8 localizes to the host nucleus and triggers cell death when the protein is expressed in planta. Cell death induction by CRN8 is dependent on its localization to the p...

  11. A Phytophthora infestans G-Protein β Subunit Is Involved in Sporangium Formation

    OpenAIRE

    Latijnhouwers, Maita; Govers, Francine

    2003-01-01

    The heterotrimeric G-protein pathway regulates cellular responses to a wide range of extracellular signals in virtually all eukaryotes. It also controls various developmental processes in the oomycete plant pathogen Phytophthora infestans, as was concluded from previous studies on the role of the G-protein α-subunit PiGPA1 in this organism. The expression of the P. infestans G-protein β-subunit gene Pigpb1 was induced in nutrient-starved mycelium before the onset of sporangium formation. The ...

  12. A Phytophthora infestans G-protein beta subunit is involved in sporangium formation

    OpenAIRE

    Latijnhouwers, M.; Govers, F.

    2003-01-01

    The heterotrimeric G-protein pathway regulates cellular responses to a wide range of extracellular signals in virtually all eukaryotes. It also controls various developmental processes in the oomycete plant pathogen Phytophthora infestans, as was concluded from previous studies on the role of the G-protein alpha-subunit PiGPA1 in this organism. The expression of the P. infestans G-protein beta-subunit gene Pigpb1 was induced in nutrient-starved mycelium before the onset of sporangium formatio...

  13. An Andean origin of Phytophthora infestans inferred from mitochondrial and nuclear gene genealogies

    OpenAIRE

    Gómez-Alpizar, Luis; Carbone, Ignazio; Ristaino, Jean Beagle

    2007-01-01

    Phytophthora infestans (Mont.) de Bary caused the 19th century Irish Potato Famine. We assessed the genealogical history of P. infestans using sequences from portions of two nuclear genes (β-tubulin and Ras) and several mitochondrial loci P3, (rpl14, rpl5, tRNA) and P4 (Cox1) from 94 isolates from South, Central, and North America, as well as Ireland. Summary statistics, migration analyses and the genealogy of current populations of P. infestans for both nuclear and mitochondrial loci are con...

  14. Phytophthora infestans Has a Plethora of Phospholipase D Enzymes Including a Subclass That Has Extracellular Activity

    OpenAIRE

    2011-01-01

    In eukaryotes phospholipase D (PLD) is involved in many cellular processes. Currently little is known about PLDs in oomycetes. Here we report that the oomycete plant pathogen Phytophthora infestans has a large repertoire of PLDs divided over six subfamilies: PXPH-PLD, PXTM-PLD, TM-PLD, PLD-likes, and type A and B sPLD-likes. Since the latter have signal peptides we developed a method using metabolically labelled phospholipids to monitor if P. infestans secretes PLD. In extracellular medium of...

  15. Phytophthora infestans has a plethora of phospholipase D enzymes including a subclass that has extracellular activity.

    Directory of Open Access Journals (Sweden)

    Harold J G Meijer

    Full Text Available In eukaryotes phospholipase D (PLD is involved in many cellular processes. Currently little is known about PLDs in oomycetes. Here we report that the oomycete plant pathogen Phytophthora infestans has a large repertoire of PLDs divided over six subfamilies: PXPH-PLD, PXTM-PLD, TM-PLD, PLD-likes, and type A and B sPLD-likes. Since the latter have signal peptides we developed a method using metabolically labelled phospholipids to monitor if P. infestans secretes PLD. In extracellular medium of ten P. infestans strains PLD activity was detected as demonstrated by the production of phosphatidic acid and the PLD specific marker phosphatidylalcohol.

  16. Evaluación de la resistencia aparente de individuos de encina a Phytophthora cinnamomi Rands.

    OpenAIRE

    Ariza-Mateos, David; Jorge Cerrudo, Inmaculada; Jorrín-Novo, Jesús V.; Porras Tejero, Carlos Javier; Navarro Cerrillo, Rafael M.

    2009-01-01

    En este trabajo se ha inoculado con Phytophthora cinnamomi plantas de encina producidas a partir de bellotas de árboles seleccionados en campo por su resistencia o susceptibilidad aparente a esta enfermedad. La altura final de los brinzales no mostró diferencias significativas, siendo estas más evidentes en los valores de fluorescencia y concentración de fenoles solubles en la raíz. La concentración de fenoles solubles en las raíces, ocho meses después, de la inoculación fue mayor en todos lo...

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

    Science.gov (United States)

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

    2015-06-01

    As the causal agent of late blight on potato, Phytophthora infestans is one of the most destructive plant pathogens worldwide and widely known as the Irish potato famine pathogen. Understanding the genetic structure of P. infestans populations is important both for breeding and deployment of resistant varieties and for development of disease control strategies. Here, we investigate the population genetic structure of P. infestans in a potato germplasm nursery in northwestern China. In total, 279 isolates were recovered from 63 potato varieties or lines in 2010 and 2011, and were genotyped by mitochondrial DNA haplotypes and a set of nine simple-sequence repeat markers. Selected isolates were further examined for virulence on a set of differential lines containing each resistance (R) gene (R1 to R11). The overall P. infestans population was characterized as having a low level of genetic diversity and resistance to metalaxyl, and containing a high percentage of individuals that virulent to all 11 R genes. Both A1 and A2 mating types as well as self-fertile P. infestans isolates were present but there was no evidence of sexual reproduction. The low level of genetic differentiation in P. infestans populations is probably due to the action of relatively high levels of migration as supported by analysis of molecular variance (P < 0.01). Migration and asexual reproduction were the predominant mechanisms influencing the P. infestans population structure in the germplasm nursery. Therefore, it is important to ensure the production of pathogen-free potato seed tubers to aid sustainable production of potato in northwestern China. PMID:25738550

  18. Anti-Phytopthora capsici Activities and Potential Use as Antifungal in Agriculture of Alpinia galanga Swartz, Curcuma longa Linn, Boesenbergia pandurata Schut and Chromolaena odorata: Bioactivities Guided Isolation of Active Ingredients

    Directory of Open Access Journals (Sweden)

    Wilart Pompimon

    2009-01-01

    Full Text Available Problem statement: Plant derived fungicides are now being subjects of many research groups. These secondary metabolites have enormous potential to inspire and influence modern agrochemical research. The study aimed to investigate the antifungal activity and their potential use as fungicides in the agriculture of crude extracts and purified compounds derived from plants used in traditional medicines. Approach: Four medicinal plants including A. galanga, C. longa, B. pandurata and C. odorata were selected and percolated with hexane, ethyl acetate, acetone or methanol. The extracts were purified and elucidated their chemical structures. Disc mycelial growth inhibition was applied in order to determine their anti P. capsici activity and the field study was performed to determine their potential use in controlling fungal infection in chili plants compared with commercial fungicides such as captan and bio-control Trichoderma virens. Results: All crude extract inhibited mycelial growth of the fungus performed with similar efficacy. ED90 was equal to 300 ppm. Among plants studied B. pandurata was the most potent against P. capsici. The proposed active ingredients were pinostrobin and pinocembrin. In the field study, pinocembrin mediated the same anti P. capsici activity as captan. B. pandurata can protect chili from infection, thus increasing crop yield of chili comparable to Trichoderma virens. Conclusion: The results clearly showed that the extracts of the four plants studied could be considered as potential sources of novel fungicides. Particularly, B. pandurata has a very high potential as raw material for developing the antifungal molecule of non-petrochemical, naturally eco-friendly, easily obtainable and not toxic to human beings and environment, at least for use in chili growing.

  19. The influence of competition and host plant resistance on selection of Phytophthora infestans populations in Michigan State and Northern Ireland

    Science.gov (United States)

    The current investigation used multiple cultivars of potato and genotypes of Phytophthora infestans to study the P. infestans genotype x cultivar interaction, and investigate the potential influence of competition and level of field resistance on selection of the surrounding population of P. infesta...

  20. Gene-for-gene relationships between strawberry and the causal agent of red stele root rot, Phytophthora fragariae var. fragariae.

    NARCIS (Netherlands)

    Weg, van de W.E.

    1997-01-01

    Red stele (red core) root rot is the major soil-borne disease of strawberries (Fragaria spp.) in many areas with cool, moist soil conditions. It is caused by the soil-borne fungus Phytophthora fragariae var. fragariae. Red stele is a quarantine disease in Europe with a zero tolerance for commercial

  1. RESISTANCE TO PHYTOPHTHORA ERYTHROSEPTICA AND PYTHIUM ULTIMUM IN A POTATO CLONE DERIVED FROM S. BERTHAULTII AND S. ETUBEROSUM

    Science.gov (United States)

    Tubers of several potato clones and cultivars were screened for susceptibility to infection by zoospores of Phytophthora erythroseptica and mycelia of Pythium ultimum over a three year period, from 2003-2005. Incidence of infected tubers (%) and penetration of rot (mm) were the parameters used to de...

  2. Biological control of Black Pod Disease and Seedling Blight of cacao caused by Phytophthora Species using Trichoderma from Aceh Sumatra

    Science.gov (United States)

    The cocoa tree, Theobroma cacao L., suffers large yield losses in Aceh Indonesia to the disease black pod rot, caused by Phytophthora spp. Despite having the largest area under cacao production in Sumatra, farmers in the Aceh region have low overall production because of losses to insect pests and b...

  3. Letter to the Editor : Standardizing the nomenclature for clonal lineages of the sudden oak death pathogen, Phytophthora ramorum

    NARCIS (Netherlands)

    Grünwald, N.J.; Goss, E.M.; Ivors, K.; Garbelotto, M.; Martin, F.N.; Prospero, S.; Hansen, E.; Bonants, P.J.M.; Hamelin, R.C.; Chastagner, M.; Werres, S.; Rizzo, D.M.; Abad, G.; Beales, P.; Bilodeau, G.J.; Blomquist, C.L.; Brasier, C.; Brière, S.C.; Chandelier, A.; Davidson, J.M.; Denman, S.; Elliott, M.; Frankel, S.J.; Goheen, E.M.; Gruyter, de H.; Heungens, K.; James, D.; Kanaskie, A.; McWilliams, M.G.; Man in't Veld, W.; Moralejo, E.; Osterbauer, N.K.; Palm, M.E.; Parke, J.L.; Perez Sierra, A.M.; Shamoun, S.F.; Shishkoff, N.; Tooley, P.W.; Vettraino, A.M.; Webber, J.; Widmer, T.L.

    2009-01-01

    Phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages which can only be distinguished by performing molecular marker-based analyses. However, in the recent literature there exists no consensus on naming of these lineages. H

  4. Diagnostic values and utility of immunological, morphological, and molecular methods for in planta detection of phytophthora ramorum

    NARCIS (Netherlands)

    Kox, L.F.F.; Brouwershaven, van I.R.; Vossenberg, van de B.T.L.H.; Beld, van den H.E.; Bonants, P.J.M.; Gruyter, de J.

    2007-01-01

    In this study, six methods for the detection of Phytophthora ramorum in planta were compared using naturally infested rhododendron plant material. The methods included two immunological methods, one an enzyme-linked immunosorbent assay (ELISA) and the other using a lateral flow format (LFD). Three m

  5. Validation of a TaqMan diagnostic assay for the systematic development of Phytophthora genus and species specific markers

    Science.gov (United States)

    The genus Phytophthora contains many species that are not native to the USA and have the potential to cause significant damage to agriculture and native ecosystems. A genus and species-specific diagnostic assay was developed based on mitochondrial gene order differences that allowed for the systemat...

  6. Real-time PCR assay to distinguish the four Phytophthora ramorum lineages using cellulose binding elicitor lectin (CBEL) locus

    Science.gov (United States)

    Phytophthora ramorum is a pathogenic oomycete responsible for causing sudden oak death in the Western United States and sudden larch death in the United Kingdom. This pathogen has so far caused extensive mortality of oak and tanoak in California and of Japanese larch in the United Kingdom. Until rec...

  7. Migration Patterns of the Emerging Plant Pathogen Phytophthora ramorum on the West Coast of the United States of America

    Science.gov (United States)

    Phytophthora ramorum (Oomycetes) is the causal agent of sudden oak death and ramorum blight on trees, shrubs, and woody ornamentals in the forests of coastal California and southwestern Oregon and in nurseries of California, Oregon, and Washington. In this study, we investigated the genetic structur...

  8. Phytophthora taxa associated with cultivated Agathosma, with emphasis on the P. citricola complex and P. capensis sp. nov.

    NARCIS (Netherlands)

    Bezuidenhout, C.M.; Denman, S.; Kirk, S.A.; Botha, W.J.; Mostert, L.; McLeod, A.

    2010-01-01

    Agathosma species, which are indigenous to South Africa, are also cultivated for commercial use. Recently growers experienced severe plant loss, and symptoms shown by affected plants suggested that a soilborne disease could be the cause of death. A number of Phytophthora taxa were isolated from dise

  9. A predicted functional gene network for the plant pathogen Phytophthora infestans as a framework for genomic biology

    NARCIS (Netherlands)

    Seidl, M.F.; Schneider, A.; Govers, F.; Snel, B.

    2013-01-01

    Background - Associations between proteins are essential to understand cell biology. While this complex interplay between proteins has been studied in model organisms, it has not yet been described for the oomycete late blight pathogen Phytophthora infestans. Results - We present an integrative prob

  10. Suppression of phytopathogenic fungi by hexane extract of Nepenthes ventricosa x maxima leaf.

    Science.gov (United States)

    Shin, Kwang-Soo; Lee, Samkeun; Cha, Byeong Jin

    2007-12-01

    The hexane extract of Nepenthes ventricosa x maxima leaf exhibited antifungal activity against Alternaria alternata, Aspergillus niger, Bipolaris oryzae, Fusarium oxysporum, Phytophthora capsici, Rhizoctonia solani, Rhizopus stolonifer var. stolonifer and Sclerotinia sclerotiorum. PMID:17573203

  11. Auto-aggregation in zoospores of Phytophthora infestans: the cooperative roles of bioconvection and chemotaxis.

    Science.gov (United States)

    Savory, Andrew I M; Grenville-Briggs, Laura J; Wawra, Stephan; van West, Pieter; Davidson, Fordyce A

    2014-05-01

    Phytophthora infestans is a highly destructive plant pathogen. It was the cause of the infamous Irish potato famine in the nineteenth century and remains to this day a significant global problem with associated costs estimated at $3 billion annually. Key to the success of this pathogen is the dispersal of free-swimming cells called zoospores. A poorly understood aspect of zoospore behaviour is auto-aggregation--the spontaneous formation of large-scale patterns in cell density. Current competing hypotheses suggest that these patterns are formed by one of two distinct mechanisms: chemotaxis and bioconvection. In this paper, we present mathematical and experimental results that together provide strong evidence that auto-aggregation can only result from a combination of these mechanisms, each having a distinct, time-separated role. A better understanding of the underlying infection mechanisms of P. infestans and potentially other Phytophthora species will in the longer term lead to advances in preventative treatment and thus potentially significant savings in socio-economic costs. PMID:24598206

  12. De Novo Sequencing, Assembly, and Analysis of the Root Transcriptome of Persea americana (Mill.) in Response to Phytophthora cinnamomi and Flooding

    OpenAIRE

    Reeksting, Bianca J.; Coetzer, Nanette; Mahomed, Waheed; Engelbrecht, Juanita; van den Berg, Noëlani

    2014-01-01

    Avocado is a diploid angiosperm containing 24 chromosomes with a genome estimated to be around 920 Mb. It is an important fruit crop worldwide but is susceptible to a root rot caused by the ubiquitous oomycete Phytophthora cinnamomi. Phytophthora root rot (PRR) causes damage to the feeder roots of trees, causing necrosis. This leads to branch-dieback and eventual tree death, resulting in severe losses in production. Control strategies are limited and at present an integrated approach involvin...

  13. Brassica carinata for control of Phytophthora spp. in strawberry field crops

    Directory of Open Access Journals (Sweden)

    Carmen Barrau

    2009-12-01

    Full Text Available Soil biofumigation (SB and soil solarization (SS are nonchemical methods for the control of soilborne pathogens. SS uses solar radiation to heat soil and SB is based on the action of volatile compounds produced by the decomposition of Cruciferae, essentially glucosinolates (Gs and isothiocyanates (ITCs. Brassica spp. are used as biofumigant because of their different concentrations and types of ITCs that are different in their toxicity against pathogenic fungi. Suppressiveness of the Brassica varies between species. Biofumigant effect depends on plant age and environmental growth conditions. Brassica carinata, the most effective species on the in vitro control of Phytophthora spp., was selected as biofumigant to evaluate and compare the ability of SB and SS to control Phytophthora spp. in soil and to enhance field production of strawberry. SB with B. carinata + SS reduce P. cactorum in soil and increases strawberry yield and fruit weigh.A biofumigação do solo (SB e a solarização do solo (SS são métodos não químicos para a luta contra os micróbios patogénicos do solo. A SS usa a radiação solar para aquecer o solo e o SB é baseado na acção dos compostos temporários produzidos pela decomposição das Crucíferas, essencialmente glucosinolatos (Gs e isothiocianatos (ITCs. Brassica spp. é usada como biofumigante por causa da concentração de compostos biofumigantes e tipos diferentes de ITCs que diferem na toxicidade face aos fungos patogénicos. A capacidade supressiva de Brassica varia com a espécie. O efeito de Biofumigação depende da idade de planta e das condições ambientais de crescimento. Brassica carinata é a espécie mais eficaz in vitro, na luta contra Phytophthora spp., foi seleccionada como biofumigante para avaliar e comparar a capacidade de SB e SS na luta contra este fungo no solo, e para avaliar a produção de morango. A SB com B. carinata + SS reduz P. cactorum no solo e aumenta o rendimento da produção de

  14. Isolation of Indigenous Phytophthora palmivora from Indonesia, Their Morphological and Pathogenecity Characterization

    Directory of Open Access Journals (Sweden)

    Rubiyo Rubiyo

    2008-05-01

    Full Text Available AbstractThis experiment aims to know the solar energy efficiency of four clones of cocoa that cultivated under three different shading plants. This experiment has been done from September until December 2013 located at Kaliwining Experiment Farm with characteristic 45 m above sea level, soil type is low humic gley, soil texture is silty clay loam, and climate classification type D based on Scmidht and Fergusson Classification. This experiment used Nested Design as Experimental Design with species of shading plant as main plot which are Teak (Tectona grandis L., Krete (Cassia surattensis (Burm. F., Lamtoro (Leucaena leucocephala L. and Cocoa clones as sub plot which are Sulawesi 1, Sulawesi 2, KKM 22, KW 165. The observation of solar energy efficiency consists of daily solar radiation intensity, solar radiation intensity above plant, solar radiation intensity under plant, and also plant total dry weight. The experimental result showed that there is differences (heterogenity between shading location based on homogenity test by Bartlett Method. There are some interaction between the kind of shading plant and clones in parameter of interception efficiency, absorbtion efficiency, the efficiency of solar energy that caught by plant, and solar energy conversion efficiency. The efficiency of solar energy that caught by plant will affect the solar energy conversion efficiency with R2 = 0,86.  Keywords : Solar Energy Efficiency, Cocoa Clones, Shading Plant, Nested Design, Bartlett Method

  15. Primeiro relato da podridão da estipe da pupunheira, causada por Phytophthora palmivora, no estado do Paraná First report of stem rot on peach palm caused by Phytophthora palmivora ain the State of Paraná

    Directory of Open Access Journals (Sweden)

    Álvaro F. dos Santos

    2004-12-01

    Full Text Available Phytophthora palmivora foi isolado de plantas de pupunheira (Bactris gasipaes com sintomas de podridão da estipe, no Paraná, em 2002. Testes de patogenicidade e o subseqüente reisolamento do fungo confirmaram a hipótese de que P. palmivora é o agente causal da podridão do estipe. Este é o primeiro relato de P. palmivora causando podridão do estipe na pupunheira no estado do Paraná.Phytophthora palmivora was isolated from infected peach palm (Bactris gasipaes plants with stem rot symptoms in Paraná State, in 2002. Pathogenicity tests and subsequent reisolations of P. palmivora confirmed the hypothesis that this fungus was the causal agent of the disease. This is the first report of P. palmivora causing stem rot on peach palm (Bactris gasipaes in the southern State of Paraná.

  16. Genties Phytophthora patogenai, pažeidžiantys juodalksnius VDU Kauno botanikos sode

    OpenAIRE

    Verbylaitė, Ilona; Snieškienė, Vilija; Stankevičienė, Antanina

    2012-01-01

    Vytauto Didžiojo universiteto Kauno botanikos sode nuo 2009 m. yra stebimi juodalksniai, turintys pažeidimo požymių, kurie būdingi genties Phytophthora patogenams. Per ketverius metus pažeistų juodalksių padaugėjo: nuo 1,11 % (2009 m.) iki 26,67 % (2012 m.). Liga plinta ant įvairaus amžiaus juodalksnių, augančių ne toliau kaip 5 m nuo vandens telkinių, ypač tose vietose, kurios 1–2 mėnesius būna apsemtos ar labai drėgnos. From 2009 Alnus glutinosa with marks of damage which are specific fo...

  17. Computational models in plant-pathogen interactions: the case of Phytophthora infestans

    Directory of Open Access Journals (Sweden)

    González Barrios Andres F

    2009-11-01

    Full Text Available Abstract Background Phytophthora infestans is a devastating oomycete pathogen of potato production worldwide. This review explores the use of computational models for studying the molecular interactions between P. infestans and one of its hosts, Solanum tuberosum. Modeling and conclusion Deterministic logistics models have been widely used to study pathogenicity mechanisms since the early 1950s, and have focused on processes at higher biological resolution levels. In recent years, owing to the availability of high throughput biological data and computational resources, interest in stochastic modeling of plant-pathogen interactions has grown. Stochastic models better reflect the behavior of biological systems. Most modern approaches to plant pathology modeling require molecular kinetics information. Unfortunately, this information is not available for many plant pathogens, including P. infestans. Boolean formalism has compensated for the lack of kinetics; this is especially the case where comparative genomics, protein-protein interactions and differential gene expression are the most common data resources.

  18. Biochemical contents of pepper seedlings inoculated with phytophthora infestans and arbuscular mycorrhiza

    Directory of Open Access Journals (Sweden)

    Odebode A.C.

    2004-01-01

    Full Text Available The effect of interactions between Arbuscular Glomus etunicatum and fungus Phytophthora infestans on biochemical contents of pepper plants was investigated in a greenhouse experiment. The sugar contents (i.e. Glucose fructose and sucrose were higher in the control and mycorrhizal inoculated pepper seedlings and the lowest in pathogen inoculated seedlings. Free amino acids were the highest in the simultaneously inoculated pepper seedlings while total phenol was found to be the highest in pepper seedlings inoculated with P. infestans. The levels of nitrogen, phosphorus and potassium varied in the inoculated pepper seedlings without any significant difference in the treatment. The results obtained suggest protective influence of mycorrhiza by enhancing the nutritional status of the inoculated pepper seedlings.

  19. Proton activation studies of changes in mineral composition of eucalyptus obliqua due to phytophthora cinnamomi

    International Nuclear Information System (INIS)

    As part of a study of disease caused by Phytophthora cinnamomi in native vegetation, the mineral composition of diseased plants was compared with those free from disease, but grown under the same conditions. Young plants of Eucalyptus obliqua, three years old and with well-formed lignotubers, were selected (a) diseased plant from soil containing a high concentration of P. cinnamomi, and (b) unaffected plant from an adjacent area where the soil was free from this pathogen. The plants were ashed and their mineral composition was compared by activation analysis using proton beams from the Melbourne University Cyclotron. Results showed a 70% reduction in iron and 41% in titanium from diseased plants compared with disease-free plants. The reduction in iron is associated with severe chlorosis which occurs as a primary symptom in most plants attacked by this pathogen

  20. Phytophthora elicitor PB90 induced apoptosis in suspension cultures of tobacco

    Institute of Scientific and Technical Information of China (English)

    JI Rui; ZHANG Zhengguang; WANG Yuanchao; ZHENG Xiaobo

    2005-01-01

    The protein elicitor PB90 secreted by Phytophthora boehmeriae is an efficient elicitor inducing the hypersensitive response and systemic acquired resistance in tobacco plants. Here, we observed cell death in suspension-cultured cells of Nicotiana tabacum BY-2 with PB90 treatment using Trypan blue staining method. And this cell death could be suppressed by cycloheximide, an inhibitor of proteins synthesis, which implies that PB90-induced cell death was an active cell death process requiring new protein synthesis. DAPI staining revealed that PB90 induce rapid chromatin condensation, margination, apoptotic bodies' formation and DNA laddering, further TUNEL assay also observed the specific breakage of 3′-OH ends. All of the above common morphological characteristics indicated that PB90 induced apoptosis in suspension cultures of tobacco, suggesting that hypersensitive response induced by PB90 is an apoptotic process.

  1. Diverse Evolutionary Trajectories for Small RNA Biogenesis Genes in the Oomycete Genus Phytophthora.

    Science.gov (United States)

    Bollmann, Stephanie R; Fang, Yufeng; Press, Caroline M; Tyler, Brett M; Grünwald, Niklaus J

    2016-01-01

    Gene regulation by small RNA pathways is ubiquitous among eukaryotes, but little is known about small RNA pathways in the Stramenopile kingdom. Phytophthora, a genus of filamentous oomycetes, contains many devastating plant pathogens, causing multibillion-dollar damage to crops, ornamental plants, and natural environments. The genomes of several oomycetes including Phytophthora species such as the soybean pathogen P. sojae, have been sequenced, allowing evolutionary analysis of small RNA-processing enzymes. This study examined the evolutionary origins of the oomycete small RNA-related genes Dicer-like (DCL), and RNA-dependent RNA polymerase (RDR) through broad phylogenetic analyses of the key domains. Two Dicer gene homologs, DCL1 and DCL2, and one RDR homolog were cloned and analyzed from P. sojae. Gene expression analysis revealed only minor changes in transcript levels among different life stages. Oomycete DCL1 homologs clustered with animal and plant Dicer homologs in evolutionary trees, whereas oomycete DCL2 homologs clustered basally to the tree along with Drosha homologs. Phylogenetic analysis of the RDR homologs confirmed a previous study that suggested the last common eukaryote ancestor possessed three RDR homologs, which were selectively retained or lost in later lineages. Our analysis clarifies the position of some Unikont and Chromalveolate RDR lineages within the tree, including oomycete homologs. Finally, we analyzed alterations in the domain structure of oomycete Dicer and RDR homologs, specifically focusing on the proposed domain transfer of the DEAD-box helicase domain from Dicer to RDR. Implications of the oomycete domain structure are discussed, and possible roles of the two oomycete Dicer homologs are proposed. PMID:27014308

  2. De novo pyrimidine biosynthesis in the oomycete plant pathogen Phytophthora infestans.

    Science.gov (United States)

    García-Bayona, Leonor; Garavito, Manuel F; Lozano, Gabriel L; Vasquez, Juan J; Myers, Kevin; Fry, William E; Bernal, Adriana; Zimmermann, Barbara H; Restrepo, Silvia

    2014-03-10

    The oomycete Phytophthora infestans, causal agent of the tomato and potato late blight, generates important economic and environmental losses worldwide. As current control strategies are becoming less effective, there is a need for studies on oomycete metabolism to help identify promising and more effective targets for chemical control. The pyrimidine pathways are attractive metabolic targets to combat tumors, virus and parasitic diseases but have not yet been studied in Phytophthora. Pyrimidines are involved in several critical cellular processes and play structural, metabolic and regulatory functions. Here, we used genomic and transcriptomic information to survey the pyrimidine metabolism during the P. infestans life cycle. After assessing the putative gene machinery for pyrimidine salvage and de novo synthesis, we inferred genealogies for each enzymatic domain in the latter pathway, which displayed a mosaic origin. The last two enzymes of the pathway, orotate phosphoribosyltransferase and orotidine-5-monophosphate decarboxylase, are fused in a multi-domain enzyme and are duplicated in some P. infestans strains. Two splice variants of the third gene (dihydroorotase) were identified, one of them encoding a premature stop codon generating a non-functional truncated protein. Relative expression profiles of pyrimidine biosynthesis genes were evaluated by qRT-PCR during infection in Solanum phureja. The third and fifth genes involved in this pathway showed high up-regulation during biotrophic stages and down-regulation during necrotrophy, whereas the uracil phosphoribosyl transferase gene involved in pyrimidine salvage showed the inverse behavior. These findings suggest the importance of de novo pyrimidine biosynthesis during the fast replicative early infection stages and highlight the dynamics of the metabolism associated with the hemibiotrophic life style of pathogen. PMID:24361203

  3. Evaluation of phenotypic stability of resistance to Phytophthora spp. in cacao clones Avaliação da estabilidade fenotípica da resistência a Phytophthora spp. em clones de cacaueiro

    OpenAIRE

    Luiz Roberto M. Pinto; Stela Dalva V.M. Silva; Milton M. Yamada

    2007-01-01

    Resistance of fourteen Theobroma cacao clones to Phytophthora spp. was evaluated using stem inoculations on grafted seedlings. Concepts of phenotypic stability were used to interpret the results and to express horizontality of the resistance. The linear regression coefficient 'b', the determination coefficient (R²) and average lesion size were used to determine the level of horizontal resistance, the phenotypic stability and the predictability of all clones. The results indicated that clones ...

  4. Identification of Three Elicitins and a Galactan-Based Complex Polysaccharide from a Concentrated Culture Filtrate of Phytophthora infestans Efficient against Pectobacterium atrosepticum

    Directory of Open Access Journals (Sweden)

    Guillaume Saubeau

    2014-09-01

    Full Text Available The induction of plant immunity by Pathogen Associated Molecular Patterns (PAMPs constitutes a powerful strategy for crop protection. PAMPs indeed induce general defense responses in plants and thus increase plant resistance to pathogens. Phytophthora infestans culture filtrates (CCFs are known to induce defense responses and decrease the severity of soft rot due to Pectobacterium atrosepticum in potato tubers. The aim of this study was to identify and characterize the active compounds from P. infestans filtrate. The filtrate was fractionated by gel filtration, and the protection effects against P. atrosepticum and the ability to induce PAL activity were tested for each fraction. The fraction active in protection (F1 also induced PAL activity, as did the whole filtrate. Three elicitins (INF1, INF4 and INF5 were identified in F1b, subfraction of F1, by MALDI-TOF-MS and MS/MS analyses. However, deproteinized F1b still showed biological activity against the bacterium, revealing the presence of an additional active compound. GC-MS analyses of the deproteinized fraction highlighted the presence of a galactan-based complex polysaccharide. These experiments demonstrate that the biological activity of the CCF against P. atrosepticum results from a combined action of three elicitins and a complex polysaccharide, probably through the activation of general defense responses.

  5. Identification of three elicitins and a galactan-based complex polysaccharide from a concentrated culture filtrate of Phytophthora infestans efficient against Pectobacterium atrosepticum.

    Science.gov (United States)

    Saubeau, Guillaume; Gaillard, Fanny; Legentil, Laurent; Nugier-Chauvin, Caroline; Ferrières, Vincent; Andrivon, Didier; Val, Florence

    2014-01-01

    The induction of plant immunity by Pathogen Associated Molecular Patterns (PAMPs) constitutes a powerful strategy for crop protection. PAMPs indeed induce general defense responses in plants and thus increase plant resistance to pathogens. Phytophthora infestans culture filtrates (CCFs) are known to induce defense responses and decrease the severity of soft rot due to Pectobacterium atrosepticum in potato tubers. The aim of this study was to identify and characterize the active compounds from P. infestans filtrate. The filtrate was fractionated by gel filtration, and the protection effects against P. atrosepticum and the ability to induce PAL activity were tested for each fraction. The fraction active in protection (F1) also induced PAL activity, as did the whole filtrate. Three elicitins (INF1, INF4 and INF5) were identified in F1b, subfraction of F1, by MALDI-TOF-MS and MS/MS analyses. However, deproteinized F1b still showed biological activity against the bacterium, revealing the presence of an additional active compound. GC-MS analyses of the deproteinized fraction highlighted the presence of a galactan-based complex polysaccharide. These experiments demonstrate that the biological activity of the CCF against P. atrosepticum results from a combined action of three elicitins and a complex polysaccharide, probably through the activation of general defense responses. PMID:25264828

  6. Genomic characterization of a South American Phytophthora hybrid mandates reassessment of the geographic origins of Phytophthora infestans

    DEFF Research Database (Denmark)

    Martin, Michael David; Garrett Vieira, Filipe Jorge; Ho, Simon Y. W.; Wales, Nathan; Schubert, Mikkel; Seguin-Orlando, Andaine; Ristaino, Jean B.; Gilbert, M. Thomas P.

    2016-01-01

    outbreak remains disputed, as does the New World center of origin of the species itself. Both Mexico and South America have been proposed, generating considerable controversy. Here, we readdress the pathogen's origins using a genomic data set encompassing 71 globally sourced modern and historical samples...

  7. Dual RNA-sequencing of Eucalyptus nitens during Phytophthora cinnamomi challenge reveals pathogen and host factors influencing compatibility

    Directory of Open Access Journals (Sweden)

    Febe Elizabeth Meyer

    2016-03-01

    Full Text Available Damage caused by Phytophthora cinnamomi Rands remains an important concern on forest tree species. The pathogen causes root and collar rot, stem cankers and dieback of various economically important Eucalyptus spp. In South Africa, susceptible cold tolerant Eucalyptus plantations have been affected by various Phytophthora spp. with P. cinnamomi considered one of the most virulent. The molecular basis of this compatible interaction is poorly understood. In this study, susceptible Eucalyptus nitens plants were stem inoculated with P. cinnamomi and tissue was harvested five days post inoculation. Dual RNA-sequencing, a technique which allows the concurrent detection of both pathogen and host transcripts during infection, was performed. Approximately 1% of the reads mapped to the draft genome of P. cinnamomi while 78% of the reads mapped to the Eucalyptus grandis genome. The highest expressed P. cinnamomi gene in planta was a putative crinkler effector (CRN1. Phylogenetic analysis indicated the high similarity of this P. cinnamomi CRN1 to that of Phytophthora infestans. Some CRN effectors are known to target host nuclei to suppress defense. In the host, over 1400 genes were significantly differentially expressed in comparison to mock inoculated trees, including suites of pathogenesis related (PR genes. In particular, a PR-9 peroxidase gene with a high similarity to a Carica papaya PR-9 ortholog previously shown to be suppressed upon infection by Phytophthora palmivora was down-regulated two-fold. This PR-9 gene may represent a cross-species effector target during P. cinnamomi infection. This study identified pathogenicity factors, potential manipulation targets and attempted host defense mechanisms activated by E. nitens that contributed to the susceptible outcome of the interaction.

  8. Pathogenic Fitness, Metalaxyl Sensitivity and Isozyme Analysis of Phytophthora infestans Isolates from Mauritius

    OpenAIRE

    N. Taleb-Hossenkhan; A. Ibrahim

    2015-01-01

    Phytophthora infestans, the causal agent of potato and tomato late blight disease continues to be a serious threat in almost all potato and tomato growing areas around the world, with dramatic and disastrous economic consequences. In Mauritius, the disease is reported every year and many of the commercial potato varieties (Spunta, Delaware and Mondial) previously found to be moderately resistant or susceptible to the disease, have now become highly susceptible. This study reports the first ph...

  9. Resistance Induction and Enhanced Tuber Production by Pre-inoculation with Bacterial Strains in Potato Plants against Phytophthora infestans

    OpenAIRE

    Kim, Hyo-Jeong; Jeun, Yong-Chull

    2006-01-01

    Efficacy of resistance induction by the bacterial isolates Pseudomonas putida (TRL2-3), Micrococcus luteus (TRK2-2) and Flexibacteraceae bacterium (MRL412), which were isolated from the rhizosphere of plants growing in Jeju Mountain, were tested in a greenhouse. The disease severity caused by Phytophthora infestans was effectively reduced in the potato plants pre-inoculated with bacterial isolates compared with those of the untreated control plants growing in a greenhouse. In order to estimat...

  10. Dual RNA-Sequencing of Eucalyptus nitens during Phytophthora cinnamomi Challenge Reveals Pathogen and Host Factors Influencing Compatibility.

    Science.gov (United States)

    Meyer, Febé E; Shuey, Louise S; Naidoo, Sitha; Mamni, Thandekile; Berger, Dave K; Myburg, Alexander A; van den Berg, Noëlani; Naidoo, Sanushka

    2016-01-01

    Damage caused by Phytophthora cinnamomi Rands remains an important concern on forest tree species. The pathogen causes root and collar rot, stem cankers, and dieback of various economically important Eucalyptus spp. In South Africa, susceptible cold tolerant Eucalyptus plantations have been affected by various Phytophthora spp. with P. cinnamomi considered one of the most virulent. The molecular basis of this compatible interaction is poorly understood. In this study, susceptible Eucalyptus nitens plants were stem inoculated with P. cinnamomi and tissue was harvested five days post inoculation. Dual RNA-sequencing, a technique which allows the concurrent detection of both pathogen and host transcripts during infection, was performed. Approximately 1% of the reads mapped to the draft genome of P. cinnamomi while 78% of the reads mapped to the Eucalyptus grandis genome. The highest expressed P. cinnamomi gene in planta was a putative crinkler effector (CRN1). Phylogenetic analysis indicated the high similarity of this P. cinnamomi CRN1 to that of Phytophthora infestans. Some CRN effectors are known to target host nuclei to suppress defense. In the host, over 1400 genes were significantly differentially expressed in comparison to mock inoculated trees, including suites of pathogenesis related (PR) genes. In particular, a PR-9 peroxidase gene with a high similarity to a Carica papaya PR-9 ortholog previously shown to be suppressed upon infection by Phytophthora palmivora was down-regulated two-fold. This PR-9 gene may represent a cross-species effector target during P. cinnamomi infection. This study identified pathogenicity factors, potential manipulation targets, and attempted host defense mechanisms activated by E. nitens that contributed to the susceptible outcome of the interaction. PMID:26973660

  11. Growth Inhibition of Cocoa Pod Rot Fungus Phytophthora palmivora byPseudomonas fluorescence and Bacillus subtilis bacteria

    OpenAIRE

    Sakti Widyanta Pratama; Sri Sukamto; Lis Nur Asyiah; Yeni Vida Ervina

    2013-01-01

    Black pod disease caused by Phytophthora palmivorafungus is one of the important diseases on cocoa crop. Pod rot is the most important disease because it may cause loss of cocoa pod. Until now, the fungal pathogen of cocoa black pod disease is still a crucial problem and there is no fungicide that is really effective against the disease. One alternative to control the cocoa black pod disease is by using biological agents as biofungicide, including utilizing Pseudomonas fluorescenceand Bacillu...

