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Sample records for characterize phytophthora capsici

  1. Induction and Characterization of Laboratory Mutants of Phytophthora capsici Resistant to Dimethomorph and Flumorph

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Laboratory studies were conducted to evaluate the risk of Phytophthora capsici developing resistance to two morphlines, dimethomorph and flumorph. Metalaxyl, the well-known high risk of resistance fungicides, was used as reference fungicide. Resistant mutants for the three fungicides were isolated by treating mycelium with ultraviolet radiation.Metalaxyl-resistant mutants were obtained with high frequency and exhibited high level of resistance with factors more than 100 folds, while mutation frequency for dimethomorph-resistance was relatively low and the resistance factors ranged from 3.0 to 13.9 folds. Most dimethomorph-resistant mutants decreased in hyphal growth rate and the spoulation ability, which have a large impact upon the epidemic development of dimethomorph-resistant populations. These results suggested that the risk of resistant pathogen population was much lower for dimethomorph than for metalaxyl.Both the frequency of developing resistance and level of resistance (resistance factors = 1.8-14.6) to dimethomorph were similar to those of its structure analogue flumorh. Moreover, the cross-resistance were found between them,which suggested the risks of developing resistance to dimethomorph and flumorph in the pathogen were very closely related. As P. capsici can potentially develop resistance to dimethomorph and flumorph, and oomycetes usually have the high risk to develop resistance to fungicides, appropriate management against resistance development should be taken.

  2. 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.

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

    Science.gov (United States)

    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

  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. 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.

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

    Science.gov (United States)

    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...

  7. 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.

  8. 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.

  9. 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.

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

    Science.gov (United States)

    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...

  11. Phytophthora capsici - Loss of Heterozygosity (LOH): A Widespread Mechanism for Rapid Adaptation ( 7th Annual SFAF Meeting, 2012)

    Energy Technology Data Exchange (ETDEWEB)

    Mudge, Joanne [NCGR

    2012-06-01

    Joanne Mudge on "Phytophthora capsici - Loss of Heterozygosity (LOH): A Widespread Mechanism for Rapid Mutation" at the 2012 Sequencing, Finishing, Analysis in the Future Meeting held June 5-7, 2012 in Santa Fe, New Mexico.

  12. 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.

  13. 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

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

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    Adrián Zapata-Vázquez

    2012-01-01

    Full Text Available 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.

  15. 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

  16. Proteomic profile of the plant-pathogenic oomycete Phytophthora capsici in response to the fungicide pyrimorph.

    Science.gov (United States)

    Pang, Zhili; Chen, Lei; Miao, Jianqiang; Wang, Zhiwen; Bulone, Vincent; Liu, Xili

    2015-09-01

    Pyrimorph is a novel fungicide from the carboxylic acid amide (CAA) family used to control plant-pathogenic oomycetes such as Phytophthora capsici. The proteomic response of P. capsici to pyrimorph was investigated using the iTRAQ technology to determine the target site of the fungicide and potential biomarker candidates of drug efficacy. A total of 1336 unique proteins were identified from the mycelium of wild-type P. capsici isolate (Hd3) and two pyrimorph-resistant mutants (R3-1 and R3-2) grown in the presence or absence of pyrimorph. Comparative analysis revealed that the three P. capsici isolates Hd3, R3-1, and R3-2 produced 163, 77, and 13 unique proteins, respectively, which exhibited altered levels of abundance in response to the pyrimorph treatment. Further investigations, using Cluster of Orthologous Groups of Proteins (COG) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified 35 proteins related to the mode of action of pyrimorph against P. capsici and 62 proteins involved in the stress response of P. capsici to pyrimorph. Many of the proteins with altered expression were associated with glucose and energy metabolism. Biochemical analysis using d-[U-(14) C]glucose verified the proteomics data, suggesting that the major mode of action of pyrimorph in P. capsici is the inhibition of cell wall biosynthesis. These results also illustrate that proteomics approaches are useful tools for determining the pathways targeted by novel fungicides as well as for evaluating the tolerance of plant pathogens to environmental challenges, such as the presence of fungicides.

  17. Pathogenicity differentiation of isolates of Phytophthora capsici to pepper%辣椒疫霉(Phytophthora capsici)对辣椒的致病力分化研究

    Institute of Scientific and Technical Information of China (English)

    李萍; 江涛; 高智谋; 戚仁德; 汪涛

    2012-01-01

    The studies on pathogenicity differentiation of isolates in Phytophthora capsici Leonian on pepper were carried out to explore the relationship between pathogenicity differentiation and isolate localities, the correlation between the pathogenicity and mycelium growth rates, and to provide more information for disease-resistant cultivar breeding and integrated management of the disease. Twenty-three isolates of P. capsici were obtained from the diseased peppers collected from Hefei, Huainan, Hexian, Qianshan, Yuexi, Nanjing and Qionglai by means of tissue isolation. The pathogenicity of the isolates from different areas was investigated by applying mycelium block stem wound inoculation on pepper seedlings and leaf in vitro inoculation, respectively. The cluster analysis of the pathogenicity data was done by unweighted pair group method with arithmetic averages (UPGMA) and the relationship between pathogenicity and geographical origin of isolates were analyzed. The mycelium growth rates of the isolates were tested and the correlation between the pathogenicity to pepper and growth rates was investigated. The results showed that all the tested isolates caused pepper blight on the stems and leaves inoculated, but there was significant difference in the diameters of the stem lesions and the severity caused by different isolates. Based on the average diameters of the stem lesions, the pathogenicity of the isolates could be classified into three categories, strong, intermediate and weak. The pathogenicity tested with stem wound inoculation in vivo was positively correlated to that tested with leaf in vitro inoculation (r =0.576 5,R2 =0.332 4). However, the pathogenicity of P. capsici to pepper seedlings had little correlation with growth rate (R2 =0.013 7). It was suggested that there was significant differentiation in pathogenicity of isolates in P. capsici on pepper. The isolates could be classified into three types of pathogenicity, strongly, intermediately and weakly

  18. 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

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

    OpenAIRE

    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 ...

  20. 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

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

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    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.

  2. 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

  3. 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

  4. 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

  5. Genome-Wide Identification and Analysis of the SBP-Box Family Genes under Phytophthora capsici Stress in Pepper (Capsicum annuum L.).

    Science.gov (United States)

    Zhang, Huai-Xia; Jin, Jing-Hao; He, Yu-Mei; Lu, Bo-Ya; Li, Da-Wei; Chai, Wei-Guo; Khan, Abid; Gong, Zhen-Hui

    2016-01-01

    SQUAMOSA promoter binding protein (SBP)-box genes encode plant-specific transcription factors that are extensively involved in many physiological and biochemical processes, including growth, development, and signal transduction. However, pepper (Capsicum annuum L.) SBP-box family genes have not been well characterized. We investigated SBP-box family genes in the pepper genome and characterized these genes across both compatible and incompatible strain of Phytophthora capsici, and also under different hormone treatments. The results indicated that total 15 members were identified and distributed on seven chromosomes of pepper. Phylogenetic analysis showed that SBP-box genes of pepper can be classified into six groups. In addition, duplication analysis within pepper genome, as well as between pepper and Arabidopsis genomes demonstrated that there are four pairs of homology of SBP-box genes in the pepper genome and 10 pairs between pepper and Arabidopsis genomes. Tissue-specific expression analysis of the CaSBP genes demonstrated their diverse spatiotemporal expression patterns. The expression profiles were similarly analyzed following exposure to P. capsici inoculation and hormone treatments. It was shown that nine of the CaSBP genes (CaSBP01, 02, 03, 04, 05, 06, 11, 12, and 13) exhibited a dramatic up-regulation after compatible HX-9 strain (P. capsici) inoculation, while CaSBP09 and CaSBP15 were down-regulated. In case of PC strain (P. capsici) infection six of the CaSBP genes (CaSBP02, 05, 06, 11, 12, and 13) were arose while CaSBP14 was down regulated. Furthermore, Salicylic acid, Methyl jasmonate and their biosynthesis inhibitors treatment indicated that some of the CaSBP genes are potentially involved in these hormone regulation pathways. This genome-wide identification, as well as characterization of evolutionary relationships and expression profiles of the pepper CaSBP genes, will help to improve pepper stress tolerance in the future.

  6. Genome-wide identification and analysis of the SBP-box family genes under Phytophthora capsici stress in pepper (Capsicum annuum L.

    Directory of Open Access Journals (Sweden)

    Huai-Xia eZhang

    2016-04-01

    Full Text Available SQUAMOSA promoter binding protein (SBP-box genes encode plant-specific transcription factors that are extensively involved in many physiological and biochemical processes, including growth, development, and signal transduction. However, pepper (Capsicum annuum L. SBP-box family genes have not been well characterized. We investigated SBP-box family genes in the pepper genome and characterized these genes across both compatible and incompatible strain of Phytophthora capsici, and also under different hormone treatments. The results indicated that total 15 members were identified and distributed on 7 chromosomes of pepper. Phylogenetic analysis showed that SBP-box genes of pepper can be classified into six groups. In addition, duplication analysis within pepper genome, as well as between pepper and Arabidopsis genomes demonstrated that there are 4 pairs of homology of SBP-box genes in the pepper genome and 10 pairs between pepper and Arabidopsis genomes. Tissue-specific expression analysis of the CaSBP genes demonstrated their diverse spatiotemporal expression patterns. The expression profiles were similarly analyzed following exposure to P. capsici inoculation and hormone treatments. It was shown that 9 of the CaSBP genes (CaSBP01, 02, 03, 04, 05, 06, 11, 12 and 13 exhibited a dramatic up-regulation after compatible HX-9 strain (P. capsici inoculation, while CaSBP09 and CaSBP15 were down-regulated. In case of PC strain (P. capsici infection six of the CaSBP genes (CaSBP02, 05, 06, 11, 12 and 13 were arose while CaSBP14 was down regulated. Furthermore, Salicylic acid (SA, Methyl jasmonate (MeJA and their biosynthesis inhibitors treatment indicated that some of the CaSBP genes are potentially involved in these hormone regulation pathways. This genome-wide identification, as well as characterization of evolutionary relationships and expression profiles of the pepper CaSBP genes, will help to improve pepper stress tolerance in the future.

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

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    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

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

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    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.

  9. Occurrence and controling measures of pepper phytophthora capsici%辣椒疫病的发生及防治技术初探

    Institute of Scientific and Technical Information of China (English)

    肖银玉

    2012-01-01

    2009~2011年对武平县东留乡辣椒疫病发生情况进行田间调查,分析武平县辣椒疫病发生流行因素;进行不同品种对辣椒疫病的抗病性比较试验及防治药剂筛选试验,筛选抗疫病品种及防治药剂,并提出综合防治技术。%A field survey on the occurrence of pepper phytophthora capsici had been conducted in Dongliu township of Wuping County during 2009~2011.The epidemic factors of pepper phytophthora capsici disease in Wuping County were analyzed.In order to screen pepper cultivars resistant to phytophthora capsici disease and its controling fungicide,a comparison test of disease resistance among different cultivars and a screening test among different fungicides were conducted.A set of comprehensive measures to prevent and cure pepper phytophthora capsici disease were also put forward.

  10. 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

  11. 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

  12. Antagonistas a Phytophthora capsici inoculados en sustratos de germinación de Capsicum annuum Leonian y Mucuna deeringiana Bort.

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    Juliana Bautista-Calles

    2014-01-01

    Full Text Available Existen microorganismos benéficos a las plantas que se emplean de manera específica y aislada para favorecer la germinación y crecimiento. El beneficio es mayor si, en lugar de inocular un microorganismo específico al sustrato, se inoculan grupos de éstos para que disminuyan la incidencia de las enfermedades inducidas por fitopatógenos de la raíz; y, a su vez, favorezcan la emergencia y crecimiento de los cultivos. El objetivo de este trabajo, con enfoque holístico, fue evaluar las variables emergencia y altura de plántulas en almácigo, e incidencia en el invernadero al reintroducir antagonistas a Phytophthora capsici en grupos de 8, 16, 24 y 32 aislamientos de microorganismos, en los sustratos de germinación del chile (Capsicum annuum y frijol terciopelo (Mucuna deeringiana. Los tratamientos con grupos de antagonistas presentaron al menos uno de los efectos benéficos esperados (en comparación con el testigo, al incrementar la emergencia, la mayor altura de plántulas en el almácigo, y la menor incidencia por P. capsici en el invernadero. Los tratamientos que presentaron la mayor altura de plántulas en almácigo, fueron los tratamientos con grupos de 18, 24 y 32 antagonistas, que incluyeron el grupo de ocho actinomicetos. El mejor tratamiento fue con ocho aislamientos de actinomicetos, que presentó la mayor emergencia de plántulas para ambos cultivos en el almácigo y la menor incidencia de P. capsici en el cultivo de chile en invernadero.

  13. 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...

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

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    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.

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

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    Mao Sopheareth

    2013-03-01

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

  16. 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...

  17. Resistance to the novel fungicide pyrimorph in Phytophthora capsici: risk assessment and detection of point mutations in CesA3 that confer resistance.

    Science.gov (United States)

    Pang, Zhili; Shao, Jingpeng; Chen, Lei; Lu, Xiaohong; Hu, Jian; Qin, Zhaohai; Liu, Xili

    2013-01-01

    Pyrimorph is a novel fungicide with high activity against the plant pathogen Phytophthora capsici. We investigated the risk that P. capsici can develop resistance to pyrimorph. The baseline sensitivities of 226 P. capsici isolates, tested by mycelial growth inhibition, showed a unimodal distribution with a mean EC(50) value of 1.4261 (± 0.4002) µg/ml. Twelve pyrimorph-resistant mutants were obtained by repeated exposure to pyrimorph in vitro with a frequency of approximately 1 × 10(-4). The resistance factors of the mutants ranged from 10.67 to 56.02. Pyrimorph resistance of the mutants was stable after 10 transfers on pyrimorph-free medium. Fitness in sporulation, cystospore germination, and pathogenicity in the pyrimorph-resistant mutants was similar to or less than that in the parental wild-type isolates. On detached pepper leaves and pepper plants treated with the recommended maximum dose of pyrimorph, however, virulence was greater for mutants with a high level of pyrimorph resistance than for the wild type. The results suggest that the risk of P. capsici developing resistance to pyrimorph is low to moderate. Among mutants with a high level of pyrimorph resistance, EC(50) values for pyrimorph and CAA fungicides flumorph, dimethomorph, and mandipropamid were positively correlated. This indicated that point mutations in cellulose synthase 3 (CesA3) may confer resistance to pyrimorph. Comparison of CesA3 in isolates with a high level of pyrimorph resistance and parental isolates showed that an amino acid change from glutamine to lysine at position 1077 resulted in stable, high resistance in the mutants. Based on the point mutations, an allele-specific PCR method was developed to detect pyrimorph resistance in P. capsici populations.

  18. Resistance to the novel fungicide pyrimorph in Phytophthora capsici: risk assessment and detection of point mutations in CesA3 that confer resistance.