  12. Multiple new Phytophthora species from ITS Clade 6 associated with natural ecosystems in Australia: evolutionary and ecological implications

    OpenAIRE

    T. Jung; Stukely, M.J.C.; Hardy, G.E.St.J.; White, D.; Paap, T.; Dunstan, W.A.; Burgess, T.I.

    2011-01-01

    During surveys of dying vegetation in natural ecosystems and associated waterways in Australia many new taxa have been identified from Phytophthora ITS Clade 6. For representative isolates, the region spanning the internal transcribed spacer region of the ribosomal DNA, the nuclear gene encoding heat shock protein 90 and the mitochondrial cox1 gene were PCR amplified and sequenced. Based on phylogenetic analysis and morphological and physiological comparison, four species and one informally d...

  13. A Multidisciplinary Approach for Identifying Stage-specific Transcription Factor Binding Sites in the Irish Potato Famine Pathogen, Phytophthora infestans

    OpenAIRE

    Roy, Sourav

    2011-01-01

    Phytophthora infestans, an oomycete within the phylum Heterokontophyta is one of the most devastating phytopathogens, causing late blight in potato and tomato. Its pathogenic success depends on the formation of different asexual spores such as sporangia and zoospores. Our goal was to identify what regulates transition between each of the five different asexual stages viz. hyphae, spores, cleaving sporangia, swimming zoospores and germinating cysts, by understanding what determines stage-spec...

  14. Stomatal conductance and root-to-shoot signalling in chestnut saplings exposed to Phytophthora cinnamomi or partial soil drying

    OpenAIRE

    Maurel, Marion; Robin, Cécile; Simonneau, Thierry; Loustau, Denis; Dreyer, Erwin; Desprez-Loustau, Marie Laure

    2004-01-01

    The effects of root infection by Phytophthora cinnamomi on stomatal conductance in Castanea sativa L. saplings were investigated to determine the potential role of root-derived chemical signals. A split-root experiment was carried out, in which inoculation of the pathogen or drought was applied to the root systems in either one or both compartments. At the end of the experiment plant sap extracts were collected and their effects on stomatal conductance were determined by leaf bioassay. Inocul...

  15. Suitability of various copper-free leaf treatment products for the control of Phytophthora infestans in organic potato farming

    OpenAIRE

    Nechwatal, Jan; Zellner, Michael

    2015-01-01

    Potato late blight (Phytophthora infestans) causes severe losses in potato yield and quality in organic production. Still, the disease can only be effectively controlled by the application of copper fungicides. Due to copper accumulation in the soil and expected detrimental effects on the environment and non-target organisms, a reduction in the usage of Cu fungicides is urgently required. Within the course of a project aiming at the reduction and avoidance of Cu in organic farming, trials wer...

  16. Evaluation of the protective effect of Phlomis purpurea against Phytophthora cinnamomi in Fagaceae and of root metabolites involved

    OpenAIRE

    Neves, D.

    2014-01-01

    Tese de doutoramento, Ciências Agrárias (Proteção de Plantas), Faculdade de Ciência e Tecnologia, Universidade do Algarve, 2014 Phytophthora cinnamomi Rands devastates natural ecosystems and crops around the world causing enormous economic losses. The “montado” ecosystem is threatened by this highly aggressive pathogen. Much concern involving fungicide use highlighted the need to develop new environmentally friendly means of control. In this work, Phlomis purpurea L., which was recentl...

  17. Pistachio gummosis disease caused by Phytophthora species and its control management with soil solarisation method in Iran.

    Science.gov (United States)

    Saremi, H; Okhovvat, S M; Saremi, Ha

    2008-01-01

    Pistachio (Pistacia vera L.) is the most important commercial product in Iran and root rot or crown rot (Gummosis) is the most serious diseases of this crop. During 2005-2007 Infected trees of Pistachio orchards were visited and plant samples plus soils around the infected trees collected from Kerman province in Iran. Samples were transferred to laboratory and cultured on common medium and using citrus leaves pieces as baits on water-saturated soils. Different Phytophthora species were isolated and studied to be identified. Three Phytophthora species including P. megasperma, P. drechsleri and P. citrophthora were the principal cause of pistachio gummosis and root rot in Iran. However, Phytophthora pistaciae as new species was introduced as aggressive species to different Pistachio cultivars. Since chemical control was not property managed the disease, soil disinfestations by soil solarisation method was carried in Kenrman as the nearly warmer climate in studied areas to manage the pathogen. Application of this method reduced population density of the pathogen from 1300 to 200 CFU -g/soil after 6 weeks. This method was effective, non negative side and economic which can be used in all agricultural areas. PMID:19226755

  18. Assessing the effectiveness of Byssochlamys nivea and Scopulariopsis brumptii in pentachlorophenol removal and biological control of two Phytophthora species.

    Science.gov (United States)

    Bosso, Luciano; Scelza, Rosalia; Varlese, Rosaria; Meca, Giuseppe; Testa, Antonino; Rao, Maria A; Cristinzio, Gennaro

    2016-04-01

    Bioremediation and biological-control by fungi have made tremendous strides in numerous biotechnology applications. The aim of this study was to test Byssochlamys nivea and Scopulariopsis brumptii in sensitivity and degradation to pentachlorophenol (PCP) and in biological-control of Phytophthora cinnamomi and Phytophthora cambivora. B. nivea and S. brumptii were tested in PCP sensitivity and degradation in microbiological media while the experiments of biological-control were carried out in microbiological media and soil. The fungal strains showed low PCP sensitivity at 12.5 and 25 mg PCP L(-1) although the hyphal size, fungal mat, patulin, and spore production decreased with increasing PCP concentrations. B. nivea and S. brumptii depleted completely 12.5 and 25 mg PCP L(-1) in liquid culture after 28 d of incubation at 28 °C. Electrolyte leakage assays showed that both fungi have low sensitivity to 25 mg PCP L(-1) and produced no toxic compounds for the plant. B. nivea and S. brumptii were able to inhibit the growth of the two plant pathogens in laboratory studies and reduce the mortality of chestnut plants caused by two Phytophthorae in greenhouse experiments. The two fungal strains did not produce volatile organic compounds able to reduce the growth of two plant pathogens tested. PMID:27020163

  19. Efeito do lodo de esgoto na indução de supressividade in vitro a Phytophthora nicotianae Effect of sewage sludge in vitro to suppress Phytophthora nicotianae

    Directory of Open Access Journals (Sweden)

    Carolina Leoni

    2003-01-01

    Full Text Available Uma alternativa de manejo das doenças causadas por Phytophthora spp. é o uso de matéria orgânica. No presente trabalho foi avaliada a potencialidade do lodo de esgoto na indução de supressividade in vitro a P. nicotianae. O efeito do lodo de esgoto incorporado ao solo na sobrevivência de P. nicotianae foi avaliado mediante um experimento fatorial com dois fatores: doses de lodo de esgoto (0, 10, 20 e 40% p/p e concentrações de inóculo [0, 10 ou 20 g de grãos de trigo (Triticum aestivum colonizados kg-1]. Aos 21 dias, quando aumentaram as doses de lodo de esgoto, a sobrevivência de P. nicotianae e os pHs das misturas diminuíram, e as condutividades elétricas (CE aumentaram. As correlações entre a CE e a sobrevivência do patógeno foram negativas e significativas (P>0,05. Para estudar o efeito dos compostos químicos envolvidos na supressividade, foram obtidos extratos em água, H2SO4 2N e KOH 0,4N de misturas de areia – lodo de esgoto (20% p/p, e foram acrescentados ao meio de cultura e seu efeito avaliado no crescimento das colônias de P. nicotianae. O extrato ácido (H2SO4 2N do tratamento com 20% de lodo de esgoto inibiu significativamente (P>0,05 o crescimento da colônia do patógeno. O efeito biológico foi estudado mediante isolamento de microrganismos em meio de cultura e seleção por antagonismo. No bioensaio com plântulas de alfafa (Medicago sativa destacaram-se os isolados F9.1 (Aspergillus sp. e A12.1 (actinomiceto, não identificado; e no teste de culturas pareadas destacou-se um Trichoderma sp. e dois actinomicetos por antibiose, e um Trichoderma sp. e três Aspergillus sp. por hiperparasitismo.Soil organic matter amendments may provide an alternative management practice for soil diseases caused by Phytophthora spp. In this paper we have evaluated the effectiveness of residential sewage sludge to suppress P. nicotianae under laboratory conditions. The effect of sewage sludge on P. nicotianae survival was

  20. Draft Genome Sequence of a Biocontrol Rhizobacterium, Chryseobacterium kwangjuense Strain KJ1R5, Isolated from Pepper (Capsicum annuum).

    Science.gov (United States)

    Jeong, Jin-Ju; Park, Hongjae; Park, Byeong Hyeok; Mannaa, Mohamed; Sang, Mee Kyung; Choi, In-Geol; Kim, Ki Deok

    2016-01-01

    Strain KJ1R5 of the rhizobacterium ITALIC! Chryseobacterium kwangjuenseis an effective biocontrol agent against Phytophthora blight of pepper caused by a destructive soilborne oomycete, ITALIC! Phytophthora capsici Here, we present the draft genome sequence of strain KJ1R5, which contains genes related to biocontrol, plant growth promotion, and environmental stress adaptation. PMID:27103726

  1. Draft Genome Sequence of a Biocontrol Rhizobacterium, Chryseobacterium kwangjuense Strain KJ1R5, Isolated from Pepper (Capsicum annuum)

    Science.gov (United States)

    Jeong, Jin-Ju; Park, Hongjae; Park, Byeong Hyeok; Mannaa, Mohamed; Sang, Mee Kyung

    2016-01-01

    Strain KJ1R5 of the rhizobacterium Chryseobacterium kwangjuense is an effective biocontrol agent against Phytophthora blight of pepper caused by a destructive soilborne oomycete, Phytophthora capsici. Here, we present the draft genome sequence of strain KJ1R5, which contains genes related to biocontrol, plant growth promotion, and environmental stress adaptation. PMID:27103726

  2. Metalaxyl Resistance in Phytophthora infestans: Assessing Role of RPA190 Gene and Diversity Within Clonal Lineages.

    Science.gov (United States)

    Matson, Michael E H; Small, Ian M; Fry, William E; Judelson, Howard S

    2015-12-01

    Prior work has shown that the inheritance of resistance to metalaxyl, an oomycete-specific fungicide, is complex and may involve multiple genes. Recent research indicated that a single nucleotide polymorphism (SNP) in the gene encoding RPA190, the largest subunit of RNA polymerase I, confers resistance to metalaxyl (or mefenoxam) in some isolates of the potato late blight pathogen Phytophthora infestans. Using both DNA sequencing and high resolution melt assays for distinguishing RPA190 alleles, we show here that the SNP is absent from certain resistant isolates of P. infestans from North America, Europe, and Mexico. The SNP is present in some members of the US-23 and US-24 clonal lineages, but these tend to be fairly sensitive to the fungicide based on artificial media and field test data. Diversity in the level of sensitivity, RPA190 genotype, and RPA190 copy number was observed in these lineages but were uncorrelated. Controlled laboratory crosses demonstrated that RPA190 did not cosegregate with metalaxyl resistance from a Mexican and British isolate. We conclude that while metalaxyl may be used to control many contemporary strains of P. infestans, an assay based on RPA190 will not be sufficient to diagnose the sensitivity levels of isolates. PMID:26551315

  3. Phenotypic variation within a clonal lineage of Phytophthora infestans infecting both tomato and potato in Nicaragua.

    Science.gov (United States)

    Blandón-Díaz, J U; Widmark, A-K; Hannukkala, A; Andersson, B; Högberg, N; Yuen, J E

    2012-03-01

    Late blight caused by Phytophthora infestans (Mont.) de Bary is a constraint to both potato and tomato crops in Nicaragua. The hypothesis that the Nicaraguan population of P. infestans is genotypically and phenotypically diverse and potentially subdivided based on host association was tested. A collection of isolates was analyzed using genotypic markers (microsatellites and mitochondrial DNA haplotype) and phenotypic markers (mating type, virulence, and fungicide sensitivity). The genotypic analysis revealed no polymorphism in 121 of 132 isolates of P. infestans tested. Only the Ia haplotype and the A2 mating type were detected. Most of the tested isolates were resistant to metalaxyl. The virulence testing showed variation among isolates of P. infestans. No evidence was found of population differentiation among potato and tomato isolates of P. infestans based on the genotypic and phenotypic analysis. We conclude that the Nicaraguan population of P. infestans consists of a single clonal lineage (NI-1) which belongs to the A2 mating type and the Ia mitochondrial DNA haplotype. Moreover, based on the markers used, this population of P. infestans does not resemble the population in countries from which potato seed is imported to Nicaragua or the population in neighboring countries. The data presented here indicate that the NI-1 clonal lineage is the primary pathogen on both potato and tomato, and its success on both host species is unique in a South American context. PMID:22085300

  4. Transient fusion and selective secretion of vesicle proteins in Phytophthora nicotianae zoospores

    Directory of Open Access Journals (Sweden)

    Weiwei Zhang

    2013-12-01

    Full Text Available Secretion of pathogen proteins is crucial for the establishment of disease in animals and plants. Typically, early interactions between host and pathogen trigger regulated secretion of pathogenicity factors that function in pathogen adhesion and host penetration. During the onset of plant infection by spores of the Oomycete, Phytophthora nicotianae, proteins are secreted from three types of cortical vesicles. Following induction of spore encystment, two vesicle types undergo full fusion, releasing their entire contents onto the cell surface. However, the third vesicle type, so-called large peripheral vesicles, selectively secretes a small Sushi domain-containing protein, PnCcp, while retaining a large glycoprotein, PnLpv, before moving away from the plasma membrane. Selective secretion of PnCcp is associated with its compartmentalization within the vesicle periphery. Pharmacological inhibition of dynamin function, purportedly in vesicle fission, by dynasore treatment provides evidence that selective secretion of PnCcp requires transient fusion of the large peripheral vesicles. This is the first report of selective protein secretion via transient fusion outside mammalian cells. Selective secretion is likely to be an important aspect of plant infection by this destructive pathogen.

  5. Transient fusion and selective secretion of vesicle proteins in Phytophthora nicotianae zoospores.

    Science.gov (United States)

    Zhang, Weiwei; Blackman, Leila M; Hardham, Adrienne R

    2013-01-01

    Secretion of pathogen proteins is crucial for the establishment of disease in animals and plants. Typically, early interactions between host and pathogen trigger regulated secretion of pathogenicity factors that function in pathogen adhesion and host penetration. During the onset of plant infection by spores of the Oomycete, Phytophthora nicotianae, proteins are secreted from three types of cortical vesicles. Following induction of spore encystment, two vesicle types undergo full fusion, releasing their entire contents onto the cell surface. However, the third vesicle type, so-called large peripheral vesicles, selectively secretes a small Sushi domain-containing protein, PnCcp, while retaining a large glycoprotein, PnLpv, before moving away from the plasma membrane. Selective secretion of PnCcp is associated with its compartmentalization within the vesicle periphery. Pharmacological inhibition of dynamin function, purportedly in vesicle fission, by dynasore treatment provides evidence that selective secretion of PnCcp requires transient fusion of the large peripheral vesicles. This is the first report of selective protein secretion via transient fusion outside mammalian cells. Selective secretion is likely to be an important aspect of plant infection by this destructive pathogen. PMID:24392285

  6. Mitochondrial genome sequences and comparative genomics ofPhytophthora ramorum and P. sojae

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Frank N.; Douda, Bensasson; Tyler, Brett M.; Boore,Jeffrey L.

    2007-01-01

    The complete sequences of the mitochondrial genomes of theoomycetes of Phytophthora ramorum and P. sojae were determined during thecourse of their complete nuclear genome sequencing (Tyler, et al. 2006).Both are circular, with sizes of 39,314 bp for P. ramorum and 42,975 bpfor P. sojae. Each contains a total of 37 identifiable protein-encodinggenes, 25 or 26 tRNAs (P. sojae and P. ramorum, respectively)specifying19 amino acids, and a variable number of ORFs (7 for P. ramorum and 12for P. sojae) which are potentially additional functional genes.Non-coding regions comprise approximately 11.5 percent and 18.4 percentof the genomes of P. ramorum and P. sojae, respectively. Relative to P.sojae, there is an inverted repeat of 1,150 bp in P. ramorum thatincludes an unassigned unique ORF, a tRNA gene, and adjacent non-codingsequences, but otherwise the gene order in both species is identical.Comparisons of these genomes with published sequences of the P. infestansmitochondrial genome reveals a number of similarities, but the gene orderin P. infestans differs in two adjacent locations due to inversions.Sequence alignments of the three genomes indicated sequence conservationranging from 75 to 85 percent and that specific regions were morevariable than others.

  7. Analysis of simple sequence repeats markers derived from Phytophthora sojae expressed sequence tags

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhendong; HUO Yunlong; WANG Xiaoming; HUANG Junbin; WU Xiaofei

    2004-01-01

    Five thousand and eight hundred publicly available expressed sequence tags (ESTs) of Phytophthora sojae were electronically searched and 415 simple sequence repeats (SSRs) were identified in 369 ESTs. The average density of SSRs was one SSR per 8.9 kb of EST sequence screened. The most frequent repeats were trinucleotide repeats (50.1%) and the least frequent were tetranucleotide repeats (8.2%). Forty primer pairs were designed and tested on 5 strains of P. sojae. Thirty-three primer pairs had successful PCR amplifications. Of the 33 functional primer pairs, 28 primer pairs produced characteristic SSR bands of the expected size, and 15 primer pairs (45.5%) detected polymorphism among 5 tested strains of P. sojae. Based on the polymorphisms detected with 20 EST-SSR markers, the 5 tested strains of P. sojae were clustered into 3 groups. In this study, the SSR markers of P. sojae were developed for the first time. These markers could be useful for identification, genetic variation study, and molecular mapping of P. sojae and its relative species.

  8. Cloning of genes encoding nonhost hypersensitive response-inducing elicitors from Phytophthora boehmeriae

    Institute of Scientific and Technical Information of China (English)

    LI Jun; ZHANG HaiFeng; ZHANG ZhengGuang; WANG YuanChao; ZHENG XiaoBo

    2007-01-01

    We have devised a high-throughput functional cloning method to isolate cDNAs from Phytophthora boehmeriae of which the products elicit a hypersensitive response (HR) in tobacco. The cDNAs were cloned into a binary potato virus X (PVX)-based expression vector and transformed into Agrobacterium tumefeciens (Mog101). 4100 colonies were individually toothpick-inoculated onto leaflets of Nicotiana benthamiana. 12 cDNAs were identified whose expression induced formation of a necrotic lesion around the inoculation site. 7 of these clones have different sequences. One of these clones PBC43 encodes specific elicitin. Clone PBC163 encodes a protein highly homologous to Rab; PBC241 encodes a prohibitin protein; PBN62 encodes a Heat Shock Protein 60 (HSP60). The other five cDNAs reveal no homology to known protein and are thus considered novel. These observations suggest that this functional screening method is a versatile strategy to identify cDNAs of pathogens that encode elicitors and other HR-inducing proteins.

  9. BABA-primed defense responses to Phytophthora infestans in the next vegetative progeny of potato

    Science.gov (United States)

    Floryszak-Wieczorek, Jolanta; Arasimowicz-Jelonek, Magdalena; Abramowski, Dariusz

    2015-01-01

    The transcript of the PR1 gene accumulation as an informative marker of systemic acquired resistance (SAR) was analyzed in β-aminobutyric acid (BABA) primed potato in the short-lasting (3 days) and long-lasting (28 days) time periods after induction and in the vegetative descendants of primed plants derived from tubers and from in vitro seedlings. BABA pretreatment resulted either in minimal or no PR1 gene expression, but sequential treatment with BABA followed by virulent Phytophthora infestans provided data on the imprint of post-stress information and its duration until fertilization, in the form of an enhanced PR1 transcript accumulation and a transient increase of basal resistance to the late blight disease. The primed state for defense of the susceptible potato cultivar was transmitted to its vegetative progeny as a potentiated PR1 mRNA accumulation following challenge inoculation. However, variation was observed between vegetative accessions of the BABA-primed potato genotype in responsiveness to disease. In contrast to plants derived from tubers, potato propagated through in vitro seedlings largely lost inducible resistance traits, although itretained primed PR1 gene expression. PMID:26528308

  10. Bud Rot Caused by Phytophthora palmivora: A Destructive Emerging Disease of Oil Palm.

    Science.gov (United States)

    Torres, G A; Sarria, G A; Martinez, G; Varon, F; Drenth, A; Guest, D I

    2016-04-01

    Oomycetes from the genus Phytophthora are among the most important plant pathogens in agriculture. Epidemics caused by P. infestans precipitated the great Irish famine and had a major impact on society and human history. In the tropics, P. palmivora is a pathogen of many plant species including cacao (Theobroma cacao), citrus (Citrus sp.), durian (Durio zibethines), jackfruit (Artrocarpus heterophyllus), rubber (Hevea brasiliensis), and several palm species including coconut (Cocos nucifera), and the African oil palm (Elaeis guineensis) as determined recently. The first localized epidemics of bud rot in oil palm in Colombia were reported in 1964. However, recent epidemics of bud rot have destroyed more than 70,000 ha of oil palm in the Western and Central oil palm growing regions of Colombia. The agricultural, social, and economic implications of these outbreaks have been significant in Colombia. Identification of the pathogen after 100 years of investigating the disease in the world enabled further understanding of infection, expression of a range of symptoms, and epidemiology of the disease. This review examines the identification of P. palmivora as the cause of bud rot in Colombia, its epidemiology, and discusses the importance of P. palmivora as a major threat to oil palm plantings globally. PMID:26714102

  11. Association mapping for partial resistance to Phytophthora sojae in soybean (Glycine max (L.) Merr.)

    Indian Academy of Sciences (India)

    Jutao Sun; Na Guo; Jun Lei; Lihong Li; Guanjun Hu; Han Xing

    2014-08-01

    Association mapping is a powerful high-resolution mapping tool for complex traits. The objective of this study was to identify QTLs for partial resistance to Phytophthora sojae. In this study, we evaluated a total of 214 soybean accessions by the hypocotyl inoculation method, and 175 were susceptible. The 175 susceptible accessions were then evaluated for P. sojae partial resistance using slant board assays. The 175 accessions were screened with 138 SSR markers that generated 730 SSR alleles. A subset of 495 SSR loci with minor allele frequency (MAF) ≥0.05 was used for association mapping by the Tassel general linear model (GLM) and mixed linear model (MLM) programmes. This soybean population could be divided into two subpopulations and no or weak relatedness was detected between pairwise accessions. Four SSR alleles, Satt634-133, Satt634-149, Sat_222-168 and Satt301-190, associated with partial resistance to P. sojae were detected by both GLM and MLM methods. Of these identified markers, one marker, Satt301, was located in regions where P. sojae resistance QTL have been previously mapped using linkage analysis. The identified markers will help to understand the genetic basis of partial resistance, and facilitate future marker-assistant selection aimed to improve resistance to P. sojae and reduce disease-related mortality in soybean.

  12. Identification of key molecular components of the resistance of cherry tomato against Phytophthora infestans

    International Nuclear Information System (INIS)

    Cherry tomato Solanum lycopersicum var cerasiforme CV matt's wild cherry is a very resistant cultivar to most Phytophthora infestans isolates. Two isolates were identified, us 940480 and us 970001 that cause an incompatible and a compatible interaction respectively. Us 970001 is one of the few isolates producing a compatible interaction with this cultivar. To identify genes with a differential gene expression between compatible and incompatible interactions, gene expression patterns were analyzed with tomato CDNA microarrays including 12,899 independent tomato CDNA clones at different time points after inoculation. A diverse set of statistical tools were used to identify key components of the plant response to the pathogen. Forty-three genes were up-regulated during the incompatible reaction at time point 36 hours, 15 globally at all-time points and twelve were found both in globally and at 36 hours. Northern blots analysis was performed to confirm differential expression showed by microarray analysis and to study the differential expression of more plant resistance genes (PR) genes between compatible and incompatible interactions for this interaction.

  13. Biocontrol of Phytophthora infestans, Fungal Pathogen of Seedling Damping Off Disease in Economic Plant Nursery

    Directory of Open Access Journals (Sweden)

    B. Loliam

    2012-01-01

    Full Text Available This research aims to control Seedling damping off disease in plants by using antagonistic actinomycetes against the causative fungi. Phytophthora infestans was isolated from the infected tomato plant seedling obtained from an economic plant nursery in Amphoe Pak Chong, Nakhon Ratchasima Province, Thailand. The chitinolytic Streptomyces rubrolavendulae S4, isolated from termite mounds at the grove of Amphoe Si-Sawat, Kanchanaburi Province, Thailand, was proven to be the most effective growth inhibition of fungal pathogens tested on potato dextrose agar. Tomato and chili seedlings that colonized with antagonistic S. rubrolavendulae S4 were grown in P. infestans artificial inoculated peat moss. Percents of noninfested seedling in fungal contaminated peat moss were compared to the controls with uninoculated peat moss. In P. infestans contaminated peat moss, the percents of survival of tomato and chili seedling were significantly increased (0.05. It was clearly demonstrated that S. rubrolavendulae S4 can prevent the tomato and chili seedling damping off disease in economic plant nurseries.

  14. Effects of microgravity on the susceptibility of soybean to Phytophthora sojae.

    Science.gov (United States)

    Nedukha, O M; Leach, J E; Ryba-White, M; Hilaire, E; Guikema, J; Kordyum, E L

    1998-07-01

    The study of pathogenicity of higher plants under conditions of microgravity is of great importance for the future production of food in space. Previous work suggests that microgravity affects both microbes and plants. Bacterial numbers increased after 17 days in an algae-bacterium association on the biosatellite "Kosmos-1887". This was speculated to result from an increase in the multiplication rate of the bacteria. Sporangia of both Actinomices brevis, in the shuttles "Soyuz-19" and "Appolon", and Phycomyces blakes, in biosatellite "Kosmos-936", formed after 10 days in microgravity. Sporangia did not form in the ground controls in the same time suggesting that the rate of fungal development is enhanced in microgravity. Plant responses to pathogens in microgravity have not been studied, however, microgravity profoundly impacts plant cell development, cytology, and physiology. In microgravity, developing cell walls are thinner and contain less lignin than ground-grown plants. The demonstrated effects of microgravity on both plants and microbes lead us to hypothesize that plants may be more susceptible to pathogens under conditions of microgravity. The aim of this study was to determine the influence of microgravity on the susceptibility of soybean to the fungal root rot pathogen, Phytophthora sojae. PMID:11542328

  15. Phytophthora palmivora, agente da podridão de raiz e frutos de mamoeiro no Estado de Alagoas Phytophthora palmivora, causal agent of root and fruit rots of papaya in the State of Alagoas, Brazil

    OpenAIRE

    Juliana Paiva Carnaúba; Márcio Félix Sobral; Daniela Cavalcanti de Medeiros Furtado; Izael Oliveira Silva; Kirley Michelly Marques da Silva; Edna Peixoto da Rocha Amorim

    2006-01-01

    O mamoeiro (Carica papaya) é uma das mais importantes fruteiras tropicais, e seus frutos contribuem com uma produção de 1,65 milhão de toneladas por ano para o Brasil. Um isolado de Phytophthora sp. obtido de frutos de mamoeiro da cultivar Havaí, em Alagoas, foi caracterizado morfologicamente e sua patogenicidade foi confirmada em frutos e mudas deste hospedeiro. Em meio suco V-8, os esporangióforos apresentaram-se delgados, simples ou pouco ramificados, enquanto os esporângios se apresentara...

  16. RESISTENCIA DE Phytophthora infestans (Montagne) de Bary A METALAXIL, EN CULTIVO DE PAPAS EN EL NORTE DE CHILE Resistance of Phytophthora infestans (Montagne) de Bary to metalaxyl in potato crops in Northern Chile

    OpenAIRE

    Fernando Riveros B.; Rodrigo Sotomayor; Viviana Rivera; Gary Secor; Boris Espinoza

    2003-01-01

    Con el objeto de determinar la sensibilidad a metalaxil de dos poblaciones de Phytophthora infestans (Montagne) de Bary, en cultivos de papa (Solanum tuberosum L.) en diferentes localidades de la IV y V Región de Chile, se estudiaron mediante ensayos in vitro e in vivo 254 aislamientos, los cuales inicialmente fueron calificado como sensibles o resistentes de acuerdo a su crecimiento sobre agar centeno B y 10 mg L-1 de metalaxil. Su concentración efectiva media (CE 50), fue estimada mediante ...

  17. Phytophthora niederhauserii sp. nov., a polyphagous species associated with ornamentals, fruit trees and native plants in 13 countries.

    Science.gov (United States)

    Abad, Z Gloria; Abad, Jorge A; Cacciola, Santa Olga; Pane, Antonella; Faedda, Roberto; Moralejo, Eduardo; Pérez-Sierra, Ana; Abad-Campos, Paloma; Alvarez-Bernaola, Luis A; Bakonyi, József; Józsa, András; Herrero, Maria Luz; Burgess, Treena I; Cunnington, James H; Smith, Ian W; Balci, Yilmaz; Blomquist, Cheryl; Henricot, Béatrice; Denton, Geoffrey; Spies, Chris; Mcleod, Adele; Belbahri, Lassaad; Cooke, David; Kageyama, Koji; Uematsu, Seiji; Kurbetli, Ilker; Değirmenci, Kemal

    2014-01-01

    A non-papillate, heterothallic Phytophthora species first isolated in 2001 and subsequently from symptomatic roots, crowns and stems of 33 plant species in 25 unrelated botanical families from 13 countries is formally described here as a new species. Symptoms on various hosts included crown and stem rot, chlorosis, wilting, leaf blight, cankers and gumming. This species was isolated from Australia, Hungary, Israel, Italy, Japan, the Netherlands, Norway, South Africa, Spain, Taiwan, Turkey, the United Kingdom and United States in association with shrubs and herbaceous ornamentals grown mainly in greenhouses. The most prevalent hosts are English ivy (Hedera helix) and Cistus (Cistus salvifolius). The association of the species with acorn banksia (Banksia prionotes) plants in natural ecosystems in Australia, in affected vineyards (Vitis vinifera) in South Africa and almond (Prunus dulcis) trees in Spain and Turkey in addition to infection of shrubs and herbaceous ornamentals in a broad range of unrelated families are a sign of a wide ecological adaptation of the species and its potential threat to agricultural and natural ecosystems. The morphology of the persistent non-papillate ellipsoid sporangia, unique toruloid lobate hyphal swellings and amphigynous antheridia does not match any of the described species. Phylogenetic analysis based on sequences of the ITS rDNA, EF-1α, and β-tub supported that this organism is a hitherto unknown species. It is closely related to species in ITS clade 7b with the most closely related species being P. sojae. The name Phytophthora niederhauserii has been used in previous studies without the formal description of the holotype. This name is validated in this manuscript with the formal description of Phytophthora niederhauserii Z.G. Abad et J.A. Abad, sp. nov. The name is coined to honor Dr John S. Niederhauser, a notable plant pathologist and the 1990 World Food Prize laureate. PMID:24871599

  18. Growth Inhibition of Cocoa Pod Rot Fungus Phytophthora palmivora byPseudomonas fluorescence and Bacillus subtilis bacteria

    Directory of Open Access Journals (Sweden)

    Sakti Widyanta Pratama

    2013-08-01

    Full Text Available Black pod disease caused by Phytophthora palmivorafungus is one of the important diseases on cocoa crop. Pod rot is the most important disease because it may cause loss of cocoa pod. Until now, the fungal pathogen of cocoa black pod disease is still a crucial problem and there is no fungicide that is really effective against the disease. One alternative to control the cocoa black pod disease is by using biological agents as biofungicide, including utilizing Pseudomonas fluorescenceand Bacillus subtilis bacteria. The research was done by isolation of P. palmivora from infected pods of Kaliwining Experimental Station to obtain pure cultures of fungus and by multiplication of P. fluorescence and B. subtilis. Antagonist test was performed by inoculating P. palmivora into a petri dish in a distance of 3 cm from the edge. P. fluorescenceand B. Subtilis were inoculated into petridishes in three days after the fungal treatment. Control was inoculated with isolate of P. palmivora only. Fungal growth was measured everyday by measuring radius of fungal colonies first time 24 hours after inoculation. Growth of Phytophthora palmivora in the two treatmens were used to calculate the percentage of inhibition. The results of this study indicated that P. fluorescence and B. subtiliswere able to inhibit fungal growth of P. palmivora. Both bacterial antagonists had the same effectiveness in inhibiting the growth of P. palmivora fungus based on the percentage of inhibition and effectiveness criteria. Based on the results of translucent zones indicated that B. subtiliswas more powerfull in inhibiting growth of P. Palmivora compared to P. fluorescence. Key words: Black pod disease of cocoa, biological control, Phytophthora palmivora, Pseudomonas fluorescence, Bacillus subtilis

  19. A novel method for efficient and abundant production of Phytophthora brassicae zoospores on Brussels sprout leaf discs

    Directory of Open Access Journals (Sweden)

    Govers Francine

    2009-08-01

    Full Text Available Abstract Background Phytophthora species are notorious oomycete pathogens that cause diseases on a wide range of plants. Our understanding how these pathogens are able to infect their host plants will benefit greatly from information obtained from model systems representative for plant-Phytophthora interactions. One attractive model system is the interaction between Arabidopsis and Phytophthora brassicae. Under laboratory conditions, Arabidopsis can be easily infected with mycelial plugs as inoculum. In the disease cycle, however, sporangia or zoospores are the infectious propagules. Since the current P. brassicae zoospore isolation methods are generally regarded as inefficient, we aimed at developing an alternative method for obtaining high concentrations of P. brassicae zoospores. Results P. brassicae isolates were tested for pathogenicity on Brussels sprout plants (Brassica oleracea var. gemmifera. Microscopic examination of leaves, stems and roots infected with a GFP-tagged transformant of P. brassicae clearly demonstrated the susceptibility of the various tissues. Leaf discs were cut from infected Brussels sprout leaves, transferred to microwell plates and submerged in small amounts of water. In the leaf discs the hyphae proliferated and abundant formation of zoosporangia was observed. Upon maturation the zoosporangia released zoospores in high amounts and zoospore production continued during a period of at least four weeks. The zoospores were shown to be infectious on Brussels sprouts and Arabidopsis. Conclusion The in vitro leaf disc method established from P. brassicae infected Brussels sprout leaves facilitates convenient and high-throughput production of infectious zoospores and is thus suitable to drive small and large scale inoculation experiments. The system has the advantage that zoospores are produced continuously over a period of at least one month.

  20. Preemergence infection of potato sprouts by Phytophthora infestans in the highland tropics of Ecuador

    DEFF Research Database (Denmark)

    Kromann, Peter; Taipe, Arturo; Andrade-Piedra, Jorge L.;

    2008-01-01

    Experiments were conducted to determine whether preemergence infection of potato sprouts by Phytophthora infestans occurs in the highland tropics of Ecuador. In three separate experiments in the field, P. infestans was identified on the preemerged sprouts of 49, 5, and 43% of tubers, respectively...... over 24 h in the field. Deposition had been measured at 1 m from a severely infected potato plot. Our study demonstrated the potential for preemergence infection of potato sprouts by P. infestans in the highlands of Ecuador, where year-round aerial inoculum is present. Preemergence infection is...

  1. Gene-for-gene relationships between strawberry and the causal agent of red stele root rot, Phytophthora fragariae var. fragariae.

    OpenAIRE

    Weg, van de, W.E.

    1997-01-01

    Red stele (red core) root rot is the major soil-borne disease of strawberries (Fragaria spp.) in many areas with cool, moist soil conditions. It is caused by the soil-borne fungus Phytophthora fragariae var. fragariae. Red stele is a quarantine disease in Europe with a zero tolerance for commercial stock plants. Any lot of such plants with even just a trace of the disease has to be destroyed. The plot on which the plants were harvested has to be abandoned for commercial strawberry propagation...

  2. The efficiency of some fungicides applied to control the Phytophthora infestans (Mont de Bary fungus on potato

    Directory of Open Access Journals (Sweden)

    Daniela POPA

    2008-05-01

    Full Text Available The research was carried on at Targu - Secuiesc within 2002-2004 and its objective was to determine the most efficient fungicides to control the late potato blight caused by the fungus Phytophthora infestans. All the applied products were efficient in controlling the disease in comparison to the untreated control variant.The results of the research show that during the observed period the products Curzate and Acrobat proved to be highly efficient in a constant manner at the three varieties: Ostara, Sante and Desiree. The lowest frequency of infected tubers was registered at the varieties treated with Altima, Acrobat, Tatoo C.

  3. Efecto de algunos aceites esenciales sobre el crecimiento de phytophthora infestans (mont.) de bary en condiciones de laboratorio

    OpenAIRE

    Carrillo Yazmid Adriana; Gòmez Maria Isabel; Cotes Josè Miguel; Ñustez Carlos Eduardo

    2010-01-01

    Entre los factores más limitantes del cultivo de papa se encuentra
    Phytophthora infestans, agente causal de la llamada “gota”.
    El control químico de esta enfermedad representa entre el 7 y
    el 10% de los costos totales del cultivo, y tiene un alto impacto
    ambiental por la contaminación que ocasiona. La búsqueda
    y aplicación de prácticas alternativas para el control de este
    patógeno es importante para disminuir tanto la utilizaci...

  4. Efecto de algunos aceites esenciales sobre el crecimiento de phytophthora infestans (mont.) de bary en condiciones de laboratorio

    OpenAIRE

    Carrillo, Yazmid Adriana; Gòmez, Maria Isabel; Cotes, Josè Miguel; Ñustez, Carlos Eduardo

    2010-01-01

    Entre los factores más limitantes del cultivo de papa se encuentraPhytophthora infestans, agente causal de la llamada “gota”.El control químico de esta enfermedad representa entre el 7 yel 10% de los costos totales del cultivo, y tiene un alto impactoambiental por la contaminación que ocasiona. La búsqueday aplicación de prácticas alternativas para el control de estepatógeno es importante para disminuir tanto la utilización defungicidas como los costos de producción del cultivo. Numerososestu...

  5. Characterization of ancient and modern genomes by SNP detection and phylogenomic and metagenomic analysis using PALEOMIX

    DEFF Research Database (Denmark)

    Schubert, Mikkel; Ermini, Luca; Der Sarkissian, Clio;

    2014-01-01

    -generation sequencing reads, PALEOMIX carries out adapter removal, mapping against reference genomes, PCR duplicate removal, characterization of and compensation for postmortem damage, SNP calling and maximum-likelihood phylogenomic inference, and it profiles the metagenomic contents of the samples. As such, PALEOMIX...... allows for a series of potential applications in paleogenomics, comparative genomics and metagenomics. Applying the PALEOMIX pipeline to the three ancient and seven modern Phytophthora infestans genomes as described here takes 5 d using a 16-core server....

  6. Antagonism of Serratia marcescens towards Phytophthora parasitica and its effects in promoting the growth of citrus Antagonismo de Serratia marcescens contra Phytophthora parasitica e seu efeito na promoção do crescimentos de citros

    Directory of Open Access Journals (Sweden)

    Brigida Pimentel Villar de Queiroz

    2006-12-01

    Full Text Available Phytophthora parasitica causes serious widespread, and difficult-to-control root rots in warmer regions. This oomycete is one of the most important pathogen of citrus. This paper reports the biological control of the pathogen by a strain of Serratia marcescens R-35, isolated from citrus rhizosphere. In greenhouse trials, the bacterium suppressed more than 50% of the disease and promoted the plant growth.Phytophthora parasitica é um oomiceto que causa sérios problemas fitossanitários em diferentes espécies de plantas em regiões tropicais e o controle tem sido difícil. Este patógeno é um dos mais importante à citricultura. Este trabalho relata o controle biológico do patógeno por uma linhagem de Serratia marcescens R-35, isolada da rizosfera de citros. Em condições de casa-de-vegetação, a bactéria reduziu em mais de 50% a incidência da doença, ao mesmo tempo que promoveu o crescimento de plantas.

  7. Identification of microorganisms of Phytophthora genre associated to Quercus sp. and Pinus sp. species in the provinces of Guatemala and Sacatepéquez

    Directory of Open Access Journals (Sweden)

    José Humberto Calderón Díaz

    2015-07-01

    Full Text Available The mean purpose of this research was to identify microorganism belonging to Phytophthora genera which are affecting mixed natural forests and nurseries of Pinus sp. and Quercus sp. These species have economic and social impact in provinces such as Guatemala and Sacatepéquez. Soil and vegetal tissue were used to isolate Phytophthora from natural forest of Guatemala, 45 Pinus sp. and 10 Quercus sp. were sampled and from nurseries 88 Pinus sp. and 11 Quercus sp. From Sacatepéquez province, from natural forest system were sampled 48 Pinus sp. and 15 Quercus sp. From nurseries were sampled 58 Pinus sp. and 25 Quercus sp. After processing the samples from soil and roots 13 were found positive to Phytophthora sp. in Pinus maximinoi, 10 from Guatemala and three from Sacatepéquez provinces. The culture of Phytophthora sp. on PDA produced two colonies without define form and five stoloniferous, five semipetaloid, one stelade type colonies. VP16 isolate was inoculated in five species of pine for pathogenicity test, causing high percentages of incidence and severity on Pinus caribaea, P. oocarpa, P. pseudostrobus and P. maximinoi and low rates of incidence and severity on Pinus tecunumanii.

  8. Spraying Leaves of Pear Nursery Trees with Urea and Copper Ethylenediaminetetraacetic Acid Alters Tree Nitrogen Concentration without Influencing Tree Susceptibility to Phytophthora syringae

    Science.gov (United States)

    We investigated the effects of nitrogen (N) availability and spraying trees with urea, copper chelate (CuEDTA), and phosphonate-containing fungicides on tree N status and susceptibility to infection by Phytophthora syringae. Increasing soil N availability increased susceptibility and increased N and...

  9. Revealing the importance of meristems and roots for the development of hypersensitive responses and full foliar resistance to Phytophthora infestans in the resistant potato cultivar Sarpo Mira

    DEFF Research Database (Denmark)

    Orlowska, Elzbieta Zofia; Basile, Alessio; Kandzia, Izabela;

    2012-01-01

    The defence responses of potato against Phytophthora infestans were studied using the highly resistant Sarpo Mira cultivar. The effects of plant integrity, meristems, and roots on the hypersensitive response (HR), plant resistance, and the regulation of PR genes were analysed. Sarpo Mira shoots a...

  10. Production of Phytophthora infestans-resistant potato (Solanum tuberosum) utilising Ensifer adhaerens OV14

    DEFF Research Database (Denmark)

    Wendt, Toni; Doohan, Fiona; Mullins, Ewen

    2012-01-01

    Arabidopsis thaliana (0.12%) and potato (mean transformation frequency 35.1%). Thereafter, Ensifer adhaerens was used to generate blight- (causative organism Phytophthora infestans) resistant potato using the Solanum bulbocastanum ‘resistance to blight’ (RB) gene. Resistant genotypes were confirmed by...

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

    NARCIS (Netherlands)

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

    2014-01-01

    The oomycete Phytophthora infestans is the causal agent of late blight in potato and tomato. Since the underlying processes that govern pathogenicity and development in P. infestans are largely unknown, we have performed a large-scale phosphoproteomics study of six different P. infestans life stages

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

    NARCIS (Netherlands)

    Resjö, S.; Ali, A.; Meijer, H.J.G.; Seidl, M.F.; Snel, B.; Sandin, M.; Levander, F.; Govers, F.; Andreasson, E.

    2014-01-01

    The oomycete Phytophthora infestans is the causal agent of late blight in potato and tomato. Since the underlying processes that govern pathogenicity and development in P. infestans are largely unknown, we have performed a large-scale phosphoproteomics study of six different P. infestans life stages

  13. Population genetics of Phytophthora infestans in Denmark reveals dominantly clonal populations and specific alleles linked to metalaxyl-M resistance

    DEFF Research Database (Denmark)

    Montes, Melanie Sarah; Nielsen, B.J.; Schmidt, S.G.; Bødker, L.; Kjøller, Rasmus; Rosendahl, Søren

    2015-01-01

    Control of the potato late blight pathogen Phytophthora infestans relies heavily on chemicals. The fungicide metalaxyl-M (Mefenoxam) has played an important role in controlling the disease, but insensitivity to the fungicide in certain isolates is now of major concern. A genetic basis for resista...

  14. Trade-offs and evolution of thermal adaptation in the Irish potato famine pathogen Phytophthora infestans.

    Science.gov (United States)

    Yang, Li-Na; Zhu, Wen; Wu, E-Jiao; Yang, Ce; Thrall, Peter H; Burdon, Jeremy J; Jin, Li-Ping; Shang, Li-Ping; Zhan, Jiasui

    2016-08-01

    Temperature is one of the most important environmental parameters with crucial impacts on nearly all biological processes. Due to anthropogenic activity, average air temperatures are expected to increase by a few degrees in coming decades, accompanied by an increased occurrence of extreme temperature events. Such global trends are likely to have various major impacts on human society through their influence on natural ecosystems, food production and biotic interactions, including diseases. In this study, we used a combination of statistical genetics, experimental evolution and common garden experiments to investigate the evolutionary potential for thermal adaptation in the potato late blight pathogen, Phytophthora infestans, and infer its likely response to changing temperatures. We found a trade-off associated with thermal adaptation to heterogeneous environments in P. infestans, with the degree of the trade-off peaking approximately at the pathogen's optimum growth temperature. A genetic trade-off in thermal adaptation was also evidenced by the negative association between a strain's growth rate and its thermal range for growth, and warm climates selecting for a low pathogen growth rate. We also found a mirror effect of phenotypic plasticity and genetic adaptation on growth rate. At below the optimum, phenotypic plasticity enhances pathogen's growth rate but nature selects for slower growing genotypes when temperature increases. At above the optimum, phenotypic plasticity reduces pathogen's growth rate but natural selection favours for faster growing genotypes when temperature increases further. We conclude from these findings that the growth rate of P. infestans will only be marginally affected by global warming. PMID:27288627

  15. C239S Mutation in the β-Tubulin of Phytophthora sojae Confers Resistance to Zoxamide

    Science.gov (United States)

    Cai, Meng; Miao, Jianqiang; Song, Xi; Lin, Dong; Bi, Yang; Chen, Lei; Liu, Xili; Tyler, Brett M.

    2016-01-01

    Zoxamide is the sole β-tubulin inhibitor registered for the control of oomycete pathogens. The current study investigated the activity of zoxamide against Phytophthora sojae and baseline sensitivity was established with a mean EC50 of 0.048 μg/ml. The data is critical for monitoring changes in zoxamide-sensitivity in the field. Three stable resistant mutants with a high resistance level were obtained by selection on zoxamide amended media. Although the development of resistance occurred at a low frequency, there were no apparent fitness penalty in the acquired mutants in terms of growth rate, sporulation, germination and pathogenicity. Based on the biological profiles and low mutagenesis rate, the resistance risk of P. sojae to zoxamide can be estimated as low to medium. Further investigation revealed all the zoxamide-resistant mutants had a point mutation of C239S in their β-tubulin. Zoxamide also exhibited high activity against most species from the genus Pythium in which only Pythium aphanidermatum was found naturally resistant to zoxamide and harboring the natural point mutation S239 in the β-tubulin. Back-transformation in P. sojae with the mutated allele (S239) confirmed the C239S mutation can induce resistance to zoxamide, and the resistance level was positively related to the expression level of the mutated gene. In contrast, the overexpression of the wild type gene was unable to cause zoxamide resistance. It is the first report on the resistance molecular mechanism of zoxamide in oomycetes. Based on our study, C239 is supposed to be a key target site of zoxamide, which distinguishes zoxamide from benzimidazoles and accounts for its low resistance risk. The result can provide advice on the design of new β-tubulin inhibitors in future.

  16. Biochemical and physiological responses of oil palm to bud rot caused by Phytophthora palmivora.

    Science.gov (United States)

    Moreno-Chacón, Andrés Leonardo; Camperos-Reyes, Jhonatan Eduardo; Ávila Diazgranados, Rodrigo Andrés; Romero, Hernán Mauricio

    2013-09-01

    In recent years, global consumption of palm oil has increased significantly, reaching almost 43 million tons in 2010. The sustainability of oil palm (Elaeis guineensis) cultivation has been compromised because of the bud rot disease whose initial symptoms are caused by Phytophthora palmivora. There was a significant incidence of the disease, from an initial stage 1 of the disease to the highest stage 5, that affected photosynthetic parameters, content of pigments, sugars, polyamines, enzymatic antioxidant activities, phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and β-(1,3) glucanase (β-Gluc, EC 3.2.1.39). In healthy palms photosynthesis was 13.29 μmol CO2 m(-2) s(-1) in average, while in stage 5 the average photosynthesis was around 3.66 μmol CO2 m(-2) s(-1). Additionally, total chlorophyll was reduced by half at the last stage of the disease. On the contrary, the contents of putrescine, spermine and spermidine increased three, nine and twelve times with respect to stage 5, respectively. Antioxidant enzyme activities, as well as the phenylalanine ammonia-lyase and β-(1,3) glucanase showed an increase as the severity of the disease increased, with the latter increasing from 0.71 EAU in healthy palms to 2.60 EAU in plants at stage 5 of the disease. The peroxidase (POD, EC 1.11.1.7) enzymatic activity and the content of spermidine were the most sensitive indicators of disease. PMID:23796724

  17. Myb transcription factors and light regulate sporulation in the oomycete Phytophthora infestans.

    Directory of Open Access Journals (Sweden)

    Qijun Xiang

    Full Text Available Life cycle progression in eukaryotic microbes is often influenced by environment. In the oomycete Phytophthora infestans, which causes late blight on potato and tomato, sporangia have been reported to form mostly at night. By growing P. infestans under different light regimes at constant temperature and humidity, we show that light contributes to the natural pattern of sporulation by delaying sporulation until the following dark period. However, illumination does not permanently block sporulation or strongly affect the total number of sporangia that ultimately form. Based on measurements of sporulation-induced genes such as those encoding protein kinase Pks1 and Myb transcription factors Myb2R1 and Myb2R3, it appears that most spore-associated transcripts start to rise four to eight hours before sporangia appear. Their mRNA levels oscillate with the light/dark cycle and increase with the amount of sporangia. An exception to this pattern of expression is Myb2R4, which is induced several hours before the other genes and declines after cultures start to sporulate. Transformants over-expressing Myb2R4 produce twice the number of sporangia and ten-fold higher levels of Myb2R1 mRNA than wild-type, and chromatin immunoprecipitation showed that Myb2R4 binds the Myb2R1 promoter in vivo. Myb2R4 thus appears to be an early regulator of sporulation. We attempted to silence eight Myb genes by DNA-directed RNAi, but succeeded only with Myb2R3, which resulted in suppressed sporulation. Ectopic expression studies of seven Myb genes revealed that over-expression frequently impaired vegetative growth, and in the case of Myb3R6 interfered with sporangia dormancy. We observed that the degree of silencing induced by a hairpin construct was correlated with its copy number, and ectopic expression was often unstable due to epigenetic silencing and transgene excision.

  18. 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.

  19. Myb transcription factors and light regulate sporulation in the oomycete Phytophthora infestans.

    Science.gov (United States)

    Xiang, Qijun; Judelson, Howard S

    2014-01-01

    Life cycle progression in eukaryotic microbes is often influenced by environment. In the oomycete Phytophthora infestans, which causes late blight on potato and tomato, sporangia have been reported to form mostly at night. By growing P. infestans under different light regimes at constant temperature and humidity, we show that light contributes to the natural pattern of sporulation by delaying sporulation until the following dark period. However, illumination does not permanently block sporulation or strongly affect the total number of sporangia that ultimately form. Based on measurements of sporulation-induced genes such as those encoding protein kinase Pks1 and Myb transcription factors Myb2R1 and Myb2R3, it appears that most spore-associated transcripts start to rise four to eight hours before sporangia appear. Their mRNA levels oscillate with the light/dark cycle and increase with the amount of sporangia. An exception to this pattern of expression is Myb2R4, which is induced several hours before the other genes and declines after cultures start to sporulate. Transformants over-expressing Myb2R4 produce twice the number of sporangia and ten-fold higher levels of Myb2R1 mRNA than wild-type, and chromatin immunoprecipitation showed that Myb2R4 binds the Myb2R1 promoter in vivo. Myb2R4 thus appears to be an early regulator of sporulation. We attempted to silence eight Myb genes by DNA-directed RNAi, but succeeded only with Myb2R3, which resulted in suppressed sporulation. Ectopic expression studies of seven Myb genes revealed that over-expression frequently impaired vegetative growth, and in the case of Myb3R6 interfered with sporangia dormancy. We observed that the degree of silencing induced by a hairpin construct was correlated with its copy number, and ectopic expression was often unstable due to epigenetic silencing and transgene excision. PMID:24704821

  20. An ephemeral sexual population of Phytophthora infestans in the Northeastern United States and Canada.

    Directory of Open Access Journals (Sweden)

    Giovanna Danies

    Full Text Available Phytophthora infestans, the causal agent of late blight disease, has been reported in North America since the mid-nineteenth century. In the United States the lack of or very limited sexual reproduction has resulted in largely clonal populations of P. infestans. In 2010 and 2011, but not in 2012 or 2013, 20 rare and diverse genotypes of P. infestans were detected in a region that centered around central New York State. The ratio of A1 to A2 mating types among these genotypes was close to the 50∶50 ratio expected for sexual recombination. These genotypes were diverse at the glucose-6-phosphate isomerase locus, differed in their microsatellite profiles, showed different banding patterns in a restriction fragment length polymorphism assay using a moderately repetitive and highly polymorphic probe (RG57, were polymorphic for four different nuclear genes and differed in their sensitivity to the systemic fungicide mefenoxam. The null hypothesis of linkage equilibrium was not rejected, which suggests the population could be sexual. These new genotypes were monomorphic in their mitochondrial haplotype that was the same as US-22. Through parentage exclusion testing using microsatellite data and sequences of four nuclear genes, recent dominant lineages US-8, US-11, US-23, and US-24 were excluded as possible parents for these genotypes. Further analyses indicated that US-22 could not be eliminated as a possible parent for 14 of the 20 genotypes. We conclude that US-22 could be a parent of some, but not all, of the new genotypes found in 2010 and 2011. There were at least two other parents for this population and the genotypic characteristics of the other parents were identified.

  1. 丁子香酚对辣椒疫病的田间防治试验%Field Efficacy of Eugenol Against Phytophthora Blight

    Institute of Scientific and Technical Information of China (English)

    罗诗龙; 凌晓曦; 王运生; 易图永

    2011-01-01

    For screening botanical fungicides to control phytophthora blight, 3 g/kg eugenol and 25% metalaxyl-propamocarb hydrochloride were tested to control phytophthora blight by spray. Field efficacy trials showed that: 3 g/kg eugenol and 25% metalaxyl-propamocarb hydrochloride could control phytophthora blight successfully. Control efficacy was over 70% to control phytophthora blight after 3 g/kg eugenol was diluted 2000 times and 25% metalaxyl-propamocarb hydrochloride was diluted 1000 times. It was suggested that eugenol and metalaxyl-propamocarb hydrochloride were efficient to control phytophthora blight with highly control effect and safety to non-target organisms, and could extend in practice.%为筛选出防治辣椒疫病有效的植物源药剂,采用喷雾法,比较丁子香酚和甲霜·霜霉威在田间对辣椒疫病的防治效果.田间药效试验发现:丁子香酚和甲霜·霜霉威是防治辣椒疫病较好的药剂,具有防效高和对非靶标生物安全的特点,可以在生产上推广.用量为3g/kg丁子香酚可溶液剂2000倍液、25%甲霜·霜霉威可湿性粉剂1000倍液.施药时期掌握在辣椒疫病发病初期施第1次药,以后间隔7天再施药1次,防治效果在70%以上.

  2. Solarização para controle de Phytophthora parasitica em mudas de citros

    Directory of Open Access Journals (Sweden)

    MAY-DE MIO LOUISE L.

    2002-01-01

    Full Text Available O uso de solarização tem-se mostrado eficiente para o controle de fitopatógenos habitantes do solo. No caso de Phytophthora parasitica, agente causal de podridão de raízes em viveiros de citros (Citrus spp., utiliza-se, normalmente, desinfestação com brometo de metila, produto altamente tóxico ao homem e à comunidade microbiana do solo. Neste trabalho, verificou-se a eficiência da solarização em substrato pré-colonizado com P. parasitica por meio de dois métodos: sacos plásticos e coletor solar. Os experimentos foram realizados no inverno e no verão. No inverno, o delineamento foi em blocos ao acaso com oito tratamentos (coletor solar por 24 h e 48 h, saco plástico por 24 h e 48 h, coletor solar por 48 h + Trichoderma spp., Trichoderma spp., testemunha à sombra inoculada e não inoculada e quatro repetições com 15 plantas. A avaliação foi feita pelo teste de isca para recuperação do patógeno e pelo desenvolvimento das plântulas de citros após três meses do transplantio para os tubetes. No verão, os tratamentos foram um, dois, sete e 14 dias de solarização em sacos plásticos, e a avaliação foi feita apenas pelo teste de isca para recuperação do patógeno. A solarização do substrato para produção de mudas em coletor solar (tubos com 10 cm de diâmetro por 24 h (inverno e verão e em sacos plásticos (20 x 25 x 4 cm³ por 48 h no verão eliminou P. parasitica propiciando melhor desenvolvimento das mudas.

  3. Response to artificial inoculation with Phytophthora infestans of potato clones insensitive to culture filtrate of the fungus

    International Nuclear Information System (INIS)

    Induction of general resistance to Phytophthora infestans (Mont.) de Bary by in vitro culture has been reported for cvs. 'Bintje' and 'Kennebec'. In both cases, sporangia suspension of the fungus were used as selective agent. As reported for many host-pathogen interactions, culture filtrate or purified toxins may also contribute to the selection of resistant genotypes. Challenge of mutagenized buds of cv. 'Spunta' with culture filtrate of P. infestans allowed selection of insensitive clones. To verify the possible correlation between culture filtrate insensitivity and disease resistance, different inoculation technique were applied to these clones. Considering that general resistance to late blight is a complex trait, different tests were performed to evaluate the behaviour during various stages of pathogenesis, such as infection, invasion, mycelial growth and sporulation. 7 refs, 1 tab

  4. An efficient assay for detection of Phytophthora cinnamomi in the rhizosphere of Sweet Chestnut (Castanea sativa Mill.)

    OpenAIRE

    E. Gouveia; Coelho, V; Sousa, N.; Coutinho, S.; Nunes, L.; Maria Loreto Monteiro

    2009-01-01

    O ciclo biológico de Phytophthora cinnamomi Rands e P. cambivora (Petri) Buisman espécies associadas com a Doença da Tinta do Castanheiro, ocorre integralmente no ambiente solo. A presença de qualquer uma destas espécies parasitas inviabiliza as novas plantações de castanheiro e coloca sérios problemas à manutenção dos soutos já instalados. Para garantir a ausência de propágulos dos parasitas no material de multiplicação do castanheiro e avaliar o estado sanitário dos solos é necessário que o...

  5. A proteomics study of in vitro cyst germination and appressoria formation in ¤Phytophthora infestans¤

    DEFF Research Database (Denmark)

    Ebstrup, T.; Saalbach, G.; Egsgaard, H.

    2005-01-01

    A proteomics study using two-dimensional gel electrophoresis (2-DE) and mass spectrometry was performed on Phytophthora infestans. Proteins from cysts, germinated cysts and appressoria grown in vitro were isolated and separated by 2-DE. Statistical quantitative analysis of the protein spots from...... five independent experiments of each developmental stage revealed significant up-regulation of ten spots on gels from germinated cysts compared to cysts. Five spots were significantly up-regulated on gels from appressoria compared to germinated cysts and one of these up-regulated spots...... of the proteins that were up-regulated in germinated cysts and appressoria can be grouped into the following categories: protein synthesis (e.g. a DEAD box RNA helicase), amino acid metabolism, energy metabolism and reactive oxygen species scavenging. The spot not detected in appressoria was identified as the P...

  6. Biological control of late blight (Phytophthora infestans (Mont.) de Bary) in tomatoes with mycoextracts from Fusarium culmorum and Fusarium graminearum.

    Science.gov (United States)

    Cărăbet, A F; Grozea, I; Chirita, R; Badea, A M

    2008-01-01

    Following a screening completed over several species of fungus for establishing the efficiency of the extracts produced from them, against agent causing the late blight--Phytophthora infestans--two species of fungus were selected--Fusarium graminearum and Fusarium culmorum--in order to employ them and their strains with different virulence in the pathosystem fungi/Lycopersicumm esculentum. The utilized extracts are based on ethanol and obtained from mycelium and culture filtrate. Extract was applied 2 and respectively 7 days before the artificial inoculation, realized on the detached tomato's leaves and maintained at 17 degrees C and air relative humidity of 100%. The evaluation was done 6 days after the inoculation. The results show that for the treatment applied 2 days before inoculation the intensity of the attack was reduced by aprox. 60% compared with the control but for the inoculation at 7 days after the treatment, the intensity was not diminished. PMID:19226762

  7. Espécies de Phytophthora associadas à gomose em pomares de citros no Estado do Paraná, Brasil

    Directory of Open Access Journals (Sweden)

    Marilda Pereira Caixeta

    2013-12-01

    Full Text Available A gomose dos citros é considerada uma doença de grande importância para a citricultura no Brasil e em nível mundial. A etiologia desta doença compreende um complexo de espécies de Phytophthora. Embora importante, pouco se conhece sobre a gomose nas regiões produtoras de citros no Estado do Paraná. Por isso, este trabalho teve como objetivo identificar espécies de Phytophthora associadas à gomose em pomares de citros no Paraná. Nas regiões Norte, Noroeste e Vale do Ribeira foram retiradas amostras de raízes de plantas com sintomas de gomose e também de solo da rizosfera. Em laboratório, empregando pêra cv. D'anjou como isca e meio de cultivo batata-dextrose-ágar, foram obtidos 21 isolados de Phytophthora spp. Todos os isolados infectaram mudas de limão 'Cravo', reproduzindo os sintomas de gomose e também apresentaram crescimento micelial a 8º C e a 36º C, com exceção do isolado PR20 para 36º C . "In vitro", esses isolados foram heterotálicos, sendo 20 compatíveis ao tipo padrão A2 e um compatível ao tipo padrão A1. Vinte isolados formaram esporângios persistentes e papilados, com 25,5 - 62,0 µm de comprimento (C e 27,9 - 49,6 µm de largura (L e a relação C/L foi de 1,38:1. Um isolado (PR20 apresentou esporângios medindo 40,3 - 55,8 µm de comprimento e 27,9 - 37,2 µm de largura, formando esporângios persistentes, papilados ou bipapilados e de formas distorcidas, não formando clamidósporos. A temperatura ótima para crescimento desse isolado foi entre 20 a 28º C, enquanto para os demais foi de 24 a 32º C, tendo estes produção abundante de clamidósporos globosos de diâmetro variando entre 21,7 a 43,4 µm. De acordo com as características morfofisiológicas apresentadas, dos 21 isolados analisados, 20 pertenceram à espécie P. nicotianae e um à espécie P. citrophthora. A análise de sequências de genes da região ITS1-5.8S-ITS2 do rDNA e usando o teste de "Single-Strand Conformation Polymorphism

  8. The behaviour of certain potato varieties and lines towards the attack of the Phytophthora infestans (Mont de Bary fungus

    Directory of Open Access Journals (Sweden)

    Daniela POPA

    2008-05-01

    Full Text Available This paper presents the behaviour of some potato varieties and lines towards the attack of the Phytophthora infestans (Mont de Bary fungus under the field conditions of the Potato Research and Development Station, Targu-Secuiesc. During the observed period (2001-2003 the appearance of new forms of attack was registered, for example the attack on the stem, on the leaf petioles, as well as a greater number of infected tubers. The greatest number of blighted stems belonged to the varieties Sante and Ostara, and the smallest one was registered in the case of the variety Lady Roseta, followed by Desiree and Nemere. The results prove that there is a direct relationship between the frequency of the attack on the stems and that of the blighted tubers in the case of every variety, except for the varieties Lady Roseta and Nemere at which the smallest number of infected tubers was registered.

  9. Diversidad genética de aislamientos de Phytophthora infestans en plantaciones de papa en Costa Rica con el uso de RAPDs

    OpenAIRE

    Oswaldo P\\u00E1ez; Roberto Valverde; Luis G\\u00F3mez; Arturo Brenes

    2005-01-01

    Para determinar la diversidad genética de Phytophthora infestans en Costa Rica, 62 aislamientos de este patógeno fueron recolectados en plantaciones de papa en las zonas de Cartago, Zarcero, Fraijanes y Heredia durante 1999-2001 y analizados con el uso de RAPDs. Todos los aislamientos fueron previamente evaluados para el tipo de apareamiento y la resistencia al metalaxyl. Se seleccionó 11 imprimadores con los cuales fue posible formar 17 grupos RAPD cuyas frecuen...

  10. Monitoramento da população de Phytophthora infestans na região da Zona da Mata de Minas Gerais de 1998 a 2000

    OpenAIRE

    REIS AILTON; SUASSUNA NELSON D.; ALFENAS ACELINO C.; MIZUBUTI EDUARDO S. G.

    2002-01-01

    Foram caracterizados 212 isolados de Phytophthora infestans obtidos de 51 lavouras de tomate (Lycopersicon esculentum)e batata (Solanum tuberosum), em sete municípios da Zona da Mata, MG. Todos os isolados tiveram o grupo de compatibilidade determinado; 96 isolados foram caracterizados para a isoenzima glucose 6-fosfato-isomerase (Gpi); 71 isolados foram analisados quanto à resistência ao metalaxyl; e determinou-se o espectro de virulência de 46 isolados. Todos os 212 isolados testados foram ...

  11. Molecular genetic studies in Fragaria species: Agrobacterium-mediated transformation and fine mapping of the Phytophthora fragariae resistance gene Rpf1.

    OpenAIRE

    Haymes, K.M.

    1997-01-01

    The fungus Phytophthora fragariae, is able to cause red stele root rot in the strawberry. Symptoms of the disease is discolouration of the stele of the roots, rotting away of the infected roots, dwarfism, wilting, and finally plant death. Chemical control of red stele with soil fumigants reduce the inoculum potential of the fungus in the soil but does not eliminate it completely. Resistant cultivars are looked upon more favourably by growers since the consumer and environmentalist are demandi...

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

    Directory of Open Access Journals (Sweden)

    Angela Chaparro-Garcia

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

  13. Genome sequences of two Phytophthora species responsible for Sudden Oak Death and Soybean Root Rot provide novel insights into their evolutionary origins and mechanisms of pathogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Tyler, Brett M.; Tripathi, Sucheta; Aerts, Andrea; Bensasson, Douda; Dehal, Paramvir; Dubchak, Inna; Garbelotto, Matteo; Gijzen, Mark; Huang, Wayne; Ivors, Kelly; Jiang, Rays; Kamoun, Sophien; Krampis, Konstantinos; Lamour, Kurt; McDonald, Hayes; Medina, Monica; Morris, Paul; Putnam, Nik; Rash, Sam; Salamov, Asaf; Smith, Brian; Smith, Joe; Terry, Astrid; Torto, Trudy; Grigoriev, Igor; Rokhsar, Daniel; Boore, Jeffrey

    2005-12-01

    The approximately 60 species of Phytophthora are all destructive pathogens, causing rots of roots, stems, leaves and fruits of a wide range of agriculturally and ornamentally important plants (1). Some species, such as P. cinnamomi, P. parasitica and P. cactorum, each attack hundreds of different plant host species, whereas others are more restricted. Some of the crops where Phytophthora infections cause the greatest financial losses include potato, soybean, tomato, alfalfa, tobacco, peppers, cucurbits, pineapple, strawberry, raspberry and a wide range of perennial tree crops, especially citrus, avocado, almonds, walnuts, apples and cocoa, and they also heavily affect the ornamental, nursery and forestry industries. The economic damage overall to crops in the United States by Phytophthora species is estimated in the tens of billions of dollars, including the costs of control measures, and worldwide it is many times this amount (1). In the northern midwest of the U.S., P. sojae causes $200 million in annual losses to soybean alone, and worldwide causes around $1-2 billion in losses per year. P. infestans infections resulted in the Irish potato famine last century and continues to be a difficult and worsening problem for potato and tomato growers worldwide, with worldwide costs estimated at $5 billion per year.

  14. Isolation and Characterization of Trichoderma spp. for Antagonistic Activity Against Root Rot and Foliar Pathogens.

    Science.gov (United States)

    Kumar, Krishna; Amaresan, N; Bhagat, S; Madhuri, K; Srivastava, R C

    2012-06-01

    Trichoderma, soil-borne filamentous fungi, are capable of parasitising several plant pathogenic fungi. Twelve isolates of Trichoderma spp. isolated from different locations of South Andaman were characterized for their cultural, morphological and antagonistic activity against soil borne and foliar borne pathogens. The sequencing of these isolates showed seven different species. The isolates revealed differential reaction patterns against the test pathogens viz., Sclerotium rolfsii, Colletotrichum gloeosporioides and C. capsici. However, the isolates, TND1, TWN1, TWC1, TGD1 and TSD1 were most effective in percentage inhibition of mycelial growth of test pathogens. Significant chitinase and β-1,3-glucanase activities of all Trichoderma isolates has been recorded in growth medium. T. viride was found with highest chitinase whereas T. harzianum was recorded with highest β-1,3-glucanase activities. PMID:23729873

  15. Interception of Phytophthora syringae on Citrus fruits imported from California, USA%进境美国加州脐橙中丁香疫霉Phytophthora syringae截获

    Institute of Scientific and Technical Information of China (English)

    罗加凤; 刘跃庭; 廖芳; 胡晓红; 刘鹏; 黄国明

    2012-01-01

    Several brown rot fruits have been found from Californian fresh orange sample. Three isolates similar to Phytophthora syringae were obtained from these rot fruits. The colonies grew slowly on PDA and V8 juice agar (V8A). They were stellate, tiled and thin on V8A, but on PDA, the margin was chrysanthemum petaloid; mycelia dense, milk-white-colored. Sporangia and catenulate hyphal swellings formed in sterilizing water and soil extract water in 48h. The isolates were homothallic. Oospores were produced abundantly on PDA and V8A mixed with fresh Citrus fruit tissue or leaf of rhododendron. The isolates were wounded-inoculated on fresh Citrus fruits. Typical brown rot symptoms are apparent on inoculated fruits in 7d. DNA of hyphae was amplified with ITS1/ITS4 primers. In comparision with P. Syringae from NCBIGenBank databases, the sequences had 99% identity. All the results of tests showed that the isolates were Phytophthorasyringae.%从产自美国加利福尼亚州的新鲜脐橙样品中发现多个腐烂病果,通过分离培养得到3个疑似丁香疫霉Phytophthora syringae菌株,对3个菌株进行形态学研究、致病性测定和分子序列比对分析.结果表明病菌在V8A培养基上菌落稀疏、平铺,呈星状,菌丝紧贴培养基生长或埋于基质内生长;在PDA培养基上菌落呈菊花花瓣状,菌丝致密,乳白色;游动孢子囊和菌丝膨大体在无菌水和土壤浸出液中黑暗条件下48h后产生;菌株为同宗配合,卵孢子在带有新鲜脐橙果实组织或杜鹃叶片的V8A培养基中大量产生;创伤接种脐橙果实,7d后接种脐橙出现典型的褐腐症状;通用引物ITS 1/ITS4扩增测序,Blastn分析表明序列与GenBank中P.syringae序列相似性为99%.依据上述研究结果,将分离获得的3株菌鉴定为丁香疫霉Phytophthora syringae,系国内首次截获的一种植物检疫性真菌病害.

  16. VARIABILIDAD GENÉTICA DE AISLAMIENTOS COLOMBIANOS DE Phytophthora infestans (Mont de Bary EN SOLANÁCEAS CULTIVADAS EN COLOMBIA GENETIC VARIABILITY OF ISOLATES OF Phytophthora infestans (Mont. de Bary IN SOLANACEOUS CROPS FROM COLOMBIA

    Directory of Open Access Journals (Sweden)

    Natalia Raigosa Gómez

    2009-06-01

    Full Text Available Se estudio el nivel de variabilidad genética de una población de 35 aislamientos de Phytophthora infestans obtenidos en diferentes hospedantes y regiones geográficas de Colombia, mediante las técnicas de haplotipos mitocondriales y RAPD. Los resultados encontrados sugieren la existencia en el país de los haplotipos mitocondriales Ia en los aislamientos que afectan tomate de árbol (Solanum betaceum y IIa en cultivos de papa; dichos haplotipos están asociados a los linajes genéticos EC-3 y EC-1, respectivamente. Sin embargo, tres aislamientos obtenidos en tomate de mesa (S. lycopersicum, pimentón (Capsicum sp. y pepino de agua (S. muricatum requieren de un análisis posterior, debido a la falta de correlación entre los perfiles de restricción generados con los cuatro pares de cebadores utilizados en esta prueba y los haplotipos mitocondriales mencionados en la literatura. De otra parte, mediante cuatro cebadores RAPD, fue posible encontrar variabilidad al interior de los dos linajes genéticos, siendo interesante el hecho que los aislamientos obtenidos en tomate de árbol (EC-3 fueron divididos en dos grupos, relacionados con una distancia genética de 0,17. Estos hallazgos indican que es importante contemplar las fuentes de variación asexual en el análisis de la estructura poblacional de este oomycete y por tanto en el diseño de las estrategias de control de las enfermedades que causa P. infestans en cultivos de solanáceas de importancia económica.The level of genetic variability of 35 isolates of Phytophthora infestans obtained from different hosts and geographical regions of Colombia was studied through mitochondrial haplotypes and RAPD techniques. Results suggested the existence of mitochondrial haplotypes Ia affecting tree tomato (Solanum betaceum and IIa in potato, which are associated with genetic lineages EC-3 and EC-1, respectively. However, three isolates obtained from tomato (S. lycopersicum, capsicum (Capsicum sp. and

  17. Reação de híbridos somáticos de citros à infecção por Phytophthora nicotianae Reaction of citrus somatic hybrids to the infection by Phytophthora nicotianae

    Directory of Open Access Journals (Sweden)

    Meire Menezes Bassan

    2010-06-01

    Full Text Available Este trabalho avaliou a resistência à infecção de tronco e de raízes por Phytophthora nicotianae em híbridos somáticos de citros com potencial para serem utilizados como porta-enxertos. Os híbridos somáticos avaliados foram laranja 'Hamlin' (Citrus sinensis + toranja 'Indian Red' (Citrus grandis (plantas 1 e 2 e laranja 'Hamlin' (C. sinensis + toranja 'Singapura' (C. grandis. Plantas de limão 'Cravo' (Citrus limonia, laranja 'Caipira' (C. sinensis, laranja-azeda (C. aurantium e Poncirus trifoliata 'Davis A' (Poncirus trifoliata foram utilizadas como plantas-controle devido à reação conhecida à infecção pelo patógeno. Avaliações realizadas entre 30 e 60 dias após as inoculações com o patógeno incluíram o comprimento das lesões no tronco e a massa seca do sistema radicular nas plantas avaliadas. O híbrido somático laranja 'Hamlin' + toranja 'Indian Red' (planta 1 mostrou-se tolerante a P. nicotianae, indicando potencial para continuidade nas suas avaliações como porta-enxerto para citros.This study aimed to evaluate the resistance to trunk and root infection by Phytophthora nicotianae in citrus somatic hybrids with potential to be utilized as rootstocks. The somatic hybrids evaluated were 'Hamlin' sweet orange (Citrus sinensis + 'Indian Red' pummelo (Citrus grandis (plants 1 and 2, and 'Hamlin' sweet orange (C. sinensis + 'Singapura' pummelo (C. grandis. Plants of 'Rangpur' lime (Citrus limonia, 'Caipira' sweet orange (C. sinensis, sour orange (C. aurantium, and Poncirus trifoliata 'Davis A' (Poncirus trifoliata were used as control due to their known reaction to the pathogen. Evaluations performed between 30 and 60 days after pathogen inoculation included the length of trunk lesions, and root dry mass of the root system of evaluated plants. The somatic hybrid 'Hamlin' sweet orange + 'Indian Red' pummelo (plant 1 was tolerant to P. nicotianae, indicating potential to be further evaluated as a rootstock.