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    Zhili Pang

    Full Text Available Pyrimorph is a novel fungicide with high activity against the plant pathogen Phytophthora capsici. We investigated the risk that P. capsici can develop resistance to pyrimorph. The baseline sensitivities of 226 P. capsici isolates, tested by mycelial growth inhibition, showed a unimodal distribution with a mean EC(50 value of 1.4261 (± 0.4002 µg/ml. Twelve pyrimorph-resistant mutants were obtained by repeated exposure to pyrimorph in vitro with a frequency of approximately 1 × 10(-4. The resistance factors of the mutants ranged from 10.67 to 56.02. Pyrimorph resistance of the mutants was stable after 10 transfers on pyrimorph-free medium. Fitness in sporulation, cystospore germination, and pathogenicity in the pyrimorph-resistant mutants was similar to or less than that in the parental wild-type isolates. On detached pepper leaves and pepper plants treated with the recommended maximum dose of pyrimorph, however, virulence was greater for mutants with a high level of pyrimorph resistance than for the wild type. The results suggest that the risk of P. capsici developing resistance to pyrimorph is low to moderate. Among mutants with a high level of pyrimorph resistance, EC(50 values for pyrimorph and CAA fungicides flumorph, dimethomorph, and mandipropamid were positively correlated. This indicated that point mutations in cellulose synthase 3 (CesA3 may confer resistance to pyrimorph. Comparison of CesA3 in isolates with a high level of pyrimorph resistance and parental isolates showed that an amino acid change from glutamine to lysine at position 1077 resulted in stable, high resistance in the mutants. Based on the point mutations, an allele-specific PCR method was developed to detect pyrimorph resistance in P. capsici populations.

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

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    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.

  20. Resistance assessment for oxathiapiprolin in Phytophthora capsici and the detection of a point mutation (G769W in PcORP1 that confers resistance

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    Jianqiang eMiao

    2016-04-01

    Full Text Available 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 adaption 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.

  1. Identification and Expression Analysis of Candidate Genes Associated with Defense Responses to Phytophthora capsici in Pepper Line “PI 201234”

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    Pingyong Wang

    2015-05-01

    Full Text Available Phytophthora capsici (Leonian, classified as an oomycete, seriously threatens the production of pepper (Capsicum annuum. Current understanding of the defense responses in pepper to P. capsici is limited. In this study, RNA-sequencing analysis was utilized to identify differentially expressed genes in the resistant line “PI 201234”, with 1220 differentially expressed genes detected. Of those genes, 480 were up-regulated and 740 were down-regulated, with 211 candidate genes found to be involved in defense responses based on the gene annotations. Furthermore, the expression patterns of 12 candidate genes were further validated via quantitative real-time PCR (qPCR. These genes were found to be significantly up-regulated at different time points post-inoculation (6 hpi, 24 hpi, and 5 dpi in the resistant line “PI 201234” and susceptible line “Qiemen”. Seven genes were found to be involved in cell wall modification, phytoalexin biosynthesis, symptom development, and phytohormone signaling pathways, thus possibly playing important roles in combating exogenous pathogens. The genes identified herein will provide a basis for further gene cloning and functional verification studies and will aid in an understanding of the regulatory mechanism of pepper resistance to P. capsici.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Uso de portainjerto sobre el rendimiento, calidad del fruto y resistencia a Phytophthora capsici Leonian en pimiento morrón

    Directory of Open Access Journals (Sweden)

    Esteban Sánchez Chávez

    2015-01-01

    Full Text Available El pimiento morrón es uno de los principales chiles producidos en México a campo abierto después del chile jalapeño y el serrano. El principal factor que limita la producción de este cultivo, es la incidencia de marchitez del chile, enfermedad causada por el hongo Phytophthora capsici la cual ocasiona pérdidas entre 10 y 100% de la producción. Una alternativa viable para el control de la enfermedad, es el uso de portainjertos en hortalizas. El objetivo del presente trabajo fue estudiar el efecto del uso de portainjerto sobre el rendimiento, calidad del fruto y resistencia a P. capsici en pimiento morrón. Se utilizaron las variedades comerciales de pimiento morrón Fascinato y Janette y el portainjerto comercial Terrano. El experimento se desarrolló en un sistema de malla sombra en Delicias, Chihuahua, México durante el ciclo de producción 2012. Se usó un diseño experimental de bloques completos al azar con cuatro tratamientos y cuatro repeticiones; los tratamientos fueron: Terrano injertado con Fascinato, Terrano injertado con Janette, Fascinato sin injertar y Janette sin injertar. Las variables evaluadas fueron: rendimiento, calidad del fruto y mortandad de plantas. Los resultados obtenidos indican que la combinación variedad/portainjerto Fascinato/Terrano y Janette/Terrano produjeron los más altos rendimientos en fruto, registrándose incrementos del 53.47 % y 49.40 % respectivamente en relación a las mismas variedades sin injertar. Además, Fascinato/Terrano presentó la menor mortandad de plantas provocada por P. capsici (32 %, seguida por Janette/Terrano (36 %; mientras que las variedades Fascinato y Janette sin injertar presentaron la mayor cantidad de plantas muertas (57 % y 53 %, respectivamente, lo que indica que el portainjerto Terrano confirió resistencia a la enfermedad provocada por P. capsici. El portainjerto Terrano aumentó la producción en un 50 % y mejoró los parámetros de calidad del fruto del pimiento morr

  7. 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

  8. Arabidopsis lectin receptor kinases LecRK-IX.1 and LecRK-IX.2 are functional analogs in regulating phytophthora resistance and plant cell death

    NARCIS (Netherlands)

    Wang, Yan; Cordewener, Jan H G; America, Antoine H P; Shan, Weixing; Bouwmeester, Klaas; Govers, Francine

    2015-01-01

    L-type lectin receptor kinases (LecRK) are potential immune receptors. Here, we characterized two closely-related Arabidopsis LecRK, LecRK-IX.1 and LecRK-IX.2, of which T-DNA insertion mutants showed compromised resistance to Phytophthora brassicae and Phytophthora capsici, with double mutants showi

  9. SMART技术构建的辣椒疫霉菌与辣椒互作AD-cDNA文库%Construction of AD-cDNA Library for Interaction ofPhytophthora capsici and Pepper in SMART Technology

    Institute of Scientific and Technical Information of China (English)

    周志国; 明月梅

    2015-01-01

    为了分离和克隆辣椒中疫霉菌诱导基因,以接种辣椒疫霉菌的叶片为材料,利用SMART技术构建辣椒疫霉菌与辣椒互作的双杂交cDNA文库。结果表明:该文库容量为3.6×106 cfu,重组率88%左右,插入片段集中在300~2000 bp之间,平均长度约为800 bp,表明获得的文库质量较高,该文库将为分子育种提供重要的基因资源。%In order to identify thePhytophthora capsici stress induced genes of pepper, a double-hybrid cDNA library ofPhytophthora capsici infected pepper leaves was constructed using SMART technology. The results showed that the cDNA library contained 3.6×106 independent clones, and the recombination rate was 88%. Insert fragments ranged from 300 bp to 2 000 bp, and the average length of the library was about 800 bp. These data demonstrate that the library is qualified, and able to provide important genetic resources for molecular breeding.

  10. 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

  11. 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。

  12. THE DIFFERENTIAL EXPRESSION OF THE ERF GENE IN PEPPER(CAPSICUMANNUUM L.) UNDER PHYTOPHTHORA CAPSICI STRESS%实时荧光定量PCR检测疫霉侵染下辣椒ERF基因的差异表达

    Institute of Scientific and Technical Information of China (English)

    罗辉; 贺俐; 吴杨

    2011-01-01

    本研究利用real-time荧光定量PCR技术检测辣椒疫霉菌(Phytophthora capsici.)胁迫下辣椒抗病基因ERF的mRNA转录水平变化.结果表明:与对照相比,疫霉侵染下辣椒ERF基因的表达量随着胁迫时间延长呈现出先升高后降低的变化特点,该基因在早期被诱导表达,在胁迫6h后表达量达到最大值,之后逐渐下降,相对表达量变化范围为2.83~31.07.

  13. 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

  14. 辽宁省辣椒疫病菌多态性及致病力分化研究初探%Preliminary study on polymorphism and pathogenicity of Phytophthora capsici Leonian in Liaoning

    Institute of Scientific and Technical Information of China (English)

    王辉; 刘长远; 赵奎华; 孙军德

    2012-01-01

    [Objective] The definite relation was found between polymorphism, pathogenicitydifferentiation of Phytophthora capsici Leonian and regionality in Liaoning Province. [Methods] Using Sequence related Amplified Polymorphism (SRAP) technology, the 25 strains of Phytophthora capsici Leonian in Liaoning were amplified in PCR method and evaluated by clustering analyses of NTSYS-PC. The pathogenic differentiation was researched by root-drenching method, and it was examined with hierarchical cluster combination by SPSS 11.5. [Results] The results showed that the DNA of 25 strains were amplified by 27 primer pairs. A total of 578 bands were identified, of which 548 bands were polymorphic. The percentages of polymorphic fragments of each primer pairs were ranged from 84% to 100%. There were abundant polymorphism clustering analysis showed that the genetic similarity among the 25 strains of Phytophthora capsici Leonian were very high. The similarity coefficients varied from 0.56 to 0.91. They were divided into four groups at 0.68 for similarity coefficient, significant correlations were not obvious among the sources of these strains, and there were not regional characteristics. 80% strains were intermediate pathogenicity. [Conclusion] The tested strains were not significantly regional characteristics, and there was no regularity of pathogenicity differentiation from different areas.%[目的]明确辽宁省辣椒疫病菌多态性及致病力分化与区域性关系.[方法]利用SRAP技术对辽宁省25个辣椒疫病菌菌株进行了PCR扩增及NTSYS-PC聚类分析,用灌根法进行致病力分化试验并对试验结果进行SPSS 11.5分层聚类分析.[结果]利用筛选出的27组引物对25个菌株进行扩增,得到578条条带,每对引物多态性比率在84%-100%之间,多态性丰富;供试菌株间遗传相似性较高,相似系数0.56-0.91,以相似系数0.68为阈值划分,25个菌株可聚为4组.试验菌株80%为中等致病力,聚类结果较为

  15. 辣椒种质疫病抗性鉴定及防治药剂的筛选%Identification of Phytophthora capsici Resistance in Capsicum annuum and Fungicide Screening

    Institute of Scientific and Technical Information of China (English)

    何烈干; 马辉刚; 陈学军; 方荣; 周坤华; 兰波

    2014-01-01

    The resistances of pepper materials to Phytophthora capsici were identified by means of root-ir-rigating method.The results showed great differences in the disease resisitances of the tested materials,inclu-ding 32 with infection,15 with moderate resistance,10 with resistance and 13 with high resistance,VC42-1, VC48-1,Xian bian-H and Zhong-21×X8F had extraordinarily high resistance to Phytophthora capsici.Labora-tory toxicity tests of eight fungicides to Phytophthora capsici were carried out by means of mycelium growth meth-od.The results showed that the inhibitive effects of 50%Dimethomorph WP,68%Mefenoxam-M· Mancozeb WDG and 64%Oxadixyl· Mancozeb WP were better than those of other fungicides to the growth of mycelium,and the EC50 values of the three fungicides were 0.124 2,5.063 0 and 8.003 5μg per millimeter respectively. The field trial results showed that 50%Dimethomorph WP,68%Mefenoxam-M· Mancozeb WDG and 72%Cymoxanil· Mancozeb WP had the best inhibitory effects among all the tested fungicides.Based on the results of toxicity tests and field trials,Dimethomorph and Mefenoxam-M· Mancozeb could be recommended for con-trolling phytophtora blight with a inhibitory effect of more than 70%.%采用了游动孢子灌根法对70份辣椒材料进行了疫病抗性鉴定,结果表明:参试材料的抗病性存在较大差异,其中感病材料32份,中抗材料15份,抗病材料10份,高抗材料13份,VC42-1、VC48-1、线边H、中21×X8F等材料具有极高抗性。采用菌落直径法测定8种药剂对辣椒疫霉的毒力,结果表明,50%烯酰吗啉可湿性粉剂、68%精甲霜·锰锌水分散粒剂和64%噁霜·锰锌可湿性粉剂对菌丝抑制作用相对较强,其EC50值分别为0.1242,5.0630,8.0035μg/mL。对8种药剂的田间防治效果进行比较,结果表明,50%烯酰吗啉可湿性粉剂、68%精甲霜·锰锌水分散粒剂和72%霜脲·锰锌可湿性粉剂的防治效果最好。对比

  16. 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

  17. Characterization of Phytophthora infestans resistance to mefenoxam using FTIR spectroscopy.

    Science.gov (United States)

    Pomerantz, A; Cohen, Y; Shufan, E; Ben-Naim, Y; Mordechai, S; Salman, A; Huleihel, M

    2014-12-01

    Phytophthora infestans (P. infestans) is the causal agent of late blight in potato and tomato. This pathogen devastated the potato crops in Ireland more than a century years ago and is still causing great losses worldwide. Although fungicides controlling P. infestans have been used successfully for almost 100 years, some isolates have developed resistance to most common fungicides. Identification and characterization of these resistant isolates is required for better control of the disease. Current methods that are based on microbiological and molecular techniques are both expensive and time consuming. Fourier Transform Infra-Red spectroscopy (FTIR) is an inexpensive and reagent-free technique that provides accurate results in only a few minutes. In this study the infrared absorption spectra of the sporangia of P. infestans were measured to evaluate the potential of FTIR spectroscopy in tandem with multivariate analysis in order to classify those sporangia into those that were resistant and those that were non-resistant to the phenylamide fungicide mefenoxam. Based on individual measurements, our results show that FTIR spectroscopy enables classification of P. infestans isolates into mefenoxam resistant and mefenoxam non-resistant types with specificity of 81.9% and sensitivity of 75.5%. Using average spectra per leaf, it was possible to improve the classification results to 88% sensitivity and 95% specificity.

  18. Comparisons of Ribosomal Protein Gene Promoters Indicate Superiority of Heterologous Regulatory Sequences for Expressing Transgenes in Phytophthora infestans.

    Science.gov (United States)

    Poidevin, Laetitia; Andreeva, Kalina; Khachatoorian, Careen; Judelson, Howard S

    2015-01-01

    Molecular genetics approaches in Phytophthora research can be hampered by the limited number of known constitutive promoters for expressing transgenes and the instability of transgene activity. We have therefore characterized genes encoding the cytoplasmic ribosomal proteins of Phytophthora and studied their suitability for expressing transgenes in P. infestans. Phytophthora spp. encode a standard complement of 79 cytoplasmic ribosomal proteins. Several genes are duplicated, and two appear to be pseudogenes. Half of the genes are expressed at similar levels during all stages of asexual development, and we discovered that the majority share a novel promoter motif named the PhRiboBox. This sequence is enriched in genes associated with transcription, translation, and DNA replication, including tRNA and rRNA biogenesis. Promoters from the three P. infestans genes encoding ribosomal proteins S9, L10, and L23 and their orthologs from P. capsici were tested for their ability to drive transgenes in stable transformants of P. infestans. Five of the six promoters yielded strong expression of a GUS reporter, but the stability of expression was higher using the P. capsici promoters. With the RPS9 and RPL10 promoters of P. infestans, about half of transformants stopped making GUS over two years of culture, while their P. capsici orthologs conferred stable expression. Since cross-talk between native and transgene loci may trigger gene silencing, we encourage the use of heterologous promoters in transformation studies.