  18. Evaluation of phenotypic stability of resistance to Phytophthora spp. in cacao clones Avaliação da estabilidade fenotípica da resistência a Phytophthora spp. em clones de cacaueiro

    Directory of Open Access Journals (Sweden)

    Luiz Roberto M. Pinto

    2007-12-01

    Full Text Available Resistance of fourteen Theobroma cacao clones to Phytophthora spp. was evaluated using stem inoculations on grafted seedlings. Concepts of phenotypic stability were used to interpret the results and to express horizontality of the resistance. The linear regression coefficient 'b', the determination coefficient (R² and average lesion size were used to determine the level of horizontal resistance, the phenotypic stability and the predictability of all clones. The results indicated that clones P 7 and MA 15 present highest levels of horizontal resistance and stability, but with moderate predictability. Clones CAS 1 and CEPEC 13 were classified as those with high horizontal resistance, stability and predictability, while clones PA 30, UF 650 and SIAL 88 and EET 59 showed intermediate resistance and stability and high predictability. Clones SPA 17, OC 61, PA 150, SIAL 505, ICS 1 and R 41 presented high susceptibility and intermediate or low stability and moderate or high predictability.A resistência de quatorze clones de Theobroma cacao a Phytophthora spp. foi avaliada utilizando inoculações em hastes de mudas enxertadas de cacau. Utilizaram-se os conceitos de estabilidade fenotípica para interpretar os resultados e expressar a horizontalidade da resistência. O coeficiente 'b' da regressão linear, o coeficiente de determinação (R² e a média das lesões foram utilizadas para determinar o nível de resistência horizontal, a estabilidade fenotípica e a previsibilidade de comportamento dos clones. Os resultados indicaram que os clones P 7 e MA 15 apresentaram os níveis mais altos de resistência e estabilidade, porém com previsibilidade moderada. Os clones CAS 1 e CEPEC 13 foram classificados como de alta resistência horizontal, estabilidade e previsibilidade enquanto que os clones PA 30, UF 650, SIAL 88 e EET 59 apresentaram resistência intermediária e alta previsibilidade. Os clones SPA 17, OC 61, PA 150, SIAL 505, ICS 1 e R 41

  19. Isolation and identification of plant growth promoting rhizobacteria from cucumber rhizosphere and their effect on plant growth promotion and disease suppression

    Directory of Open Access Journals (Sweden)

    Shaikhul eIslam

    2016-02-01

    Full Text Available Plant growth promoting rhizobacteria (PGPR are the rhizosphere bacteria that may be utilized to augment plant growth and suppress plant diseases. The objectives of this study were to identify and characterize PGPR indigenous to cucumber rhizosphere in Bangladesh, and to evaluate their ability to suppress Phytophthora crown rot in cucumber. A total of sixty six isolates were isolated, out of which ten (PPB1, PPB2, PPB3, PPB4, PPB5, PPB8, PPB9, PPB10, PPB11 and PPB12 were selected based on their in vitro plant growth promoting attributes and antagonism of phytopathogens. Phylogenetic analysis of 16S rRNA sequences identified these isolates as new strains of Pseudomonas stutzeri, Bacillus subtilis, Stenotrophomonas maltophilia and B. amyloliquefaciens. The selected isolates produced high levels (26.78 to 51.28 μg mL−1 of indole-3-acetic acid, while significant acetylene reduction activities (1.79 to 4.9 µmole C2H4 mg-1 protein h-1 were observed in eight isolates. Cucumber plants grown from seeds that were treated with these PGPR strains displayed significantly higher levels of germination, seedling vigor, growth, and N content in root and shoot tissue compared to non-treated control plants. All selected isolates were able to successfully colonize the cucumber roots. Moreover, treating cucumber seeds with these isolates significantly suppressed Phytophthora crown rot caused by Phytophthora capsici, and characteristic morphological alterations in Ph. capsici hyphae that grew towards PGPR colonies were observed. Since these PGPR inoculants exhibited multiple traits beneficial to the host plants, they may be applied in the development of new, safe, and effective seed treatments as an alternative to chemical fungicides.

  20. Isolation and Identification of Plant Growth Promoting Rhizobacteria from Cucumber Rhizosphere and Their Effect on Plant Growth Promotion and Disease Suppression

    Science.gov (United States)

    Islam, Shaikhul; Akanda, Abdul M.; Prova, Ananya; Islam, Md. T.; Hossain, Md. M.

    2016-01-01

    Plant growth promoting rhizobacteria (PGPR) are the rhizosphere bacteria that may be utilized to augment plant growth and suppress plant diseases. The objectives of this study were to identify and characterize PGPR indigenous to cucumber rhizosphere in Bangladesh, and to evaluate their ability to suppress Phytophthora crown rot in cucumber. A total of 66 isolates were isolated, out of which 10 (PPB1, PPB2, PPB3, PPB4, PPB5, PPB8, PPB9, PPB10, PPB11, and PPB12) were selected based on their in vitro plant growth promoting attributes and antagonism of phytopathogens. Phylogenetic analysis of 16S rRNA sequences identified these isolates as new strains of Pseudomonas stutzeri, Bacillus subtilis, Stenotrophomonas maltophilia, and Bacillus amyloliquefaciens. The selected isolates produced high levels (26.78–51.28 μg mL-1) of indole-3-acetic acid, while significant acetylene reduction activities (1.79–4.9 μmole C2H4 mg-1 protein h-1) were observed in eight isolates. Cucumber plants grown from seeds that were treated with these PGPR strains displayed significantly higher levels of germination, seedling vigour, growth, and N content in root and shoot tissue compared to non-treated control plants. All selected isolates were able to successfully colonize the cucumber roots. Moreover, treating cucumber seeds with these isolates significantly suppressed Phytophthora crown rot caused by Phytophthora capsici, and characteristic morphological alterations in P. capsici hyphae that grew toward PGPR colonies were observed. Since these PGPR inoculants exhibited multiple traits beneficial to the host plants, they may be applied in the development of new, safe, and effective seed treatments as an alternative to chemical fungicides. PMID:26869996

  1. Assessment of metabolic capacity of Trichoderma inhamatum Bol12 QD biocontrol on native strains of Phytophthora infestans in vitro

    Directory of Open Access Journals (Sweden)

    Puño Ramon

    2011-08-01

    Full Text Available Plant pathogen Phytophthora infestans is a cause of decreased crop yield of tomato, to control these losses, farmers use chemicals. This has consequences for the environment, human health and beneficial organisms in the ecosystem. The objective was to obtain and identify native isolates of Trichoderma spp. In soil planted with tomato Tlayacapan, Morelos (Mexico, Alternaria solani problems and Phytophthora infestans, also determine their antagonistic capacity in vitro. Trichoderma was isolated directly from soil by dilution in culture medium plate with potato dextrose agar (PDA. On the other side plate dilutions of yeast T. QD Bol12 inhamatum crops produced in batch for 30 days to compare the effectiveness of biocontrol. The filtered yeast inhibited mycelial growth kinetic of the agent in laboratory with the 1:2 dilution growth was 32.5% for the 1:4 dilution mycelial growth was 69.1% and finally to the dilution of 1:8 of the yeast biocontrol mycelium grew to 95.2%. To demonstrate the inhibitory activity on the pathogen in field crops, there were 3 L batch for four months. The application of three doses (undiluted, diluted 1:2 and 1:4 plus a control dilution water only was performed in a complete block design with four replications randomly with the tomato crop, belonging to the variety Santa Cruz Kada Gigante in the plots of the Academic Rural United Campesina Carmen Pampa. Statistical analysis by Duncan's test showed that the pure leaven reduce infection by Phytophthora infestans significantly in tomato. Appeared another tomato plant pathogen, Septoria lycopersici, in the course of fieldwork. We also evaluated the effect of the dose of yeast to this disease, and also noticed a significant reduction with all doses of yeast. These experiments demonstrated that the seeds of T. QD Bol12 inhamatum have biocontrol effect on the tomato crop. The antagonistic capacity was assessed using the cellophane and the kind of antagonism with the dual culture

  2. Monitoramento da população de Phytophthora infestans na região da Zona da Mata de Minas Gerais de 1998 a 2000 Monitoring Phytophthora infestans population in the Zona da Mata region of Minas Gerais, Brazil, from 1998 to 2000

    OpenAIRE

    AILTON REIS; Nelson D. Suassuna; Alfenas, Acelino C; EDUARDO S. G. MIZUBUTI

    2002-01-01

    Foram caracterizados 212 isolados de Phytophthora infestans obtidos de 51 lavouras de tomate (Lycopersicon esculentum)e batata (Solanum tuberosum), em sete municípios da Zona da Mata, MG. Todos os isolados tiveram o grupo de compatibilidade determinado; 96 isolados foram caracterizados para a isoenzima glucose 6-fosfato-isomerase (Gpi); 71 isolados foram analisados quanto à resistência ao metalaxyl; e determinou-se o espectro de virulência de 46 isolados. Todos os 212 isolados testados foram ...

  3. A simple method for diagnostic of Phytophthora infestans (Mont. de Bary from potato agricultural fields of potato

    Directory of Open Access Journals (Sweden)

    Touseef Hussain

    2015-12-01

    Full Text Available A correct detection and appropriate identification of causal pathogens associated with crop plants or seeds are considered to be the most important issue in designing the proper management plans for plant diseases. This study was designed to detect Phytophthora infestans inoculum from potato grown soil. A high detection rate of P.infestans was obtained from the naturally infested soil of potato fields. Naturally soils were firstly moistened in a plastic pots and then pre-incubated at ±18°C for 3 days, baiting with potato tuber slice for 24, 48, and 72 h. The baits were then thoroughly washed, flooded with 10–15 ml of distilled water in Petri-dishes and incubated under continuous darkness in chamber ±18ºC. Sporangia started to emerge from the margins of potato tuber slice. They were easily observed under the stereomicroscope. Pure culture of the fungus was obtained by isolating from baited tubers on a Rye Agar medium. This is the first report of recovery of P. infestans from naturally infested potato growing soils using susceptible potato tuber (K. Bahar as bait in India. All isolates were determined to be A2 mating type.

  4. Phytophthora infestans field isolates from Gansu province, China are genetically highly diverse and show a high frequency of self fertility.

    Science.gov (United States)

    Han, Miao; Liu, Gang; Li, Ji-Ping; Govers, Francine; Zhu, Xiao-Qiong; Shen, Chong-Yao; Guo, Li-Yun

    2013-01-01

    The genetic diversity of 85 isolates of Phytophthora infestans collected in 2007 from Gansu province in China was determined and compared with 21 isolates collected before 2004. Among them, 70 belonged to the A1 mating type and 15 were self-fertile (SF). The mitochondrial DNA haplotypes revealed both Ia (25%) and IIa (75%) haplotypes. Metalaxyl resistance occurred with high frequency (54%) in Gansu. Simple sequence repeat (SSR) genotyping revealed 26 genotypes (13 from the Tianshui region) among the 85 isolates, and 18 genotypes among the 21 isolates collected before 2004, without overlap in genotypes detected in the two groups. Cluster analysis showed clear subdivisions within the different mating type isolates. Among Gansu's isolates, Nei's and Shannon's diversity indices were highest in isolates collected in Tianshui where both A1 and SF isolates were found. Analysis of molecular variance of isolates from Gansu indicated that 51% and 49% of the variance was explained by within-area and among-area variance, respectively. The results suggest that the occurrence of SF isolates increases the risk of sexual reproduction, the formation of oospore as initial inocula in the field, and affects the genotypic diversity in the population. PMID:23194320

  5. Macrocyclic Trichothecenes from Myrothecium roridum Strain M10 with Motility Inhibitory and Zoosporicidal Activities against Phytophthora nicotianae.

    Science.gov (United States)

    Mondol, Muhammad Abdul Mojid; Surovy, Musrat Zahan; Islam, M Tofazzal; Schüffler, Anja; Laatsch, Hartmut

    2015-10-14

    The cytotoxicity of the extract obtained from Myrothecium roridum M10 and a characteristic (1)H signal at δH ∼8 led to the assumption that verrucarin/roridin-type compounds were present. Upscaling on rice medium led to the isolation of four new metabolites: verrucarins Y (1) and Z (6) (macrocyclic trichothecenes), bilain D (12) (a diketopiperazine derivative), and hamavellone C (14) (an unusual cyclopropyl diketone). In addition, nine known trichothecenes [verrucarin A (3), 16-hydroxyverrucarin A (5), verrucarin B (7), 16-hydroxyverrucarin B (8), verrucarin J (2), verrucarin X (4), roridin A (9), roridin L-2 (10), and trichoverritone (11)] and a bicyclic lactone [myrotheciumone A (15)] were identified. Their structures and configurations were determined by spectroscopic methods, published data, Mosher's method, and considering biosyntheses. Some trichothecenes showed motility inhibition followed by lysis of the zoospores against devastating Phytophthora nicotianae within 5 min. Compounds 2, 3, 7, and 9 also exhibited potent activities against Candida albicans and Mucor miehei. PMID:26320597

  6. Green fluorescent protein (GFP) as a vital marker for studying the interaction of Phytophthora sojae and soybean

    Institute of Scientific and Technical Information of China (English)

    CHEN XiaoRen; CHENG BaoPing; WANG XinLe; DONG SuoMeng; WANG YongLin; ZHENG XiaoBo; WANG YuanChao

    2009-01-01

    Transgenic Phytophthora sojae strains that produce green fluorescent protein (GFP) were obtained after stable DNA integration using the Hsp70 promoter and the Ham34 terminator of Bremia lactucae.The expression of GFP during different developmental stages of P.sojae was observed using fluorescent microscopy.Based on this reporter system,the histopathologic events caused by the pathogen in soybean leaves,hypocotyls and roots were monitored.Meanwhile,the difference in resistance between different soybean cultivars against P.sojae was analyzed microscopically in roots.The results indicate that GFP can be stably expressed in zoosporangia,zoospores,cysts,hyphae and oospores of .sojae.Using the GFP marker,the infecting pathogens in leaves,hypocotyls and roots of host could be distinctly visualized.The germ tube length of cysts germinating on the roots of resistant cultivar Nannong 8848 was longer than that on the roots of susceptible culUvar Hefeng 35.These results show for the first time that this eukaryotic reporter can be used in P.sojae as a stable and vital marker,allowing the study of genetics of this hemibiotrophic pathogen.

  7. Photosynthetic and leaf water potential responses of Alnus glutinosa saplings to stem-base inoculaton with Phytophthora alni subsp. alni.

    Science.gov (United States)

    Clemenz, Christian; Fleischmann, Frank; Häberle, Karl-Heinz; Matyssek, Rainer; Osswald, Wolfgang

    2008-11-01

    Three-year-old Alnus glutinosa (L.) Gaertn. (alder) saplings were single or double inoculated at the stem base with Phytophthora alni subsp. alni Brasier & S.A. Kirk under natural climatic conditions. Lesion formation on the bark showed a biphasic pattern of development, with extension occurring at a moderate rate in spring, and more rapidly during late summer. However, large variability was encountered in pathogen development within the population of infected saplings, ranging from high susceptibility to almost complete resistance. Infection resulted in severe growth retardation, and death within two years of inoculation in 75% of the saplings. During disease development, rates of transpiration and CO(2) uptake were significantly reduced. Consequently, minimum leaf water potentials were less negative in infected saplings than in control saplings. Surviving saplings matched control trees in photosynthetic capacity, transpiration rate and water potential during the second year of infection. Leaf starch concentration of infected saplings was significantly higher than in control saplings, possibly indicating that the destruction of bark tissue by the pathogen impaired phloem transport from leaves to roots. PMID:18765375

  8. Diverse mechanisms shape the evolution of virulence factors in the potato late blight pathogen Phytophthora infestans sampled from China.

    Science.gov (United States)

    Wu, E-Jiao; Yang, Li-Na; Zhu, Wen; Chen, Xiao-Mei; Shang, Li-Ping; Zhan, Jiasui

    2016-01-01

    Evolution of virulence in plant pathogens is still poorly understood but the knowledge is important for the effective use of plant resistance and sustainable disease management. Spatial population dynamics of virulence, race and SSR markers in 140 genotypes sampled from seven geographic locations in China were compared to infer the mechanisms driving the evolution of virulence in Phytophthora infestans (P. infestans). All virulence types and a full spectrum of race complexity, ranging from the race able to infect the universally susceptible cultivar only to all differentials, were detected. Eight and two virulence factors were under diversifying and constraining selection respectively while no natural selection was detected in one of the virulence types. Further analyses revealed excesses in simple and complex races but deficiency in intermediate race and negative associations of annual mean temperature at the site from which pathogen isolates were collected with frequency of virulence to differentials and race complexity in the pathogen populations. These results suggest that host selection may interact with other factors such as climatic conditions in determining the evolutionary trajectory of virulence and race structure in P. infestans and global warming may slow down the emergence of new virulence in the pathogen. PMID:27193142

  9. Indoor Toxicity Test of Eugenol etc.against Phytophthora melonis%丁子香酚对黄瓜疫霉菌的室内毒力测定

    Institute of Scientific and Technical Information of China (English)

    杨泓威; 易图永; 雷颖; 戴良英

    2012-01-01

    Phytophlhora melonis is a soil-borne disease which will seriously damage the production of cucumber. Screen of the fungicides that had evident inhibitory effect against Pkytophtkora melonis is a main way to prevent and control the disease. By the mycelium growth rate method, the toxicity of eugenol and cylosinpeptidemycin on Phytophthora melonis and eugenol on Phytophlhora melonis and Maguiporthe grisea were tested. The results showed that in comparison with cytosinpeptidemycin, eugenol had better inhibitory effect on Phytophlhora melonis, the Ecjo value of eugenol and cytosinpeptidemycin on Phytophthora melonisveie 0.622 3 and 20.673 9 mg/L, respectively; the inhibitory effect of eugenol on Magnaporthe grisea was better than that on Phytophthora melonis, the Ecjo value of eugenol on Magnaporthe grisea was 0.469 7 mg/L.%黄瓜疫霉病是一种严重危害黄瓜生产的土传病害,筛选对黄瓜疫霉菌有强烈抑制作用的药剂是防治黄瓜疫霉病的主要方法.通过菌丝生长速率法,比较了丁子香酚和嘧肽霉素对黄瓜疫霉菌,以及丁子香酚对黄瓜疫霉菌和稻瘟病菌的室内毒力.对于黄瓜疫霉菌,丁子香酚的效果优于嘧肽霉素,EC50值分别为0.622 3和20.673 9 mg/L.而在使用丁子香酚的情况下,对稻瘟病菌的防治效果又好于对黄瓜疫霉菌,其EC50值为0.469 7 mg/L.

  10. Evaluation of natural plant extracts, antagonists and fungicides in controlling root rot, collar rot, fruit (brown rot and gummosis of citrus caused by Phytophthora spp. in vitro

    Directory of Open Access Journals (Sweden)

    G.P. Jagtap

    2012-07-01

    Full Text Available The results revealed that all the six bioagents tested in vitro applying dual culture technique against Phytophthora nicotianae, Phytophthora citrophthora and Phytophthora palmivora significantly inhibited the mycelial growth of the test pathogen over untreated control. However, bioagent, Trichoderma harzianum recorded minimum mean colony diameter (7.73 cm2 and highest inhibition (87.85% of mycelial growth of P. nicotianae over untreated control followed by the bioagent T. viride, T. koningii which recorded mean colony diameter of 9.95 cm2, 14.15 cm2 and mean mycelial inhibition of 84.36 %, 77.76%, respectively. Evaluation of different botanicals by Poisoned Food Technique showed that all plant extracts tested in vitro were found significantly effective in reducing the percentage mycelial growth of P. nicotianae, P. citrophthora and P. palmivora over untreated control. However, plant extract (@ 5, 10 and 15% of Garlic, recorded lowest mean colony diameter (47.45 mm and highest mean mycelial growth inhibition (47.26% followed by Neem, Onion which recorded the mycelial growth of 55.20 mm, 60.85 mm, and the mean mycelial growth inhibition of 38.65%, 32.38%, respectively. Results revealed that all the nine fungicides tested in vitro applying Poisoned Food Technique against P. nicotianae, P. citrophthora and P. palmivora significantly inhibited the mycelial growth of the test pathogen over untreated control. However, fungicide, Cymoxynil 8% + Mancozeb 64% (Curzate M-8 recorded minimum mean colony diameter (16.12 mm and maximum mean inhibition (82.09% of mycelial growth of the test pathogen over untreated control (mean colony diameter 90.00 mm and mean inhibition 0.00 followed by the fungicide Metalaxyl-M 4% + Mancozeb 64% (Ridomil Gold, Metyram (Polyram, which recorded mean colony diameter of 20.16 mm, 24.16 mm and mean mycelial inhibition of 77.59%, 73.14%, respectively.

  11. A Gene Expressed during Sexual and Asexual Sporulation in Phytophthora infestans is a Member of the Puf Family of Translational Regulators

    DEFF Research Database (Denmark)

    Cvitanich, Cristina; Judelson, Howard S.

    2003-01-01

    A gene from Phytophthora infestans that was previously identified as being induced during the development of sexual spores was also found to be active during asexual sporulation. The gene, M90, was expressed as a 3.1-kb primary transcript containing two introns and was predicted to encode a member...... gametangial initials and persisted in mature oospores. Expression was also observed in hyphal tips just prior to asexual sporulation, in sporangiophores, in mature sporangia, and in zoospores. The signal quickly disappeared once spores made the transition to hyphae after germination. Nutrient limitation did...... not induce the gene. Potential roles for a translational regulator during both sexual development and asexual sporulation are discussed....

  12. Persistence of the mitochondrial lineage responsible for the Irish potato famine in extant New World Phytophthora infestans

    DEFF Research Database (Denmark)

    Martin, Michael David; Ho, Simon Y W; Wales, Nathan;

    2014-01-01

    The plant pathogen Phytophthora infestans emerged in Europe in 1845, triggering the Irish potato famine and massive European potato crop losses that continued until effective fungicides were widely employed in the 20(th) century. Today the pathogen is ubiquitous, with more aggressive and virulent......)-century Europe, three from 1950s U.K. and 34 from modern populations across the New World. We use phylogenetic analyses to identify the HERB-1 lineage in modern populations from both Mexico and South America, and to demonstrate distinct mitochondrial haplotypes were present in 19(th)-century Europe, with this...

  13. The soybean-Phytophthora resistance locus Rps1-k encompasses coiled coil-nucleotide binding-leucine rich repeat-like genes and repetitive sequences

    Directory of Open Access Journals (Sweden)

    Bhattacharyya Madan K

    2008-03-01

    Full Text Available Abstract Background A series of Rps (resistance to Pytophthora sojae genes have been protecting soybean from the root and stem rot disease caused by the Oomycete pathogen, Phytophthora sojae. Five Rps genes were mapped to the Rps1 locus located near the 28 cM map position on molecular linkage group N of the composite genetic soybean map. Among these five genes, Rps1-k was introgressed from the cultivar, Kingwa. Rps1-k has been providing stable and broad-spectrum Phytophthora resistance in the major soybean-producing regions of the United States. Rps1-k has been mapped and isolated. More than one functional Rps1-k gene was identified from the Rps1-k locus. The clustering feature at the Rps1-k locus might have facilitated the expansion of Rps1-k gene numbers and the generation of new recognition specificities. The Rps1-k region was sequenced to understand the possible evolutionary steps that shaped the generation of Phytophthora resistance genes in soybean. Results Here the analyses of sequences of three overlapping BAC clones containing the 184,111 bp Rps1-k region are reported. A shotgun sequencing strategy was applied in sequencing the BAC contig. Sequence analysis predicted a few full-length genes including two Rps1-k genes, Rps1-k-1 and Rps1-k-2. Previously reported Rps1-k-3 from this genomic region 1 was evolved through intramolecular recombination between Rps1-k-1 and Rps1-k-2 in Escherichia coli. The majority of the predicted genes are truncated and therefore most likely they are nonfunctional. A member of a highly abundant retroelement, SIRE1, was identified from the Rps1-k region. The Rps1-k region is primarily composed of repetitive sequences. Sixteen simple repeat and 63 tandem repeat sequences were identified from the locus. Conclusion These data indicate that the Rps1 locus is located in a gene-poor region. The abundance of repetitive sequences in the Rps1-k region suggested that the location of this locus is in or near a

  14. TRAMPEO DE Phytophthora cinnamomi EN BOSQUE DE ENCINO CON DOS ESPECIES ORNAMENTALES E INDUCCIÓN DE SU ESPORULACIÓN

    OpenAIRE

    Alejandra Almaraz-Sánchez; Dionicio Alvarado-Rosales; Luz de L. Saavedra-Romero

    2013-01-01

    La mortalidad del encino se ha acentuado recientemente en varios estados del país. La etiología en muchos casos se desconoce. Los bosques de encino están siendo afectados por la “enfermedad de la tinta” (Phytophthora cinnamomi Rands.) en los estados de Colima, Jalisco y Guerrero. La enfermedad causada por P. cinnamomi es de gran importancia; sin embargo, el aislamiento y la esporulación del patógeno representan una gran dificultad. Debido a lo anterior, los objetivos del presente estudio fuer...

  15. A Gene Expressed during Sexual and Asexual Sporulation in Phytophthora infestans Is a Member of the Puf Family of Translational Regulators

    OpenAIRE

    Cvitanich, Cristina; Judelson, Howard S

    2003-01-01

    A gene from Phytophthora infestans that was previously identified as being induced during the development of sexual spores was also found to be active during asexual sporulation. The gene, M90, was expressed as a 3.1-kb primary transcript containing two introns and was predicted to encode a member of the Puf family of translational regulators. The protein showed up to 51% amino acid identity to other Puf proteins within its 353-amino-acid RNA-binding domain. Little similarity extended beyond ...

  16. ALTERNATIVAS MICROBIOLÓGICAS PARA EL MANEJO DE Phytophthora cinnamomi Rands., EN Persea americana Mill. BAJO CONDICIONES DE CASA-MALLA

    OpenAIRE

    Joaquín G. Ramírez Gil; Darío A. Castañeda Sánchez; Juan G. Morales Osorio

    2014-01-01

    Para la producción de aguacate en Colombia es necesario establecer alternativas de manejo amigables con el medio ambiente y de bajo costo para el control de la enfermedad conocida como marchitez, cuyo principal agente causal es Phytophthora cinnamomi. El uso de microorganismos del suelo, es una opción viable para mejorar la nutrición y sanidad en Persea americana, buscando ser más competitivos en aras de afrontar los tratados de libre comercio y poder aprovechar el potencial exportador que pr...

  17. RESISTENCIA DE Phytophthora infestans (Montagne de Bary A METALAXIL, EN CULTIVO DE PAPAS EN EL NORTE DE CHILE Resistance of Phytophthora infestans (Montagne de Bary to metalaxyl in potato crops in Northern Chile

    Directory of Open Access Journals (Sweden)

    Fernando Riveros B.

    2003-04-01

    Full Text Available Con el objeto de determinar la sensibilidad a metalaxil de dos poblaciones de Phytophthora infestans (Montagne de Bary, en cultivos de papa (Solanum tuberosum L. en diferentes localidades de la IV y V Región de Chile, se estudiaron mediante ensayos in vitro e in vivo 254 aislamientos, los cuales inicialmente fueron calificado como sensibles o resistentes de acuerdo a su crecimiento sobre agar centeno B y 10 mg L-1 de metalaxil. Su concentración efectiva media (CE 50, fue estimada mediante un modelo de regresión lineal entre el logaritmo de seis concentraciones de metalaxil (0, 150, 250, 350, 450 y 550 mg L-1 y porcentaje de inhibición transformado a unidades Probit. Los resultados de ambas temporadas demostraron que la totalidad de los aislamientos de P. infestans fueron resistentes a metalaxil. Aislamientos colectados en la IV Región durante 1999 presentaron variaciones de CE 50 entre 243 y 687 mg L-1 de metalaxil, 9,6% de ellos prresentó CE 50 inferior a 300 mg L-1 de metalaxil. Aislamientos colectados en la V Región variaron su CE 50 entre 233 y 633 mg L-1 de metalaxil y solamente 10,1% de ellos presentó CE 50 inferior a 300 mg L-1 de metalaxil. La totalidad de los aislamientos colectados en la temporada 2000 fueron resistentes al fungicida, 89,6 y 78,1% de los colectados en la IV y V Región respectivamente, presentaron CE 50 superiores a 350 mg L-1 de metalaxil. Los resultados del bioensayo fueron consistentes con el trabajo in vitro.The objective of this study was to determine the sensitivity to metalaxyl of two populations of Phytophthora infestans (Montagne de Bary, affecting potato (Solanum tuberosum L. crops in the IV and V Regions of Chile. A total of 254 isolates were studied in vitro and in vivo which were initially classified as sensitive or resistant according to their growth on Rye B media amended with 10 mg L-1 metalaxyl. CE 50 (effective concentration values were estimated for each isolate from a regression curve of

  18. Dinámica microbial del suelo asociada a diferentes estrategias de manejo de Phytophthora cinnamomi Rands en aguacate

    Directory of Open Access Journals (Sweden)

    Joaquín Guillermo Ramírez Gil

    2013-12-01

    Full Text Available La marchitez del aguacate es la enfermedad más limitante de este cultivo, cuyo agente causal más relevante es el oomycete Phytophthora cinnamomi Rands. Es por esto que se han desarrollado diferentes estrategias para su manejo integrado, pero aún prevalece el uso de productos químicos, como única medida de manejo, generando impactos negativos en el ambiente y la salud. Uno de los efectos perjudiciales que se ocasiona es la alteración de las poblaciones microbianas en el suelo. Este trabajo estuvo encaminado a conocer la dinámica microbiana del suelo, bajo diferentes estrategias de manejo de esta enfermedad, para lo cual se midió su dinamismo mediante unidades formadoras de colonias (UFC, para hongos, bacterias y actinomicetos, a partir de muestras de suelo y rizósfera de la raíz, bajo incubación en condiciones de anaerobiosis y aerobiosis, además se midió la actividad microbiana total, en condiciones de laboratorio, como complemento se cuantificaron microorganismos como: Trichiderma spp, bacterias formadoras de endosporas (BAFE, celulolíticos, proteolíticos, amilolíticos, solubilizadores de fosfato, fijadores asimbióticos de nitrógeno y promotores del crecimiento, como Pseudomonas spp., fluorescentes. Los resultados encontrados en esta investigación, sugieren que el uso individual y combinado de mantillo orgánico, material compostado de estiércol bovino, enmienda mineral y cascarilla de arroz y la propuesta de integración; incrementan significativamente la población y actividad microbiana aerobia, en la cual se identificaron microorganismos antagonistas como, Trichiderma spp., celulolíticos, Pseudomonas spp. fluorescentes y BAFE.

  19. Ancient isolation and independent evolution of the three clonal lineages of the exotic sudden oak death pathogen Phytophthora ramorum.

    Science.gov (United States)

    Goss, E M; Carbone, I; Grünwald, N J

    2009-03-01

    The genus Phytophthora includes some of the most destructive plant pathogens affecting agricultural and native ecosystems and is responsible for a number of recent emerging and re-emerging infectious diseases of plants. Sudden oak death, caused by the exotic pathogen P. ramorum, has caused extensive mortality of oaks and tanoaks in Northern California, and has brought economic losses to US and European nurseries as well due to its infection of common ornamental plants. In its known range, P. ramorum occurs as three distinct clonal lineages. We inferred the evolutionary history of P. ramorum from nuclear sequence data using coalescent-based approaches. We found that the three lineages have been diverging for at least 11% of their history, an evolutionarily significant amount of time estimated to be on the order of 165,000 to 500,000 years. There was also strong evidence for historical recombination between the lineages, indicating that the ancestors of the P. ramorum lineages were members of a sexually reproducing population. Due to this recombination, the ages of the lineages varied within and between loci, but coalescent analyses suggested that the European lineage may be older than the North American lineages. The divergence of the three clonal lineages of P. ramorum supports a scenario in which the three lineages originated from different geographic locations that were sufficiently isolated from each other to allow independent evolution prior to introduction to North America and Europe. It is thus probable that the emergence of P. ramorum in North America and Europe was the result of three independent migration events. PMID:19222751

  20. Dissection of two soybean QTL conferring partial resistance to Phytophthora sojae through sequence and gene expression analysis

    Directory of Open Access Journals (Sweden)

    Wang Hehe

    2012-08-01

    Full Text Available Abstract Background Phytophthora sojae is the primary pathogen of soybeans that are grown on poorly drained soils. Race-specific resistance to P. sojae in soybean is gene-for-gene, although in many areas of the US and worldwide there are populations that have adapted to the most commonly deployed resistance to P. sojae ( Rps genes. Hence, this system has received increased attention towards identifying mechanisms and molecular markers associated with partial resistance to this pathogen. Several quantitative trait loci (QTL have been identified in the soybean cultivar ‘Conrad’ that contributes to the expression of partial resistance to multiple P. sojae isolates. Results In this study, two of the Conrad QTL on chromosome 19 were dissected through sequence and expression analysis of genes in both resistant (Conrad and susceptible (‘Sloan’ genotypes. There were 1025 single nucleotide polymorphisms (SNPs in 87 of 153 genes sequenced from Conrad and Sloan. There were 304 SNPs in 54 genes sequenced from Conrad compared to those from both Sloan and Williams 82, of which 11 genes had SNPs unique to Conrad. Eleven of 19 genes in these regions analyzed with qRT-PCR had significant differences in fold change of transcript abundance in response to infection with P. sojae in lines with QTL haplotype from the resistant parent compared to those with the susceptible parent haplotype. From these, 8 of the 11 genes had SNPs in the upstream, untranslated region, exon, intron, and/or downstream region. These 11 candidate genes encode proteins potentially involved in signal transduction, hormone-mediated pathways, plant cell structural modification, ubiquitination, and basal resistance. Conclusions These findings may indicate a complex defense network with multiple mechanisms underlying these two soybean QTL conferring resistance to P. sojae. SNP markers derived from these candidate genes can contribute to fine mapping of QTL and marker assisted breeding for

  1. Comparison of antifungal activities of various essential oils on the Phytophthora drechsleri, the causal agent of fruit decay

    Directory of Open Access Journals (Sweden)

    Ali Mohammadi

    2015-10-01

    Full Text Available Background and Objectives: The efficacy of Mentha piperita L, Zataria multiflora Boiss and Thymus vulgaris L essential oils (EOs was evaluated for controlling the growth of Phytophthora drechsleri, the causative agent of damage to many crops that is consumed directly by humans.Materials and Methods: The EOs used in this study was purchased from Magnolia Co, Iran. The pour plate method in petri dishes containing Potato Dextrose Agar (PDA was used to evaluate the antifungal properties of EOs. The minimal inhibitory concentrations (MIC, minimum fungicidal concentration (MFC as well as mycelial growth inhibition (MGI were measured. The IC50 value (the concentration inhibited 50% of the mycelium growth was calculated by probit analysis.Results and Conclusion: The fungal growth was significantly reduced by increasing concentrations of tested EOs. The complete reduction was obtained with Shirazi thyme at all concentrations, whereas the complete reduction for peppermint and thyme was observed at 0.4% and 0.8% (v/v concentrations, respectively. Meanwhile, the minimum inhibition wasobserved when 0.1% peppermint (MGI values of 9.37% was used. The IC50, MIC and MFC values of Shirazi thyme was 0.053, 0.1% and 0.2%, respectively. Similarly, MIC and MFC values of peppermint and thyme were recorded 0.4% and 0.8%, respectively. The results obtained from this study may contribute to the development of new antifungal agents to protect the crops from this pathogenic fungus and many agricultural plant pathogens causing drastic crop losses.

  2. GK4, a G-protein-coupled receptor with a phosphatidylinositol phosphate kinase domain in Phytophthora infestans, is involved in sporangia development and virulence.

    Science.gov (United States)

    Hua, Chenlei; Meijer, Harold J G; de Keijzer, Jeroen; Zhao, Wei; Wang, Yuanchao; Govers, Francine

    2013-04-01

    For dispersal and host infection plant pathogens largely depend on asexual spores. Pathogenesis and sporulation are complex processes that are governed by cellular signalling networks including G-protein and phospholipid signalling. Oomycetes possess a family of novel proteins called GPCR-PIPKs (GKs) that are composed of a seven-transmembrane spanning (7-TM) domain fused to a phosphatidylinositol phosphate kinase (PIPK) domain. Based on this domain structure GKs are anticipated to link G-protein and phospholipid signal pathways; however, their functions are currently unknown. Expression analyses of the 12 GK genes in Phytophthora infestans and their orthologues in Phytophthora sojae, revealed differential expression during asexual development. PiGK1 and PiGK4 were fused to monomeric red fluorescent protein (mRFP) and ectopically expressed in P. infestans. In growing hyphae different subcellular distribution patterns were observed indicating that these two GKs act independently during development. We focused on the functional analyses of PiGK4. Its localization suggested involvement in cell differentiation and elongation and its 7-TM domain showed a canonical GPCR membrane topology. Silencing of GK4 and overexpression of full-length and truncated constructs in P. infestans revealed that PiGK4 is not only involved in spore germination and hyphal elongation but also in sporangia cleavage and infection. PMID:23448716

  3. Population genetic structure of Phytophthora cinnamomi associated with avocado in California and the discovery of a potentially recent introduction of a new clonal lineage.