  19. 辣椒疫霉对双炔酰菌胺敏感性及对其它杀菌剂的交互抗性%Sensitivity of Phytophthora capsici to mandipropamid and its cross resistance with other fungicides

    Institute of Scientific and Technical Information of China (English)

    韩秀英; 赵卫松; 齐永志; 王文桥; 马志强; 张小凤

    2011-01-01

    The sensitivities of 115 isolates of Phytophthora capsici collected from different regions to mandipropamid were tested by measuring mycelial growth rate. Ten resistant-mutants and 4 sensitive isolates to mandipropamid were used to study its cross resistance with dimethomorph, metalaxyl, azoxystrobin and cymoxanil by comparing their sensitivity to diverse active mechanism fungicides. The results showed that there were no significant differences among the EC50 of mandipropamid to isolates from Qingzhou,Shouguang, Dinxing and Gaocheng regions, and all those isolates were more sensitive to mandipropamid.The linear regression showed that there were no cross resistances between mandipropamid and other diverse active mechanism fungicides. After 11 successive incubation, the sensitivities of 2 of 10 resistant-mutants to mandipropamid could maintain their resistance inheritable stability with the EC50 of 1429.524μg/mL and 6 872.476 μg/mL respectively, but the other 8 could not maintain it. Our results indicatedthat the continuous use of mandipropamid was beneficial to development of resistance populations.%采用菌丝生长速率法测定了不同地区115个辣椒疫霉菌株对双炔酰菌胺的敏感性,同时测定了紫外诱导和药剂驯化的10个抗性突变体及其4个亲本菌株对双炔酰菌胺、烯酰吗琳、甲霜灵、噻菌醋和霜脲氰的敏感性.山东青州、寿光和河北定兴、藁城4地辣椒疫霉菌株均对双炔酰菌胺较敏感,且敏感性差异不显著.不同抗性水平菌株对5种药剂的敏感性测定和相关性分析结果显示双炔酰菌胺与其它几类药剂之间均不存在交互抗性.10个抗性突变体继代培养11代后,8个抗性突变体抗药性不能稳定遗传;2个抗性突变体抗药性不仅能够稳定遗传,且EC50值维持在很高水平,分别为1429.524pg/mL和6872.47pg/mL,因此,双炔酞菌胺的连续使用有利于抗药群体的发展.

  20. 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

  1. Genetic characterization of Phytophthora nicotianae by the analysis of polymorphic regions of the mitochondrial DNA.

    Science.gov (United States)

    A new method based on the analysis of mitochondrial intergenic regions characterized by intraspecific variation in DNA sequences was developed and applied to the study of the plant pathogen Phytophthora nicotianae. Two regions flanked by genes trny and rns and trnw and cox2 were identified by compa...

  2. CHARACTERIZATION OF Phytophthora infestans POPULATIONS IN ANTIOQUIA, COLOMBIA CARACTERIZACIÓN DE LAS POBLACIONES DE Phytophthora infestan EN ANTIOQUIA, COLOMBIA

    Directory of Open Access Journals (Sweden)

    Elizabeth Gilchrist Ramelli

    2009-12-01

    Full Text Available From the Phytophthora infestans collection of the Universidad Nacional de Colombia, the isolates collected in different locations in Antioquia, Colombia between 1994 and 2000 were evaluated. These isolates were obtained from late blight lessons in different hosts. In 2000, these isolates were characterized by mating type, mitochondrial haplotype and virulence races. All isolates were of the A1 mating type and two mitochondrial haplotypes were identified: IIa, present in isolates from all the hosts tested, and Ib present only in isolates from tomato and water cucumber (Solanum muricatum. The Antioquia population of P. infestans showed a large complexity of virulence factors (10 out 11, especially those isolates collected from potato, while the tomato population was less complex. The A1 mating type and the mitochondrial haplotype IIa has been associated with the EC1 population that possibly is replacing the US1 population.De la colección de Phytophthora infestans de la Universidad Nacional de Colombia, se evaluaron aquellos aislamientos provenientes de diferentes localidades de Antioquia, Colombia entre 1994 y 2000. Dichos aislamientos fueron obtenidos de lesiones de tizón tardío en diferentes hospederos. En el año 2000 se caracterizaron por el tipo de apareamiento, haplotipo mitocondrial y razas de virulencia. Todos los aislamientos correspondieron al tipo de apareamiento A1 y se presentaron dos haplotipos mitocondriales: IIa, en aislamientos de todos los hospederos evaluados, y Ib solamente en aislamientos colectados de tomate y pepino de agua (Solanum muricatum. La población antioqueña de P. infestans presenta una amplia complejidad de factores de virulencia (10 de 11, especialmente para los aislamientos colectados de papa, mientras que la población de tomate fue menos compleja. El tipo de apareamiento A1 y el haplotipo mitocondrial IIa han sido asociados a la población EC1 que posiblemente está desplazando la población US1.

  3. 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

  4. 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...

  5. 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.;

    2016-01-01

    As the oomycete pathogen causing potato late blight disease, Phytophthora infestans triggered the famous 19th-century Irish potato famine and remains the leading cause of global commercial potato crop destruction. But the geographic origin of the genotype that caused this devastating initial outb...

  6. Cloning and characterization of cDNA encoding an elicitor of Phytophthora colocasiae.

    Science.gov (United States)

    Mishra, Ajay Kumar; Sharma, Kamal; Misra, Raj Shekhar

    2010-02-28

    The rapid and effective activation of disease resistance responses is essential for plant defense against pathogen attack. These responses are initiated when pathogen-derived molecules (elicitors) are recognized by the host. A cDNA encoding elicitor, the major secreted extracellular glycoprotein of Phytophthora colocasiae, a pathogen of taro (Colocasia esculenta) plants, was isolated, sequenced and characterized. The expression of the corresponding elicitor gene during the disease cycle of P. colocasiae was analyzed. Elicitor was shown to be expressed in mycelium grown in culture media, whereas it was not expressed in sporangiospores and zoospores. In planta, during infection of taro, particularly during the biotrophic stage, expression of elicitor was down-regulated compared to in vitro. The highest levels of expression of elicitor were observed in in vitro grown mycelium and in late stages of infection when profuse sporulation and leaf necrosis occur. The elicitation of the suspension-cultured taro cells was effective in the induction of the enzyme activity of l-phenylalanine-ammonia lyase, peroxidase and lipoxygenase as well as the expression of defense-related endochitinase gene. All these biological activities were exerted within a low concentration range. The glycoprotein represents a powerful tool to investigate further the signals and their transduction pathways involved in induced disease resistance. It may also be useful to engineer broad disease protection in taro plant against Phytophthora leaf blight. PMID:19230634

  7. Biological characteristics of garlic root border-like cells and its antimicrobial activity against Phytophthora capsici%大蒜类似根缘细胞生物学特性及其对辣椒疫霉菌的抑制活性

    Institute of Scientific and Technical Information of China (English)

    廖静静; 张立猛; 张潇丹; 郑祥; 焦永鸽; 何霞红; 朱书生; 杨敏

    2015-01-01

    生产实践表明,利用大蒜与辣椒轮作能有效控制辣椒疫病的危害。大蒜根系分泌物的抑菌活性与病害的控制有关。本文分析了大蒜根冠细胞脱落物的种类以及不同温湿度和根长对大蒜根冠细胞脱落物产生的影响,并测定细胞脱落物水培液对辣椒疫霉菌的抑制活性。结果表明,大蒜根冠细胞脱落物为椭圆、长椭圆形和长形类似根缘细胞。这些类似根缘细胞的产生受根长、温度和湿度的影响。根系在2%水琼脂的平板内,20℃条件下培养至25 mm 以上产生的类似根缘细胞最多。大蒜类似根缘细胞水培液对辣椒疫霉菌游动孢子游动和孢子囊释放都具有显著的抑制活性。该研究表明,大蒜根系产生的类似根缘细胞也是化感抑菌物质释放的重要途径。%On the basis of practical production,it was proved that garlic and pepper rotation was beneficial to con-trol of phytophthora blight.Inhibitory activity of garlic root exudates was associated with the disease control.This study analyzed the type of garlic sloughed root cap cells and the effect of temperature,humidity and the root length on the production of this kind of cell.The antimicrobial activity of the hydroponic liquid of sloughed root cap cells against Phytophthora capsici Ieonian was also tested.The results indicated that the sloughed root cap cells of garlic were border-like cells (BLCs),including oval,long oval and elongated cells.The production of BLCs was affected by temperature,humidity and the length of roots.Garlic roots could produce a large number of BLCs when garlic roots grew to 25 mm in length at 20 ℃ in plates containing 100 mL 2% water agar.Hydroponic liquid of BLCs showed inhibitory activity against zoospore release from sporangia and zoospores’motility.This study demonstrated that border-like cells may be an important source of garlic antimicrobial substances.

  8. Phytophthora capsici 遊走子嚢の遊走子分割過程におけるβ-シトステロールの動向(農学部門)

    OpenAIRE

    宮田, 善雄/大杉 武/正子 朔; YOSHIO/OSUGI TAKESHI/MASAGO HAJIME, MIYATA; 京都府立大学農学部植物病学研究室/京都府立大学農学部植物病学研究室/京都府立大学農学部植物病学研究室; Laboratoty of Plant Pathology, Faculty of Agriculture, Kyoto Prefectural University/Laboratoty of Plant Pathology, Faculty of Agriculture, Kyoto Prefectural University/Laboratoty of Plant Pathology, Faculty of Agriculture, Kyoto Prefectural University

    1980-01-01

    Phytophthora capsiciの遊走子嚢の遊走子型発芽(間接発芽の1形態)は, 遊走子への分割が先行する。この過程は, ゴルジ体由来の小胞群が, 発達して割腔胞となり, 並列融合して割腔が形成され, 遊走子への分割が完了するのであるが, この分割には, β-シトステロールなどの植物ステロールの存在が必要である。β-(23,24-^3H)シトステロールを用いた電顕オートラジオグラフィーにより, 菌体内に取込まれたβ-シトステロールは, 核やミトコンドリアなど, 種々のミクロオルガネラに広く分布するが, 分割過程の進行にともなって, 割腔胞, さらには遊走子細胞膜の, それぞれ生体膜上にも, かなりの頻度で存在するようになる。β-(4-^C)シトステロールを用いた庶糖密度勾配遠心分離法による, 細胞オルガネラ分画のトレーサー実験においても, 遊走子分割過程の進行とともに, ゴルジ分画や, 割腔胞が含まれると考えられるリソゾーム分画においては, ステロールが減少し, 逆に, 遊走子細胞膜分画において, 著しいステロールの増大することがわかった。これらのことから, 菌体内に取込...

  9. 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

  10. 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...

  11. 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...

  12. 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.

  13. 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

  14. Genetic mapping and characterization of two novel Phytophthora resistance genes from soybean landrace PI567139B

    Science.gov (United States)

    Phytophthora root and stem rot (PRR) disease, caused by P. sojae, is a widespread soybean disease resulting in an annual yield loss of $1~2 billion worldwide. To control the disease, breeders primarily employ race-specific resistant genes which are named Rps genes which have been identified to be lo...

  15. 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

  16. 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

  17. Purification and characterization of elicitor protein from Phytophthora colocasiae and basic resistance in Colocasia esculenta.

    Science.gov (United States)

    Mishra, Ajay Kumar; Sharma, Kamal; Misra, Raj Shekhar

    2009-01-01

    An elicitor was identified in the fungus Phytophthora colocasiae. The molecular weight of the purified elicitor was estimated by means of gel filtration chromatography and SDS-PAGE and was estimated as 15kDa. Protease treatment severely reduced its activity, allowing the conclusion that the elicitor is proteinaceous. Infiltration of a few nanograms of this proteinaceous elicitor into taro leaves caused the formation of lesions that closely resemble hypersensitive response lesions. The elicitation of the cells was effective in the induction of the activity of lipoxygenase. Cellular damage, restricted to the infiltrated zone, occurred only several hours later, after the infiltration of the elicitor protein. After few days, systemic acquired resistance was also induced. Thus, taro plant cells that perceived the glycoprotein generated a cascade of signals acting at local, short, and long distances, and causing the coordinate expression of specific defence. The obtained results give important information regarding the plant-pathogen interactions, mainly as subsidy for taro improvement against Phytophthora leaf blight.

  18. Molecular mapping and characterization of two genes conferring resistance to Phytophthora sojae in a soybean landrace PI 567139B

    Science.gov (United States)

    Phytophthora root and stem rot (PRR), caused by the soil-borne oomycete pathogen Phytophthora sojae, is one of the most destructive diseases of soybean. PRR can be effectively controlled by race-specific genes conferring resistance to P. sojae (Rps). However, the Rps genes are usually non-durable, a...

  19. 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

  20. 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.

  1. Host-pathogen interactions. XIV. Isolation and partial characterization of an elicitor from yeast extract. [Glycine max, Phytophthora megasperma

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, M.G.; Albersheim, P.

    1978-01-01

    An elicitor of glyceollin accumulation in soybeans (Glycine max L.) has been isolated from a commercially available extract of brewers' yeast. Yeast is not a known pathogen of plants. The elicitor was isolated by precipitation in 80% (v/v) ethanol followed by column chromatography on DEAE-cellulose, sulfopropyl-Sephadex, and concanavalin A-Sepharose. Compositional and structural analysis showed the elicitor to be a glucan containing terminal, 3-, 6-, and 3,6-linked glucosyl residues. The yeast elicitor stimulates the accumulation of glyceollin in the cotyledons and hypocotyls of soybeans when as little as 15 nanograms or 100 nanograms of the elicitor is applied to the respective tissues. The yeast elicitor is very similar in both structure and absolute elicitor activity to an elicitor isolated from the mycelial walls of Phytophthora megasperma var. sojae, a pathogen of soybeans. These and other results of this laboratory suggest that plants are able to respond to the presence of a wide range of fungi by recognizing, as foreign to the plant, structural polysaccharides of the mycelial walls of the fungi.

  2. First report of phytophthora fruit rot on bitter gourd (Mormodica charantia) and sponge gourd (Luffa cylindrica) caused by phytophthora capsici

    Science.gov (United States)

    Luffa sponge (smooth gourd) and bitter gourds (bitter melon) are specialty cucurbit vegetables cultivated in the United States (US) on a small scale for select markets. Luffa gourds are also grown for the sponge obtained from dried fruit for personal hygiene and skin care. These two cucurbits prod...

  3. 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

  4. 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

  5. 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...

  6. Interaction between the moss Physcomitrella patens and Phytophthora: a novel pathosystem for live-cell imaging of subcellular defence.

    Science.gov (United States)

    Overdijk, Elysa J R; DE Keijzer, Jeroen; DE Groot, Deborah; Schoina, Charikleia; Bouwmeester, Klaas; Ketelaar, Tijs; Govers, Francine

    2016-08-01

    Live-cell imaging of plant-pathogen interactions is often hampered by the tissue complexity and multicell layered nature of the host. Here, we established a novel pathosystem with the moss Physcomitrella patens as host for Phytophthora. The tip-growing protonema cells of this moss are ideal for visualizing interactions with the pathogen over time using high-resolution microscopy. We tested four Phytophthora species for their ability to infect P. patens and showed that P. sojae and P. palmivora were only rarely capable to infect P. patens. In contrast, P. infestans and P. capsici frequently and successfully penetrated moss protonemal cells, showed intracellular hyphal growth and formed sporangia. Next to these successful invasions, many penetration attempts failed. Here the pathogen was blocked by a barrier of cell wall material deposited in papilla-like structures, a defence response that is common in higher plants. Another common response is the upregulation of defence-related genes upon infection and also in moss we observed this upregulation in tissues infected with Phytophthora. For more advanced analyses of the novel pathosystem we developed a special set-up that allowed live-cell imaging of subcellular defence processes by high-resolution microscopy. With this set-up, we revealed that Phytophthora infection of moss induces repositioning of the nucleus, accumulation of cytoplasm and rearrangement of the actin cytoskeleton, but not of microtubules.