    Science.gov (United States)

    Pagliaccia, D; Pond, E; McKee, B; Douhan, G W

    2013-01-01

    Phytophthora root rot (PRR) of avocado (Persea americana), caused by Phytophthora cinnamomi, is the most serious disease of avocado worldwide. Previous studies have determined that this pathogen exhibits a primarily clonal reproductive mode but no population level studies have been conducted in the avocado-growing regions of California. Therefore, we used amplified fragment length polymorphism based on 22 polymorphic loci and mating type to investigate pathogen diversity from 138 isolates collected in 2009 to 2010 from 15 groves from the Northern and Southern avocado-growing regions. Additional isolates collected from avocado from 1966 to 2007 as well as isolates from other countries and hosts were also used for comparative purposes. Two distinct clades of A2 mating-type isolates from avocado were found based on neighbor joining analysis; one clade contained both newer and older collections from Northern and Southern California, whereas the other clade only contained isolates collected in 2009 and 2010 from Southern California. A third clade was also found that only contained A1 isolates from various hosts. Within the California population, a total of 16 genotypes were found with only one to four genotypes identified from any one location. The results indicate significant population structure in the California avocado P. cinnamomi population, low genotypic diversity consistent with asexual reproduction, potential evidence for the movement of clonal genotypes between the two growing regions, and a potential introduction of a new clonal lineage into Southern California. PMID:23228146

  4. On-site detection of Phytophthora spp.—single-stranded target DNA as the limiting factor to improve on-chip hybridization

    International Nuclear Information System (INIS)

    We report on a lab-on-a-chip approach for on-site detection of Phytophthora species that allows visual signal readout. The results demonstrate the significance of single-stranded DNA (ssDNA) generation in terms of improving the intensity of the hybridization signal and to improve the reliability of the method. Conventional PCR with subsequent heat denaturation, sodium hydroxide-based denaturation, lambda exonuclease digestion and two asymmetric PCR methods were investigated for the species P. fragariae, P. kernoviae, and P. ramorum. The positioning of the capture probe within the amplified yeast GTP-binding protein (YPT1) target DNA was also of interest because it significantly influences the intensity of the signal. Statistical tests were used to validate the impact of the ssDNA generation methods and the capture-target probe position. The single-stranded target DNA generated by Linear-After-The-Exponential PCR (LATE-PCR) was found to produce signal intensities comparable to post-PCR exonuclease treatment. The LATE-PCR is the best method for the on-site detection of Phytophthora because the enzymatic digestion after PCR is more laborious and time-consuming. (author)

  5. The Top 10 oomycete pathogens in molecular plant pathology.

    Science.gov (United States)

    Kamoun, Sophien; Furzer, Oliver; Jones, Jonathan D G; Judelson, Howard S; Ali, Gul Shad; Dalio, Ronaldo J D; Roy, Sanjoy Guha; Schena, Leonardo; Zambounis, Antonios; Panabières, Franck; Cahill, David; Ruocco, Michelina; Figueiredo, Andreia; Chen, Xiao-Ren; Hulvey, Jon; Stam, Remco; Lamour, Kurt; Gijzen, Mark; Tyler, Brett M; Grünwald, Niklaus J; Mukhtar, M Shahid; Tomé, Daniel F A; Tör, Mahmut; Van Den Ackerveken, Guido; McDowell, John; Daayf, Fouad; Fry, William E; Lindqvist-Kreuze, Hannele; Meijer, Harold J G; Petre, Benjamin; Ristaino, Jean; Yoshida, Kentaro; Birch, Paul R J; Govers, Francine

    2015-05-01

    Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens which threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant-pathogenic oomycete species based on scientific and economic importance. In total, we received 263 votes from 62 scientists in 15 countries for a total of 33 species. The Top 10 species and their ranking are: (1) Phytophthora infestans; (2, tied) Hyaloperonospora arabidopsidis; (2, tied) Phytophthora ramorum; (4) Phytophthora sojae; (5) Phytophthora capsici; (6) Plasmopara viticola; (7) Phytophthora cinnamomi; (8, tied) Phytophthora parasitica; (8, tied) Pythium ultimum; and (10) Albugo candida. This article provides an introduction to these 10 taxa and a snapshot of current research. We hope that the list will serve as a benchmark for future trends in oomycete research. PMID:25178392

  6. Diversity and activity of biosurfactant-producing Pseudomonas in the rhizosphere of black pepper in Vietnam

    NARCIS (Netherlands)

    Tran, H.; Kruijt, M.; Raaijmakers, J.M.

    2008-01-01

    Aims: Phytophthora capsici is a major pathogen of black pepper and zoospores play an important role in the infection process. Fluorescent pseudomonads that produce biosurfactants with zoosporicidal activities were isolated from the black pepper rhizosphere in Vietnam, and their genotypic diversity a

  7. Evaluation of automated cell disruptor methods for oomycetous and ascomycetous model organisms

    Science.gov (United States)

    Two automated cell disruptor-based methods for RNA extraction; disruption of thawed cells submerged in TRIzol Reagent (method QP), and direct disruption of frozen cells on dry ice (method CP), were optimized for a model oomycete, Phytophthora capsici, and compared with grinding in a mortar and pestl...

  8. Um método eficiente para a detecção de Phytophthora cinnamomi associada com a Doença da Tinta do Castanheiro na rizosfera de Castanheiro (Castanea sativa Mill. An efficient assay for detection of Phytophthora cinnamomi in the rhizosphere of Sweet Chestnut (Castanea sativa Mill.

    Directory of Open Access Journals (Sweden)

    E. Gouveia

    2009-01-01

    Full Text Available O ciclo biológico de Phytophthora cinnamomi Rands e P. cambivora (Petri Buisman espécies associadas com a Doença da Tinta do Castanheiro, ocorre integralmente no ambiente solo. A presença de qualquer uma destas espécies parasitas inviabiliza as novas plantações de castanheiro e coloca sérios problemas à manutenção dos soutos já instalados. Para garantir a ausência de propágulos dos parasitas no material de multiplicação do castanheiro e avaliar o estado sanitário dos solos é necessário que os métodos de detecção sejam sensíveis e rápidos, o que nem sempre é conseguido com as espécies de Phytophthora cujo ciclo de vida ocorre no ambiente solo. Neste estudo desenvolveuse e optimizou-se um método de biodetecção conjugado com a utilização de meios de cultura selectivos. Como material biológico utilizaram-se discos de folha de castanheiro (Castanea sativa, azevinho (Ilex aquifolium e camélia (Camellia japonica, em condições de temperatura constante (25º e em condições normais de laboratório com a adição ou não de biocidas (pimaricina e penicilina na água de diluição do solo. Os discos de folha de castanheiro foram mais eficientes na detecção de Phytophthora, obtendo-se maior percentagem de isolamentos positivos no meio de cultura selectivo (P10VPH. Os resultados obtidos neste estudo permitiram estabelecer um protocolo experimental de fácil utilização e tornar mais eficiente a detecção de Phytophthora cinnamomi associada com a Doença da Tinta do Castanheiro.The life cycle of Phytophthora cinnamomi Rands and P. cambivora (PetriBuisman, both species associated with Ink Disease of Chestnut, occurs entirely in soil. The presence of any of these parasitic species is a limiting constraint for new plantations of sweet chestnut and represents a serious problem for established groves. Sensitive and fast detection methods are necessary to guarantee the absence of inoculum in the propagation material and to

  9. Análisis de componentes del sistema productivo de aguacate, con incidencia probable de Phytophthora en Cesar, Colombia

    Directory of Open Access Journals (Sweden)

    A. Tofiño

    2012-01-01

    Full Text Available Debido a la disminución del 35% en rendimiento y mortalidad creciente del aguacatero, se realizó un estudio en los municipios Curumaní y La Paz Robles del Departamento del Cesar (Colombia, con el objetivo de identificar los principales factores agroecológicos y de manejo que afectaron la sanidad y productividad, al igual que las zonas con mayores ventajas comparativas para siembra. Para ello, se evaluaron: tejidos radicales, variables del sistema productivo, descriptores físicos, químicos y microbiológicos de suelo, analizados por componentes principales. Se confirmó infección en raíces por Phytophthora spp y Fusarium sp, con incidencia variable entre municipios. La prueba de Fisher (5%, no mostró relación significativa (P>0.05 entre presencia de patógenos y síntomas en árboles. En Curumaní, las variables de mayor contribución, al 32.70% de la varianza explicada por el primer componente principal, fueron: ufc de bacterias, temperatura, porcentaje de arena y pH; mientras que en La Paz Robles (44.30%, fueron: porcentaje de limo, materia orgánica y número de géneros fúngicos. El análisis de conglomerados indicó mayor heterogeneidad en el sistema productivo de fincas de Curumaní, con respecto a La Paz Robles. En ambos municipios, el porcentaje de materia orgánica mostró relación positiva con el número de géneros de hongos identificados y el porcentaje de arcilla afectó el rendimiento de frutos. Se encontró mayor frecuencia de patógenos con respecto a benéficos, y la incidencia de pudrición radical, estuvo influenciada por suelos ácidos, bajos niveles de nutrientes, materia orgánica y prácticas agrícolas inadecuadas. Las veredas promisorias para inversión fueron Paraíso porvenir, Los naranjos, y Las nubes.

  10. Functionally redundant RXLR effectors from Phytophthora infestans act at different steps to suppress early flg22-triggered immunity.

    Science.gov (United States)

    Zheng, Xiangzi; McLellan, Hazel; Fraiture, Malou; Liu, Xiaoyu; Boevink, Petra C; Gilroy, Eleanor M; Chen, Ying; Kandel, Kabindra; Sessa, Guido; Birch, Paul R J; Brunner, Frédéric

    2014-04-01

    Genome sequences of several economically important phytopathogenic oomycetes have revealed the presence of large families of so-called RXLR effectors. Functional screens have identified RXLR effector repertoires that either compromise or induce plant defense responses. However, limited information is available about the molecular mechanisms underlying the modes of action of these effectors in planta. The perception of highly conserved pathogen- or microbe-associated molecular patterns (PAMPs/MAMPs), such as flg22, triggers converging signaling pathways recruiting MAP kinase cascades and inducing transcriptional re-programming, yielding a generic anti-microbial response. We used a highly synchronizable, pathogen-free protoplast-based assay to identify a set of RXLR effectors from Phytophthora infestans (PiRXLRs), the causal agent of potato and tomato light blight that manipulate early stages of flg22-triggered signaling. Of thirty-three tested PiRXLR effector candidates, eight, called Suppressor of early Flg22-induced Immune response (SFI), significantly suppressed flg22-dependent activation of a reporter gene under control of a typical MAMP-inducible promoter (pFRK1-Luc) in tomato protoplasts. We extended our analysis to Arabidopsis thaliana, a non-host plant species of P. infestans. From the aforementioned eight SFI effectors, three appeared to share similar functions in both Arabidopsis and tomato by suppressing transcriptional activation of flg22-induced marker genes downstream of post-translational MAP kinase activation. A further three effectors interfere with MAMP signaling at, or upstream of, the MAP kinase cascade in tomato, but not in Arabidopsis. Transient expression of the SFI effectors in Nicotiana benthamiana enhances susceptibility to P. infestans and, for the most potent effector, SFI1, nuclear localization is required for both suppression of MAMP signaling and virulence function. The present study provides a framework to decipher the molecular

  11. Functionally redundant RXLR effectors from Phytophthora infestans act at different steps to suppress early flg22-triggered immunity.

    Directory of Open Access Journals (Sweden)

    Xiangzi Zheng

    2014-04-01

    Full Text Available Genome sequences of several economically important phytopathogenic oomycetes have revealed the presence of large families of so-called RXLR effectors. Functional screens have identified RXLR effector repertoires that either compromise or induce plant defense responses. However, limited information is available about the molecular mechanisms underlying the modes of action of these effectors in planta. The perception of highly conserved pathogen- or microbe-associated molecular patterns (PAMPs/MAMPs, such as flg22, triggers converging signaling pathways recruiting MAP kinase cascades and inducing transcriptional re-programming, yielding a generic anti-microbial response. We used a highly synchronizable, pathogen-free protoplast-based assay to identify a set of RXLR effectors from Phytophthora infestans (PiRXLRs, the causal agent of potato and tomato light blight that manipulate early stages of flg22-triggered signaling. Of thirty-three tested PiRXLR effector candidates, eight, called Suppressor of early Flg22-induced Immune response (SFI, significantly suppressed flg22-dependent activation of a reporter gene under control of a typical MAMP-inducible promoter (pFRK1-Luc in tomato protoplasts. We extended our analysis to Arabidopsis thaliana, a non-host plant species of P. infestans. From the aforementioned eight SFI effectors, three appeared to share similar functions in both Arabidopsis and tomato by suppressing transcriptional activation of flg22-induced marker genes downstream of post-translational MAP kinase activation. A further three effectors interfere with MAMP signaling at, or upstream of, the MAP kinase cascade in tomato, but not in Arabidopsis. Transient expression of the SFI effectors in Nicotiana benthamiana enhances susceptibility to P. infestans and, for the most potent effector, SFI1, nuclear localization is required for both suppression of MAMP signaling and virulence function. The present study provides a framework to decipher the

  12. Scientific Opinion on the Pest Risk Analysis on Phytophthora ramorum prepared by the FP6 project RAPRA

    DEFF Research Database (Denmark)

    Baker, R.; Candresse, T.; Dormannsné Simon, E.;

    2011-01-01

    The Panel on Plant Health was asked to deliver a scientific opinion on the Pest Risk Analysis on Phytophthora ramorum prepared by the FP6 project RAPRA, taking into account comments by Member States and additional information since RAPRA. P. ramorum is the oomycete causing sudden oak death in the...... risk of further entry (of known or new lineages and/or mating types), establishment and […] impact”. It is advisable to avoid introductions of different lineages because of inherent phenotypic differences and the potential for sexual recombination. The Panel supports the management options proposed in...... the EU. Recent large-scale outbreaks in Japanese larch (Larix kaempferi) plantations in the UK and Ireland have worsened the potential consequences in the risk assessment area. However, the Panel concludes that the broad narrative in the RAPRA report stands and supports its conclusion that “There is a...

  13. A Novel Pathogenesis-Related Class 10 Protein Gly m 4l, Increases Resistance upon Phytophthora sojae Infection in Soybean (Glycine max [L.] Merr.)

    Science.gov (United States)

    Fan, Sujie; Jiang, Liangyu; Wu, Junjiang; Dong, Lidong; Cheng, Qun; Xu, Pengfei; Zhang, Shuzhen

    2015-01-01

    Phytophthora root and stem rot of soybean, caused by Phytophthora sojae (P. sojae), is a destructive disease in many soybean planting regions worldwide. In a previous study, an expressed sequence tag (EST) homolog of the major allergen Pru ar 1 in apricot (Prunus armeniaca) was identified up-regulated in the highly resistant soybean ‘Suinong 10’ infected with P. sojae. Here, the full length of the EST was isolated using rapid amplification of cDNA ends (RACE). It showed the highest homolgy of 53.46% with Gly m 4 after comparison with the eight soybean allergen families reported and was named Gly m 4-like (Gly m 4l, GenBank accession no. HQ913577.1). The cDNA full length of Gly m 4l was 707 bp containing a 474 bp open reading frame encoding a polypeptide of 157 amino acids. Sequence analysis suggests that Gly m 4l contains a conserved ‘P-loop’ (phosphate-binding loop) motif at residues 47–55 aa and a Bet v 1 domain at residues 87–120 aa. The transcript abundance of Gly m 4l was significantly induced by P. sojae, salicylic acid (SA), NaCl, and also responded to methyl jasmonic acid (MeJA) and ethylene (ET). The recombinant Gly m 4l protein showed RNase activity and displayed directly antimicrobial activity that inhibited hyphal growth and reduced zoospore release in P. sojae. Further analyses showed that the RNase activity of the recombinant protein to degrading tRNA was significantly affected in the presence of zeatin. Over-expression of Gly m 4l in susceptible ‘Dongnong 50’ soybean showed enhanced resistance to P. sojae. These results indicated that Gly m 4l protein played an important role in the defense of soybean against P. sojae infection. PMID:26474489

  14. A Novel Pathogenesis-Related Class 10 Protein Gly m 4l, Increases Resistance upon Phytophthora sojae Infection in Soybean (Glycine max [L.] Merr..

    Directory of Open Access Journals (Sweden)

    Sujie Fan

    Full Text Available Phytophthora root and stem rot of soybean, caused by Phytophthora sojae (P. sojae, is a destructive disease in many soybean planting regions worldwide. In a previous study, an expressed sequence tag (EST homolog of the major allergen Pru ar 1 in apricot (Prunus armeniaca was identified up-regulated in the highly resistant soybean 'Suinong 10' infected with P. sojae. Here, the full length of the EST was isolated using rapid amplification of cDNA ends (RACE. It showed the highest homology of 53.46% with Gly m 4 after comparison with the eight soybean allergen families reported and was named Gly m 4-like (Gly m 4l, GenBank accession no. HQ913577.1. The cDNA full length of Gly m 4l was 707 bp containing a 474 bp open reading frame encoding a polypeptide of 157 amino acids. Sequence analysis suggests that Gly m 4l contains a conserved 'P-loop' (phosphate-binding loop motif at residues 47-55 aa and a Bet v 1 domain at residues 87-120 aa. The transcript abundance of Gly m 4l was significantly induced by P. sojae, salicylic acid (SA, NaCl, and also responded to methyl jasmonic acid (MeJA and ethylene (ET. The recombinant Gly m 4l protein showed RNase activity and displayed directly antimicrobial activity that inhibited hyphal growth and reduced zoospore release in P. sojae. Further analyses showed that the RNase activity of the recombinant protein to degrading tRNA was significantly affected in the presence of zeatin. Over-expression of Gly m 4l in susceptible 'Dongnong 50' soybean showed enhanced resistance to P. sojae. These results indicated that Gly m 4l protein played an important role in the defense of soybean against P. sojae infection.

  15. SCR96, a small cysteine-rich secretory protein of Phytophthora cactorum, can trigger cell death in the Solanaceae and is important for pathogenicity and oxidative stress tolerance.

    Science.gov (United States)

    Chen, Xiao-Ren; Li, Yan-Peng; Li, Qi-Yuan; Xing, Yu-Ping; Liu, Bei-Bei; Tong, Yun-Hui; Xu, Jing-You

    2016-05-01

    Peptides and small molecules produced by both the plant pathogen Phytophthora and host plants in the apoplastic space mediate the relationship between the interplaying organisms. Various Phytophthora apoplastic effectors, including small cysteine-rich (SCR) secretory proteins, have been identified, but their roles during interaction remain to be determined. Here, we identified an SCR effector encoded by scr96, one of three novel genes encoding SCR proteins in P. cactorum with similarity to the P. cactorum phytotoxic protein PcF. Together with the other two genes, scr96 was transcriptionally induced throughout the developmental and infection stages of the pathogen. These genes triggered plant cell death (PCD) in the Solanaceae, including Nicotiana benthamiana and tomato. The scr96 gene did not show single nucleotide polymorphisms in a collection of P. cactorum isolates from different countries and host plants, suggesting that its role is essential and non-redundant during infection. Homologues of SCR96 were identified only in oomycetes, but not in fungi and other organisms. A stable protoplast transformation protocol was adapted for P. cactorum using green fluorescent protein as a marker. The silencing of scr96 in P. cactorum caused gene-silenced transformants to lose their pathogenicity on host plants and these transformants were significantly more sensitive to oxidative stress. Transient expression of scr96 partially recovered the virulence of gene-silenced transformants on plants. Overall, our results indicate that the P. cactorum scr96 gene encodes an important virulence factor that not only causes PCD in host plants, but is also important for pathogenicity and oxidative stress tolerance. PMID:26307454

  16. De novo sequencing, assembly, and analysis of the root transcriptome of Persea americana (Mill. in response to Phytophthora cinnamomi and flooding.

    Directory of Open Access Journals (Sweden)

    Bianca J Reeksting

    Full Text Available Avocado is a diploid angiosperm containing 24 chromosomes with a genome estimated to be around 920 Mb. It is an important fruit crop worldwide but is susceptible to a root rot caused by the ubiquitous oomycete Phytophthora cinnamomi. Phytophthora root rot (PRR causes damage to the feeder roots of trees, causing necrosis. This leads to branch-dieback and eventual tree death, resulting in severe losses in production. Control strategies are limited and at present an integrated approach involving the use of phosphite, tolerant rootstocks, and proper nursery management has shown the best results. Disease progression of PRR is accelerated under high soil moisture or flooding conditions. In addition, avocado is highly susceptible to flooding, with even short periods of flooding causing significant losses. Despite the commercial importance of avocado, limited genomic resources are available. Next generation sequencing has provided the means to generate sequence data at a relatively low cost, making this an attractive option for non-model organisms such as avocado. The aims of this study were to generate sequence data for the avocado root transcriptome and identify stress-related genes. Tissue was isolated from avocado infected with P. cinnamomi, avocado exposed to flooding and avocado exposed to a combination of these two stresses. Three separate sequencing runs were performed on the Roche 454 platform and produced approximately 124 Mb of data. This was assembled into 7685 contigs, with 106 448 sequences remaining as singletons. Genes involved in defence pathways such as the salicylic acid and jasmonic acid pathways as well as genes associated with the response to low oxygen caused by flooding, were identified. This is the most comprehensive study of transcripts derived from root tissue of avocado to date and will provide a useful resource for future studies.

  17. De novo sequencing, assembly, and analysis of the root transcriptome of Persea americana (Mill.) in response to Phytophthora cinnamomi and flooding.

    Science.gov (United States)

    Reeksting, Bianca J; Coetzer, Nanette; Mahomed, Waheed; Engelbrecht, Juanita; van den Berg, Noëlani

    2014-01-01

    Avocado is a diploid angiosperm containing 24 chromosomes with a genome estimated to be around 920 Mb. It is an important fruit crop worldwide but is susceptible to a root rot caused by the ubiquitous oomycete Phytophthora cinnamomi. Phytophthora root rot (PRR) causes damage to the feeder roots of trees, causing necrosis. This leads to branch-dieback and eventual tree death, resulting in severe losses in production. Control strategies are limited and at present an integrated approach involving the use of phosphite, tolerant rootstocks, and proper nursery management has shown the best results. Disease progression of PRR is accelerated under high soil moisture or flooding conditions. In addition, avocado is highly susceptible to flooding, with even short periods of flooding causing significant losses. Despite the commercial importance of avocado, limited genomic resources are available. Next generation sequencing has provided the means to generate sequence data at a relatively low cost, making this an attractive option for non-model organisms such as avocado. The aims of this study were to generate sequence data for the avocado root transcriptome and identify stress-related genes. Tissue was isolated from avocado infected with P. cinnamomi, avocado exposed to flooding and avocado exposed to a combination of these two stresses. Three separate sequencing runs were performed on the Roche 454 platform and produced approximately 124 Mb of data. This was assembled into 7685 contigs, with 106 448 sequences remaining as singletons. Genes involved in defence pathways such as the salicylic acid and jasmonic acid pathways as well as genes associated with the response to low oxygen caused by flooding, were identified. This is the most comprehensive study of transcripts derived from root tissue of avocado to date and will provide a useful resource for future studies. PMID:24563685

  18. Genetic analysis of plant endophytic Pseudomonas putida BP25 and chemo-profiling of its antimicrobial volatile organic compounds.

    Science.gov (United States)

    Sheoran, Neelam; Valiya Nadakkakath, Agisha; Munjal, Vibhuti; Kundu, Aditi; Subaharan, Kesavan; Venugopal, Vibina; Rajamma, Suseelabhai; Eapen, Santhosh J; Kumar, Aundy

    2015-04-01

    Black pepper associated bacterium BP25 was isolated from root endosphere of apparently healthy cultivar Panniyur-5 that protected black pepper against Phytophthora capsici and Radopholus similis - the major production constraints. The bacterium was characterized and mechanisms of its antagonistic action against major pathogens are elucidated. The polyphasic phenotypic analysis revealed its identity as Pseudomonas putida. Multi locus sequence typing revealed that the bacterium shared gene sequences with several other isolates representing diverse habitats. Tissue localization assays exploiting green fluorescence protein expression clearly indicated that PpBP25 endophytically colonized not only its host plant - black pepper, but also other distantly related plants such as ginger and arabidopsis. PpBP25 colonies could be enumerated from internal tissues of plants four weeks post inoculation indicated its stable establishment and persistence in the plant system. The bacterium inhibited broad range of pathogens such as Phytophthora capsici, Pythium myriotylum, Giberella moniliformis, Rhizoctonia solani, Athelia rolfsii, Colletotrichum gloeosporioides and plant parasitic nematode, Radopholus similis by its volatile substances. GC/MS based chemical profiling revealed presence of Heneicosane; Tetratetracontane; Pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); Tetracosyl heptafluorobutyrate; 1-3-Eicosene, (E)-; 1-Heneicosanol; Octadecyl trifluoroacetate and 1-Pentadecene in PpBP25 metabolite. Dynamic head space GC/MS analysis of airborne volatiles indicated the presence of aromatic compounds such as 1-Undecene;Disulfide dimethyl; Pyrazine, methyl-Pyrazine, 2,5-dimethyl-; Isoamyl alcohol; Pyrazine, methyl-; Dimethyl trisulfide, etc. The work paved way for profiling of broad spectrum antimicrobial VOCs in endophytic PpBP25 for crop protection. PMID:25801973

  19. Biological control of Phytophthora root rot of avocato with microorganisms grown in organic mulches Controle biológico da podridão radicular de Phytophthora no abacateiro utilizando substratos orgânicos colonizados

    Directory of Open Access Journals (Sweden)

    Jefferson L. da S. Costa

    2000-10-01

    Full Text Available Organic mulches colonized with microbial biocontrol agents, termed bioenhanced mulches, were tested for their ability to reduce Phytophthora root rot of avocado (Persea americana Mill.. Benomyl-resistant mutants of Gliocladium virens (KA 230-1 and Trichoderma harzianum (KA 159.2 isolated from suppressive soils and selected as efficient antagonists of P. cinnamomi were evaluated for their ability to colonize different mulches under controlled laboratory conditions. Sudangrass and a coarse yardwaste were found to be better substrates than a fine yardwaste, woodwaste or rice hulls for biocontrol agents propagules production. The most suitable conditions for colonization were an optimum temperature of 24°C, a moisture content of 20% for sudangrass and 30% for the coarse yardwaste, and a continuous light exposure during a 15-day incubation period. In the greenhouse, fresh sudangrass and a coarse yardwaste colonized with G. virens and used as a surface mulch proved to be the best combination for reducing the population of P. cinnamomi in 4-liter pots containing artificially-infested soil. Healthy avocado roots made up 31-37% of the roots in the G. virens-mulch combinations compared to 0% healthy in infested controls after two months.Compostos orgânicos colonizados com agentes de controle microbiológico, então denominados compostos bioativados, foram testados quanto a sua habilidadade controlar à podridão radicular de Phytophtora no abacateiro (Persea americana Mill. Mutantes de Gliocladium virens (KA 230-1 e Trichoderma harzianun (KA 159-2 resistentes a benomyl recuperados de solos supressivos e selecionados como eficientes antagonistas à P. cinnamoni foram avaliados quanto à sua capacidade de colonizar diversos compostos orgânicos em condições de laboratório. O Capim Sudão e um Composto de Jardim de alta granulação demonstraram quanto à sua capacidade de multiplicar propágulos de agentes de biocontrole, serem superiores à um

  20. Genetic Diversity of Phytophthora infestans sensu lato in Ecuador Provides New Insight Into the Origin of This Important Plant Pathogen.

    Science.gov (United States)

    Adler, N E; Erselius, L J; Chacón, M G; Flier, W G; Ordoñez, M E; Kroon, L P N M; Forbes, G A

    2004-02-01

    ABSTRACT The metapopulation structure of Phytophthora infestans sensu lato is genetically diverse in the highlands of Ecuador. Previous reports documented the diversity associated with four putative clonal lineages of the pathogen collected from various hosts in the genus Solanum. This paper simultaneously analyzes diversity of the complete collection of isolates, including a large number that had not yet been reported. This analysis confirmed the existence of three pathogen populations, which all appear to be clonal lineages, and that correspond to those previously reported as US-1, EC-1, and EC-3. No evidence was found from the analyses of recently collected isolates that would contradict earlier reports about these three lineages. In contrast, new data from a group of isolates from several similar hosts caused us to modify the previous description of clonal lineage EC-2 and its previously proposed hosts, S. brevifolium and S. tetrapetalum. Given the uncertainty associated with the identification of these hosts, which all belong to the section Anarrhichomenum, we refer to them as the Anarrhichomenum complex, pending further taxonomic clarification. New pathogen genotypes associated with the Anarrhichomenum complex were isolated recently that are A1 mating type and Ia mitochondrial DNA (mtDNA) haplotype, and therefore differ from the previously described EC-2 lineage, which is A2 and Ic, respectively. Because of uncertainty on host identification, we do not know if the new genotypes are limited to one host species and therefore represent yet another host-adapted clonal lineage. For now, we refer to the new genotypes and previously described EC-2 genotypes, together, as the pathogen group attacking the Anarrhichomenum complex. Two A2 isolates identical to the previously described EC-2 archetype were collected from severely infected plants of pear melon (S. muricatum). Pear melon is generally attacked by US-1, and this is the first clear case we have documented in

  1. Exploration on production of rhamnolipid biosurfactants using native Pseudomonas aeruginosa strains

    Directory of Open Access Journals (Sweden)

    RAVISH BHAT

    2015-08-01

    Full Text Available Biosurfactants are structurally diverse surface-active molecules, produced on living surfaces, mostly microbial cell surfaces or excreted extracellularly. Rhamnolipid biosurfactants have wide spectrum use and are predominantly produced by the bacteria Pseudomonas aeruginosa. In this study, 75 Pseudomonas strains isolated from distinct native habitats were screened following oil spreading technique, methylene blue agar method, hemolytic blood agar method and surface tension measurement of the cell free culture. Ten selected isolates were tested for their ability to produce rhamnolipid biosurfactants in glycerol mediated broth. The best among them, Pa24, was confirmed as Pseudomonas aeruginosa through 16S rRNA sequence analysis. Experiments carried out on the ability of P. aeruginosa strain Pa24 revealed its potential to utilize range of vegetable oils such as coconut oil, palm oil, jatropha oil, neem oil and mineral glycerol as sole source of carbon and produce rhamnolipid biosurfactant. The extracted biosurfactant was characterized by thin layer chromatography and high performance thin layer chromatography as mixture of di-rhamnolipid and mono-rhamnolipid biosurfactants. The crude extract of rhamnolipid was tested in-vitro for antifungal activity against Phytophthora capsici and Phytophthora infestans and the MIC50 were found to be 815.8 ppm and 373.9 ppm, respectively. Further exploration on different renewable carbon sources including agriculture industrial wastes to produce rhamnolipid biosurfactants can improve the efficiency and reduce the environmental pollution through waste discharge from these industries.

  2. Identification of Quercus agrifolia (coast live oak resistant to the invasive pathogen Phytophthora ramorum in native stands using Fourier-transform infrared (FT-IR spectroscopy

    Directory of Open Access Journals (Sweden)

    Anna Olivia Conrad

    2014-10-01

    Full Text Available Over the last two decades coast live oak (CLO dominance in many California coastal ecosystems has been threatened by the alien invasive pathogen Phytophthora ramorum, the causal agent of sudden oak death. In spite of high infection and mortality rates in some areas, the presence of apparently resistant trees has been observed, including trees that become infected but recover over time. However, identifying resistant trees based on recovery alone can take many years. The objective of this study was to determine if Fourier-transform infrared (FT-IR spectroscopy, a chemical fingerprinting technique, can be used to identify CLO resistant to P. ramorum prior to infection. Soft independent modeling of class analogy identified spectral regions that differed between resistant and susceptible trees. Regions most useful for discrimination were associated with carbonyl group vibrations. Additionally, concentrations of two putative phenolic biomarkers of resistance were predicted using partial least squares regression; > 99% of the variation was explained by this analysis. This study demonstrates that chemical fingerprinting can be used to identify resistance in a natural population of forest trees prior to infection with a pathogen. FT-IR spectroscopy may be a useful approach for managing forests impacted by sudden oak death, as well as in other situations where emerging or existing forest pests and diseases are of concern.

  3. The importin α subunit PsIMPA1 mediates the oxidative stress response and is required for the pathogenicity of Phytophthora sojae.

    Science.gov (United States)

    Yang, Xinyu; Ding, Fa; Zhang, Lei; Sheng, Yuting; Zheng, Xiaobo; Wang, Yuanchao

    2015-09-01

    The sensing of extracellular signals and their transduction into an appropriate response are crucial for the survival and virulence of plant pathogens. Eukaryotic plant pathogens must overcome the obstacles posed by nuclear membranes to manipulate gene expression to adapt to the host challenge. A highly sophisticated mechanism is the use of importins to transport proteins into the nucleus. In this study, we identified a conserved importin α gene, PsIMPA1, in Phytophthora sojae that was differentially expressed during the life cycle of this soybean pathogen. PsIMPA1 expression was lowest in zoospores and cysts but relatively consistent during the other life cycle stages, except for a slight increase at 6h post infection. Silenced mutants Psimpa1 had a decreased growth rate, an aberrant mycelial morphology, and a severely impaired ability to form oospores and sporangia. In addition, the Psimpa1 mutants exhibited reduced pathogenicity compared to the wild type. 3,3-Diaminobenzidine (DAB) staining and in vitro hydrogen peroxide tolerance assays showed that the scavenging of reactive oxygen species by these mutants was significantly impaired. Taken together, these results indicate that PsIMPA1 regulates multiple processes during the life cycle of P. sojae. PMID:26159511

  4. Establishment of the straightforward electro-transformation system for Phytophthora infestans and its comparison with the improved PEG/CaCl₂ transformation.

    Science.gov (United States)

    Dong, Lei; Zhu, Xiangyuan; Cui, Haichen; Ojika, Makoto; Wang, Ruigang; Liu, Huirong

    2015-05-01

    Phytophthora infestans is the most devastating pathogen of potato. For the biology study of P. infestans at the molecular level, one of the difficulties is the technique for the genetic transformation. In this study, the straightforward electro-transformation system was established for P. infestans with a green fluorescent protein expression vector and compared with the improved PEG/CaCl2 mediated protoplast transformation system. The results showed that the straightforward electro-transformation could work in P. infestans and 32 positive transformants were obtained per about 1.10×10(6) zoospores. The transformants per μg of vector DNA were 1.08. The transformation efficiency of the straightforward electro-transformation was approximately 2 times higher than that of the improved PEG/CaCl2 mediated protoplast transformation (17 positive transformants per about 1.05×10(6) protoplasts, 0.58 transformants per μg of vector DNA) according to the reported procedures. Furthermore, compared with the improved PEG/CaCl2 transformation, the straightforward electroporation is simpler and requires less starting materials and operating time from collecting material to obtaining the resistant transformants. Our work will lay a foundation for the biology study of P. infestans in the future. PMID:25783995

  5. PsHint1, associated with the G-protein α subunit PsGPA1, is required for the chemotaxis and pathogenicity of Phytophthora sojae.

    Science.gov (United States)

    Zhang, Xin; Zhai, Chunhua; Hua, Chenlei; Qiu, Min; Hao, Yujuan; Nie, Pingping; Ye, Wenwu; Wang, Yuanchao

    2016-02-01

    Zoospore chemotaxis to soybean isoflavones is essential in the early stages of infection by the oomycete pathogen Phytophthora sojae. Previously, we have identified a G-protein α subunit encoded by PsGPA1 which regulates the chemotaxis and pathogenicity of P. sojae. In the present study, we used affinity purification to identify PsGPA1-interacting proteins, including PsHint1, a histidine triad (HIT) domain-containing protein orthologous to human HIT nucleotide-binding protein 1 (HINT1). PsHint1 interacted with both the guanosine triphosphate (GTP)- and guanosine diphosphate (GDP)-bound forms of PsGPA1. An analysis of the gene-silenced transformants revealed that PsHint1 was involved in the chemotropic response of zoospores to the isoflavone daidzein. During interaction with a susceptible soybean cultivar, PsHint1-silenced transformants displayed significantly reduced infectious hyphal extension and caused a strong cell death in plants. In addition, the transformants displayed defective cyst germination, forming abnormal germ tubes that were highly branched and exhibited apical swelling. These results suggest that PsHint1 not only regulates chemotaxis by interacting with PsGPA1, but also participates in a Gα-independent pathway involved in the pathogenicity of P. sojae. PMID:25976113

  6. Study on the Cultural Characteristics of Phytophthora parasitica var. nicotianae%烟草黑胫病菌培养特性的研究

    Institute of Scientific and Technical Information of China (English)

    张文友; 刘铭; 尹福强; 赵云飞; 刘朝科

    2013-01-01

    研究了采自攀西地区的烟草黑胫病菌在不同培养基、不同温度及不同pH值等条件下培养特性。结果表明:烟草黑胫病菌最适合在燕麦培养基上生长,菌丝生长快。菌丝在20~36℃都能生长,28℃生长最佳。在不同pH值的培养基培养下,菌丝最适合在pH值为5.5的培养基上生长。%Phytophthora parasitica var.nicotianae was cultivated under the conditions of different cultural media ,pH value and temperature ,then observed its growth status and morphological characteristics.The results showed that oatmeal agar was most suitable for the growth of the strains of P. Nicotianae.The hyphae can grow at 20~36℃,the temperature of 28℃and the pH value of 5.5 were the best for the growth of the strains of P.Nicotianae.

  7. Evaluation de la résistance de certaines variétés de pomme de terre biologique au mildiou Phytophthora infestans (Mont de Bary

    Directory of Open Access Journals (Sweden)

    Ferjaoui, S.

    2010-01-01

    Full Text Available Evaluation of the Resistance of some Varieties of Biological Potato to the Mildew Phytophthora infestans. To control the mildew, in particular in biological productions, the varietal resistance of potato could be an advantage to associate with other cultural measurements. For this purpose, sixteen varieties potentially interesting in conventional and biological production were tested with regard to the mildew. Eleven varieties were subscribed in the list A (Alaska, Arinda, Baraka, Fabula, Liseta, Mondial, Platina, Safrane, Santana, Spunta and Timate and five are in the process of evaluation (Carréra, Cicéro, Derby, Vivaldi, and Voyager. It seemed that the mildew affected all the tested varieties. However, some of them appeared more tolerant than others. Indeed, the Derby and Voyager varieties revealed to be able to delay the starting of the disease of one month. Cicéro, Vivaldi and Timate could delay the development of mildew disease of twelve days, relatively to its appearance on susceptible varieties. Furthermore, the foliar level of destruction remained very limited compared to that on susceptible varieties and not exceed 10% for Timate. The varieties Fabula, Liséta, Carréra, Mondial, Spunta, Platina, Safrane, Arinda, Santana and Baraka showed an early and fast starting of the epidemy. In addition, the tolerance or varietal resistance could not resolve the problem when tubers are affected, since a relatively weak rate of leaves contamination is enough to cause a very important economic loss on the tubers.

  8. Distribution of rishitin and lubimin in potato-tuber tissue infected by an incompatible race of Phytophthora infestans and the site where rishitin is synthesized

    International Nuclear Information System (INIS)

    Cut surface of potato tuber (R1-cultivar) was inoculated with an incompatible race of Phytophthora infestans. Then the slices prepared from the infected tissue were analyzed for their rishitin and lubimin content. Most of rishitin and lubimin was found in a zone in which the cells became brown with only a trace in the healthy tissue adjacent to the brown zone. However, the amount of lubimin was very low as compared with that of rishitin. In the inoculation fluid within the hole made in the tuber tissue, a large amount of rishitin and lubimin was found. In this case, lubimin was found in greater amount than rishitin during the early period of infection, but later the amount of rishitin exceeded that of lubimin. It was demonstrated by incorporation of acetate-2-14C into rishitin that rishitin was synthesized mostly in the adjacent healthy tissue which had not been invaded by the parasite. Rishitin synthesis was especially active in the first several healthy cell layers neighbouring the brown tissue. Since, at this time, hyphal development has already stopped, these cells were never invaded by the parasite and did never turn brown. Rishitin seemed not to be synthesized in the browned tissue. It is concluded that the rishitin sythesized in the adjacent healthy cells is transported to the brown cells and accumulates there. It also diffuses and accumulates outside the brown cells. (auth.)

  9. Genome-wide prediction and functional validation of promoter motifs regulating gene expression in spore and infection stages of Phytophthora infestans.

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    Sourav Roy

    2013-03-01

    Full Text Available Most eukaryotic pathogens have complex life cycles in which gene expression networks orchestrate the formation of cells specialized for dissemination or host colonization. In the oomycete Phytophthora infestans, the potato late blight pathogen, major shifts in mRNA profiles during developmental transitions were identified using microarrays. We used those data with search algorithms to discover about 100 motifs that are over-represented in promoters of genes up-regulated in hyphae, sporangia, sporangia undergoing zoosporogenesis, swimming zoospores, or germinated cysts forming appressoria (infection structures. Most of the putative stage-specific transcription factor binding sites (TFBSs thus identified had features typical of TFBSs such as position or orientation bias, palindromy, and conservation in related species. Each of six motifs tested in P. infestans transformants using the GUS reporter gene conferred the expected stage-specific expression pattern, and several were shown to bind nuclear proteins in gel-shift assays. Motifs linked to the appressoria-forming stage, including a functionally validated TFBS, were over-represented in promoters of genes encoding effectors and other pathogenesis-related proteins. To understand how promoter and genome architecture influence expression, we also mapped transcription patterns to the P. infestans genome assembly. Adjacent genes were not typically induced in the same stage, including genes transcribed in opposite directions from small intergenic regions, but co-regulated gene pairs occurred more than expected by random chance. These data help illuminate the processes regulating development and pathogenesis, and will enable future attempts to purify the cognate transcription factors.

  10. The Full-Size ABCG Transporters Nb-ABCG1 and Nb-ABCG2 Function in Pre- and Postinvasion Defense against Phytophthora infestans in Nicotiana benthamiana.

    Science.gov (United States)

    Shibata, Yusuke; Ojika, Makoto; Sugiyama, Akifumi; Yazaki, Kazufumi; Jones, David A; Kawakita, Kazuhito; Takemoto, Daigo

    2016-05-01

    The sesquiterpenoid capsidiol is the major phytoalexin produced by Nicotiana and Capsicum species. Capsidiol is produced in plant tissues attacked by pathogens and plays a major role in postinvasion defense by inhibiting pathogen growth. Using virus-induced gene silencing-based screening, we identified two Nicotiana benthamiana (wild tobacco) genes encoding functionally redundant full-size ABCG (PDR-type) transporters, Nb-ABCG1/PDR1 and Nb-ABCG2/PDR2, which are essential for resistance to the potato late blight pathogen Phytophthora infestans Silencing of Nb-ABCG1/2 compromised secretion of capsidiol, revealing Nb-ABCG1/2 as probable exporters of capsidiol. Accumulation of plasma membrane-localized Nb-ABCG1 and Nb-ABCG2 was observed at the site of pathogen penetration. Silencing of EAS (encoding 5-epi-aristolochene synthase), a gene for capsidiol biosynthesis, reduced resistance to P. infestans, but penetration by P. infestans was not affected. By contrast, Nb-ABCG1/2-silenced plants showed reduced penetration defense, indicating that Nb-ABCG1/2 are involved in preinvasion defense against P. infestans Plastidic GGPPS1 (geranylgeranyl diphosphate synthase) was also found to be required for preinvasion defense, thereby suggesting that plastid-produced diterpene(s) are the antimicrobial compounds active in preinvasion defense. These findings suggest that N. benthamiana ABCG1/2 are involved in the export of both antimicrobial diterpene(s) for preinvasion defense and capsidiol for postinvasion defense against P. infestans. PMID:27102667

  11. Artifical Microrna Mediated Gene Silencing of Phytophthora infestans Single Effector Avr3a Gene Imparts Moderate Type of Late Blight Resistance in Potato

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    Aditi Thakur

    2015-01-01

    Full Text Available RNAi based “host plant mediated pathogen gene silencing” has emerged as a novel strategy for the efficient control of pathogens infecting various important food crops. Artifical microRNAs (amiRNAs represent a robust and recently developed miRNA based strategy for the effective posttranscriptional gene silencing in plants. Phytophthora infestans RXLR effector Avr3a suppresses hypersensitive cell death in host cells and responsible for virulence. In the present investigation, the effect of artificial microRNAs are studied on the target transcript, Avr3a gene of P. infestans. Five Avr3a amiRNA gene constructs developed targeting five different regions of Avr3a gene of P. infestans and were transformed into two popular Indian potato cultivars i.e., Kufri Khyati and Kufri Pukharaj. Screening analysis study revealed that most of the transgenic lines were susceptible (15 and few lines (4 were found to be moderately or partially resistance. Target effector gene expression level and the pathogen load were determined to identify whether the resistant observed was RNA mediated. Real time PCR analysis showed that there is reduction in pathogen load as well as in transcript level of Avr3a in resistant lines as compared to the non-transgenic control. This revealed that, the invading P. infestans withdraws the dsRNA/amiRNAs from the host cell leading to the silencing of the Avr3a gene expression causing pathogen death and/or loss of virulence. The amiRNA technology developed in this study appears to be potential and promising for durable and long lasting resistance in potato to combat the notorious oomycete, P. infestans.

  12. Monitoramento da população de Phytophthora infestans na região da Zona da Mata de Minas Gerais de 1998 a 2000

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    REIS AILTON

    2002-01-01

    Full Text Available Foram caracterizados 212 isolados de Phytophthora infestans obtidos de 51 lavouras de tomate (Lycopersicon esculentume batata (Solanum tuberosum, em sete municípios da Zona da Mata, MG. Todos os isolados tiveram o grupo de compatibilidade determinado; 96 isolados foram caracterizados para a isoenzima glucose 6-fosfato-isomerase (Gpi; 71 isolados foram analisados quanto à resistência ao metalaxyl; e determinou-se o espectro de virulência de 46 isolados. Todos os 212 isolados testados foram classificados como do grupo A1 de compatibilidade. A maioria dos isolados testados para Gpi (95 apresentou o fenótipo 86/100, típico da linhagem clonal US-1. Apenas um isolado apresentou o fenótipo 100/100 para Gpi. Quanto à resistência ao metalaxyl, em 1998 a freqüência de isolados sensíveis, intermediários e resistentes foi de 40%, 40% e 20%, respectivamente, e em 2000 de 3,2%; 61,3% e 35,5%, respectivamente. Quanto ao espectro de virulência, todos os 46 isolados analisados foram virulentos sobre a cultivar de tomate 'Kada'. A maioria foi virulenta em plantas de tomate com os genes Ph1 (91% ou Ph2 (95 %. Todos os isolados foram virulentos em batata 'Bintje'. Houve pequena variação do espectro de virulência sobre clones de batata, quando esses foram inoculados com isolados coletados em diferentes anos. Há evidências que a população de P. infestans da Zona da Mata, MG é constituída de isolados da linhagem clonal US-1, de várias raças e baixa sensibilidade ao fungicida metalaxyl.

  13. Study on resistance of potato with transferred avirulent genes to Phytophthora infestans%转无毒基因马铃薯抗晚疫病的研究

    Institute of Scientific and Technical Information of China (English)

    杨希才; 刘国胜; 王文慧; 田波; 居玉玲; 罗智敏

    2001-01-01

    晚疫病菌(Phytophthora infestans)引起的马铃薯晚疫病是危害全球马铃薯生产的严重病害.通过基因工程方法把外源基因导入植物体内以增强抗病性被证明是一条行之有效的途径.应用植物基因工程技术将具有能激活植物自身防御系统的无毒基因与适合于植物背景、非专一性的病原物诱导启动子组合成嵌合基因构建到植物表达载体中.通过农杆菌或基因枪的介导转化植物,可筛选出高效广谱的抗真菌和细菌病害的转基因植株.本研究从病原细菌Pseudomonas syringae PV. tomato中获得的无毒基因avrD (0*93 kb) 和从病原真菌Phytophthora parasitica中获得的无毒基因Elicitin(0.294 kb)分别与非专一性病原物诱导启动子Pill和BG组成含2个嵌合基因(Pill-avrD, BG-Elicitin)的植物表达载体pYH144和pYHEt.通过农杆菌LBA4404介导转化马铃薯,其中用pYH144载体转化2个品种(克新1号,2号),用pYHEt载体转化3个品种(Desiree,克新2号,4号),通过组织培养分别获得潮霉素(Hygromycin B)标记的转基因马铃薯试管苗.将转基因试管苗扩繁,应用马铃薯脱毒微型种薯生产技术获得转无毒基因微型薯,在温室(15~25℃和湿度高)条件下,观察转无毒基因马铃薯植株中对晚疫病菌自然感染的抗性.1998年和1999年(每年的3-5月)的温室试验初步表明:用avrD和elicitin基因分别转化的转无毒基因马铃薯植株都具有较明显的对晚疫病菌侵染的抗性,大部分转基因植株不表现或表现轻微的感病症状,对照植株(未转化)则表现明显的感病症状.转基因植株生长正常,且在感染后期(恢复期)生长良好.对照植株在恢复期生长弱和缓慢.在获得较多数量的转无毒基因马铃薯微型种薯的时候,将进行人工接种晚疫病菌和田间种植试验,从中筛选出抗真菌病和细菌病的转基因马铃薯株系.%Potato late blight caused by Phytophthora infestans is a

  14. New role for Cdc14 phosphatase: localization to basal bodies in the oomycete phytophthora and its evolutionary coinheritance with eukaryotic flagella.

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    Audrey M V Ah-Fong

    Full Text Available Cdc14 protein phosphatases are well known for regulating the eukaryotic cell cycle, particularly during mitosis. Here we reveal a distinctly new role for Cdc14 based on studies of the microbial eukaryote Phytophthora infestans, the Irish potato famine agent. While Cdc14 is transcribed constitutively in yeast and animal cells, the P. infestans ortholog is expressed exclusively in spore stages of the life cycle and not in vegetative hyphae where the bulk of mitosis takes place. PiCdc14 expression is first detected in nuclei at sporulation, and during zoospore formation the protein accumulates at the basal body, which is the site from which flagella develop. The association of PiCdc14 with basal bodies was supported by co-localization studies with the DIP13 basal body protein and flagellar β-tubulin, and by demonstrating the enrichment of PiCdc14 in purified flagella-basal body complexes. Overexpressing PiCdc14 did not cause defects in growth or mitosis in hyphae, but interfered with cytoplasmic partitioning during zoosporogenesis. This cytokinetic defect might relate to its ability to bind microtubules, which was shown using an in vitro cosedimentation assay. The use of gene silencing to reveal the precise function of PiCdc14 in flagella is not possible since we showed previously that silencing prevents the formation of the precursor stage, sporangia. Nevertheless, the association of Cdc14 with flagella and basal bodies is consistent with their phylogenetic distribution in eukaryotes, as species that lack the ability to produce flagella generally also lack Cdc14. An ancestral role of Cdc14 in the flagellar stage of eukaryotes is thereby proposed.

  15. Curdlan β-1,3-glucooligosaccharides induce the defense responses against Phytophthora infestans infection of potato (Solanum tuberosum L. cv. McCain G1) leaf cells.

    Science.gov (United States)

    Li, Jing; Zhu, Li; Lu, Guangxing; Zhan, Xiao-Bei; Lin, Chi-Chung; Zheng, Zhi-Yong

    2014-01-01

    Activation of the innate immune system before the invasion of pathogens is a promising way to improve the resistance of plant against infection while reducing the use of agricultural chemicals. Although several elicitors were used to induce the resistance of potato plant to microbial pathogen infection, the role of curdlan oligosaccharide (CurdO) has not been established. In the current study, the defense responses were investigated at biochemical and proteomic levels to elucidate the elicitation effect of CurdOs in foliar tissues of potato (Solanum tuberosum L. cv. McCain G1). The results indicate that the CurdOs exhibit activation effect on the early- and late-defense responses in potato leaves. In addition, glucopentaose was proved to be the shortest active curdlan molecule based on the accumulation of H₂O₂ and salicylic acid and the activities of phenylalanine amino-lyase, β-1,3-glucanase and chitinase. The 2D-PAGE analysis reveals that CurdOs activate the integrated response reactions in potato cells, as a number of proteins with various functions are up-regulated including disease/defense, metabolism, transcription, and cell structure. The pathogenesis assay shows that the ratio of lesion area of potato leaf decreased from 15.82%±5.44% to 7.79%±3.03% when the plants were treated with CurdOs 1 day before the infection of Phytophthora infestans. Furthermore, the results on potato yield and induction reactions indicate that the defense responses induced by CurdOs lasted for short period of time but disappeared gradually. PMID:24816730

  16. Curdlan β-1,3-glucooligosaccharides induce the defense responses against Phytophthora infestans infection of potato (Solanum tuberosum L. cv. McCain G1 leaf cells.

    Directory of Open Access Journals (Sweden)

    Jing Li

    Full Text Available Activation of the innate immune system before the invasion of pathogens is a promising way to improve the resistance of plant against infection while reducing the use of agricultural chemicals. Although several elicitors were used to induce the resistance of potato plant to microbial pathogen infection, the role of curdlan oligosaccharide (CurdO has not been established. In the current study, the defense responses were investigated at biochemical and proteomic levels to elucidate the elicitation effect of CurdOs in foliar tissues of potato (Solanum tuberosum L. cv. McCain G1. The results indicate that the CurdOs exhibit activation effect on the early- and late-defense responses in potato leaves. In addition, glucopentaose was proved to be the shortest active curdlan molecule based on the accumulation of H₂O₂ and salicylic acid and the activities of phenylalanine amino-lyase, β-1,3-glucanase and chitinase. The 2D-PAGE analysis reveals that CurdOs activate the integrated response reactions in potato cells, as a number of proteins with various functions are up-regulated including disease/defense, metabolism, transcription, and cell structure. The pathogenesis assay shows that the ratio of lesion area of potato leaf decreased from 15.82%±5.44% to 7.79%±3.03% when the plants were treated with CurdOs 1 day before the infection of Phytophthora infestans. Furthermore, the results on potato yield and induction reactions indicate that the defense responses induced by CurdOs lasted for short period of time but disappeared gradually.

  17. Resistência de clones e híbridos de porta-enxertos de citros à gomose de tronco causada por Phytophthora parasitica

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    Medina Filho Herculano P.

    2003-01-01

    Full Text Available Sete grupos de híbridos entre porta-enxertos elite de citros (Citrus sp. e seus genitores foram estudados quanto a reação à infecção de tronco por Phytophthora parasitica, em plantas adultas no campo. Inocularam-se artificialmente, em duas posições do tronco, 132 plantas nucelares dos genitores e 486 híbridos entre limão (Citrus limonia Cravo 'Limeira' (C, Poncirus trifoliata 'Davis A' (T, tangerina (C.sunki 'Sunki' (S e laranja Azeda (C. aurantium 'São Paulo' (A. A classificação do grau de resistência à gomose de tronco em plantas adultas no campo foi possível somente quando baseada na média do tamanho de lesões de mais de 30 plantas nucelares, devido às grandes variações observadas em plantas individuais do mesmo clone, impossibilitando a seleção precoce de híbridos baseada em valores de plantas individuais. O trifoliata e a laranja Azeda mostraram-se bastante resistentes, desenvolvendo, em geral, lesões de tamanho reduzido. A tangerina Sunki e o limão Cravo desenvolveram lesões maiores, embora a tangerina Sunki tenha mostrado uma tendência em desenvolver lesões maiores que às do limão Cravo. Híbridos de trifoliata apresentaram, no geral, lesões intermediárias. Os híbridos de Azeda apresentaram lesões de tamanhos bastante variáveis, porém a maioria, com lesões grandes. Da mesma forma comportaram-se os híbridos recíprocos entre Sunki e Cravo.

  18. ALTERNATIVAS MICROBIOLÓGICAS PARA EL MANEJO DE Phytophthora cinnamomi Rands., EN Persea americana Mill. BAJO CONDICIONES DE CASA-MALLA

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    Joaquín G. Ramírez Gil

    2014-01-01

    Full Text Available Para la producción de aguacate en Colombia es necesario establecer alternativas de manejo amigables con el medio ambiente y de bajo costo para el control de la enfermedad conocida como marchitez, cuyo principal agente causal es Phytophthora cinnamomi. El uso de microorganismos del suelo, es una opción viable para mejorar la nutrición y sanidad en Persea americana, buscando ser más competitivos en aras de afrontar los tratados de libre comercio y poder aprovechar el potencial exportador que presenta este frutal. Entendiendo la complejidad del sistema de la microbiota del suelo, consecuencia de su gran diversidad y de las distintas relaciones ecológicas que lo gobiernan, este trabajo estuvo encaminado a evaluar en condiciones de invernadero el efecto de cepas de Trichoderma sp. , Glomus fasciculatum y una cepa de Pseudomonas sp., en el desarrollo de plántulas de P. americana , sin inocular e inoculadas con P. cinnamomi. Los resultados encontrados en este trabajo sugieren que G. fasciculatum y Pseudomonas sp., solos o en combinación, favorecen el desarrollo de plántulas de aguacate, mientras que Trichoderma sp. presentó los mejores resultados en la reducción del progreso de la enfermedad de marchitez en plantas inoculadas con P. cinnamomi . Los microorganismos del suelo presentan un enorme potencial para el desarrollo y protección contra patógenos en P. americana , pero se hace necesario entender todas las relaciones para poder potenciar su uso como biofertilizantes y agentes de biocontrol.

  19. Rapid metabolic profiling of Nicotiana tabacum defence responses against Phytophthora nicotianae using direct infrared laser desorption ionization mass spectrometry and principal component analysis

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    Weis Engelbert

    2010-06-01

    Full Text Available Abstract Background Successful defence of tobacco plants against attack from the oomycete Phytophthora nicotianae includes a type of local programmed cell death called the hypersensitive response. Complex and not completely understood signaling processes are required to mediate the development of this defence in the infected tissue. Here, we demonstrate that different families of metabolites can be monitored in small pieces of infected, mechanically-stressed, and healthy tobacco leaves using direct infrared laser desorption ionization orthogonal time-of-flight mass spectrometry. The defence response was monitored for 1 - 9 hours post infection. Results Infrared laser desorption ionization orthogonal time-of-flight mass spectrometry allows rapid and simultaneous detection in both negative and positive ion mode of a wide range of naturally occurring primary and secondary metabolites. An unsupervised principal component analysis was employed to identify correlations between changes in metabolite expression (obtained at different times and sample treatment conditions and the overall defence response. A one-dimensional projection of the principal components 1 and 2 obtained from positive ion mode spectra was used to generate a Biological Response Index (BRI. The BRI obtained for each sample treatment was compared with the number of dead cells found in the respective tissue. The high correlation between these two values suggested that the BRI provides a rapid assessment of the plant response against the pathogen infection. Evaluation of the loading plots of the principal components (1 and 2 reveals a correlation among three metabolic cascades and the defence response generated in infected leaves. Analysis of selected phytohormones by liquid chromatography electrospray ionization mass spectrometry verified our findings. Conclusion The described methodology allows for rapid assessment of infection-specific changes in the plant metabolism, in particular

  20. Selection and validation of potato candidate genes for maturity corrected resistance to Phytophthora infestans based on differential expression combined with SNP association and linkage mapping

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    Meki Shehabu Muktar

    2015-09-01

    Full Text Available Late blight of potato (Solanum tuberosum L. caused by the oomycete Phytophthora infestans (Mont. de Bary, is one of the most important bottlenecks of potato production worldwide. Cultivars with high levels of durable, race unspecific, quantitative resistance are part of a solution to this problem. However, breeding for quantitative resistance is hampered by the correlation between resistance and late plant maturity, which is an undesirable agricultural attribute. The objectives of our research are (i the identification of genes that condition quantitative resistance to P. infestans not compromised by late plant maturity and (ii the discovery of diagnostic single nucleotide polymorphism (SNP markers to be used as molecular tools to increase efficiency and precision of resistance breeding. Twenty two novel candidate genes were selected based on comparative transcript profiling by SuperSAGE (serial analysis of gene expression in groups of plants with contrasting levels of maturity corrected resistance (MCR. Reproducibility of differential expression was tested by quantitative real time PCR and allele specific pyrosequencing in four new sets of genotype pools with contrasting late blight resistance levels, at three infection time points and in three independent infection experiments. Reproducibility of expression patterns ranged from 28% to 97%. Association mapping in a panel of 184 tetraploid cultivars identified SNPs in five candidate genes that were associated with MCR. These SNPs can be used in marker-assisted resistance breeding. Linkage mapping in two half-sib families (n = 111 identified SNPs in three candidate genes that were linked with MCR. The differentially expressed genes that showed association and/or linkage with MCR putatively function in phytosterol synthesis, fatty acid synthesis, asparagine synthesis, chlorophyll synthesis, cell wall modification and in the response to pathogen elicitors.

  1. Effect of partially purified components of zoospores and mycelia of phytophthora infestans on uptake of 3H-leucine by potato tuber disks

    International Nuclear Information System (INIS)

    The zoosporial component of Phytophthora infestans, which was previously reported to cause reduction of 3H-leucine uptake by potato tuber disks, was partially purified. Precipitate (A-fraction) was obtained by homogenizing zoospores with acetate buffer at pH 4.5 and centrifuging at 20,000 x g, and the A-fraction was suspended in borate buffer at pH 8.8, boiled for 1 hr and then centrifuged at 20,000 x g, giving the precipitate (B-fraction) and supernatant (C-fraction). Ten ml of 10 mM tris-HCl buffer containing 1 mM CaCl2 at pH 7.4 was used to suspend A and B-fraction. The buffer was used as a control. A, B and C fractions obtained from 5 - 6 x 106 zoosprores reducted uptake of 3H-leucine by the tuber disks of potato cv. Rishiri, but the inhibition rates caused by these fractions differed markedly. However, very high correlation was found between inhibition rates of 3H-leucine uptake and sugar contents of these fractions. There was no difference in the inhibition rates between the zoosporial components of incompatible and compatible races, when the activities were expressed in terms of the sugar contents. The mycelial components of P. infestans extracted by the modified method of Lisker and Kuc which was used to extract phytoalexin elicitor from that of P. infestans, also had the same effect as the zoosporial components (A, B, and C-fraction) on 3H-leucine uptake by the disks. C-fraction containing 15 μg of sugar per ml sufficed to inhibit 3H-leucine uptake at the maximum rate, and the maximum rate of inhibition was attained within 2 hr after the zoosporial component (C-fraction containing 30 μg sugar/ml) was administered to the disks. (author)

  2. Messa a punto di un metodo per l'individuazione di β-1,3- glucanasi e chitinasi attraverso Native PAGE su estratti di piante di Prunus avium L. inoculate con Phytophthora spp.

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    Anna De Rogatis

    2009-12-01

    Full Text Available Tecnique to detect on ß-1,3- glucanase and chitinasi by native PAGE, in Prunus avium (L.clones inoculated with Phytophthora spp. ß-1,3-glucanase and chitinase activities have been detected by native PAGE (poliacrylamide gel electrophoresis on leaf extracts of wild cherry (P. avium inoculated with different species of Phytophthora spp.. These pathogens are aggressive in wild cherry and they can cause wiltings and death of the plant. These two PR (pathogen-related proteins are normally produced by plants as first resistance strategy towards pathogens. The PR activities are involved in ifal cell wall degradation and growth. Usually, the techniques to detect them are based on colorimetric assay performed with the total protein extracts or in the poliacrylamide gels, through expensive procedures. In this work a direct colorimetric detection on a Carboximetil (cm-Curdlan RBB (Remazol Brilliant Blu and Glycol Chitosan substrate, is used to reveal ß-1,3-glucanase and chitinasi respectively. This protocol resulted to be very sensible in detecting the two proteins, very simply, reliable and cheap.

  3. Isolation and anti-oomycete activity of nyasol from Anemarrhena asphodeloides rhizomes.

    Science.gov (United States)

    Park, Hee Jin; Lee, Jung Yeop; Moon, Surk Sik; Hwang, Byung Kook

    2003-11-01

    The methanol extract of Anemarrhena asphodeloides rhizomes exhibited strong antifungal activity against the plant pathogenic fungi Magnaphothe grisea, Rhizoctonia solani, and the plant pathogenic oomycete Phytophthora capsici. The antifungal substance isolated from the rhizomes of A. asphodeloides was identified to be nyasol, (Z)-1,3-bis(4-hydroxyphenyl)-1,4-pentadiene by NMR and mass spectral analysis. Nyasol effectively inhibited the mycelial growth of Colletotrichum orbiculare, P. capsici, Pythium ultimum, R. solani, and Cladosporium cucumerinum in a range of 1-50 mug/ml, but did not affect the growth of bacteria and yeast. In a greenhouse test, treatment with the antifungal compound nyasol was significantly effective in suppressing the Phytophthora blight on pepper plants. PMID:14561517

  4. Isolation and In Vivo and In Vitro Antifungal Activity of Phenylacetic Acid and Sodium Phenylacetate from Streptomyces humidus

    OpenAIRE

    Hwang, Byung Kook; Lim, Song Won; Kim, Beom Seok; Lee, Jung Yeop; Moon, Surk Sik

    2001-01-01

    The antifungal substances SH-1 and SH-2 were isolated from Streptomyces humidus strain S5-55 cultures by various purification procedures and identified as phenylacetic acid and sodium phenylacetate, respectively, based on the nuclear magnetic resonance, electron ionization mass spectral, and inductively coupled plasma mass spectral data. SH-1 and SH-2 completely inhibited the growth of Pythium ultimum, Phytophthora capsici, Rhizoctonia solani, Saccharomyces cerevisiae, and Pseudomonas syringa...

  5. Mejoramiento Genético de la Papa en Colombia, para Resistencia a la "Gota" Causada por el PhytophthoraInfestans, (Mont. de Bary

    Directory of Open Access Journals (Sweden)

    Estrada Ramos Nelson

    1954-06-01

    Full Text Available Se hace una revisión de la literatura más importante y reciente publicada en EE. UU., Inglaterra, Holanda, Alemania y Rusia, países que más sehan preocupado por resolver el problema del Phytophthora en la papa, y la relacionada especialmente con el aspecto de pérdidas que causa, razas del parásito, métodos genéticos para la obtención de variedades resistentes y sistemas de prueba de la resistencia. Además se incluyen datos estadísticos para demostrar la importancia del Cultivo en el país. Se indican los métodos seguidos en Colombia para el mejoramiento, partiendo especialmente de líneas de la especie silvestre. S. demíssumcombinándola con las variedades nativas cultivadas del tipo andigenumadaptadas a grandes alturas y a los días cortos de los trópicos. Los resultados hasta la fecha indican la posibilidad de obtener después de 3 ó4 generaciones de retrocruzamientos, una buena variedad para cultivo y altamente resistente a la enfermedad. También se aconseja el empleo de líneas y variedades extranjeras resistentes, una vez que se hayan probado a las razas de Phytophthorapropias de Colombia. . Se indica que ya existe material de fitomejoramiento bastante avanzado que es prácticamente inmune pero que requiere subsiguiente mejoramiento. Hay probabilidades así, de obtener variedades inmunes o altamente resistentes a las razas actualmente existentes aunque su identidad parece no corresponder exactamente con las de otros países como Holanda, Inglaterra y Estados Unidos. Se establece una falta de identidad entre las pruebas de campo y las del laboratorio aunque pueden complementarse. Puede suponerse, de acuerdo con las reacciones obtenidas en el material extranjero resistente, la posibilidad de existencia de varias razas, pero no tan virulentas como en los países que tienen variedades resistentes. Es aconsejable el mejoramiento permanente de las variedades, para poder combatir los nuevos biotipos del pat

  6. SELECCIÓN In Vitro DE FORMAS TOLERANTES DE PAPA (Solanum tuberosum, L. A FILTRADOS DE Phytophthora infestans (Mont. de Bary

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    María M. Hernández

    2003-01-01

    Full Text Available Se realizaron una serie de experimentos para determinar la acción patogénica de filtrados de P. infestans (Mont. de Bary, sobre diferentes órganos de papa y verificar si éstos podían ser empleados en la selección in vitro de formas tolerantes a este patógeno. Se emplearon hojas desprendidas, así como el polen de clones con diferente respuesta al patógeno en el campo, los cuales fueron sometidos a la acción del filtrado y se encontró que éste poseía una acción hospedero específica, o sea, los clones respondieron a su acción en dependencia de su resistencia al patógeno, por lo cual este podía ser usado para la selección de formas resistentes. Los filtrados fueron empleados para seleccionar brotes de callos sometidos a su acción y estos fueron llevados finalmente al campo para evaluar su tolerancia frente al patógeno, incluyéndose la evaluación de la incidencia de Alternaria solani, que es la más importante después de Phytophthora infestans, para comprobar si los somaclones obtenidos presentaban un nivel de tolerancia superior al donante en sentido general. El donante empleado fue la var Desirée, que presenta buenas características en cuanto a rendimiento y calidad de los tubérculos, pero es susceptible al tizón causado por P. infestans. Los resultados demostraron que los clones superaron al donante de manera general, no sólo en cuanto a resistencia a ambos patógenos, sino en los principales caracteres agronómicos y el rendimiento, lo cual abre grandes perspectivas para el empleo de estas técnicas en el mejoramiento genético del cultivo.

  7. EVALUACIÓN DE INDICADORES QUE CARACTERIZAN LA ACCIÓN PROTECTORA DEL QUITOSANO EN Nicotiana tabacum L. vs Phytophthora nicotianae BREDA DE HAAN

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    Dianevys González-Peña Fundora

    2015-01-01

    Full Text Available El quitosano es un polímero de glucosamina con importantes propiedades como compuesto antimicrobiano e inductor de respuestas defensivas en plantas, el cual emerge como una alternativa ecológica al empleo de pesticidas. El objetivo del presente trabajo fue evaluar el efecto que ejerce este polímero en el crecimiento y la esporulación de un aislado de Phytophthora nicotianae Breda de Haan, así como en la actividad glucanasa en plantas de tabaco (Nicotiana tabacum L. infectadas con el patógeno. Para ello se inoculó un disco con micelio de P. nicotianae en placas Petri con medio de cultivo PDA-V8 y diferentes concentraciones de quitosano. La inhibición del crecimiento del micelio estuvo marcada por el tipo de ácido disolvente y las concentraciones empleadas. Se observó una relación directa entre el efecto inhibitorio y los niveles del polímero en el medio de cultivo. Además, disminuyó la esporulación de P. nicotianae al adicionar hasta 3,0 g L-1y hubo un efecto biostático del crecimiento de la colonia, pero no biocida. Por otra parte, las plantas de tabaco de 30 días de sembradas, tratadas con quitosano o inoculadas con el aislado SS-11 a través de la raíz, variaron la concentración de proteínas y la actividad glucanasa en el tiempo. También se alcanzó un 26 % de protección vegetal al aplicar 0,5 g L-1 del polímero a plantas de tabaco. Los resultados muestran el efecto del quitosano como inhibidor del desarrollo de P. nicotianae, así como su potencialidad para incrementar la actividad glucanasa y la protección del cultivo ante la presencia de este patógeno.

  8. Avaliação de métodos de inoculação de Phytophthora parasitica em plântulas e plantas jovens de citros

    OpenAIRE

    SIVIERO AMAURI; FURTADO EDSON L.; BOAVA LEONARDO P.; BARBASSO DANILO V.; Machado, Marcos A

    2002-01-01

    Este trabalho teve como objetivo avaliar métodos de inoculação de Phytophthoraparasitica em plântulas e plantas jovens de citros (Citrus spp.) visando sua utilização em estudos de resistência de porta-enxertos à gomose de Phytophthora. Os métodos de inoculação testados foram: contato planta sem ferimento-patógeno, casca destacada, inserção de disco de meio de cultura contendo micélio sob a casca, método do disco e inserção de agulha e palito infestados em plântulas e plantas jovens de citros....

  9. Tolerância de híbridos e de clones de porta-enxertos de citros à infecção de raízes por Phytophthora nicotianae Tolerance of hybrids and rootstock clones of citrus to root rot infection caused by Phytophthora nicotianae

    Directory of Open Access Journals (Sweden)

    Herculano P. Medina Filho

    2004-04-01

    Full Text Available Estudaram-se clones de porta-enxertos de citros (Citrus spp., híbridos e genitores quanto à tolerância das raízes a Phytophthora nicotianae através de inoculações em substrato de argila expandida. Investigaram-se progênies nucelares dos clones Poncirus trifoliata 'Rich 16-6', citrumelo 'Swingle' (C. paradisi x P. trifoliolata , tangerinas 'Cleópatra' (Citrus reshni e 'Suen Kat' (C. sunki, limão'Volkameriano' (C. volkameriana, dos genitores tangerina 'Sunki' (C. sunki (S, limão 'Cravo' (C. limonia (C, laranja 'Azeda' (C. aurantium ((A, Poncirus trifoliata 'Davis A' (T, e progênies nucelares de híbridos entre eles, totalizando 2303 plântulas. Avaliou-se a taxa de sobrevivência, redução de raízes e partes aéreas, peso de raízes e de partes aéreas, diâmetro do caule e altura, comparando-se plântulas inoculadas e não inoculadas. Atribuíram-se também notas subjetivas para volume de raízes, enfolhamento, coloração das folhas e altura. Desenvolveu-se um índice total de redução (ITR baseado na taxa de sobrevivência e nos parâmetros mencionados. Mostraram-se altamente tolerantes os trifoliatas 'Davis A' e 'Rich 16-6', o citrumelo 'Swingle', três híbridos TxS, dois SxT e dois SxA, com ITR 80%. A metodologia de inoculação e avaliação discriminou com precisão progênies nucelares dos clones e dos híbridos, evidenciando o potencial de seleção principalmente dos híbridos SxT e recíprocos.Clones of citrus rootstocks, hybrids and their parents were evaluated for tolerance to root rot incited by Phytophthora nicotianae. It were evaluated 'Rich 16-6' Trifoliate orange (Poncirus trifoliata, citrumelo 'Swingle' (C. paradisi x P. trifoliolata, 'Cleopatra' (Citrus reshni and 'Suen Kat' (C. sunki mandarins, 'Volkamer' lemon (C. volkameriana, the parents 'Sunki' mandarin (C. sunki (S, Rangpur lime (C. limonia (C, Sour orange (C. aurantium (A and 'Davis A' Trifoliate orange (T, and the nucellar progenies of hybrids between

  10. Efecto Antagónico in vitro de Actinomicetos Aislados de Purines de Chipaca (Bidens pilosa L. Frente a Phytophthora infestans (Mont de Bary In vitro Antagonistic Effect of Actinomycetes Isolated from Chipaca (Bidens pilosa L. Purins Against Phytophthora infestans (Mont de Bary

    Directory of Open Access Journals (Sweden)

    Yudy Astrid Fonseca Ardila

    2011-12-01

    Full Text Available Se estudió el efecto inhibidor de los actinomicetos presentes en purines o extractos fermentados de plantas de chipaca (Bidens pilosa L., sobre el crecimiento de Phytophthora infestans (Mont de Bary, causante del tizón tardío de la papa. Se elaboraron cuatro purines de flores, raíces, hojas-tallos y su mezcla. De estos purines se obtuvieron 25 aislamientos de actinomicetos, cada uno de los cuales se enfrentó con P. infestans en placas de medio de cultivo, utilizando la técnica de anillos de Gauze y estableciendo las concentraciones iniciales de esporas mediante conteos microscópicos en cámara de Neubauer. Los actinomicetos no crecieron en el purin de flores debido, posiblemente, a que en él no se utiliza suelo rizosférico o porque su pH (9 es mayor que el rango normal de crecimiento de estos microorganismos ( pH 6 -; 8. Se evidenció inhibición del crecimiento del oomycete por parte de 8 aislamientos de actinomicetos con porcentajes de inhibición entre 33,3 - 77,8%, provenientes de los purines de raíces, tallos-hojas y mezcla de partes de la planta. La mayor inhibición se obtuvo en los aislamientos AC001, AC010, AC011 y AC025 con conteos de 0,4, 6,0, 3,0, y 3,6 x10(5 esporas mL-1.Purins or liquid fermented extracts of chipaca (Bidens pilosa L. were prepared to establish the inhibitory effect of the actinomycetes found in such biopharmaceutical preparations on the growth of Phytophthora infestans (Mont de Bary, the causative of potato late blight disease. Four purins made from flowers, roots, leaf-steams and a mixture of them were prepared; 25 actinomycete isolates were obtained from these purins and their ability to resist challenge by P. infestans was ascertained in medium plates using the ring Gauze technique and establishing initial concentrations of spores by microscopic counting in Neubauer chamber. Actinomycetes did not grow in flower purin as rhizosphere soil was not used in its preparation or because this particular pH (9

  11. Ação antagônica de rizobactérias contra Phytophthora parasitica e p. citrophthora e seu efeito no desenvolvimento de plântulas de citros

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    AMORIM EDNA PEIXOTO DA ROCHA

    2002-01-01

    Full Text Available O antagonismo de Pseudomonas putida biovar A (C1-1B, P. putida biovar B (Santa Bárbara, P. fluorescens (C2-8C e RA2, Bacillus subtilis (OG e RC2 e Flavobacterium sp. (CIS/NA contra Phytophthora parasitica e P. citrophthora , agentes da podridão radicular dos citros, foi avaliado através da inibição do crescimento micelial (cultura pareada e redução na percentagem de infecção da doença em mudas de citros (tratamento de sementes com rizobactérias. Na seleção preliminar, 33 isolados bacterianos foram testados. Sementes de citros pré-germinadas foram tratadas por imersão nas suspensões das bactérias (10(9 ufc/ml, e plantadas em tubetes contendo solo natural infestado com o fitopatógeno (50 ml de suspensão/ kg de solo. A avaliação da percentagem de infecção foi efetuada após 15 dias. In vitro, os isolados bacterianos RC2, OG, CIS/NA e C1-1B foram os mais ativos inibidores do crescimento micelial de Phytophthora. Em condições de casa de vegetação, todos os isolados proporcionaram redução na percentagem de infecção da doença em todos os ensaios realizados. Promoção de crescimento de plantas foi verificada pela inoculação de plântulas com as linhagens OG, RC2, CiS/Na e C1-1B.