  7. L-type lectin receptor kinases in Nicotiana benthamiana and tomato and their role in Phytophthora resistance.

    Science.gov (United States)

    Wang, Yan; Weide, Rob; Govers, Francine; Bouwmeester, Klaas

    2015-11-01

    Membrane-bound receptors play crucial roles as sentinels of plant immunity against a large variety of invading microbes. One class of receptors known to be involved in self/non-self-surveillance and plant resistance comprises the L-type lectin receptor kinases (LecRKs). Previously, we reported that several Arabidopsis LecRKs play a role in resistance to Phytophthora pathogens. In this study, we determined whether homologues of these LecRKs from the Solanaceous plants Nicotiana benthamiana and tomato (Solanum lycopersicum) play similar roles in defence against Phytophthora. In genome-wide screenings, a total of 38 (Nb)LecRKs were identified in N. benthamiana and 22 (Sl)LecRKs in tomato, each consisting of both a lectin and a kinase domain. Phylogenetic analysis revealed that, in contrast to Arabidopsis, which has a LecRK family comprising nine clades, Solanaceous species have just five of these nine clades (i.e. IV, VI, VII, VIII, and IX), plus four additional clades that lack Arabidopsis homologues. Several of the Solanaceous LecRKs were selected for functional analysis using virus-induced gene silencing. Infection assays with Phytophthora capsici and Phytophthora infestans on LecRK-silenced plants revealed that N. benthamiana and tomato homologues in clade IX play a role in Phytophthora resistance similar to the two Arabidopsis LecRKs in this clade, suggesting conserved functions of clade IX LecRKs across different plant families. This study provides a first insight into the diversity of Solanaceous LecRKs and their role in plant immunity, and shows the potential of LecRKs for Phytophthora resistance breeding. PMID:26248665

  8. Characterization of an Arabidopsis-Phytophthora pathosystem: resistance requires a functional PAD2 gene and is independent of salicylic acid, ethylene and jasmonic acid signalling.

    Science.gov (United States)

    Roetschi, A; Si-Ammour, A; Belbahri, L; Mauch, F; Mauch-Mani, B

    2001-11-01

    Arabidopsis accessions were screened with isolates of Phytophthora porri originally isolated from other crucifer species. The described Arabidopsis-Phytophthora pathosystem shows the characteristics of a facultative biotrophic interaction similar to that seen in agronomically important diseases caused by Phytophthora species. In susceptible accessions, extensive colonization of the host tissue occurred and sexual and asexual spores were formed. In incompatible combinations, the plants reacted with a hypersensitive response (HR) and the formation of papillae at the sites of attempted penetration. Defence pathway mutants such as jar1 (jasmonic acid-insensitive), etr1 (ethylene receptor mutant) and ein2 (ethylene-insensitive) remained resistant towards P. porri. However, pad2, a mutant with reduced production of the phytoalexin camalexin, was hyper-susceptible. The accumulation of salicylic acid (SA) and PR1 protein was strongly reduced in pad2. Surprisingly, this lack of SA accumulation does not appear to be the cause of the hyper-susceptibility because interference with SA signalling in nahG plants or sid2 or npr1 mutants had only a minor effect on resistance. In addition, the functional SA analogue benzothiadiazol (BTH) did not induce resistance in susceptible plants including pad2. Similarly, the complete blockage of camalexin biosynthesis in pad3 did not cause susceptibility. Resistance of Arabidopsis against P. porri appears to depend on unknown defence mechanisms that are under the control of PAD2.

  9. Morphological and Molecular Description of Phytophthora insolita Isolated from Citrus Orchard in India

    Directory of Open Access Journals (Sweden)

    Swapnil Bawage

    2013-01-01

    Full Text Available Citrus, an important cash crop in India, is adversely affected by Phytophthora nicotianae, P. palmivora, and P. citrophthora. Phytophthora insolita is known to be associated with citrus and reported for the first time in India. It is a rare and poorly characterized Phytophthora species, as its natural host and pathogenic impact are unclear. Previously, it was reported only in Taiwan and China; so to confirm our suspected isolate is P. insolita, regions of internal transcribed spacer, elongation factor, beta-tubulin, and cytochrome oxidase genes were sequenced. This study provides description of the lone Indian P. insolita isolate with respect to molecular identity, morphology, mating behaviour, and pathogenicity.

  10. 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

  11. 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

  12. 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, ...

  13. 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-...

  14. Phytophthora sojae avirulence effector Avr3b is a secreted NADH and ADP-ribose pyrophosphorylase that modulates plant immunity.

    Directory of Open Access Journals (Sweden)

    Suomeng Dong

    2011-11-01

    Full Text Available Plants have evolved pathogen-associated molecular pattern (PAMP-triggered immunity (PTI and effector-triggered immunity (ETI to protect themselves from infection by diverse pathogens. Avirulence (Avr effectors that trigger plant ETI as a result of recognition by plant resistance (R gene products have been identified in many plant pathogenic oomycetes and fungi. However, the virulence functions of oomycete and fungal Avr effectors remain largely unknown. Here, we combined bioinformatics and genetics to identify Avr3b, a new Avr gene from Phytophthora sojae, an oomycete pathogen that causes soybean root rot. Avr3b encodes a secreted protein with the RXLR host-targeting motif and C-terminal W and Nudix hydrolase motifs. Some isolates of P. sojae evade perception by the soybean R gene Rps3b through sequence mutation in Avr3b and lowered transcript accumulation. Transient expression of Avr3b in Nicotiana benthamiana increased susceptibility to P. capsici and P. parasitica, with significantly reduced accumulation of reactive oxygen species (ROS around invasion sites. Biochemical assays confirmed that Avr3b is an ADP-ribose/NADH pyrophosphorylase, as predicted from the Nudix motif. Deletion of the Nudix motif of Avr3b abolished enzyme activity. Mutation of key residues in Nudix motif significantly impaired Avr3b virulence function but not the avirulence activity. Some Nudix hydrolases act as negative regulators of plant immunity, and thus Avr3b might be delivered into host cells as a Nudix hydrolase to impair host immunity. Avr3b homologues are present in several sequenced Phytophthora genomes, suggesting that Phytophthora pathogens might share similar strategies to suppress plant immunity.

  15. 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...

  16. Ectopic expression of Dahlia merckii defensin DmAMP1 improves papaya resistance to Phytophthora palmivora by reducing pathogen vigor.

    Science.gov (United States)

    Zhu, Yun J; Agbayani, Ricelle; Moore, Paul H

    2007-06-01

    Phytophthora spp., some of the more important casual agents of plant diseases, are responsible for heavy economic losses worldwide. Plant defensins have been introduced as transgenes into a range of species to increase host resistance to pathogens to which they were originally susceptible. However, the effectiveness and mechanism of interaction of the defensins with Phytophthora spp. have not been clearly characterized in planta. In this study, we expressed the Dahlia merckii defensin, DmAMP1, in papaya (Carica papaya L.), a plant highly susceptible to a root, stem, and fruit rot disease caused by Phytophthora palmivora. Extracts of total leaf proteins from transformed plants inhibited growth of Phytophthora in vitro and discs cut from the leaves of transformed plants inhibited growth of Phytophthora in a bioassay. Results from our greenhouse inoculation experiments demonstrate that expressing the DmAMP1 gene in papaya plants increased resistance against P. palmivora and that this increased resistance was associated with reduced hyphae growth of P. palmivora at the infection sites. The inhibitory effects of DmAMP1 expression in papaya suggest this approach has good potential to impart transgenic resistance against Phytophthora in papaya. PMID:17216480

  17. Fine mapping of the Ph-3 gene conferring resistance to late blight (Phytophthora infestans) in tomato

    NARCIS (Netherlands)

    Zhang, C.Z.; Liu, L.; Zheng, Z.; Sun, Y.Y.; Zhou, L.X.; Yang, Y.H.; Cheng, F.; Zhang, Z.H.; Wang, X.W.; Huang, S.W.; Xie, B.Y.; Du, Y.C.; Bai, Y.; Li, J.M.

    2013-01-01

    Late blight, caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary, is a devastating disease for tomato and potato crops. In the past decades, many late blight resistance (R) genes have been characterized in potato. In contrast, less work has been conducted on tomato. The Ph-3 gene

  18. 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.

  19. Isolation and characterization by asymmetric PCR of the ENDO1 gene for glucan endo-1,3-β-D-glucosidase in Phytophthora cinnamomi associated with the ink disease of Castanea sativa Mill

    Directory of Open Access Journals (Sweden)

    Sofia Meirinho

    2010-06-01

    Full Text Available Ink disease is one of the most destructive diseases in Castanea sativa. The most common symptoms are root necrosies and a reduction in root growth, which invariably lead to the death of the trees. Phytophthora cinnamomi is an oomycete associated with this disease whose life cycle develops integrally in the soil. In the present work, was a fragment with 1231bp of the glucan endo-1,3-β-D-glucosidase gene obtained by amplification, using conserved primers and the full-length gene sequence by flanking this known sequence by asymmetric PCR. This fragment was obtained from genomic DNA of Phytophthora cinnamomi isolated in the European Regions of Castilla-Leon (Spain and Trás-os-Montes (Portugal and associated with the ink disease of Castanea sativa Mill.Doença da tinta é um das doenças mais destrutivas em Castanea sativa. Os sintomas mais comuns são necroses e uma redução em crescimento da raiz que invariavelmente leva à morte das plantas. Phytophthora cinnamomi é o oomycete associado a esta doença cujo ciclo de vida acontece integralmente no solo. Foi obtido um fragmento com 1231pb do gene glucan endo-1,3-β-D-glucosidase por amplificação usando oligonucleotidos conservados e a sequência completa do gene foi obtido flanqueando esta sequência conhecida por PCR assimétrico. Este fragmento foi obtido de ADN genómico de Phytophthora cinnamomi isolado por nós nas Regiões Europeias de Castilla-Léon (Espanha e Trás-os-Montes (Portugal e associado à doença da tinta da Castanea sativa Mill.

  20. Phytophthora porri in leek: epidemiology and resistance.

    NARCIS (Netherlands)

    Smilde, W.D.

    1996-01-01

    In winter, Phytophthora porri is an important pathogen of leek ( Allium porrum L.) in the Netherlands. The fungus survives the crop-free period in summer by oospores in soil, and infects the leaves in autumn. Field studies indicated that dispersal by rain splash is crucial for initiation of an epid

  1. Isolation and characterization by asymmetric PCR of the ENDO1 gene for glucan endo-1,3-β-D-glucosidase in Phytophthora cinnamomi associated with the ink disease of Castanea sativa Mill

    OpenAIRE

    Sofia Meirinho; Marisa Carvalho; Ángel Dominguez; Altino Choupina

    2010-01-01

    Ink disease is one of the most destructive diseases in Castanea sativa. The most common symptoms are root necrosies and a reduction in root growth, which invariably lead to the death of the trees. Phytophthora cinnamomi is an oomycete associated with this disease whose life cycle develops integrally in the soil. In the present work, was a fragment with 1231bp of the glucan endo-1,3-β-D-glucosidase gene obtained by amplification, using conserved primers and the full-length gene sequence b...

  2. Isolation and characterization by asymmetric PCR of the ENDO1G gene for Glucan endo-1,3-b-D-glucosidase in Phytophthora cinnamomi associated whit the ink disease of Castanea sativa Mill.

    OpenAIRE

    Meirinho, Sofia G.; Carvalho, Marisa; Dominguez, Ángel; Choupina, Altino

    2010-01-01

    Ink disease is one of the most destructive diseases in Castanea sativa. The most common symptoms are root necrosies and a reduction in root growth, which invariably lead to the death of the trees. Phytophthora cinnamomi is an oomycete associated with this disease whose life cycle develops integrally in the soil. In the present work, was a fragment with 1231bp of the glucan endo-1,3-b-D-glucosidase gene obtained by amplification, using conserved primers and the full-length gene seq...

  3. 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

  4. 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.

  5. 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.

  6. 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...

  7. 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...

  8. 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...

  9. Phytophthora root rot resistance in soybean E00003

    Science.gov (United States)

    Phytophthora root rot (PRR), caused by the oomycete Phytophthora sojae, is a devastating disease in soybean production. Using resistant cultivars has been suggested as the best solution for disease management. Michigan elite soybean E00003 is resistant to P. sojae and has been used as a PRR resist...

  10. 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...

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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 ...

  18. 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...

  19. 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

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

    Directory of Open Access Journals (Sweden)

    Gang Wang

    2016-07-01

    Full Text Available 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.

  1. 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.

  2. 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

  3. Screening,identification and antibacterial activity of antagonistic bacteria FC12-05 against phytophthora root rot of tomato%番茄疫霉根腐病拮抗细菌FC12-05的筛选、鉴定及其抑菌活性初探

    Institute of Scientific and Technical Information of China (English)

    冯志珍; 李金岭; 陈太春; 马志远; 段军娜; 安德荣

    2012-01-01

    【Objective】 The strong effective biocontrol bacteria for phytophthora root rot of tomato were selected from greenhouse tomato farming soil for several years.【Method】 Random samples were conducted from greenhouse tomato farming soil for many years,separated the bacteria used plant dilute,selected directionally with several fungal pathogens such as P.capsici Leonian,Botrytis cirerea,Phytophthora nicotianae,Bipolaris sorokiniana,Fusarium oxysporum f.sp.vasinfectum,Pyricularia oryzae as the indicator bacteria;We identified the antagonistic bacteria based on morphological,physiological and biochemical characteristics,and 16S rDNA phylogenetic analysis;determined the effect of the mycelial configurationthe of pathogenic fungi,the mycelium growth of pathogenic fungi,the spore germination on pathogenic fungi spores broth germination and the control efficacy of bonsai experiment in greenhouse with the sterile fermentation of antagonistic bacteria.Then we deposited the sterile fermentation of antagonistic bacteria with ammonium sulfatem,which saturation concentration respectively was 10%,20%,25%,30%,35%,40%,50%,60%,70%,80%,90% and 100%,and tested the antifungal activity of ammonium sulfate precipitation of the antagonists.【Result】 253 strains bacterium were isolated from 30 soil samples,FC12-05,a strong effect of bacterial on Phytophthora capsici Leonian,Botrytis cirerea,Phytophthora nicotianae,Bipolaris sorokiniana,Fusarium oxysporum f.sp.vasinfectum,Pyricularia oryzae;The strain FC12-05 was identified as Bacillus siamensis.The fermented liquid of strain FC12-05 had great inhibition effect on mycelium growth of P.capsici Leonian and Botrytis cinerea,the inhibition rate of mycelium growth was 95.02% and 92.43%;the EC50 values was 10.14 and 10.78 mL/L;the inhibition rate of spore germination was 94.60% and 92.43%;the EC50 values was 2.09 and 2.53 mL/L;the control effect of FC12-05 strain on phytophthora root rot of tomato was up to 93.50%;The antifungal metabolite

  4. Effect of Azoxystrobin on Oxygen Consumption and cyt b Gene Expression of Colletotrichum capsici from Chilli Fruits

    Institute of Scientific and Technical Information of China (English)

    CHEN Yu; JIN Li-hua; ZHOU Ming-guo

    2009-01-01

    Azoxystrobin acts as an inhibitor of electron transport by binding to the Qo center of cytochrome b (cyt b).Resistance to azoxystrobin was usually caused by the point mutation of cyt b gene or by the induction of alternative respiration.Oxygen consumption test for mycelia of Colletotrichura capsici showed that azoxystrobin inhibited mycelial respiration within 12 h; however,as time went on,the respiration of the mycelia recovered when the mycelia were treated with azoxystrobin and salicylhydroxamic acid (SHAM,a known inhibitor of alternative respiration),and the oxygen consumption of the mycelia could not be inhibited.Meanwhile,cytochrome b (cyt b) gene expression increased with the recovery of myeelial respiration.The increased cyt b gene expression might play a role in the development of resistance to azoxystrobin in C.capsici.

  5. 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.

  6. 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.

  7. Discovery of Phytophthora infestans genes expressed in planta through mining of cDNA libraries.

    Directory of Open Access Journals (Sweden)

    Roberto Sierra

    Full Text Available BACKGROUND: Phytophthora infestans (Mont. de Bary causes late blight of potato and tomato, and has a broad host range within the Solanaceae family. Most studies of the Phytophthora--Solanum pathosystem have focused on gene expression in the host and have not analyzed pathogen gene expression in planta. METHODOLOGY/PRINCIPAL FINDINGS: We describe in detail an in silico approach to mine ESTs from inoculated host plants deposited in a database in order to identify particular pathogen sequences associated with disease. We identified candidate effector genes through mining of 22,795 ESTs corresponding to P. infestans cDNA libraries in compatible and incompatible interactions with hosts from the Solanaceae family. CONCLUSIONS/SIGNIFICANCE: We annotated genes of P. infestans expressed in planta associated with late blight using different approaches and assigned putative functions to 373 out of the 501 sequences found in the P. infestans genome draft, including putative secreted proteins, domains associated with pathogenicity and poorly characterized proteins ideal for further experimental studies. Our study provides a methodology for analyzing cDNA libraries and provides an understanding of the plant--oomycete pathosystems that is independent of the host, condition, or type of sample by identifying genes of the pathogen expressed in planta.

  8. 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)

  9. The biology of Phytophthora infestans at its center of origin

    NARCIS (Netherlands)

    Grünwald, N.J.; Flier, W.G.

    2005-01-01

    The central highlands of Mexico are considered to be a center of genetic diversity for both the potato late blight pathogen and for tuber-bearing Solanum spp. Recent work conducted in Mexico and South America sheds new light on the biology and evolution of Phytophthora infestans and other related Ph

  10. 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

  11. 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...

  12. Can Epiphytes reduce disease symptoms caused by Phytophthora ramorum

    Science.gov (United States)

    Leaf infection of ornamental species by Phytophthora ramorum has a significant impact on the spread of this disease. Fungicides have had limited effects on controlling this disease. With increasing concerns that repeated fungicide applications will exasperate the potential for fungicide resistance...

  13. 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, ...

  14. 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

  15. Interaction between the moss Physcomitrella patens and Phytophthora

    NARCIS (Netherlands)

    Overdijk, Elysa J.R.; Keijzer, De Jeroen; Groot, De Deborah; Schoina, Charikleia; Bouwmeester, Klaas; Ketelaar, Tijs; Govers, Francine

    2016-01-01

    Live-cell imaging of plant-pathogen interactions is often hampered by the tissue complexity and multicell layered nature of the host. Here, we established a novel pathosystem with the moss Physcomitrella patens as host for Phytophthora. The tip-growing protonema cells of this moss are ideal for v

  16. Phytophthora x pelgrandis, a new natural hybrid pathogenic to Pelargonium grandiflorum hort.

    Science.gov (United States)

    Nirenberg, Helgard I; Gerlach, Wolfram F; Gräfenhan, Tom

    2009-01-01

    A new Phytophthora hybrid of Ph. cactorum (Leb. & Cohn) Schroet. and Ph. nicotianaevan Breda de Haan pathogenic to cultivars of Pelargonium grandiflorum hort. is described as Phytophthora X pelgrandis and its morphological features are documented. Morphological, physiological (e.g., temperature requirements) and molecular data (DNA sequencing, random amplified polymorphic DNA-PCR) are presented for isolates of the Phytophthora hybrid. Pathogenicity was tested on cultivars of P. grandiflorum and Nicotiana tabacum. For comparison cultures of the parental species and additional Phytophthora taxa also were examined.

  17. 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

  18. 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 ...

  19. 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.

  20. Mortality of container-grown blueberry plants inoculated with Phytophthora cinnamomi Rands

    Science.gov (United States)

    We conducted four studies to evaluate the effect of Phytophthora cinnamomi isolates and inoculum delivery methods on root rot development and mortality of container-grown blueberry plants. Phytophthora cinnamomi isolates were obtained from the root zone of symptomatic blueberry plants and identifie...

  1. 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

  2. The expansion of Phytophthora clade 8b: three new species associated with winter grown vegetable crops

    NARCIS (Netherlands)

    Bertier, L.; Brouwer, H.; Cock, de A.W.A.M.; Cooke, D.E.L.; Olsson, C.H.B.; Höfte, M.

    2013-01-01

    Despite its association with important agricultural crops, Phytophthora clade 8b is a poorly studied group of species. The clade currently consists of three officially described species (Phytophthora porri, P. brassicae and P. primulae) that are host-specific pathogens of leek, cabbages and Primula

  3. 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

  4. Molecular tools to unravel the role of genes from Phytophthora infestans

    NARCIS (Netherlands)

    West, van P.

    2000-01-01

    The oomycete plant pathogen Phytophthora infestans is the causal agent of potato late blight. P. infestans is undoubtedly the best known and most studied Phytophthora species today. This is mainly because it is such a devastating pathogen that can cause complete destruction of a potato field in only

  5. Amino terminal region of Phytophthora sojae cel12 endoglucanase confers tissue collapse function in Nicotiana

    Science.gov (United States)

    Phytophthora encodes an unusually large number of glycosyl hydrolases (GH), with many large gene families resulting from duplication events. There are ten copies of GH 12 (cel12) present in Phytophthora sojae. This is the only pathogen endoglucanase family to which plants produce an inhibitory pr...

  6. Novel quantitative trait loci for partial resistance to Phytophthora sojae in soybean PI 398841

    Science.gov (United States)

    Phytophthora root and stem rot caused by Phytophthora sojae Kaufmann and Gerdmann is one of the most severe soybean [Glycine max (L.) Merr] diseases in the US. Partial resistance is as effective in managing this disease as single-gene (Rps) mediated resistance and is more durable. The objective of t...

  7. Phycomycetes (Phytophthora spp. nov. and Pythium sp. nov. ) associated with degrading mangrove (Rhizophora mangle) leaves

    Energy Technology Data Exchange (ETDEWEB)

    Fell, J.W.; Master, I.M.

    1975-12-15

    Fungi of the genus Phytophthora were found to be associated with the initial stages of leaf litter decay of Rhizophora mangle L. and other Rhizophora species in estuarine and coastal marine waters. Phytophthora appears to be an important component of red-mangrove litter degradation systems throughout the tropics, which includes the Atlantic, Pacific, and Indian Oceans. The distributions of Phytophthora vesicula Anastasiou et Churchland and four new species of Phytophthora are discussed, as well as their occurrence in other tropical marine allochthonous spermatophytic leaf litter. The descriptions of the new species and varieties, Phytophthora bahamensis, P. epistomium, P. mycoparasitica, P. spinosa var. spinosa, and P. spinosa var. lobata, are presented. Pythium was rarely observed in the mangrove litter system, although one species, Pythium grandisporangium sp. nov., is described. (auth)

  8. 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}

  9. Four different Phytophthora species that are able to infect Scots pine seedlings in laboratory conditions

    Directory of Open Access Journals (Sweden)

    Tkaczyk Miłosz

    2016-09-01

    Full Text Available To investigate susceptibility of young Scots pine seedlings to four Phytophthora species: Phytophthora cactorum, Phytophthora cambivora, Phytophthora plurivora and Phytophthora pini; seven-day-old seedlings of Scots pine (15 seedlings per experiment were infected using agar plugs of the respective species. Control group also consisted of 15 seedlings and was inoculated with sterile agar plugs. Results unambiguously show that after 4.5 days, all seedlings show clear signs of infection and display severe symptoms of tissue damage and necrosis. Moreover, three and two seedlings in the P. cactorum and P. cambivora infected seedlings groups, respectively, collapsed. The length of largest necrosis measured 13.4±3.90 mm and was caused by P. cactorum. To rule out any putative contamination or infection by secondary pathogens, re-isolations of pathogens from infection sites were performed and were positive in 100% of plated pieces of infected seedlings. All re-isolations were, however, negative in the case of the control group. Detailed microscopic analyses of infected tissues of young seedlings confirmed the presence of numerous Phytophthora species inside and on the surface of infected seedlings. Therefore, our results suggest Phytophthora spp. and mainly P. cactorum and P. cambivora as aggressive pathogens of Scots pine seedlings and highlight a putative involvement of these species in the damping off of young Scots pine seedlings frequently observed in forest nurseries.

  10. The expansion of Phytophthora clade 8b: three new species associated with winter grown vegetable crops.

    Science.gov (United States)

    Bertier, L; Brouwer, H; de Cock, A W A M; Cooke, D E L; Olsson, C H B; Höfte, M

    2013-12-01

    Despite its association with important agricultural crops, Phytophthora clade 8b is a poorly studied group of species. The clade currently consists of three officially described species (Phytophthora porri, P. brassicae and P. primulae) that are host-specific pathogens of leek, cabbages and Primula spp., respectively. However, over the past few decades, several other clade 8b-like Phytophthoras have been found on a variety of different host plants that were all grown at low temperatures in winter seasons. In this study, a collection of 30 of these isolates was subjected to a phylogenetic study using two loci (the rDNA ITS region and the mitochondrial cox1 gene). This analysis revealed a clear clustering of isolates according to their host plants. To verify whether these isolates belong to separate species, a detailed morphological study was conducted. On the basis of genetic and morphological differences and host specificity, we now present the official description of three new species in clade 8b: Phytophthora cichorii sp. nov., P. dauci sp. nov. and P. lactucae sp. nov. Two other groups of isolates (Phytophthora taxon castitis and Phytophthora taxon parsley) might also represent new species but the data available at this time are insufficient for an official description. This brings Phytophthora clade 8b to a group of six species that are all host-specific, slow-growing and specifically infect herbaceous crops at low temperatures.

  11. Distribution and Virulence Diversity of Phytophthora sojae in China

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhen-dong; WANG Hua-bo; WANG Xiao-ming; CHANG Ru-zhen; WU Xiao-fei

    2004-01-01

    By investigating occurrence of Phytophthora root rot in fields and isolating P. sojae from diseased plants and soils, the distribution of P. sojae in China was surveyed. In addition to northeast region, P. sojae existed in Huanghe-Huaihe basin and Yangtze basin too. Eighty- three isolates of P. sojae isolated from different areas were identified on virulence using 13differential soybean cultivars, abundant virulence diversity was found in P. sojae. The greater diversity in virulence of P. sojae was in isolates from soil than from plants. And the greatest virulence diversity of P.sojae was found in Yangtze basin.

  12. 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...

  13. Evaluación de marcadores moleculares asociados con resistencia a gota (Phytophthora infestans L. en papas diploides y tetraploides

    Directory of Open Access Journals (Sweden)

    D. K. Juyó

    2012-06-01

    Full Text Available Normal 0 21 false false false ES-CO X-NONE X-NONE MicrosoftInternetExplorer4 Título en ingles: Evaluation of molecular markers associated with resistance to late blight (Phytophthora infestans L.  in diploid and tetraploid potatoes Resumen La papa, cultivo de importancia a nivel mundial es gravemente afectado por gota, enfermedad ocasionada por el oomycete Phytophthora infestans. Actualmente la forma más efectiva para combatir la enfermedad es mediante el desarrollo de cultivares resistentes al patógeno. Para esto, una estrategia es identificar genes que confieran resistencia al patógeno, para lo cual se buscan marcadores asociados con el carácter de resistencia. En este estudio se evaluaron marcadores moleculares tipo SCAR (Sequence Characterized Amplified Region: CosA, GP179, BA47f2 y Prp1 asociados con resistencia a P. infestans y el gen de resistencia R1, en 22 cultivares tetraploides pertenecientes a la subespecie andigena y cinco especies silvestres. Se evaluó el polimorfismo y se determinó si los alelos polimórficos permitían diferenciar genotipos resistentes de susceptibles. Se comparó el  tamaño de los fragmentos obtenidos con los fragmentos esperados asociados con resistencia de acuerdo a reportes. El análisis se realizó considerando presencia/ausencia de los fragmentos: CosA210, CosA250, R11400, R11800, BA47f2500, GP179570, Prp1300, Prp1600, y Prp1900. Los resultados indicaron que en los cultivares tetraploides y silvestres, se presentaron polimorfismos en todos los marcadores evaluados, con excepción del marcador GP179. No se encontró correlación entre el rasgo de resistencia y los alelos. Los resultados de este estudio muestran que hay repuesta diferencial a los marcadores entre las subsp. tuberosum y subsp. Andigena.   Palabras clave: Phytophthora infestans, resistencia a gota, marcadores diagnóstico, Solanum tuberosum subsp. Andigena. Abstract Potato is an important worldwide crop seriously affected by late

  14. Stability of partial resistance in potato cultivars exposed to aggressive strains of Phytophthora infestans

    NARCIS (Netherlands)

    Flier, W.G.; Bosch, van den G.B.M.; Turkensteen, L.J.

    2003-01-01

    Potato cultivars were evaluated for their resistance responses to aggressive strains of Phytophthora infestans in field and laboratory experiments. Analysis of variance revealed differential cultivar-by-isolate interactions for both foliar and tuber blight resistance. Differential responses occur as

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

    NARCIS (Netherlands)

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

    2002-01-01

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

  16. 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...

  17. 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...

  18. '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...

  19. 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 ...

  20. Isolation and Sequencing of Actin1, Actin2 and Tubulin1 Genes Involved in Cytoskeleton Formation in Phytophthora cinnamomi

    OpenAIRE

    Martins, Ivone; Lopez, Carmen; Dominguez, Ángel; Choupina, Altino

    2013-01-01

    Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. On the Nordeste Transmontano region (northeast Portugal), the Castanea sativa chestnut culture is extremely important. The biggest productivity and yield break occurs due to the ink disease, caused by Phytophthora cinnamomi which is one of the most widely distributed Phytophthora species, with nearly 1000 host species. The knowledge about molecular mechanisms resp...

  1. 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...