  12. Population structure of Phytophthora infestans from Ningxia%宁夏固原致病疫霉群体结构特征

    Institute of Scientific and Technical Information of China (English)

    宋俊丽; 朱杰华; 杨志辉; 王春一

    2012-01-01

    为揭示宁夏固原致病疫霉群体遗传结构,用对峙培养法和菌落直径法测定致病疫霉的交配型和甲霜灵抗性,利用限制性片段长度多态性聚合酶链反应(PCR-RFLP)技术检测致病疫霉线粒体DNA单倍型,并采用简单重复序列(SSR)和扩增片段长度多态性(AFLP)技术确定致病疫霉群体的基因型。在94株供试菌株中,发现了1株A1交配型、86株A2交配型及7株自育型菌株,全部为甲霜灵抗性菌株。菌株的线粒体单倍型均为Ⅰa型,共鉴定出2种SSR基因型,Ⅰ型占绝对优势。AFLP聚类分析显示,在相似系数0.68时分成α和β两组,宁夏固原菌株全部聚在β组。研究表明,宁夏固原致病疫霉群体结构比较单一、遗传多样性水平较低。%The population genetic structure of Phytophthora infestans collected from Guyuan of Ningxia Hui Autonomous Region was revealed by the combination of phenotypes and genotypes. The phenotypes of P. infestans i.e. mating types and metalaxyl resistance were investigated by means of dual culture with A1 and 3,2 testers on rye plates and radical growth assay on fungicide-amended media in vitro, respec- tively. Mitochondrial DNA haplotypes of isolates of P. infestans were detected with restriction fragment length polymorphism and polymerase chain reaction (PCR-RFLP). Genotypes of genomic total DNA of P. infestans were examined by simple sequence repeats (SSR) and amplified fragment length polymor- phism (AFLP). Of tested 94 isolates, only one was A1, 86 ones were A2, and the seven ones were self- fertile. Nevertheless, all tested isolates were metalaxyl-resistant. Only one mitochondrial DNA haplotype ( I a) and two SSR genotypes ( named as types I and II ) were determined among population, one ( i. e. type I ) of which was absolute predominance. Then, two AFLP clades (i. e. α and β clade) were formed at a genetic similarity value of 0. 68 and all isolates of P. infestans from Guyuan of Ningxia were

  13. The threat of hybrid Phytophthoras

    Science.gov (United States)

    The majority of invasive plant pathogens have resulted from the introduction of exotic organisms. However, another mechanism for invasiveness results from hybridization between species. This phenomenon has been documented in plants and animals, but its role in plant pathology has only recently been ...

  14. Micropropagação do porta-enxerto de macieira 'Seleção 69' tolerante à podridão do colo (Phytophthora cactorum Micropropagation of 'Seleção 69' apple rootstock tolerant the rotting (Phytophthora cactorum

    Directory of Open Access Journals (Sweden)

    Claudete Santa-Catarina

    2001-10-01

    Full Text Available A utilização de porta-enxertos anões, tolerantes a problemas fitossanitários da cultura da macieira, como a podridão do colo (Phytophthora cactorum, pode aumentar o rendimento e reduzir os custos de produção. Com o presente trabalho, objetivou-se estabelecer um protocolo de micropropagação do porta-enxerto 'Seleção 69', tolerante à podridão do colo. Ápices meristemáticos foram cultivados in vitro em meio de cultura MS, suplementado com 4,4mM de 6-Benzilaminopurina (BAP, 2,5mM de Ácido indolbutírico (AIB, 0,3mM de Ácido giberélico (GA3, 3% de sacarose e 0,6% de ágar. Foram testados o efeito da concentração de BAP (2,2 e 4,4mM e o efeito dos meios de cultura (MS, Cheng e Quoirin & Lepoivre na multiplicação das brotações. No alongamento das brotações, foram testados os efeitos do GA3 (0; 0,5; 1,0 e 1,5mM e AIB (0; 0,5 e 1,0mM. Para a fase de enraizamento ex vitro e aclimatização, foram testadas diferentes concentrações de AIB (0; 1 e 2g L-1. A taxa de desenvolvimento dos ápices meristemáticos cultivados in vitro foi de 30%. Para estimular a brotação, a melhor concentração de BAP foi 2,2mM, a qual proporcionou 2,6 brotações por explante. O meio MS proporcionou o maior número de brotações por explante (2,5, porém não diferiu estatisticamente do meio Cheng (2,0 brotações por explante. Para a fase de alongamento, o meio MS suplementado com 2,2mM de BAP e 1,0mM de AIB, proporcionou a maior altura das brotações (23mm. Na fase de enraizamento ex vitro e aclimatização, as concentrações de 0, 1 e 2g L-1 de AIB possibilitaram em média, 77,3% de enraizamento das microestacas.The use of tolerant apple rootstocks to phytossanitary problems as the rotting (Phytophthora cactorum is able to increase the production with cost reduction. The objective of the present study is to establish in vitro micropropagation protocol of the '69 Selection' rootstocks tolerant to the rotting. Meristems was cultivated in vitro

  15. Different Conditions on the Cultural Characteristics of Race O of Phytophthora Parasitica var.nicotianae%烟草黑胫病菌0号生理小种不同条件下培养特性的研究

    Institute of Scientific and Technical Information of China (English)

    苏振刚; 王静; 周佳; 李锡冲; 郑林林; 李元元; 赵百英; 杨帆; 王元英

    2011-01-01

    The cultural characteristics of race 0 of Phytophthora parasitica var.nicotianae were investigated in order to provide more basic information for further study and integrated management of the disease.The study used several cultural factors, including experimental medium, light, bacteria age, inducing agents and induction time to observe cultural characteristics of race 0 of Phytophthora parasitica var.nicotianae, such as growth rate of tobacco, sporangium production and tour dynamic spores release etc.The results showed that Oatmeal medium was suitable for mycelium growth and production of sporangium; light could limit its growth; based on the experimental period and other factors, mycelium cultivated for 21 days is more appropriate for induced; 0.1%KNO3 solution soaking mycelium contribute to sporangium production; after 72 h cultivation by 26℃, sudden drop of 12℃ for 0.5 h,combine with 1% glucose solution can promote sporangia to release zoospores, and it can also prolong time of zoospore's activities.%研究了烟草黑胫病菌0号生理小种的若干培养性状,为进一步展开与之相关的研究和综合防治提供理论基础.用培养基、光照、菌龄、诱导剂和诱导时间等不同因素研究了对烟草黑胫病菌0号生理小种的生长速度、产孢量和游动孢子释放量等方面的影响.结果表明,燕麦培养基较适于其生长和产生孢子囊,光照限制其生长;在本实验周期内,培养21 d的菌丝较适宜诱导,0.1 % KNO_3溶液浸泡菌丝有助于孢子囊的产生;经26℃培养72 h后,突降12℃处理0.5 h,结合1%葡萄糖溶液可促使抱子囊释放游动孢子,并延长后者的活动时间.

  16. IDENTIFICATION OF KEY MOLECULAR COMPONENTS OF THE RESISTANCE OF CHERRY TOMATO AGAINSTPhytophthora infestans Identificación de los principales componentes moleculares de la resistencia de tomate cherry contra Phytophthora infestans

    Directory of Open Access Journals (Sweden)

    LILIANA LÓPEZ KLEINE

    2012-12-01

    Full Text Available Cherry tomato Solanum lycopersicum var cerasiforme cv Matt's wild cherry is a very resistant cultivar to most Phytophthora infestans isolates. Two isolates were identified, US940480 and US970001 that cause an incompatible and a compatible interaction respectively. US970001 is one of the few isolates producing a compatible interaction with this cultivar. To identify genes with a differential gene expression between compatible and incompatible interactions, gene expression patterns were analyzed with tomato cDNA microarrays including 12,899 independent tomato cDNA clones at different time points after inoculation. A diverse set of statistical tools were used to identify key components of the plant response to the pathogen. Forty-three genes were up-regulated during the incompatible reaction at time point 36 hours, 15 globally at all time points and twelve were found both in globally and at 36 hours. Northern blots analysis was performed to confirm differential expression showed by microarray analysis and to study the differential expression of more plant resistance genes (PR genes between compatible and incompatible interactions for this interaction.El tomate cherry Solanum lycopersicum var cerasiforme cv Matt's es bastante resistente a la gran parte de aislamientos de Phytophthora infestans. Se han identificado dos aislamientos, US940480 y US970001 que causan interacción incompatible y compatible respectivamente. US970001 es uno de los pocos aislamientos causantes de interacción compatible con este cultivo. Con el fin de identificar genes con expresión diferencial en interacciones compatible e incompatible, analizamos DNA copia de 12899 clones independientes en tres tiempos posteriores a la inoculación del patógeno. Se aplicaron diversas herramientas estadísticas para identificar componentes moleculares claves de la respuesta de la planta al patógeno. Cuarenta y tres genes fueron detectados como activados durante la interacci

  17. 致病疫霉拮抗放线菌NB8发酵条件的优化%Optimization of fermentation conditions of Streptomyces albus NB8 against the growth of Phytophthora infestans

    Institute of Scientific and Technical Information of China (English)

    惠娇; 蒋继志; 鲍雪; 王芳

    2011-01-01

    In order to enhance the inhibitory effect of substances in fermentation liquid of Streptomyces albus NB8 strain against the growth of Phytophthora infestans, the fermentation conditions of NB8 strain were investigated by single-factor experiment. The results showed that optimal fermentation conditions were as follows:seed liquid cultured in Gause 1 medium after 5 d was inoculated with a volume of 125 mL/250 mL and amount of 1.5% into same medium, then was cultured 10 d as the initial pH7.0, 34 ℃, 50 r/rain, 12 h dark/12 h light. And the inhibitory rate reached 81% under the optimal fermentation conditions, which increased by 20% in comparison with pre-optimization. The findings indicate that NB8 strain has a great potential in control potato late blight in future.%为提高放线菌NB8(Streptomyces albus)菌株对致病疫霉(Phytophthora in festans)的抑制效率,本试验采用滤纸片法以单因子试验对拮抗放线菌NB8菌株的发酵条件进行优化.结果表明优化后的最佳发酵条件为:将NB8菌株经高氏一号液体培养5 d的种子液,以125 mL/250 mL的装液量和1.5%的接种量,在初始pH7.0、34℃、50 r/min及12 h黑暗/12 h光照下培养10 d所得发酵液对致病疫霉的抑制作用最强,抑菌率达到81%以上,比优化前提高了约20%.结果表明NB8菌株在控制马铃薯晚疫病方面有较大的应用潜力.

  18. VIGS approach reveals the modulation of anthocyanin biosynthetic genes by CaMYB in Chili pepper leaves

    Directory of Open Access Journals (Sweden)

    zhen ezhang

    2015-07-01

    Full Text Available The purple coloration of pepper leaves arises from the accumulation of anthocyanin. Three regulatory and 12 structural genes have been characterized for their involvement in the anthocyanin biosynthesis. Examination of the abundance of these genes in leaves showed that the majority of them differed between anthocyanin pigmented line Z1 and non-pigmented line A3. Silencing of the R2R3-MYB transcription factor CaMYB in pepper leaves of Z1 resulted in the loss of anthocyanin accumulation. Moreover, the expression of multiple genes was altered in the silenced leaves. The expression of MYC was significantly lower in CaMYB-silenced leaves, whereas WD40 showed the opposite pattern. Most structural genes including CHS, CHI, F3H, F3’5’H, DFR, ANS, UFGT, ANP and GST were repressed in CaMYB-silenced foliage with the exception of PAL, C4H and 4CL. These results indicated that MYB plays an important role in the regulation of anthocyanin biosynthetic related genes. Besides CaMYB silenced leaves rendered more sporulation of Phytophthora capsici Leonian indicating that CaMYB might be involved in the defense response to pathogens.

  19. VIGS approach reveals the modulation of anthocyanin biosynthetic genes by CaMYB in chili pepper leaves.

    Science.gov (United States)

    Zhang, Zhen; Li, Da-Wei; Jin, Jing-Hao; Yin, Yan-Xu; Zhang, Huai-Xia; Chai, Wei-Guo; Gong, Zhen-Hui

    2015-01-01

    The purple coloration of pepper leaves arises from the accumulation of anthocyanin. Three regulatory and 12 structural genes have been characterized for their involvement in the anthocyanin biosynthesis. Examination of the abundance of these genes in leaves showed that the majority of them differed between anthocyanin pigmented line Z1 and non-pigmented line A3. Silencing of the R2R3-MYB transcription factor CaMYB in pepper leaves of Z1 resulted in the loss of anthocyanin accumulation. Moreover, the expression of multiple genes was altered in the silenced leaves. The expression of MYC was significantly lower in CaMYB-silenced leaves, whereas WD40 showed the opposite pattern. Most structural genes including CHS, CHI, F3H, F3'5'H, DFR, ANS, UFGT, ANP, and GST were repressed in CaMYB-silenced foliage with the exception of PAL, C4H, and 4CL. These results indicated that MYB plays an important role in the regulation of anthocyanin biosynthetic related genes. Besides CaMYB silenced leaves rendered more sporulation of Phytophthora capsici Leonian indicating that CaMYB might be involved in the defense response to pathogens. PMID:26217354

  20. Antifungal activity of diketopiperazines and stilbenes against plant pathogenic fungi in vitro.

    Science.gov (United States)

    Kumar, S Nishanth; Nambisan, Bala

    2014-01-01

    The present study aimed to investigate antifungal activity of a stilbene and diketopiperazine compounds against plant pathogenic fungi, including Phytophthora capsici, P. colocasiae, Botrytis cinerea and Colletotrichum gloeosporioides. Minimal inhibition concentrations (MIC) and minimal fungicidal concentrations (MFC) of stilbenes and diketopiperazines for each fungus were determined using microplate method. Best activity was recorded by stilbenes against P. capsici and P. colocasiae. All four test compounds were effective in inhibiting different stages of the life cycle of test fungi. Stilbenes were more effective than diketopiperazines in inhibiting mycelial growth and inhibiting different stages of the life cycle of P. capsici and P. colocasiae. Rupture of released zoospores induced by stilbenes was reduced by addition of 100 mM glucose. The effects of stilbenes on mycelial growth and zoospore release, but not zoospore rupture, were reduced largely when pH value was above 7. In addition, stilbenes were investigated for its antifungal stability against Phytophthora sp. The results showed that stilbenes maintained strong fungistatic activity over a wide pH range (pH 4–9) and temperature range (70–120 °C). The compound stilbenes exhibited strong and stable broad-spectrum antifungal activity, and had a significant fungicidal effect on fungal cells. Results from prebiocontrol evaluations performed to date are probably useful in the search for alternative approaches to controlling serious plant pathogens. PMID:24122628

  1. Evaluación de la heredabilidad y selección combinada en un población de Solanum phureja Juz et Buk por resistencia a Spongospora subterranea (Wallr) Lagerh f. sp. subterranea Tomlinson y Phytophthora infestans (Mont) de Bary

    OpenAIRE

    Orozco Orozco, Luz Fanny

    2012-01-01

    Resumen: Las dos enfermedades más importantes del cultivo de la papa en Colombia son la sarna polvosa y la gota, producidas por los patógenos Spongospora subterranean f. sp. subterranea y Phytophthora infestans, respectivamente. Para estas enfermedades, el mejoramiento genético es una de las principales estrategias para su manejo. Se sabe que en Solanum phureja existen niveles diferenciales de respuesta de resistencia y/o susceptibilidad a la sarna polvosa y la gota de la papa. El objetivo de...

  2. Caracterización morfológica y evaluación de la resistencia de materiales criollos de aguacate Persea americana Mill. A la pudrición radical del aguacate Phytophthora cinnamomi Rands en el centro de investigación Palmira de CORPOICA.

    OpenAIRE

    Rodriguez Henao, Eberto

    2015-01-01

    Como aporte a la búsqueda de cultivares de aguacate Persea americana Mill., potencialmente resistentes a la enfermedad de pudrición de raíces causada por Phytophthora cinnamomi Rands, se evaluaron 21 accesiones del banco de germoplasma de aguacate antillano de CORPOICA, seleccionadas por distanciamiento genético mediante caracterización morfológica, utilizando dos cepas patogénicas de este oomiceto. El objetivo fue identificar accesiones con potencial de uso como portainjertos, práctica de ma...

  3. Fenoles, peroxidasa y fenilalanina amonio-lyasa: su relación con la resistencia genética de clones de papa (solamun tuberosum l.) contra el tizón tardío (phytophthora infestans mont de bary)

    OpenAIRE

    Héctor Lozoya Saldaña; María Teresa Colinas León; Rodolfo Rivera Hinojosa

    2007-01-01

    La resistencia horizontal de las plantas a las enfermedades involucra la activación de varios genes de defensa. Para comprobar este tipo de mecanismos se cuantificaron actividades enzimáticas relacionadas con diversos niveles de resistencia genética en genotipos de papa (Solanum tuberosum L.) contra el tizón tardío (Phytophthora infestans Mont. de Bary), expuestos a infección natural en el valle de Toluca, con y sin protección con fungicidas. Hubo respuesta diferencial en presencia y activida...

  4. 云南省马铃薯晚疫病菌交配型及生物学特性研究(英文)%MATING TYPE AND BIOLOGICAL CHARACTERISTICS OF Phytophthora infestans ISOLATES FROM YUNNAN, CHINA

    Institute of Scientific and Technical Information of China (English)

    国立耘; 杨艳丽; 罗文富

    2002-01-01

    作者对1998~2000年间采自云南省13个县、23个地点的马铃薯晚疫病菌的交配型、菌落形态、燕麦培养基上生长情况、生长速度和产孢量进行了测定.结果显示,采自云南13个县、23个地点的共157个菌株全部为A1交配型,表明云南马铃薯主产区的晚疫病菌以A1交配型为主,同时,被测的代表菌株在生长速度和产孢量上存在显著差异,表明这一地区的晚疫病菌种群内存在丰富的遗传多样性.此外,结果还显示,晚疫病菌菌株在燕麦培养基上的生长情况与其菌落形态和交配型不相关.%Phytophthora infestans from potatoes collected from Yunnan Province during 1998 to 2000 were investigated for their mating type, colony growth pattern, ability to grow on oatmeal agar, linear growth rate and amount of sporangia produced. A total of 157 isolates from 23 locations in 13 counties in Yunnan were all A1 mating type. Representative isolates showed significant variation in growth rate and amount of sporangia produced, which indicate the existence of genetic diversity among the population of P. infestans in Yunnan. Results also show that colony growth pattern and the growth on oatmeal agar did not relate to the mating type of the isolate.

  5. Rpi-blb2-Mediated Hypersensitive Cell Death Caused by Phytophthora infestans AVRblb2 Requires SGT1, but not EDS1, NDR1, Salicylic Acid-, Jasmonic Acid-, or Ethylene-Mediated Signaling

    Directory of Open Access Journals (Sweden)

    Sang-Keun Oh

    2014-09-01

    Full Text Available Potato Rpi-blb2 encodes a protein with a coiled-coil-nucleotide binding site and leucine-rich repeat (CC-NBS-LRR motif that recognizes the Phytophthora infestans AVRblb2 effector and triggers hypersensitive cell death (HCD. To better understand the components required for Rpi-blb2-mediated HCD in plants, we used virus-induced gene silencing to repress candidate genes in Rpi-blb2-transgenic Nicotiana benthamiana plants and assayed the plants for AVRblb2 effector. Rpi-blb2 triggers HCD through NbSGT1-mediated pathways, but not NbEDS1- or NbNDR1-mediated pathways. In addition, the role of salicylic acid (SA, jasmonic acid (JA, and ethylene (ET in Rpi-blb2-mediated HCD were analyzed by monitoring of the responses of NbICS1-, NbCOI1-, or NbEIN2-silenced or Rpi-blb2::NahG-transgenic plants. Rpi-blb2-mediated HCD in response to AVRblb2 was not associated with SA accumulation. Thus, SA affects Rpi-blb2-mediated resistance against P. infestans, but not Rpi-blb2-mediated HCD in response to AVRblb2. Additionally, JA and ET signaling were not required for Rpi-blb2-mediated HCD in N. benthamiana. Taken together, these findings suggest that NbSGT1 is a unique positive regulator of Rpi-blb2-mediated HCD in response to AVRblb2, but EDS1, NDR1, SA, JA, and ET are not required.

  6. Reassessment of QTLs for late blight resistance in the tomato accession L3708 using a restriction site associated DNA (RAD linkage map and highly aggressive isolates of Phytophthora infestans.

    Directory of Open Access Journals (Sweden)

    Ai-Lin Chen

    Full Text Available Tomato late blight caused by the oomycete pathogen Phytophthora infestans (Mont. de Bary is a major threat to tomato production in cool and wet environments. Intensified outbreaks of late blight have been observed globally from the 1980s, and are associated with migration of new and more aggressive populations of P. infestans in the field. The objective of this study was to reassess late blight resistance in the wild tomato accession L3708 (Solanum pimpinellifolium L. against pathogens of different aggressiveness. An F2:3 genetic mapping population was developed using L3708 as the paternal parent. Two isolates of P. infestans, Pi39A and Pi733, were used for inoculation. Pi733 is a highly aggressive genotype that defeats three known late blight resistance genes, Ph-1, Ph-2, and Ph-5t in tomato. In contrast, Pi39A is a less aggressive genotype that defeats only Ph-1. Restriction site Associated DNA Sequencing (RAD-Seq technology was used to massively sequence 90 bp nucleotides adjacent to both sides of PstI restriction enzyme cutting sites in the genome for all individuals in the genetic mapping population. The RAD-seq data were used to construct a genetic linkage map containing 440 single nucleotide polymorphism markers. Quantitative trait locus (QTL analysis identified a new disease-resistant QTL specific to Pi733 on chromosome 2. The Ph-3 gene located on chromosome 9 could be detected whichever isolates were used. This study demonstrated the feasibility and efficiency of RAD-Seq technology for conducting a QTL mapping experiment using an F2:3 mapping population, which allowed the identification of a new late blight resistant QTL in tomato.

  7. Molecular Detection of Phytophthora tentaculata in Infected Aucklandia lappa Tissues and Soil on the Basis of Ypt1 Gene%基于Ypt1基因为靶标的木香疫病病组织及病田土壤分子检测技术

    Institute of Scientific and Technical Information of China (English)

    孟军; 刘燕; 方志翔

    2013-01-01

    A species-specific PCR assay was established for rapid and accurate detection of the oomycete pathogen Phytophthora tentaculata in diseased plant tissues and infected soil.A pair of species-specific primers Ptl/Pt2 were designed on the basis of Ras-related protein (Yptl) gene sequences of the Phytophthora species.PCR amplification with the Pt primers resulted in a 386 bp product only from isolates of P.tentaculata.The detection threshold with Pt primers was 100 pg of genomic DNA.A nested PCR procedure was developed using YptlF/YptlR as the first-round amplification primers and Ptl/Pt2 as the second-round primers,which increased the detection sensitivity 100-fold to 1 pg.PCR using these Pt primers can also be used to detect P.tentaculata in naturally infected plant tissues and soil.The PCR-based method developed in this study provides a rapid and sensitive tool for detection of P.tentaculata.

  8. Molecular Characterization of LjABCG1, an ATP-Binding Cassette Protein in Lotus japonicus.

    Directory of Open Access Journals (Sweden)

    Akifumi Sugiyama

    Full Text Available LjABCG1, a full-size ABCG subfamily of ATP-binding cassette proteins of a model legume, Lotus japonicus, was reported as a gene highly expressed during the early stages of nodulation, but have not been characterized in detail. In this study we showed that the induction of LjABCG1 expression was remarkable by methyl jasmonate treatment, and reporter gene experiments indicated that LjABCG1 was strongly expressed in the nodule parenchyma and cell layers adjacent to the root vascular tissue toward the nodule. LjABCG1 was suggested to be localized at the plasma membrane based on the fractionation of microsomal membranes as well as separation via aqueous two-phase partitioning. The physiological functions of LjABCG1 in symbiosis and pathogenesis were analyzed in homologous and heterologous systems. LjABCG1 knock-down L. japonicus plants did not show clear phenotypic differences in nodule formation, and not in defense against Pseudomonas syringae, either. In contrast, when LjABCG1 was expressed in the Arabidopsis pdr8-1 mutant, the penetration frequency of Phytophthora infestans, a potato late blight pathogen, was significantly reduced in LjABCG1/pdr8-1 than in pdr8-1 plants. This finding indicated that LjABCG1, at least partially, complemented the phenotype of pdr8 in Arabidopsis, suggesting the multiple roles of this protein in plant-microbe interactions.

  9. SGT1 is required in PcINF1/SRC2-1 induced pepper defense response by interacting with SRC2-1.

    Science.gov (United States)

    Liu, Zhi-Qin; Liu, Yan-Yan; Shi, Lan-Ping; Yang, Sheng; Shen, Lei; Yu, Huan-Xin; Wang, Rong-Zhang; Wen, Jia-Yu; Tang, Qian; Hussain, Ansar; Khan, Muhammad Ifnan; Hu, Jiong; Liu, Cai-Ling; Zhang, Yang-Wen; Cheng, Wei; He, Shui-Lin

    2016-01-01

    PcINF1 was previously found to induce pepper defense response by interacting with SRC2-1, but the underlying mechanism remains uninvestigated. Herein, we describe the involvement of SGT1 in the PcINF1/SRC2-1-induced immunity. SGT1 was observed to be up-regulated by Phytophthora capsici inoculation and synergistically transient overexpression of PcINF1/SRC2-1 in pepper plants. SGT1-silencing compromised HR cell death, blocked H2O2 accumulation, and downregulated HR-associated and hormones-dependent marker genes' expression triggered by PcINF1/SRC2-1 co-overexpression. The interaction between SRC2-1 and SGT1 was found by the yeast two hybrid system and was further confirmed by bimolecular fluorescence complementation and co-immunoprecipitation analyses. The SGT1/SRC2-1 interaction was enhanced by transient overexpression of PcINF1 and Phytophthora capsici inoculation, and SGT1-silencing attenuated PcINF1/SRC2-1 interaction. Additionally, by modulating subcellular localizations of SRC2-1, SGT1, and the interacting complex of SGT1/SRC2-1, it was revealed that exclusive nuclear targeting of the SGT1/SRC2-1 complex blocks immunity triggered by formation of SGT1/SRC2-1, and a translocation of the SGT1/SRC2-1 complex from the plasma membrane and cytoplasm to the nuclei upon the inoculation of P. capsici. Our data demonstrate that the SGT1/SRC2-1 interaction, and its nucleocytoplasmic partitioning, is involved in pepper's immunity against P. capsici, thus providing a molecular link between Ca(2+) signaling associated SRC2-1 and SGT1-mediated defense signaling. PMID:26898479

  10. Transducer characterization

    International Nuclear Information System (INIS)

    For inservice inspection transducer characterization can be an important item if one wants to compare ultrasonic examination data obtained at different times (fingerprint). It is possible that the transducers used during previous examinations are lost or will become defect. In such a case it is most useful if one can check the characteristics of the replacement transducers. Some time ago an elegant characterization method was developed by the EURATOM Joint Research Centre of Ispra based on liquid crystals. This method is now under development at Neratoom and the results so far indicate that a robust characterization rig can be built at a reasonable price

  11. Trichoderma sp Native from Chili Region of Poanas, Durango, Mexico Antagonist against Phytopathogen Fungi

    Directory of Open Access Journals (Sweden)

    Gabriela B. Valencia

    2011-01-01

    Full Text Available Problem statement: Presence of Trichoderma spp. in agricultural soils decrease incidence of diseases by phytopathogen fungi. Sanity diagnostic require to know if exist beneficial microorganism and what agricultural practices help to their propagation. Approach: Samples (30 were taken from soils and sick plants of ten sites in four localities of Valley of Poanas. Phytophthora capsici Leo, Rhizoctonia solani Kuhn and Trichoderma sp were isolated in agar V8 and were identified by microscopy. Results: In the 30 samples analyzed the presence of Phytophthora capsici Leo and Rhizoctonia solani Kuhn was determined. Two isolations of Trichoderma sp were obtained from soil, they had antagonist activity against to P. capsici and R. solani on agar-V8 medium and showed chitinase activity. Sugar production in chitinase (10 mg.mL-1 by crude extract of Trichoderma growth in basal medium more chitin was determined. The average of sugar production from strains were 0.1175 and 0.1125 mg.mL-1 and standard deviations were 0.0567 and 0.0567 in four repetition. Interviews were applied to fifty farmers about cultivars and cultivation practices. At least seven types of chili were cultivated in the region of the Valley of Poanas, inorganic fertilization, irrigation systems by channel, gates and pumps were used. One hundred percent of farmers reported diseases of Damping off and Phytophthora root. Biocides were not used to control these diseases. Conclusion: The natural presence of Trichoderma spp was detected in Valley of Poanas, but some practices as inorganic fertilization and irrigation system can be contributing to propagation of phytopathogen fungi.

  12. Estudio de lixiviación de nitratos en suelos de invernaderos de pimiento biosolarizados

    OpenAIRE

    Fernández Molina, Pedro; Pascual Valero, José Antonio; Lacasa Plasencia, Alfredo

    2014-01-01

    La biosolarización del suelo en invernaderos de pimiento (Capsicum annuum L.) supone una estrategia de control de enfermedades telúricas (Phytophthora capsici y/o parasítica y Meloidogyne incognita), de vegetación adventicia y de fenómenos de fatiga muy adecuada para mantener buenos niveles productivos en sistemas de monocultivo prolongado. Este trabajo pretende evaluar las repercusiones de la aplicación de cantidades importantes de materia orgánica, hasta 100 t/ha, en estos ...

  13. Molecular Cloning of HbPR-1 Gene from Rubber Tree, Expression of HbPR-1 Gene in Nicotiana benthamiana and Its Inhibition of Phytophthora palmivora.

    Directory of Open Access Journals (Sweden)

    Uraiwan Khunjan

    Full Text Available This is the first report to present a full-length cDNA (designated HbPR-1 encoding a putative basic HbPR-1 protein from rubber tree (Hevea brasiliensis treated with salicylic acid. It was characterized and also expressed in Nicotiana benthamiana using Agrobacterium-mediated transient gene expression system in order to investigate the role of HbPR-1 gene in rubber tree against its oomycete pathogen Phytopthora palmivora and to produce recombinant HbPR-1 protein for microbial inhibition test. The HbPR-1 cDNA was 647 bp long and contained an open reading frame of 492 nucleotides encoding 163 amino acid residues with a predicted molecular mass of 17,681 Da and an isoelectric point (pI of 8.56, demonstrating that HbPR-1 protein belongs to the basic PR-1 type. The predicted 3D structure of HbPR-1 was composed of four α-helices, three β-sheets, seven strands, and one junction loop. Expression and purification of recombinant HbPR-1 protein were successful using Agrobacterium-mediated transient expression and one-step of affinity chromatography. Heterologous expression of HbPR-1 in N. benthamiana reduced necrosis areas which were inoculated with P. palmivora zoospores, indicating that the expressed HbPR-1 protein played an important role in plant resistance to pathogens. The purified recombinant HbPR-1 protein was found to inhibit 64% of P. palmivora zoospore germination on a water agar plate compared with control, suggesting that it was an antimicrobial protein against P. palmivora.

  14. Screening of antagonistic Pseudomonas fluorescens against Phytophthora in festans and disease control in vitro%致病疫霉拮抗菌荧光假单胞菌的筛选及离体防病作用

    Institute of Scientific and Technical Information of China (English)

    蒋继志; 梁廷银; 王怀远; 王兴哲

    2013-01-01

    Abstract:The paper was to screen antagonistic Pseudomonas fluorescens strains against Phytophthora infestans and controlling potato late bight in vitro.The fluorescent bacterial strains were isolated with the dilution plate method in combination with ultraviolet.Inhibition of bacterial living strains,bacterial fluid and fermentation liquid on mycelial growth of P.infestans was tested with dual culture and punch method,respectively.Disease control effect of bacterial fluid from antagonistic strain was evaluated by P.infestans,their growth inhibition rates were more than 60%.In which,M15 strain identified as P.fluorescens,had the strongest antagonistic effect,and the inhibition rates of its living strains,bacterial fluid and fermentation liquid suppression were 86.39%,88.23% and 65.88%,respectively.Prevention effect of bacterial fluid on potato tuber slices against late blight was 65.06 %.Microexamination showed that bacterial fluid of M15 strain could cause deformation of P.infestans mycelium,and was antagonistic to other phytopathogenic fungi.These findings indicate that M15 strain has a great potential in control of potato late blight in future.%为了从马铃薯根际土壤中筛选显著拮抗致病疫霉且离体防病效果显著的荧光假单胞菌,本试验以稀释平板法并结合紫外光分离根际土壤中的荧光细菌,采用对峙培养及打孔法测试菌株、菌液及发酵液对致病疫霉的抑制作用,块茎切片法评价菌液的离体防病效果.结果显示:分离纯化的30株荧光细菌中有14株对致病疫霉菌丝生长有明显抑制作用,抑菌率在60%以上;其中经初步鉴定为荧光假单胞菌(Pseudomonas fluorescens)的M15菌株抑制作用最强,活体、菌液和发酵液的抑菌率分别为86.39%,88.23%和65.88%,其菌液在马铃薯块茎切片上对晚疫病的预防效果为65.06%,显微观察发现该菌株菌液使致病疫霉菌丝体畸形,并对几种常见的植物病原真菌

  15. UV light inactivation of human and plant pathogens in unfiltered surface irrigation water.

    Science.gov (United States)

    Jones, Lisa A; Worobo, Randy W; Smart, Christine D

    2014-02-01

    Fruit and vegetable growers continually battle plant diseases and food safety concerns. Surface water is commonly used in the production of fruits and vegetables and can harbor both human- and plant-pathogenic microorganisms that can contaminate crops when used for irrigation or other agricultural purposes. Treatment methods for surface water are currently limited, and there is a need for suitable treatment options. A liquid-processing unit that uses UV light for the decontamination of turbid juices was analyzed for its efficacy in the treatment of surface waters contaminated with bacterial or oomycete pathogens, i.e., Escherichia coli, Salmonella enterica, Listeria monocytogenes, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, and Phytophthora capsici. Five-strain cocktails of each pathogen, containing approximately 10(8) or 10(9) CFU/liter for bacteria or 10(4) or 10(5) zoospores/liter for Ph. capsici, were inoculated into aliquots of two turbid surface water irrigation sources and processed with the UV unit. Pathogens were enumerated before and after treatment. In general, as the turbidity of the water source increased, the effectiveness of the UV treatment decreased, but in all cases, 99.9% or higher inactivation was achieved. Log reductions ranged from 10.0 to 6.1 and from 5.0 to 4.2 for bacterial pathogens and Ph. capsici, respectively. PMID:24242253

  16. Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival.