  2. Effects of Wheat Straw with Flooding on Soil Properties and Phytophthora Blight Control in Continuous Chili Pepper Cropping Field%麦秸淹水处理对连作土壤性状和辣椒疫病田间防控效果的影响

    Institute of Scientific and Technical Information of China (English)

    顾志光; 马艳; 安霞; 王光飞; 孙迪; 王秋君

    2014-01-01

    采用室内模拟土壤淹水的方法,研究不同麦秸用量、不同淹水时间对辣椒连作土壤理化性状和辣椒疫霉病菌数量的影响以及田间麦秸淹水处理对辣椒生长和辣椒疫病防控效果的影响。通过常规分析和定量PCR分别测定了不同淹水处理期间多种土壤理化指标和辣椒疫霉病菌的数量,调查了麦秸淹水处理后大棚辣椒的长势、产量和辣椒疫病发生率。研究结果表明:与土壤保湿处理相比,不同麦秸用量和不同淹水时间处理均能降低土壤氧化还原电位,提高土壤有机质、速效磷、速效钾、有机酸和总酚酸的含量。常规淹水和麦秸淹水处理均能降低土壤中辣椒疫霉病菌数量,在10 d和14 d两个淹水时间下,秸秆用量为0.25%时抑制效果最强,继续增加秸秆用量对辣椒疫霉病菌的抑制作用降低。辣椒生产大棚的田间淹水试验表明,添加麦秸淹水处理20 d可提高土壤中铵态氮、速效磷和速效钾的含量,降低硝态氮的含量,并可以有效防控辣椒疫病,促进辣椒植株的生长并使产量增加12%。%Crop residues may be used to control soil borne plant diseases. In a laboratory experiment, the effects of different rates of wheat straw on soil physical properties and Phytophthora capsici population were studied under different flooding time. The impact of wheat straw with flooding on the growth and yield of chili pepper was carried out in high tunnel fields. Compared to moist soil, applying wheat straw and flooding significantly decreased soil EC but increased organic matter, available phosphorus, available potassium, organic acids and phenolic acid contents. The number of P. capsici was reduced significantly in both flooding only and flooding plus wheat straw in comparison with the moist soil. Application of 0.25%wheat straw with flooding for 10 days or 14 days strongly inhibited the growth of P. capsici. However, such

  3. Global gene expression of Poncirus trifoliata, Citrus sunki and their hybrids under infection of Phytophthora parasitica

    Directory of Open Access Journals (Sweden)

    Takita Marco A

    2011-01-01

    as genes potentially involved in secondary metabolite synthesis, intracellular osmotic adjustment, signal transduction pathways of cell death, oxidative burst and defense gene expression. Furthermore, our microarray data suggest another type of resistance in Citrus-Phytophthora interaction conferred by single dominant genes (R gene since we encountered two previously reported R genes (TIR-NBS-LRR and RPS4 upregulated in the resistant genotypes relative to susceptible. We identified 7 transcripts with homology in other plants but yet unclear functional characterization which are an interesting pool for further analyses and 3 transcripts where no significant similarity was found. This is the first microarray study addressing an evaluation of transcriptional changes in response to P. parasitica in Citrus.

  4. 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.

  5. 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.;

    2016-01-01

    population of P. infestans was characterized over the course of the 2013 growing season, as was the population genetic structure, using simple sequence repeat (SSR) genotypes and single nucleotide polymorphism (SNP)-based mitochondrial haplotyping of over 80 isolates. Both mating types A1 and A2 were present......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 resistance to metalaxyl suggests the possibility for linking resistance phenotypes to specific population genetic markers, but in order to do this, the population genetic structure and mode of reproduction in a population must first be well described. The dynamics of metalaxyl-M resistance in the Danish...

  6. Population history and pathways of spread of the plant pathogen Phytophthora plurivora.

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    Corine N Schoebel

    Full Text Available Human activity has been shown to considerably affect the spread of dangerous pests and pathogens worldwide. Therefore, strict regulations of international trade exist for particularly harmful pathogenic organisms. Phytophthora plurivora, which is not subject to regulations, is a plant pathogen frequently found on a broad range of host species, both in natural and artificial environments. It is supposed to be native to Europe while resident populations are also present in the US. We characterized a hierarchical sample of isolates from Europe and the US and conducted coalescent-, migration, and population genetic analysis of sequence and microsatellite data, to determine the pathways of spread and the demographic history of this pathogen. We found P. plurivora populations to be moderately diverse but not geographically structured. High levels of gene flow were observed within Europe and unidirectional from Europe to the US. Coalescent analyses revealed a signal of a recent expansion of the global P. plurivora population. Our study shows that P. plurivora has most likely been spread around the world by nursery trade of diseased plant material. In particular, P. plurivora was introduced into the US from Europe. International trade has allowed the pathogen to colonize new environments and/or hosts, resulting in population growth.

  7. 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.

  8. Overexpression of soybean isoflavone reductase (GmIFR enhances resistance to Phytophthora sojae in soybean

    Directory of Open Access Journals (Sweden)

    Qun eCheng

    2015-11-01

    Full Text Available 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. The cDNA of GmIFR was 1199 bp containing a 939 bp open reading frame encoding a polypeptide of 312 amino acids. Sequence analysis suggested that GmIFR contained a NAD(P domain of 107 amino acids. 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 (ABA, salicylic acid (SA. It is located in the cytoplasmic when transiently expressed in Arabidopsis protoplasts. The daidzein levels reduced greatly for the seeds of transgenic plants, while levels of genistein and glycitein had little change compared to that of control plants. Furthermore, we also found that the reactive oxygen species (ROS content of transgenic soybean plants was significantly lower than that of control plants, suggesting an important role of GmIFR might function as an antioxidant to reduce ROS in soybean.

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

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    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.

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

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    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

  11. 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.

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

    NARCIS (Netherlands)

    Bouwmeester, K.; Govers, F.

    2009-01-01

    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 interac

  13. Pathogenicity, fungicide resistance, and genetic variability of Phytophthora rubi isolates from raspberry (Rubus idaeus) in the Western United States

    Science.gov (United States)

    Root rot of raspberry (Rubus idaeus), thought to be primarily caused by Phytophthora rubi, is an economically important disease in the western United States. The objectives of this study were to determine which Phytophthora species are involved in root rot, examine the efficacy of different isolatio...

  14. Genome-wide association mapping of partial resistance to Phytophthora sojae in soybean plant introductions from the Republic of Korea

    Science.gov (United States)

    Phytophthora root and stem rot is one of the most yield-limiting diseases of soybean [Glycine max (L.) Merr], caused by the oomycete Phytophthora sojae. Partial resistance is controlled by several genes and, compared to single gene (Rps gene) resistance to P. sojae, places less selection pressure on...

  15. Mapping of quantitative trait loci associated with partial resistance to phytophthora sojae and flooding tolerance in soybean

    Science.gov (United States)

    Phytophthora root rot (PRR) caused by Phytophthora sojae Kaufm. & Gerd. and flooding can limit growth and productivity, of soybean [Glycine max (L.) Merr.], especially on poorly drained soils. The primary objective of this research project was to map quantitative trait loci (QTL) associated with f...

  16. Molecular response to the pathogen Phytophthora sojae among ten soybean near isogenic lines revealed by comparative transcriptomics

    Science.gov (United States)

    Phytophthora root and stem rot (PRR) of soybean, caused by Phytophthora sojae, is effectively controlled by Rps genes in soybean. Rps genes are race-specific, yet the mechanism of resistance, as well as susceptibility, remains largely unclear. Taking advantage of RNA-seq technology, we sequenced the...

  17. 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.

  18. Examination of some morphologically unusual cultures of Phytophthora species using a mitochondrial DNA miniprep technique and a standardised sporangium caducity assessment.

    Science.gov (United States)

    Hall, G S

    Using the mitochondrial DNA miniprep technique, the identity of sixteen morphologically unusual cultures allocated to Phytophthora nicotianae, Phytophthora mexicana or Phytophthora porri was determined by comparison with a library of mtDNA band patterns obtained from reference cultures. Seven cultures were identified as Phytophthora nicotianae (including those assigned to Phytophthora mexicana and Phytophthora porri), six as strains of Phytophthora palmivora with small, ovoid, weakly caducous sporangia, and one as Phytophthora citrophthora. Some cultures of P. nicotianae had a low percentage of caducous sporangia. Percentage sporangium caducity, but not sporangium L:B ratio, is considered a useful taxonomic criterion for separating species morphologically similar to Phytophthora nicotianae. One culture from tobacco in New Zealand had a highly unusual morphology and a unique DNA band pattern, but was not identifiable. One culture from Acacia mearnsii in South Africa had a unique DNA band pattern which was identical to that of an isolate from Annona squamosa from Australia previously identified as Phytophthora palmivora, the precise identity of which is still unclear. The identity of most isolates from diseased durian was found to be Phytophthora palmivora, confirming its role as the main pathogen, but P. nicotianae was also identified from this host.

  19. [Effect of pentachloronitrobenzene (PCNB) on the ultrastructure of Mucor mucedo and Phytophthora cactorum].

    Science.gov (United States)

    Casperson, G; Lyr, H

    1982-01-01

    The effect of PCNB in various concentrations on the ultrastructure of Mucor mucedo and phytophthora cactorum was analyzed after an incubation period of 2 hours. The most striking effect in both fungi was a diffuse lysis of the internal structure of the mitochondria which differs markedly from the lysis induced by etridiazol (terrazol). Moreover an enlargement of the perinuclear space and an increased formation of vacuoles was observed. In Mucor mucedo, but not in Phytophthora cactorum a pathological thickening of the cell wall was observed. Although after 2 hours incubation with PCNB Phytophthora gave similar ultrastructural reactions in the mitochondria as Mucor, in growth experiments on agar dishes this species was 5-10 times less sensitive to PCNB compared to Mucor.

  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. 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

  2. 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

  3. Phytophthora austrocedri Elicitates Changes in Diterpene Profile of Austrocedrus chilensis.

    Science.gov (United States)

    Olate, Verónica Rachel; Vélez, María Laura; Greslebin, Alina; Schmeda-Hirschmann, Guillermo

    2015-08-18

    The populations of the Andean Cupressaceae Austrocedrus chilensis have been severely affected by a disease caused by the phytopathogenic fungus Phytophthora austrocedri. A study was undertaken to disclose changes in the resin composition of P. austrocedri-infected individuals, including naturally infected and artificially inoculated trees, compared with healthy A. chilensis trees. GC-MS and (1)H-NMR studies showed a clear differentiation among healthy and infected resins, with the diterpene isopimara-8(9),15-dien-19-ol as a relevant constituent in resins from infected trees. The effect of resin fractions from P. austrocedri infected trees on the pathogen was assessed by measuring the mycelial growth in agar plates. The most active fractions from resin obtained from infected trees inhibited fungal growth by nearly 50% at 1 mg/dish (35.37 µg/cm(2)). The main constituent in the active fractions were 18-hydroxymanool and the aldehyde torulosal. Both compounds are oxidation products of manool and can be a chemical response of the tree to the pathogen or be formed from the pathogen as a biotransformation product of manool by microbial oxidation. While the diterpene profiles from A. chilensis tree resins can easily differentiate healthy and P. austrocedri infected individuals, the possible conversion of manool to the antifungal derivatives 4 and 6 by the microorganism remains to be established.

  4. 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.

  5. 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.

  6. Phytophthora austrocedri Elicitates Changes in Diterpene Profile of Austrocedrus chilensis

    Directory of Open Access Journals (Sweden)

    Verónica Rachel Olate

    2015-08-01

    Full Text Available The populations of the Andean Cupressaceae Austrocedrus chilensis have been severely affected by a disease caused by the phytopathogenic fungus Phytophthora austrocedri. A study was undertaken to disclose changes in the resin composition of P. austrocedri-infected individuals, including naturally infected and artificially inoculated trees, compared with healthy A. chilensis trees. GC-MS and 1H-NMR studies showed a clear differentiation among healthy and infected resins, with the diterpene isopimara-8(9,15-dien-19-ol as a relevant constituent in resins from infected trees. The effect of resin fractions from P. austrocedri infected trees on the pathogen was assessed by measuring the mycelial growth in agar plates. The most active fractions from resin obtained from infected trees inhibited fungal growth by nearly 50% at 1 mg/dish (35.37 µg/cm2. The main constituent in the active fractions were 18-hydroxymanool and the aldehyde torulosal. Both compounds are oxidation products of manool and can be a chemical response of the tree to the pathogen or be formed from the pathogen as a biotransformation product of manool by microbial oxidation. While the diterpene profiles from A. chilensis tree resins can easily differentiate healthy and P. austrocedri infected individuals, the possible conversion of manool to the antifungal derivatives 4 and 6 by the microorganism remains to be established.

  7. 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.

  8. 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...

  9. 致病疫霉(Phytophthora infestans)对杀菌剂 抗药性研究进展%Advance on fungicides resistance of Phytophthora infestans

    Institute of Scientific and Technical Information of China (English)

    杨志辉; 张志铭; 朱杰华; 赵会欣

    2001-01-01

    综述了致病疫霉(Phytophthora infestans)对内吸性杀菌剂甲霜灵、霜脲氰和保护性杀菌剂代森锰锌和百菌清的抗性研究进展,总结了当前用于防治晚疫病的药剂种类并提出了抗性治理策略。对于致病疫霉抗性遗传研究和抗性治理及药剂防治都具有一定的参考价值。%Progress on the resistance of systemic fungicides (metalaxyl and cymoxanil) and protectant fungicidies ( mancozeb and chlorothalonil) to Phytophthora infestans was reviewed. Fungicides used in controlling late blight were listed and strategies on resistance management were proposed. It might be referred.on resistance inheritance research, resistance management and fungicide control.

  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. 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.

  12. 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.

  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. Research Progress in Physiological Race of Phytophthora Sojae%大豆疫霉菌(Phytophthora sojae)生理小种研究进展

    Institute of Scientific and Technical Information of China (English)

    王颖; 臧忠婧

    2002-01-01

    综述了大豆疫霉菌 (phytophthora sojae)的生理分化和生理小种的研究进展,包括传统的毒性分析到分子技术的应用,探讨了小种鉴定中发现的无毒菌株的成因及其特征.

  15. Sensitivities of Phytophthora infestans to Metalaxyl, Cymoxanil, and Dimethomorph

    Institute of Scientific and Technical Information of China (English)

    ZHU Gui-ning; HUANG Fu-xin; FENG Lan-xiang; QIN Bi-xia; YANG Yu-hong; CHEN Yong-hui; LU Xiu-hong

    2008-01-01

    The isolates of Phytophthora infestans on tomato in the Guangxi Zhuang Autonomous Region, China, were determined for the sensitivities to metalaxyl, cymoxanil and dimethomorph to give the basic information for integrating disease management. Sensitivities were tested by measuring the radial growth on agar medium amended with fungicide, compared with the floating-leaf-disk method. 239 isolates were collected from eight tomato growing areas during 2000-2006. The testing results indicated that the frequencies of sensitive, intermediate, and resistant isolates to metalaxyl were 42.26, 35.98, and 23.53%, respectively. Variations in sensitivities amongst isolates from different areas or different years were very high for metalaxyl. All isolates from Tianlin and Wuxuan were sensitive to metalaxyl, but the metalaxyl-resistant isolates predominated in Tianyang, with the frequency of 51.35%. The EC50 values of certain isolates from Tianyang were higher than 500 μg mL-1 and their resistance levels were over 100000 folds. Cymoxanil has been used for nearly 10 years in Guangxi, and dimethomorph has been used for 5-6 years. However, there was no decrease in sensitivity of P. infestans populations and the sensitivities of the pathogen were nearly normally distributed. Hence, their mean EC50 value [cymoxanil (0.1647±0.0255) μg mL-1, dimethomorph (0.0970±0.0052) μg mL-1] could be used as the baseline sensitivities for monitoring the field resistance development. The comparison with the floating-leaf-disk method indicates that both the techniques provided equivalent results. These studies suggested that metalaxyl can be continuously applied in Tianlin, Wuxuan, and Nanning due to the resistant isolates that have not been found, while for those areas with resistant isolate, the use of metalaxyl should be reduced or alternated, and cymoxanil or dimethomorph was recommended for controlling late blight disease of tomato.

  16. 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

  17. Identification of potato genes involved in Phytophthora infestans resistance by transposon mutagenesis

    NARCIS (Netherlands)

    Enckevort, van L.J.G.

    2000-01-01

    The late blight disease, caused by the oomycete Phytophthora infestans (Mont.) de Bary, is a serious threat to the potato crop every growing season. This has, for example, led to the disastrous Irish famine in the middle of the 19 th century, and continued in the 20 th century

  18. 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

  19. 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...

  20. Understanding the role of L-type lectin receptor kinases in Phytophthora resistance

    NARCIS (Netherlands)

    Wang, Y.

    2014-01-01

    Abstract Phytophthora pathogens are notorious for causing severe damage to many agriculturally and ornamentally important plants. Effective plant resistance depends largely on the capacity to perceive pathogens and to activate rapid defence. Cytoplasmic resistance (R) proteins are w

  1. Phytophthora infestans RXLR effector AVR1 and its host target Sec5

    NARCIS (Netherlands)

    Du, Y.

    2014-01-01

    Summary Late blight, caused by the oomycete Phytophthora infestans, is one of the most devastating potato diseases worldwide. To successfully colonize its host, P. infestans secretes a plethora of RXLR effectors that translocate into host cells to modulate plant defense. The RXLR ef

  2. Multiplex SSR analysis of Phytophthora infestans in different countries and the importance for potato breeding

    NARCIS (Netherlands)

    Li, Y.

    2012-01-01

    Potato is the most important non-cereal crop in the world. Late blight, caused by the oomycete pathogen Phytophthora infestans, is the most devastating disease of potato. In the mid-19th century, P. infestans attacked the European potato fields and this resulted in a widespread famine in Ireland and

  3. Genetical studies of resistance to Phytophthora porri in Allium porrum, using a new early screening method.

    NARCIS (Netherlands)

    Smilde, W.D.; Nes, van M.; Reinink, K.; Kik, C.

    1997-01-01

    A new screening method was developed to evaluate resistance of leek (Allium porrum) to Phytophthora porri, based on inoculation by 24 h-immersion of leek plantlets in the 3–6 leaf stage in a suspension of ca. 100 zoospores.ml-1. The immersion test was used for identifying new sources of resistance a

  4. 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

  5. Antifungal activity of extracts and select compounds in heartwood of seven western conifers 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 red cedar exhibited the strongest activity (EC50 589 and 646 ppm, respectively), yellow-cedar, western juniper,...

  6. 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...

  7. '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

  8. Stability of resistance to Phytophthora infestans in potato: an international evaluation

    NARCIS (Netherlands)

    Forbes, G.A.; Chacon, M.G.; Kirk, H.G.; Huarte, M.A.; Damme, van M.M.A.; Distel, S.; Mackay, G.R.; Stewart, H.E.; Lowe, R.; Duncan, J.M.; Mayton, H.S.; Fry, W.E.; Andrivon, D.; Ellisseche, D.; Pelle, R.; Platt, H.W.; MacKenzie, G.; Tarn, T.R.; Colon, L.T.; Budding, D.J.; Lozoya-Saldana, H.

    2005-01-01

    Ten institutions in nine countries joined together to test the stability of resistance of 14 potato genotypes to the oomycete pathogen Phytophthora infestans in three separate trials. Seven of the genotypes were tested in one trial involving seven locations, and all 14 were tested in two subsequent

  9. New Phytophthora populations: A shift from indirect to direct sporangial germination?

    NARCIS (Netherlands)

    Kessel, G.J.T.; Veloso, S.; Forch, M.G.; Latorse, M.P.

    2009-01-01

    Phytophthora infestans, the causal agent of potato- and tomato late blight, remains a serious threat for (commercial) potato and tomato production. In North Western Europe, frequent fungicide applications, mostly aimed to prevent infection, form the back bone of potato late blight control. Modern pr

  10. Potato R1 resistance gene confers resistance against Phytophthora infestans in transgenic tomato plants

    NARCIS (Netherlands)

    Faino, L.; Carli, P.; Testa, A.; Cristinzio, G.; Frusciante, L.; Ercolano, M.R.

    2010-01-01

    Tomato is challenged by several pathogens which cause loss of production. One such pathogen is the oomycete Phytophthora infestans which is able to attack all the aerial parts of the plant. Although a wide range of resistance sources are available, genetic control of this disease is not yet successf

  11. The potato late blight pathogen Phytophthora infestans and other pathogenic oomycota

    NARCIS (Netherlands)

    Govers, F.; Drenth, A.; Pieterse, C.M.J.

    1997-01-01

    Potato late blight, caused by a member of the Oomycota, Phytophthora infestans (Mont.) De Bary, is one of the most important and devastating diseases of potato (Solanum tuberosum). The pathogen attacks both foliage and tubers, and spreads rapidly through host tissues, thereby causing a destructive n

  12. 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

  13. 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...

  14. 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...

  15. 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...

  16. 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

  17. Identification of quantitative trait loci conditioning partial resistance to Phytophthora sojae in soybean PI 407861A

    Science.gov (United States)

    Improving resistance for Phytophthora root and stem rot is an important goal in soybean [Glycine max (L.) Merr.] breeding. Partial resistance can be as effective in managing this disease as single-gene (Rps) mediated resistance and is more durable. The objective of this study was to identify QTL con...

  18. 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

  19. tef1, a Phytophthora infestans gene encoding translation elongation factor 1-alpha

    NARCIS (Netherlands)

    Klooster, van 't J.W.; Berg-Velthuis, van den G.; West, van P.; Govers, F.

    2000-01-01

    From a set of Phytophthora infestans cDNA clones randomly selected from a potato-P. infestans interaction cDNA library, three out of 22 appeared to correspond to a gene encoding translation elongation factor 1α. The gene, called tef1, is a single copy gene in P. infestans. During the life cycle of P

  20. 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...

  1. Large subclonal variation in Phytophthora infestans populations associated with Ecuadorian potato landraces

    NARCIS (Netherlands)

    Delgado, R.A.; Monteros-Altamiro, A.R.; Li, Y.; Visser, R.G.F.; Lee, van der T.A.J.; Vosman, B.

    2013-01-01

    The population of Phytophthora infestans on potato landraces in three provinces (Carchi, Chimborazo and Loja) of Ecuador was analysed. All isolates (n = 66) were of the A1 mating type. Simple sequence repeats (SSR) were used to assess the genetic diversity of the isolates. The P. infestans isolates

  2. Diverse evolutionary trajectories for small RNA biogenesis genes in the oomycete genus Phytophthora

    Science.gov (United States)

    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, ...

  3. A Phytophthora sojae effector suppresses endoplasmic reticulum stress-mediated immunity by stabilizing plant Binding immunoglobulin Proteins

    Science.gov (United States)

    Jing, Maofeng; Guo, Baodian; Li, Haiyang; Yang, Bo; Wang, Haonan; Kong, Guanghui; Zhao, Yao; Xu, Huawei; Wang, Yan; Ye, Wenwu; Dong, Suomeng; Qiao, Yongli; Tyler, Brett M.; Ma, Wenbo; Wang, Yuanchao

    2016-01-01

    Phytophthora pathogens secrete an array of specific effector proteins to manipulate host innate immunity to promote pathogen colonization. However, little is known about the host targets of effectors and the specific mechanisms by which effectors increase susceptibility. Here we report that the soybean pathogen Phytophthora sojae uses an essential effector PsAvh262 to stabilize endoplasmic reticulum (ER)-luminal binding immunoglobulin proteins (BiPs), which act as negative regulators of plant resistance to Phytophthora. By stabilizing BiPs, PsAvh262 suppresses ER stress-triggered cell death and facilitates Phytophthora infection. The direct targeting of ER stress regulators may represent a common mechanism of host manipulation by microbes. PMID:27256489

  4. 烟草疫霉拮抗菌株P-72-10的鉴定及其拮抗代谢产物初步分析%Identification and characterization of antagonistic bacterial strain P-72-10 against Phytophthora nicotianae

    Institute of Scientific and Technical Information of China (English)

    董国菊; 李文英; 刘翠平; 周常勇; 肖崇刚

    2012-01-01

    Tobacco black shank, caused by Phytophthora nicotianae van Breda de Haan, is one of economically important disease of tobacco production. In the previous study, a strain P-72-10 was isolated from the healthy tobacco in the rhizosphere soil of Chongqing. It was selected based on its strong antagonistic activity a-gainst P. nicotianae on the plate dual-culture test and its ability to suppress tobacco black shank disease effectively in the greenhouse condition. In the study, the phylogeny of P-72-10 was analyzed, and its taxonomic position was identified using morphological and chemotaxonomic characteristics, together with 16S rDNA gene phylogenetic analysis. The colonies were cream in color on KB culture. Cells were gram-negative, rod-shaped [ (8.1 -16.2)(i,m x (1.8 -4.8) jun], motile owing to one or several polar flagella and did not form endo-spores. The growth temperature for P-72-10 ranged from 4 to 401 with the optimum at 28 -30t. The results of BIOLOG GN2 showed that P-72-10 belonged to Pseudomonas. The genomic (G +C) content was 60.72%. Phylogenetic analysis of the 16SrDNA gene sequence revealed that P-72-10 was the most closely related to P. fluorescens, with the sequence similarity of 99%. Nucleotide number of the accession was HQ888871. Taxo-nomically, strain P-72-10 was identified as P. fluorescens. On the plate culture, strain P-72-10 produced pro-teinase, celluase, and siderophore, but not chitinase.%为探讨烟草根际生防细菌的生防机制,从重庆地区连作烟田健康炳株根际土壤中分离筛选到1株对烟草疫霉具有较强拮抗作用和对黑胫病具有良好防效的细菌菌株P-72-10.根据培养性状、形态特征、生理生化特性、基因组DNA的(G+C)mol%含量测定以及16S rDNA基因序列分析确定该菌株的分类地位.该菌株菌落乳白色,能产生水溶性荧光色素,革兰氏染色反应阴性,菌体秆状、大小(8.1 ~16.2)μm ×(1.8~4.8)μm,单端生鞭毛,不形成芽孢.The BIOLOG GN2结

  5. 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...

  6. Internetprogramma geeft inzicht in eigen Phytophthora-strategie. (Internet site gives insight in effectiveness of growers personal potato late blight control strategies)

    NARCIS (Netherlands)

    Kessel, G.J.T.; Hanse, L.

    2005-01-01

    Om telers te helpen met hun bestrijdingsstrategie is het Agrobiocon programma 'Visualisatie infectie Phytophthora' ontwikkeld. Uitleg van mede ontwikkelaar Geert Kessel van Plant Research International van Wageningen UR

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. SNP markers identify widely distributed clonal lineages of Phytophthora colocasiae in Vietnam, Hawaii and Hainan Island, China.

    Science.gov (United States)

    Shrestha, Sandesh; Hu, Jian; Fryxell, Rebecca Trout; Mudge, Joann; Lamour, Kurt

    2014-01-01

    Taro (Colocasia esculenta) is an important food crop, and taro leaf blight caused by Phytophthora colocasiae can significantly affect production. Our objectives were to develop single nucleotide polymorphism (SNP) markers for P. colocasiae and characterize populations in Hawaii (HI), Vietnam (VN) and Hainan Island, China (HIC). In total, 379 isolates were analyzed for mating type and multilocus SNP profiles including 214 from HI, 97 from VN and 68 from HIC. A total of 1152 single nucleotide variant (SNV) sites were identified via restriction site-associated DNA (RAD) sequencing of two field isolates. Genotyping with 27 SNPs revealed 41 multilocus SNP genotypes grouped into seven clonal lineages containing 2-232 members. Three clonal lineages were shared among countries. In addition, five SNP markers had a low incidence of loss of heterozygosity (LOH) during asexual laboratory growth. For HI and VN, >95% of isolates were the A2 mating type. On HIC, isolates within single clonal lineages had A1, A2 and A0 (neuter) isolates. The implications for the wide dispersal of clonal lineages are discussed.

  12. SNP markers identify widely distributed clonal lineages of Phytophthora colocasiae in Vietnam, Hawaii and Hainan Island, China.

    Science.gov (United States)

    Shrestha, Sandesh; Hu, Jian; Fryxell, Rebecca Trout; Mudge, Joann; Lamour, Kurt

    2014-01-01

    Taro (Colocasia esculenta) is an important food crop, and taro leaf blight caused by Phytophthora colocasiae can significantly affect production. Our objectives were to develop single nucleotide polymorphism (SNP) markers for P. colocasiae and characterize populations in Hawaii (HI), Vietnam (VN) and Hainan Island, China (HIC). In total, 379 isolates were analyzed for mating type and multilocus SNP profiles including 214 from HI, 97 from VN and 68 from HIC. A total of 1152 single nucleotide variant (SNV) sites were identified via restriction site-associated DNA (RAD) sequencing of two field isolates. Genotyping with 27 SNPs revealed 41 multilocus SNP genotypes grouped into seven clonal lineages containing 2-232 members. Three clonal lineages were shared among countries. In addition, five SNP markers had a low incidence of loss of heterozygosity (LOH) during asexual laboratory growth. For HI and VN, >95% of isolates were the A2 mating type. On HIC, isolates within single clonal lineages had A1, A2 and A0 (neuter) isolates. The implications for the wide dispersal of clonal lineages are discussed. PMID:24895424

  13. 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.

  14. Identification of potato genes involved in Phytophthora infestans resistance by transposon mutagenesis

    OpenAIRE

    Enckevort, van, P.L.A.

    2000-01-01

    The late blight disease, caused by the oomycete Phytophthora infestans (Mont.) de Bary, is a serious threat to the potato crop every growing season. This has, for example, led to the disastrous Irish famine in the middle of the 19 th century, and continued in the 20 th century to remain a serious problem for potato growers. Since the early 1980s P. infestans populations changed more rapidly and epidemics even increased in their severity. Resistance breeding stimulated the introduction of resi...

  15. 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...

  16. 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...

  17. 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...

  18. Aggressiveness of Phytophthora infestans on detached potato leaflets in four Nordic countries

    DEFF Research Database (Denmark)

    Lehtinen, A; Andersson, B; Le, V H;

    2009-01-01

    Potato fields in Denmark, Finland, Norway and Sweden were sampled for single-lesion isolates of Phytophthora infestans. The aggressiveness of the isolates was determined on detached leaflets of potato cvs Bintje (susceptible) and Matilda (moderately resistant). The aggressiveness tests were carried...... differences between the test laboratories for infection efficiency, lesion growth rate and sporulation capacity on detached leaflets. When the laboratory effect was taken into account, the differences in aggressiveness between the countries were generally small or inconsistent between the test cultivars...