    Science.gov (United States)

    Chen, Le; Jian, Shanshan; Bi, Jinhua; Li, Yunlong; Chang, Zhizhou; He, Jian; Ye, Xiaomei

    2016-05-01

    Tomato plant waste (TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS (total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic (37±1°C) and room (20-25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416L/kg VS (volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR (polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA (volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety. PMID:27155428

  17. Inhibitory efficacy of several plant extracts and plant products on Phytophthora infestans%几种植物提取物和天然产物对马铃薯晚疫病菌的抑制作用

    Institute of Scientific and Technical Information of China (English)

    曹克强; ArienaHCvanBruggen

    2001-01-01

    The effects of garlic and scouring rush extracts and two plant products-Bio-clean and Citronella Oil, on spore germination, hyphae growth and infection of Phytophthora infestans (Mont.) de Bary on potato leaves were evaluated and measured in comparison with protective fungicide chlorothalonil and distilled water which was used as control. Highest inhibitions on germination of P. infestans were obtained with Bio-clean and garlic (Allium sativum L.). The inhibition rates on germination of sporangia and zoospores increased with increasing concentrations of these extracts and reached as high as 100 percent when the dosages were high. The germination of zoospores was totally stopped by all the concentrations of Bio-clean and garlic. Scouring rush also showed antifungal properties but with less extent. Citronella oil didn't show effectiveness on inhibiting sporangium germination but reduced the germination rate of zoospores. Garlic extracts from fresh bulbs had stronger inhibiting effect than the extract from dry garlic bulbs on the germination of sporangia and zoospores. However, there was no significant difference between the extracts of immediately made from fresh bulbs and those which was kept for a week under 4℃. The effect of scouring rush extract from fresh leaves was not significantly superior over the extract from dry leaves and the extract from fresh leaves but stored for one week on inhibiting sporangium germination. However, the inhibiting effects against zoospore germination were significantly different between the extracts from fresh leaves and that from dry leaves. Tests were made on inhibiting effects of plant extracts and plant products on hyphae growth of P. infestans on petri dishes. No mater autoclaved or not, Bio-clean 0.125% totally inhibited the formations of P. infestans colonies, which indicated that Bio-clean is not sensitive to heat. The inhibiting effect of garlic was as good as Bio-clean when it was not autoclaved. However, its effect lost

  18. Isolation and antifungal and antioomycete activities of staurosporine from Streptomyces roseoflavus strain LS-A24.

    Science.gov (United States)

    Park, Hee Jin; Lee, Jung Yeop; Hwang, In Sun; Yun, Bong Sik; Kim, Beom Seok; Hwang, Byung Kook

    2006-04-19

    The actinomycete strain LS-A24 active against some plant fungal and oomycete pathogens was isolated from a soil sample of the Sunghwan Lake in Korea. The cell wall composition and spore shape of strain LS-A24 were LL-diaminopimelic acid and spiral type, respectively. On the basis of the physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, strain LS-A24 was identical to Streptomyces roseoflavus. An antifungal and antioomycete antibiotic was isolated from LS-A24 using various chromatographic procedures. The molecular formular of the antibiotic was determined to be C(28)H(26)N(4)O(3), and on the basis of the NMR data, the antibiotic was confirmed to be staurosporine, 2,3,10,11,12,13-hexahydro-10R-methoxy-9S-methyl-11R-methylamino-9S,13R-epoxy-1H,9H-diindolo[1,2,3-gh:3',2',1'-lm]pyrrolo[3,4-j][1,7]benzodiazonin-1-one. Staurosporine completely inhibited the mycelial growth of Colletotrichum orbiculare, Phytophthora capsici, Rhizoctonia solani, Botrytis cinerea, and Cladosporium cucumerinum with minimum inhibitory concentration (MIC) values of 1-50 microg/mL for MICs. Staurosporine also was active against Saccharomyces cerevisiae, Bacillus subtilis ssp. subtilis, and Xanthomonas vesicatoria. Staurosporine and the commercial fungicide metalaxyl inhibited the development of Phytophthora blight on pepper plants. However, the control efficacy of staurosporine against the Phytophthora disease was somewhat less than that of metalaxyl. This is the first study to isolate staurosporine from S. roseoflavus and demonstrate its in vitro and in vivo antioomycete activity against P. capsici. PMID:16608228

  19. Practical materials characterization

    CERN Document Server

    2014-01-01

    Presents cross-comparison between materials characterization techniquesIncludes clear specifications of strengths and limitations of each technique for specific materials characterization problemFocuses on applications and clear data interpretation without extensive mathematics

  20. 荧光假单胞菌拮抗菌株对烟草疫霉的抑菌机制及控病效果%Antagonistic mechanism of Pseudomonas fluorescens strains against Phytophthora nicotianae and biocontrol effect on tobacco black shank

    Institute of Scientific and Technical Information of China (English)

    董国菊; 马冠华; 肖崇刚

    2012-01-01

    To explore the antagonistic mechanism of rhizospheric bacteria against Phytophthora nicotianae van Breda de Haan,five antagonistic Pseudomonas fluorescens strains were isolated from rhizospheric soils of tobacco fields in Chongqing.Efficient antagonistic strain against P.nicotianae was screened using dual culture technique and metabolites inhibitory test.Among these strains,P-72-10 showed the highest suppressive effect;it produced an inhibition zone of 13.0mm(radius) and an inhibitory rate at 68.57%.Furthermore,the growth of pathogen's hypha was also suppressed by the extracellular metabolites of strain P-72-10 from 25.39% to 46.03%.P.nicotianae was observed microscopically excessive branching of mycelia and malformation of mycelia tips;thick-walled cells with concentrated plasmas and chlamydospore-like cells.When tested on the tobacco plants grown in greenhouse,strain P-72-10 got a good biocontrol effect on tobacco black shank infection and effects on the resistant and susceptible varieties of tobacco were 53.57% and 66.37% respectively.%为探讨烟草根际生防细菌对烟草疫霉Phytophthora nicotianae的抑菌机制,从重庆地区连作烟田健康烟株根际土壤分离获得5株荧光假单胞菌Pseudomonas fluorescens拮抗菌株。通过平板对峙及代谢产物抑菌试验筛选对烟草疫霉具有高效拮抗作用的菌株,其中,P-72-10菌株抑菌效果最强,抑菌带半径达13.0 mm,相对抑制率为68.57%,且该菌株代谢产物对烟草疫霉菌丝生长有明显的抑制作用,相对抑制率达25.39%~46.03%;显微观察发现该菌株可引起烟草疫霉菌丝的分支增多,菌丝顶端膨大呈畸形,多数菌丝中间或顶端细胞的细胞壁加厚、原生质浓缩和产生类似厚壁孢子的细胞。在温室盆栽条件下P-72-10菌株对烟草黑胫病也表现出良好的控病效果,对抗病和感病品种的相对防效分别为53.57%和66.37%。

  1. Isolation, Screening and Phylogenetic Analysis of Antagonistic Endophytic Bacteria Against Phytophthora Parasitica var.Nicotianae from Flue-cured Tobacco Variety K326%烤烟品种K326内生细菌分离、抗黑胫病菌株筛选及种群组成分析

    Institute of Scientific and Technical Information of China (English)

    奚家勤; 冯云利; 薛超群; 尹启生; 莫明和; 方敦煌; 王广山; 郭建华

    2013-01-01

    从烤烟品种K326的不同生长时期分离内生细菌1000株,以烟草黑胫病菌(Phytophthora parasitica var.nicotianae)为靶标,共筛选出168株拮抗菌,这些内生细菌对黑胫病菌的抑菌率在12.54%~50.14%之间.苗期和团棵期的内生菌含量较高,但在开花和成熟期时降低了一个数量级,而拮抗菌数量呈上升趋势.对168株拮抗菌的16SrRNA基因序列进行RFLP分析,共产生10种带型.根据RFLP带型选取39株进行16S rRNA基因序列测定和系统发育分析.结果表明,这168株生防内生细菌归于2大类群:Firmicutes和Actinobacteria.Firmicutes类群中的芽孢杆菌属(Bacillus)是优势属,共6种RFLP带型,150个菌株,包括Bacillus amyloliquefaciens subsp,plantarum,Bacillus tequilensis,Bacillus methylotrophicus,Bacillus cereus,Bacillus thuringiensis和Bacillus aryabhattai. Bacillus amyloliquefaciens subsp,plantarum和Bacillus methylotrophicus的出现频率最高,共126株,占该属总菌株数的78.75%.其余18个菌株分属于4个种:即Brevibacillus formosus,Brevibacillus parabrevis,Pseudomonas umsongensis和Pseudomonas aeruginosa.%A total of 168 isolates with antagonistic effects against Phytophthora parasitica var. nicotianae (P. parasitica var.) were screened from 1000 endophytic bacteria isolated from flue-cured tobacco variety K326 at different growing stages, and bioassay results indicated that the inhibitory activities of these antagonists ranged from 12.54% to 50.14%. The biomass of endophytic bacteria was higher during the stages of seedling and rosette, which reduced by one order of magnitude during the stages of flowering and maturity; however, the number of antagonists kept an increasing trend. The RFLP analysis of 16S rRNA sequence on the 168 antagonists produced 10 RFLP patterns. Based on their RFLP patterns, 39 isolates were selected for 16S rRNA sequencing and phylogenetic analysis. The results showed that the 168 antagonists belonged to two groups of bacteria

  2. Waste Characterization Methods

    Energy Technology Data Exchange (ETDEWEB)

    Vigil-Holterman, Luciana R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Naranjo, Felicia Danielle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-02-02

    This report discusses ways to classify waste as outlined by LANL. Waste Generators must make a waste determination and characterize regulated waste by appropriate analytical testing or use of acceptable knowledge (AK). Use of AK for characterization requires several source documents. Waste characterization documentation must be accurate, sufficient, and current (i.e., updated); relevant and traceable to the waste stream’s generation, characterization, and management; and not merely a list of information sources.

  3. Effects of Infection of Phytophthora infestans on Gene Expressions of Key Enzymes in Salicylic Acid and Ethylene Biosynthesis in Potato%接种晚疫病病原菌对马铃薯水杨酸、乙烯合成关键酶基因表达的影响

    Institute of Scientific and Technical Information of China (English)

    朱佳莉; 丁艳; 徐宏章; 辛翠花; 蔡禄; 肖欢欢; 何炎红; 李娜; 郭江波

    2013-01-01

    以转基因的抗晚疫病型马铃薯(Solanum tuberosum)株系DR1、DR3a和野生型株系DG为材料,通过半定量RT-PCR研究了接种晚疫病病原菌(Phytophthora infestans)生理小种89148-9后叶片中水杨酸和乙烯合成途径关键酶苯丙氨酸解胺酶(PAL)基因(poPAL)和1-氨基环丙烷-1-羧酸(1-Aminocyclo-propane-1-carboxylic acid,ACC)合成酶(ACS)基因(poA CS)的表达情况.结果表明,接种后3个株系都能诱导poPAL和poA CS基因的表达,但大部分转基因株系叶片内该基因的诱导表达量高于野生型,并且其表达峰值多数早于野生型.说明poPAL和poA CS基因可能参与了马铃薯的抗晚疫病反应,但不同株系中这些基因的诱导表达模式不同,这可能是不同马铃薯株系抗、感晚疫病的原因所在.

  4. GLOVEBOX GLOVE CHARACTERIZATION SUMMARY

    Energy Technology Data Exchange (ETDEWEB)

    Korinko, P.

    2012-05-14

    A task was undertaken to determine primarily the permeation behavior of various glove compounds from four manufacturers. As part of the basic characterization task, the opportunity to obtain additional mechanical and thermal properties presented itself. Consequently, a total of fifteen gloves were characterized for permeation, Thermogravimetric Analysis, Puncture Resistance, Tensile Properties and Dynamic Mechanical Analysis. Detailed reports were written for each characterization technique used. This report contains the summary of the results.

  5. Materials Characterization Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Materials Characterization Facility enables detailed measurements of the properties of ceramics, polymers, glasses, and composites. It features instrumentation...

  6. Characterization of revenue equivalence

    NARCIS (Netherlands)

    Heydenreich, B.; Müller, R.; Uetz, M.J.; Vohra, R.

    2009-01-01

    The property of an allocation rule to be implementable in dominant strategies by a unique payment scheme is called revenue equivalence. We give a characterization of revenue equivalence based on a graph theoretic interpretation of the incentive compatibility constraints. The characterization holds f

  7. Characterizations of Exponentiated Distributions

    OpenAIRE

    gholamhossein g hamedani

    2013-01-01

    Variuos characterizations of the class of exponentiated distributions are presented.  These characterizations are based on a simple relationship between two truncated moments and based on functions of the nth order statistic.  The results are applied to certain well-known members of this class.

  8. Evaluación preliminar del efecto que sobre algunas enzimas del suelo tienen diferentes mecanismos de control del hongo (Phytophthora infestans en un cultivo de papa (Solanum tuberosum bajo dos tipos de manejo agrícola (orgánico y convencional

    Directory of Open Access Journals (Sweden)

    Guardiola Marta Lucía

    2004-12-01

    Full Text Available Se evaluó comparativamente el posible efecto diferencial que, sobre la actividad de las enzimas proteasa, fosfatasa ácida, fosfatasa alcalina y celulasa, además del pH y la materia orgánica del suelo, tuvieron los métodos de control de Phytophthora infestans tanto en la agricultura orgánica (purín de Chipaca Bidens pilosum como en la convencional (diversos fungicidas comerciales en plantas de papa (Solanum tuberosum. Igualmente, en los parámetros antes mencionados, se evaluó el efecto de un promotor fúngico utilizado como control del mismo hongo en ambas agriculturas. La investigación se dividió en una fase de campo y una de laboratorio. En la fase de campo, realizada durante siete meses de 1999, se acompañó la siembra, el desarrollo del cultivo y evolución de la enfermedad a través de la determinación de la incidencia y su severidad. En el laboratorio se determinó la actividad enzimática proteasa, fosfatasa ácida, fosfatasa alcalina, celulasa, así como también el pH y porcentaje de materia orgánica. Se encontró que en el manejo agrícola orgánico la actividad de la fosfatasa ácida, la fosfatasa alcalina y la proteasa así como también el pH fueron más influenciados por el estado de desarrollo de las plantas que por efecto del los tratamientos utilizados en el control del hongo. En el manejo agrícola convencional la actividad enzimática de las celulasas fue inhibida significativamente por los fungicidas. La actividad de las proteasas y fosfatasas ácidas fueron estimuladas por efecto de los fungicidas comerciales y por el estado de desarrollo de las plantas. Las actividades enzimáticas fosfatasa ácida, proteasa y celulasa presentaron comportamientos significativamente diferentes entre los cultivos convencional y orgánico. Para el control de la enfermedad, el uso de los fungicidas fue el tratamiento que mejores resultados presentó con una mayor producción de papa pero con mayores gastos de producción, mientras

  9. Panel 3 - characterization

    Energy Technology Data Exchange (ETDEWEB)

    Erck, R.A.; Erdemir, A.; Janghsing Hsieh; Lee, R.H.; Xian Zheng Pan; Deming Shu [Argonne National Lab., IL (United States); Feldman, A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Glass, J.T. [North Carolina State Univ., Raleigh (United States); Kleimer, R. [Coors Ceramics Co., Golden, CO (United States); Lawton, E.A. [JPL/Caltech, Pasadena, CA (United States); McHargue, C.J. [Univ. of Tennessee, Knoxville (United States)

    1993-01-01

    The task of this panel was to identify and prioritize needs in the area of characterization of diamond and diamond-like-carbon (DLC) films for use in the transportation industry. Until recent advances in production of inexpensive films of diamonds and DLC, it was not feasible that these materials could be mass produced. The Characterization Panel is restricting itself to identifying needs in areas that would be most useful to manufacturers and users in producing and utilizing diamond and DLC coatings in industry. These characterization needs include in-situ monitoring during growth, relation of structure to performance, and standards and definitions.

  10. Characterization of nanomaterials

    International Nuclear Information System (INIS)

    This paper provides an overview of the main techniques used for the characterization of nanomaterials. The knowledge of some basic characteristics, inherent morphology, microstructure, the distribution phase and chemical composition, it is essential to evaluate the functional properties of nanomaterials and make predictions about their behavior in operation. For the characterization of nanomaterials can be used in both imaging techniques both analytic techniques. Among the first found wide application optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Among the latter some types of spectroscopy and X-ray diffraction (XRD). For each type of material to characterize the choice of the most appropriate technique it is based on the type of details that you want to obtain, and on their scale. In this paper are discussed in detail some examples and the main methods used for the characterization of nanomaterials.

  11. How to characterize disorder

    Science.gov (United States)

    Egami, T.

    2016-05-01

    Researchers working on nuclear materials encounter disorder in the atomic structure all the time, usually caused by irradiation. The nature of disorder varies widely, from lattice defects to amorphous phase formation. Generally it is not easy to characterize the state of disorder with the accuracy necessary to elucidate the properties caused by structural disorder. However, owing to advances in the tools of characterization and rapid rise in computer power, significant progress has been made in characterizing structural disorder. We discuss how to describe and determine the structure and dynamics of disordered materials using scattering measurements and modeling. Lattice defects caused by irradiation usually has negative effects on properties, but glasses and highly disordered materials can be irradiation resistant, and could be useful as nuclear materials. Characterizing and controlling disorder is becoming an important endeavor in the field of nuclear materials.

  12. Characterization of revenue equivalence

    OpenAIRE

    Heydenreich, Birgit; Müller, Rudolf; Uetz, Marc

    2007-01-01

    The property of an allocation rule to be implementable in dominant strategies by a unique payment scheme is called revenue equivalence. In this paper we give a characterization of revenue equivalence based on a graph theoretic interpretation of the incentive compatibility constraints. The characterization holds for any (possibly in¯nite) outcome space and many of the known results about revenue equivalence are immediate consequences.

  13. Characterization of Revenue Equivalence

    OpenAIRE

    Heydenreich, B.; Müller, R.J.; Uetz, M.J.; R. Vohra

    2008-01-01

    The property of an allocation rule to be implementable in dominant strategies by a unique payment scheme is called \\emph{revenue equivalence}. In this paper we give a characterization of revenue equivalence based on a graph theoretic interpretation of the incentive compatibility constraints. The characterization holds for any (possibly infinite) outcome space and many of the known results are immediate consequences. Moreover, revenue equivalence can be identified in cases where existing theor...

  14. Exploring Western Ghats microbial diversity for antagonistic microorganisms against fungal phytopathogens of pepper and chickpea

    Directory of Open Access Journals (Sweden)

    B.N. RAMKUMAR

    2015-08-01

    Full Text Available Newly isolated microbial cultures from Western Ghat soil samples of Kerala region in India were screened for antagonistic activity by well diffusion and dual culture plating against Phytophthora capsici and Rhizoctonia solani, infecting pepper and chickpea, respectively. Bioactive samples were made by varying solvent extraction of the culture broths of the potent isolates belongs to Actinomycetes, Pseudomonas, Bacillus and Trichoderma. The efficacy of the isolates to produce other potent antifungal metabolites such as cell wall degrading enzymes, HCN and volatile compounds were also checked. Treatment with antagonistic isolates in vivo under greenhouse conditions revealed significant reduction of the disease intensity of foot rot disease of black pepper and collar rot of chick pea.

  15. Design, Synthesis, and Fungicidal Activities of Novel 5-Methyl-1H-1,2,3- trizole-4-carboxyl Amide Analogues.

    Science.gov (United States)

    Wang, Zhen-Jun; Yang, Hui-Hui; Tian, Lei; Zhao, Wei-Guang

    2016-01-01

    Succinate dehydrogenase inhibitors (SDHIs) are fungicides with an amide bond widely used to control plant diseases caused by phytopathogenic fungi. Because of broad spectrum activity of new SDHIs, they have attracted wide attention from the research community. A series of structurally novel SDHIs with a bioactive 1,2,3-triazole moiety were designed and synthesized. Bioactivity screening showed that some of designed N-phenethyl-1,2,3-trizole-4-carboxyl amide analogues exhibited good fungicidal activities toward Sclerotinia sclerotiorum and Botrytis cinerea, while some of Nbenzyl- 1,2,3-trizole-4-carboxyl amide analogues exhibited good fungicidal activities toward Phytophthora capsici and Cercospora arachidicola. EC50 value of compound 5d against Cercospora arachidicola (6.6 µg/mL) was lower than that of chlorothalonil (12.3 µg/mL). PMID:26558376

  16. Site characterization handbook

    Energy Technology Data Exchange (ETDEWEB)

    1988-06-01

    This Handbook discusses both management and technical elements that should be considered in developing a comprehensive site characterization program. Management elements typical of any project of a comparable magnitude and complexity are combined with a discussion of strategies specific to site characterization. Information specific to the technical elements involved in site characterization is based on guidance published by the Nuclear Regulatory Commission (NRC) with respect to licensing requirements for LLW disposal facilities. The objective of this Handbook is to provide a reference for both NRC Agreement States and non-Agreement States for use in developing a comprehensive site characterization program that meets the specific objectives of the State and/or site developer/licensee. Each site characterization program will vary depending on the objectives, licensing requirements, schedules/budgets, physical characteristics of the site, proposed facility design, and the specific concerns raised by government agencies and the public. Therefore, the Handbook is not a prescriptive guide to site characterization. 18 refs., 6 figs.

  17. Space Solar Cell Characterization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Measures, characterizes, and analyzes photovoltaic materials and devices. The primary focus is the measurement and characterization of solar cell response...

  18. Essential Oil from Inula britannica Extraction with SF-CO2 and Its Antifungal Activity

    Institute of Scientific and Technical Information of China (English)

    ZHAO Te; GAO Fei; ZHOU Lin; SONG Tian-you

    2013-01-01

    The aim of this study was to determine the extraction technique of supercritical fluid carbon dioxide (SF-CO2) for the essential oil from Inula britannica flowers and its antifungal activities against plant pathogenic fungi for its potential application as botanical fungicide. The effects of factors, including extraction temperature, extraction pressure, SF-CO2 flow rate, flower powder size, and time on the essential oil yield were studied using the single factor experiment. An orthogonal experiment was conducted to determine the best operating conditions for the maximum extraction oil yield. Adopting the optimum conditions, the maximum yield reached 10.01% at 40°C temperature, 30 MPa pressure, 60 mesh flower powder size, 20 L h-1 SF-CO2 flow rate, and 90 min extraction time. The antifungal activities of I. britannica essential oil using the SF-CO2 against the most important plant pathogenic fungi were also examined through in vitro and in vivo tests. Sixteen plant pathogenic fungi were inhibited to varying degrees at 1 mg mL-1 concentration of the essential oil. The mycelial growth of Gaeumannomyces graminis var. tritici was completely inhibited. The radial growths of Phytophthora capsici and Fusarium monilifome were also inhibited by 83.76 and 64.69%, respectively. In addition, the essential oil can inhibit the spore germination of Fusarium oxysporum f. sp. vasinfectum, Phytophthora capsici, Colletotrichum orbiculare, and Pyricularia grisea, and the corresponding inhibition rates were 98.26, 96.54, 87.89, and 87.35%respectively. The present study has demonstrated that the essential oil of I. britannica flowers extracted through the SF-CO2 technique is one potential and promising antifungal agent that can be used as botanical fungicide to protect crops.

  19. CRN13 candidate effectors from plant and animal eukaryotic pathogens are DNA-binding proteins which trigger host DNA damage response.

    Science.gov (United States)

    Ramirez-Garcés, Diana; Camborde, Laurent; Pel, Michiel J C; Jauneau, Alain; Martinez, Yves; Néant, Isabelle; Leclerc, Catherine; Moreau, Marc; Dumas, Bernard; Gaulin, Elodie

    2016-04-01

    To successfully colonize their host, pathogens produce effectors that can interfere with host cellular processes. Here we investigated the function of CRN13 candidate effectors produced by plant pathogenic oomycetes and detected in the genome of the amphibian pathogenic chytrid fungus Batrachochytrium dendrobatidis (BdCRN13). When expressed in Nicotiana, AeCRN13, from the legume root pathogen Aphanomyces euteiches, increases the susceptibility of the leaves to the oomycete Phytophthora capsici. When transiently expressed in amphibians or plant cells, AeCRN13 and BdCRN13 localize to the cell nuclei, triggering aberrant cell development and eventually causing cell death. Using Förster resonance energy transfer experiments in plant cells, we showed that both CRN13s interact with nuclear DNA and trigger plant DNA damage response (DDR). Mutating key amino acid residues in a predicted HNH-like endonuclease motif abolished the interaction of AeCRN13 with DNA, the induction of DDR and the enhancement of Nicotiana susceptibility to P. capsici. Finally, H2AX phosphorylation, a marker of DNA damage, and enhanced expression of genes involved in the DDR were observed in A. euteiches-infected Medicago truncatula roots. These results show that CRN13 from plant and animal eukaryotic pathogens promotes host susceptibility by targeting nuclear DNA and inducing DDR. PMID:26700936

  20. Induced resistance in tomato by SAR activators during predisposing salinity stress

    Directory of Open Access Journals (Sweden)

    Matthew Francis Pye

    2013-05-01

    Full Text Available Plant activators are chemicals that induce disease resistance. The phytohormone salicylic acid (SA is a crucial signal for systemic acquired resistance (SAR, and SA-mediated resistance is a target of several commercial plant activators, including Actigard (1,2,3-benzothiadiazole-7-thiocarboxylic acid-s-methyl-ester, BTH and Tiadinil (N-(3-chloro-4-methylphenyl-4-methyl-1,2,3-thiadiazole-5-carboxamide, TDL. BTH and TDL were examined for their impact on abscisic acid (ABA-mediated, salt-induced disease predisposition in tomato seedlings. A brief episode of salt stress to roots significantly increased the severity of disease caused by Pseudomonas syringae pv. tomato (Pst and Phytophthora capsici relative to non-stressed plants. Root treatment with TDL induced resistance to Pst in leaves and provided protection in both non-stressed and salt-stressed seedlings in WT and highly susceptible NahG plants. Non-stressed and salt-stressed ABA-deficient sitiens mutants were highly resistant to Pst. Neither TDL nor BTH induced resistance to root infection by P. capsici, nor did they moderate the salt-induced increment in disease severity. Root treatment with these plant activators increased the levels of ABA in roots and shoots similar to levels observed in salt-stressed plants. The results indicate that SAR activators can protect tomato plants from bacterial speck disease under predisposing salt stress, and suggest that some SA-mediated defense responses function sufficiently in plants with elevated levels of ABA.

  1. Site characterization plan:

    International Nuclear Information System (INIS)

    The Yucca Mountain site in Nevada is one of three candidate sites for the first geologic repository for radioactive waste. On May 28, 1986, it was recommended for detailed study in a program of site characterization. This site characterization plan (SCP) has been prepared in acordance with the requirements of the Nuclear Waste Policy Act to summarize the information collected to date about the geologic conditions at the site;to describe the conceptual designs for the repository and the waste package and to present the plans for obtaining the geologic information necessary to demonstrate the suitability of the site for a repository, to design the repository and the waste package, to prepare an environmental impact statement, and to obtain from the US Nuclear Regulatory Commission (NRC) an authorization to construct the repository. This introduction begins with a brief section on the process for siting and eveloping a repository, followed by a discussion of the pertinent legislation and regulations. A description of site characterization is presented next;it describes the facilities to be constructed for the site characterization program and explains the principal activities to be conducted during the program. Finally, the purpose, content, organizing prinicples, and organization of this site characterization plan are outlined, and compliance with applicable regulations is discussed. 880 refs., 130 figs., 25 tabs

  2. Site characterization plan:

    International Nuclear Information System (INIS)

    The Yucca Mountain site in Nevada is one of three candidate sites for the first geologic repository for radioactive waste. On May 28, 1986, it was recommended for detailed study in a program of site characterization. This site characterization plan (SCP) has been prepared in accordance with the requirements of the Nuclear Waste Policy Act to summarize the information collected to date about the geologic conditions at the site;to describe the conceptual designs for the repository and the waste package;and to present the plans for obtaining the geologic information necessary to demonstrate the suitability of the site for repository, to design the repository and the waste package, to prepare an environmental impact statement, and to obtain from the US Nuclear Regulatory Commission (NRC) an authorization to construct the repository. This introduction begins with a brief section on the process for siting and developing a repository, followed by a discussion of the pertinent legislation and regulations. A description of site characterization is presented next;it describes the facilities to be constructed for the site characterization program and explains the principal activities to be conducted during the program. Finally, the purpose, content, organizing principles, and organization of this site characterization plan are outlined, and compliance with applicable regulations is discussed

  3. Tank characterization reference guide

    International Nuclear Information System (INIS)

    Characterization of the Hanford Site high-level waste storage tanks supports safety issue resolution; operations and maintenance requirements; and retrieval, pretreatment, vitrification, and disposal technology development. Technical, historical, and programmatic information about the waste tanks is often scattered among many sources, if it is documented at all. This Tank Characterization Reference Guide, therefore, serves as a common location for much of the generic tank information that is otherwise contained in many documents. The report is intended to be an introduction to the issues and history surrounding the generation, storage, and management of the liquid process wastes, and a presentation of the sampling, analysis, and modeling activities that support the current waste characterization. This report should provide a basis upon which those unfamiliar with the Hanford Site tank farms can start their research

  4. Characterization of leaky faults

    International Nuclear Information System (INIS)

    Leaky faults provide a flow path for fluids to move underground. It is very important to characterize such faults in various engineering projects. The purpose of this work is to develop mathematical solutions for this characterization. The flow of water in an aquifer system and the flow of air in the unsaturated fault-rock system were studied. If the leaky fault cuts through two aquifers, characterization of the fault can be achieved by pumping water from one of the aquifers, which are assumed to be horizontal and of uniform thickness. Analytical solutions have been developed for two cases of either a negligibly small or a significantly large drawdown in the unpumped aquifer. Some practical methods for using these solutions are presented. 45 refs., 72 figs., 11 tabs

  5. Geostatistics for fracture characterization

    International Nuclear Information System (INIS)

    As the critical role of fractures has become more apparent in fluid flow and contaminant transport studies, the characterization of fracture networks has received considerable attention in a wide variety of applications such as nuclear waste repository design. The application of geostatistics to fracture characterization has traditionally involved modelling fractures as thin disks; assumptions about the frequency, orientation, length and width of these disks allow the construction of a 3D model of the fracture network. This paper examines alternatives whose statistical parameters are more relevant for contaminant transport studies and are also easier to infer and validate. A new algorithm for conditional simulation is presented, one that is able to honor multipoint statistics through annealing. By honoring statistics that capture with two-point spatial convariances, this algorithm offers an important new tool not only for the specific problem of fracture characterization but also for the more general problem of spatial simulation

  6. Characterizing teleportation in optics

    OpenAIRE

    Ralph, T. C.; Polkinghorne, R. E. S.; Lam, P.K.

    1999-01-01

    We discuss the characterization of continuous variable, optical quantum teleportation in terms of the two quadrature signal transfer and conditional variances between the input and output states. We derive criteria which clearly define the classical limits and highlight interesting operating points which are not obvious from a calculation of the fidelity of the teleportation alone.

  7. Characterization of Photovoltaic Generators

    Science.gov (United States)

    Boitier, V.; Cressault, Y.

    2011-01-01

    This paper discusses photovoltaic panel systems and reviews their electrical properties and use in several industrial fields. We explain how different photovoltaic panels may be characterized by undergraduate students at university using simple methods to retrieve their electrical properties (power, current and voltage) and compare these values…

  8. Characterization of revenue equivalence

    NARCIS (Netherlands)

    Heydenreich, Birgit; Müller, Rudolf; Uetz, Marc; Vohra, Rakesh

    2008-01-01

    The property of an allocation rule to be implementable in dominant strategies by a unique payment scheme is called \\emph{revenue equivalence}. In this paper we give a characterization of revenue equivalence based on a graph theoretic interpretation of the incentive compatibility constraints. The cha

  9. Mixed Fermentation of Two Antagonistic Fungi Against Phytophthora infestans and Stability of Anti-fungi Substances%2种致病疫霉拮抗真菌混合发酵及抗菌物质稳定性研究

    Institute of Scientific and Technical Information of China (English)

    蒋继志; 王兴哲; 王会仙

    2011-01-01

    为获得防治马铃薯晚疫病稳定的生防制剂,对能够有效抑制致病疫霉的拮抗菌梨黑斑病菌LH-03和白菜黑斑病菌BH-09混合发酵的可行性及发酵条件进行了确定和优化,同时对混合发酵产物的抗菌稳定性进行了初步研究.结果表明,2种真菌之间无桔抗作用,可进行混合发酵,并且发现混合发酵后可有效提高2种真菌发酵液的抑菌活性;混合发酵的最佳发酵条件为pH 6.29,25℃、黑暗、静置、培养4d,在此条件下所得发酵产物对致病疫霉的抑菌率可达92.15%,显著高于2种拮抗菌单独发酵液的抑菌效果.混合发酵液经不同温度及不同pH值处理后,其抑菌活性基本保持不变或略有下降,其中在121℃高温处理下抑菌率仍可达到66.78%,在pH 2时抑菌活性最低,但仍达到了68.67%.混合发酵液中的抗菌物质具有很强的热稳定性及较强的耐强酸和强碱性,有良好的应用潜力.%To obtain the stable biocontrol preparation for controlling potato late blight, the feasibility of mixed fermentation for antagonistic fungi Alternaria alternate LH-03 and A. Brassicae BH-09 against growth of Phytophthora infestans and the fermentation conditions were investigated, and then the stability of antagonistic substance in fermentation filter was tested in this experiment. The results showed that there were no antagonistic effects for two antagonistic fungi. The mixed fermentation could increase the anti-fungi activity to P. Infestans. The optimized conditions for mixed fermentation were pH 6. 29, 25 ℃, standing culture for 4 days in the dark. Inhibition rate of fermentation liquid at optimized condition was up to 92. 15% and stronger than that of two fungi fermentation independently. The fermentation product at optimized condition after treatment with different temperature and pH, its anti-fungi activity remained basically unchanged or declined slightly, especially for the inhibitory rate could reach

  10. Signal integrity characterization techniques

    CERN Document Server

    Bogatin, Eric

    2009-01-01

    "Signal Integrity Characterization Techniques" addresses the gap between traditional digital and microwave curricula all while focusing on a practical and intuitive understanding of signal integrity effects within the data transmission channel. High-speed interconnects such as connectors, PCBs, cables, IC packages, and backplanes are critical elements of differential channels that must be designed using today's most powerful analysis and characterization tools.Both measurements and simulation must be done on the device under test, and both activities must yield data that correlates with each other. Most of this book focuses on real-world applications of signal integrity measurements - from backplane for design challenges to error correction techniques to jitter measurement technologies. The authors' approach wisely addresses some of these new high-speed technologies, and it also provides valuable insight into its future direction and will teach the reader valuable lessons on the industry.

  11. Characterization of shocked beryllium

    International Nuclear Information System (INIS)

    Explosively driven arrested beryllium experiments were performed with post mortem characterization to evaluate the failure behaviors. The test samples were encapsulated in an aluminum assembly that was large relative to the sample, and the assembly features both axial and radial momentum traps. The sample carrier was inserted from the explosively-loaded end and has features to lock the carrier to the surrounding cylinder using the induced plastic flow. Calculations with Lagrangian codes showed that the tensile stresses experienced by the Be sample were below the spall stress. Metallographic characterization of the arrested Be showed radial cracks present in the samples may have been caused by bending moments. Fractography showed the fractures propagated from the side of the sample closest to the explosives, the side with the highest tensile stress. There was evidence that the fractures may have propagated from the circumferential crack outward and downward radially.

  12. Site characterization techniques

    Science.gov (United States)

    U.S. Geological Survey

    1995-01-01

    Geoelectrical methods have been used since the 1920's to search for metallic ore deposits. During the last decade, traditional mining geophysical techniques have been adapted for environmental site characterization. Geoelectrical geophysics is now a well developed engineering specialty, with different methods to focus both on a range of targets and on depths below the surface. Most methods have also been adapted to borehole measurements.

  13. Probabilistic Logical Characterization

    DEFF Research Database (Denmark)

    Hermanns, Holger; Parma, Augusto; Segala, Roberto; Wachter, Björn; Zhang, Lijun

    2011-01-01

    Probabilistic automata exhibit both probabilistic and non-deterministic choice. They are therefore a powerful semantic foundation for modeling concurrent systems with random phenomena arising in many applications ranging from artificial intelligence, security, systems biology to performance model...... modeling. Several variations of bisimulation and simulation relations have proved to be useful as means to abstract and compare different automata. This paper develops a taxonomy of logical characterizations of these relations on image-finite and image-infinite probabilistic automata....

  14. Unary Resolution: Characterizing Ptime.

    OpenAIRE

    Seiller, Thomas; Aubert, Clément; Bagnol, Marc

    2016-01-01

    We give a characterization of deterministic polynomial time computation based on an algebraic structure called the resolution semiring, whose elements can be understood as logic programs or sets of rewriting rules over first-order terms. This construction stems from an interactive interpretation of the cut-elimination procedure of linear logic known as the geometry of interaction.This framework is restricted to terms (logic programs, rewriting rules) using only unary symbols, and this restric...

  15. VECSEL gain characterization

    OpenAIRE

    Mangold, Mario; Wittwer, Valentin J; Sieber, Oliver D.; Hoffmann, Martin; Krestnikov, Igor L; Livshits, Daniil A.; Golling, Matthias; Südmeyer, Thomas; Keller, Ursula

    2012-01-01

    We present the first full gain characterization of two vertical external cavity surface emitting laser (VECSEL) gain chips with similar designs operating in the 960-nm wavelength regime. We optically pump the structures with continuous-wave (cw) 808-nm radiation and measure the nonlinear reflectivity for 130-fs and 1.4-ps probe pulses as function of probe pulse fluence, pump power, and heat sink temperature. With this technique we are able to measure the saturation behavior for VECSEL gain ch...

  16. ATR neutron spectral characterization

    International Nuclear Information System (INIS)

    The Advanced Test Reactor (ATR) at INEL provides intense neutron fields for irradiation-effects testing of reactor material samples, for production of radionuclides used in industrial and medical applications, and for scientific research. Characterization of the neutron environments in the irradiation locations of the ATR has been done by means of neutronics calculations and by means of neutron dosimetry based on the use of neutron activation monitors that are placed in the various irradiation locations. The primary purpose of this report is to present the results of an extensive characterization of several ATR irradiation locations based on neutron dosimetry measurements and on least-squares-adjustment analyses that utilize both neutron dosimetry measurements and neutronics calculations. This report builds upon the previous publications, especially the reference 4 paper. Section 2 provides a brief description of the ATR and it tabulates neutron spectral information for typical irradiation locations, as derived from the more historical neutron dosimetry measurements. Relevant details that pertain to the multigroup neutron spectral characterization are covered in section 3. This discussion includes a presentation on the dosimeter irradiation and analyses and a development of the least-squares adjustment methodology, along with a summary of the results of these analyses. Spectrum-averaged cross sections for neutron monitoring and for displacement-damage prediction in Fe, Cr, and Ni are given in section 4. In addition, section4 includes estimates of damage generation rates for these materials in selected ATR irradiation locations. In section 5, the authors present a brief discussion of the most significant conclusions of this work and comment on its relevance to the present ATR core configuration. Finally, detailed numerical and graphical results for the spectrum-characterization analyses in each irradiation location are provided in the Appendix

  17. Proton Beam Energy Characterization

    OpenAIRE

    Marus, Lauren A.; Engle, J.W.; John, K. D.; Birnbaum, E. R.; Nortier, F. M.

    2015-01-01

    Introduction The Los Alamos Isotope Production Facility (IPF) is actively engaged in the development of isotope production technologies that can utilize its 100 MeV proton beam. Characterization of the proton beam energy and current is vital for optimizing isotope production and accurately conducting research at the IPF. Motivation In order to monitor beam intensity during research irradiations, aluminum foils are interspersed in experimental stacks. A theoretical yield of 22Na from...

  18. Asexuality: Classification and characterization

    OpenAIRE

    Prause, Nicole; Graham, Cynthia A.

    2007-01-01

    This is a post-print version of the article. The official published version can be obtaineed at the link below. The term “asexual” has been defined in many different ways and asexuality has received very little research attention. In a small qualitative study (N = 4), individuals who self-identified as asexual were interviewed to help formulate hypotheses for a larger study. The second larger study was an online survey drawn from a convenience sample designed to better characterize asexual...

  19. Characterizing Individual Communication Patterns

    OpenAIRE

    Malmgren, R. Dean; Hofman, Jake M.; Amaral, Luis A. N.; Watts, Duncan J.

    2009-01-01

    The increasing availability of electronic communication data, such as that arising from e-mail exchange, presents social and information scientists with new possibilities for characterizing individual behavior and, by extension, identifying latent structure in human populations. Here, we propose a model of individual e-mail communication that is sufficiently rich to capture meaningful variability across individuals, while remaining simple enough to be interpretable. We show that the model, a ...

  20. Characterizing Modular Ontologies

    OpenAIRE

    Ben Abbès, Sarra; Scheuermann, Andreas; Meilender, Thomas; D'Aquin, Mathieu

    2012-01-01

    Since large monolithic ontologies are di cult to handle and reuse ontology modularization has attracted increasing attention. Several approaches and tools have been developed to support ontology modularization. Despite these e orts, a lack of knowledge about characteristics of modularly organized ontologies prevents further development. This work aims at characterizing modular ontologies. Therefore, we analyze existing modular ontologies by applying selected metrics from software engineering ...