  19. 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...

  20. 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

  1. 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

  2. Dicty_cDB: Contig-U14940-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 4e-60 EU079543_1( EU079543 |pid:none) Phytophthora capsici isolate PD_00... 233 4e-60 EU079782_1( EU079782 |...pid:none) Phytophthora vignae isolate PD_001... 233 5e-60 EU079555_1( EU079555 |pid:none) Phytophthora nicot

  3. Study on Virulence Structure of Phytophthora sojae in Xinjiang%新疆大豆疫霉菌的毒力组成研究

    Institute of Scientific and Technical Information of China (English)

    崔林开; 胡艳红

    2012-01-01

    为明确大豆疫霉菌在新疆的分布和新疆大豆疫霉菌的毒力组成,采用大豆叶碟诱捕法从新疆大豆田土壤中分离大豆疫霉菌,并采用幼苗下胚轴伤口接种法鉴定大豆疫霉菌的毒力.结果共分离到26个大豆疫霉菌株,毒力测定鉴定出20个不同的毒力型,说明新疆的大豆疫霉菌表现出丰富的毒力多样性.新疆大豆疫霉菌对抗病基因Rpsla,Rpslc和Rpslk的毒力频率均为0,因此,可应用这3个抗病基因对新疆大豆疫霉根腐病进行有效控制.%Phytophthora sojae was isolated from soil samples collected in Xinjiang by the soybean leaf-disc baiting method, and then their pathotypes were characterized using the hypocotyl slit inoculation method. A total of 26 P. sojae isolates were obtained and 20 pathotypes were identified from these isolates. The result indicated that virulence diversity of P. sojae was abundant in Xinjiang. All the isolates were avirulent to cultivars with single resistance genes Rpsla ,Rpslc, and Rpslk ,so these resistance genes had a high application value in better control of Phytophthora root and stem rot.

  4. 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

  5. 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

  6. 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.

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. Evidence for small RNAs homologous to effector-encoding genes and transposable elements in the oomycete Phytophthora infestans.

    Directory of Open Access Journals (Sweden)

    Ramesh R Vetukuri

    Full Text Available Phytophthora infestans is the oomycete pathogen responsible for the devastating late blight disease on potato and tomato. There is presently an intense research focus on the role(s of effectors in promoting late blight disease development. However, little is known about how they are regulated, or how diversity in their expression may be generated among different isolates. Here we present data from investigation of RNA silencing processes, characterized by non-coding small RNA molecules (sRNA of 19-40 nt. From deep sequencing of sRNAs we have identified sRNAs matching numerous RxLR and Crinkler (CRN effector protein genes in two isolates differing in pathogenicity. Effector gene-derived sRNAs were present in both isolates, but exhibited marked differences in abundance, especially for CRN effectors. Small RNAs in P. infestans grouped into three clear size classes of 21, 25/26 and 32 nt. Small RNAs from all size classes mapped to RxLR effector genes, but notably 21 nt sRNAs were the predominant size class mapping to CRN effector genes. Some effector genes, such as PiAvr3a, to which sRNAs were found, also exhibited differences in transcript accumulation between the two isolates. The P. infestans genome is rich in transposable elements, and the majority of sRNAs of all size classes mapped to these sequences, predominantly to long terminal repeat (LTR retrotransposons. RNA silencing of Dicer and Argonaute genes provided evidence that generation of 21 nt sRNAs is Dicer-dependent, while accumulation of longer sRNAs was impacted by silencing of Argonaute genes. Additionally, we identified six microRNA (miRNA candidates from our sequencing data, their precursor sequences from the genome sequence, and target mRNAs. These miRNA candidates have features characteristic of both plant and metazoan miRNAs.

  12. Mating type, mefenoxam sensitivity, and pathotype diversity in Phytophthora infestans isolates from tomato in Brazil Grupo de compatibilidade, sensibilidade ao mefenoxam e diversidade de patótipos de isolados de Phytophthora infestans de tomate no Brasil

    Directory of Open Access Journals (Sweden)

    Bruno Eduardo Cardozo de Miranda

    2010-07-01

    Full Text Available The objective of this work was to characterize 79 Phytophthora infestans isolates collected in tomato (Solanum lycopersicum fields, as to mating type, mefenoxam sensitivity, and pathotype composition. The isolates were sampled in 2006 and 2007 in seven Brazilian states as well as in the Distrito Federal. They were characterised as to mating type (n=79, sensitivity to fungicide mefenoxam (n=79, and virulence to three major resistance genes Ph-1, Ph-2, and Ph-3/Ph-4 (n=62. All isolates were of the mating type A1. Resistant isolates were detected in all sampled states, and its average frequency was superior to 50%. No difference was detected in pathotype diversity, neither between subpopulations collected in 2006 and 2007 nor between isolates grouped as resistant or intermediately sensitive to mefenoxam. All major resistance genes were overcome at different frequencies: Ph-1, 88.7%; Ph-2, 64.5%; and Ph-3/Ph-4, 25.8%. Isolates with virulence genes able to overcome all major resistance genes were detected at low frequencies. Tomato breeding programs in Brazil must avoid the development of cultivars with resistance based exclusively on major genes.O objetivo deste trabalho foi caracterizar 79 isolados de Phytophthora infestans, coletados em campos de tomate (Solanum lycopersicum, quanto ao grupo de compatibilidade, à sensibilidade ao mefenoxan, e à diversidade de patótipos. Os isolados foram obtidos em coletas realizadas nos anos de 2006 e 2007, em sete Estados do Brasil e no Distrito Federal. Os isolados foram usados para determinação do grupo de compatibilidade sexual (n=79, resistência ao fungicida mefenoxam (n=79 e espectro de virulência aos genes de efeito principal Ph-1, Ph-2 e Ph-3/Ph-4 (n=62. Todos os isolados foram classificados no grupo de compatibilidade A1. Isolados insensíveis ao fungicida mefenoxam foram detectados em todos os Estados amostrados, e apresentaram frequência média superior a 50%. Não houve diferença de

  13. 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

  14. 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...

  15. 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...

  16. 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...

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  18. 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

  19. 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

  20. 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

  1. Genetic diversity of Phytophthora infestans sensu lato in Ecuador provides new insight into the origin of this important plant pathogen

    NARCIS (Netherlands)

    Adler, N.E.; Erselius, L.J.; Chacón, G.M.; Flier, W.G.; Ordonez, M.E.; Kroon, L.P.N.M.; Forbes, G.A.

    2004-01-01

    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 a

  2. 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

  3. 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...

  4. Identification of a resistance gene Rpi-dlc1 to Phytophthora infestans in European accessions of Solanum dulcamara

    NARCIS (Netherlands)

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

    2010-01-01

    Initial screening of 14 Solanum dulcamara accessions enabled the identification of individuals resistant and susceptible to Phytophthora infestans. Crosses between contrasting genotypes resulted in three F2–BC1 populations segregating for resistance to late blight in a laboratory assay and under fie

  5. The Ph-3 gene from Solanum pimpinellifolium encodes CC-NBS-LRR protein conferring resistance to Phytophthora infestans

    NARCIS (Netherlands)

    Zhang, C.; Liu, L.; Wang, X.; Vossen, J.H.; Li, G.; Li, T.; Zheng, Z.; Gao, J.; Guo, Y.; Visser, R.G.F.; Junming Li, J.; Bai, Y.; Du, Yongchen

    2014-01-01

    Late blight, caused by Phytophthora infestans, is one of the most destructive diseases in tomato. The resistance (R) gene Ph-3, derived from Solanum pimpinellifolium L3708, provides resistance to multiple P. infestans isolates and has been widely used in tomato breeding programmes. In our previous s

  6. Improved Phytophthora resistance in commercial chickpea (Cicer arietinum) varieties negatively impacts symbiotic gene signalling and symbiotic potential in some varieties.

    Science.gov (United States)

    Plett, Jonathan M; Plett, Krista L; Bithell, Sean L; Mitchell, Chris; Moore, Kevin; Powell, Jeff R; Anderson, Ian C

    2016-08-01

    Breeding disease-resistant varieties is one of the most effective and economical means to combat soilborne diseases in pulse crops. Commonalities between pathogenic and mutualistic microbe colonization strategies, however, raises the concern that reduced susceptibility to pathogens may simultaneously reduce colonization by beneficial microbes. We investigate here the degree of overlap in the transcriptional response of the Phytophthora medicaginis susceptible chickpea variety 'Sonali' to the early colonization stages of either Phytophthora, rhizobial bacteria or arbuscular mycorrhizal fungi. From a total of 6476 genes differentially expressed in Sonali roots during colonization by any of the microbes tested, 10.2% were regulated in a similar manner regardless of whether it was the pathogenic oomycete or a mutualistic microbe colonizing the roots. Of these genes, 49.7% were oppositely regulated under the same conditions in the moderately Phytophthora resistant chickpea variety 'PBA HatTrick'. Chickpea varieties with improved resistance to Phytophthora also displayed lower colonization by rhizobial bacteria and mycorrhizal fungi leading to an increased reliance on N and P from soil. Together, our results suggest that marker-based breeding in crops such as chickpea should be further investigated such that plant disease resistance can be tailored to a specific pathogen without affecting mutualistic plant:microbe interactions.

  7. Joint QTL analyses for partial resistance to Phytophthora sojae using six nested inbred populations with heterogeneous conditions

    Science.gov (United States)

    Partial resistance to Phytophthora sojae in soybean is controlled by multiple quantitative trait loci (QTL). With traditional QTL mapping approaches, power to detect these QTL, frequently of small effect, can be limited by population size. Joint linkage QTL analysis of nested recombinant inbred li...

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

  10. 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...

  11. 植物内生细菌在辣椒体内的定殖动态及对辣椒疫病的防治效果%Colonization Dynamics of Endophytic Bacteria in Capsicum annuum and Their Control Effects on Pepper Phytophthora Blight

    Institute of Scientific and Technical Information of China (English)

    付思娅; 陈双林; 闫淑珍

    2013-01-01

    为了探讨具生防作用的植物内生细菌在辣椒体内的定殖动态与其防治辣椒疫病的关系,采用对峙培养法和盆栽苗防效法筛选生防菌株,依据菌体形态、生理生化性质和16S rDNA序列鉴定菌种,用抗利福平标记研究菌株在辣椒苗中的定殖动态,在同时接入植物内生细菌和灌根接种辣椒疫霉菌的条件下分析生防菌株的定殖数量与防效的关系。结果表明,菌株G9、R15和J13对辣椒疫病防效最好,经鉴定均为荧光假单胞菌Pseudomonas fluorescens。菌株G9和R15在辣椒根部定殖量高于菌株J13;定殖周期均在30~40 d,呈“先增后减”的变化趋势;菌株G9和R15在接种第15 d时定殖量最高,菌株J13在根、茎和叶中定殖量达到最高的天数分别为第9、15和15~20 d,定殖数量的变化为根>茎>叶。菌株G9定殖量达到9.73×105 cfu·g−1时辣椒疫病的防效达到100%,保持该数量的时间约6 d;菌株R15定殖量达到6.30×105 cfu·g−1以上时对辣椒疫病的防效达到100%,保持该数量的时间约14 d。研究结果展现了植物内生细菌在辣椒疫病生物防治上的应用潜力,为制定植物内生细菌防治辣椒疫病的施用技术提供了科学依据。%In order to clarify the relationships between colonization dynamics of endophytic bacteria and the control effects on pepper Phytophthora blight, endophytic bacterial strains were screened by dual culturing against Phytophthora capsici and control effects were measured on the potted seedlings. The endophytic bacteria were identified based on their morphological characteristics, biochemical characteristics and 16S rDNA sequence BLAST. Colonization dynamics of endophytic bacteria in seedlings of Capsicum annuum were also conducted by rifampicin labelling and their relationships with control effects were analyzed. The results showed that three endophytic bacterial strains G9, R15 and J13 had obvious

  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. 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.

  16. 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.

  17. Reproductive strategies of field Phytophthora infestans populations on potato and tomato in some regions of Russia

    Directory of Open Access Journals (Sweden)

    Smirnov A.N.

    2009-01-01

    Full Text Available The occurrence of zoosporangia and oospores is analyzed for 88 field populations of Phytophthora infestans (Mont. de Bary in Moscow region and other regions of Russia from 1997 to 2006. For estimation of zoosporangia and oospore frequencies in the populations, the indexes IZ (for zoosporangia and IO (for oospores are suggested. The combinations of these indexes enabled a reveal of 4 strategies for P. infestans reproduction, which were found in the field populations of the pathogen. These strategies were more numerous in P. infestans field populations on tomato than on potato (4 versus 2 in spite of the fact that potato populations in Moscow region strongly predominated. It was connected with rareness or absence of oospores in potato and their presence in tomato, especially in fruit of many populations. The knowledge about strategies of reproduction can be applied for verification of efficiency of new methods for crop protection against late blight, and for investigations of P. infestans populations.

  18. Phenotypic variation in Nordic populations of Phytophthora infestans in 2003

    DEFF Research Database (Denmark)

    Lehtinen, A; Hannukkala, A; Andersson, B;

    2008-01-01

    A total of 743 single-lesion isolates of Phytophthora infestans were collected in summer 2003 from Denmark, Finland, Norway and Sweden. Most of the isolates were tested for mating type, and subsets were tested for sensitivity to fungicides and virulence (host specific pathogenicity). Approximately...... 60% of the isolates were A1 mating type in each country. Both mating types were present in 40% of the fields where more than one isolate was tested, indicating strong potential for sexual reproduction. The proportion of metalaxyl-resistant isolates dropped to under 15% from the 60% observed...... to sporulate in the presence of this fungicide at a concentration of 1000 mg L-1. In Norway and Finland the frequencies of virulence factors and pathotypes remained nearly unchanged since the 1990s, but the mean number of virulence factors per isolate increased from 5·6 to 6·3. In Denmark and Sweden virulence...

  19. 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...

  20. 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

  1. Genetic relationships among Chinese and American isolates of Phytophthora sojae assessed by RAPD markers

    Institute of Scientific and Technical Information of China (English)

    WANG Ziying; WANG Yuanchao; ZHANG Zhengguang; ZHENG Xiaobuo

    2006-01-01

    The genetic diversity of three geographic populations of Phytophthora sojae from China and the United States was determined using random amplified polymorphic DNA (RAPD). The purpose was to explore genetic relationships among Chinese and American isolates of the organism. 21 random primers were selected among 200 random primers screened. A total of 223 reproducible RAPD fragments were scored among 111 individuals, of which 199 (89.23%) were polymorphic. Analysis of genetic variation showed that there existed higher genetic variation in the United States population in comparison to the Chinese populations. Nei's genetic identity and principal component analysis indicated that the populations of Fujian and United States are closer to each other than to Heilongjiang populations. Shannon-Wiener diversity index revealed that the United States populations have a higher genetic diversity than that of Chinese populations. These data are in support of the hypothesis that P. Sojae in the United States might not have been introduced from China.

  2. Resistance identification of bivalent fungi-resistant genes transformed soybean to Phytophthora sojae

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Soybean is one of the most important sources of edible oil and proteins in the world. However, it suffers from many kinds of fungal diseases which is a major limiting factor in soybean production. The fungal disease can be effectively controlled by breeding plant cultivars with genetic transformation. In this study, the resistance to Phytophthora sojae of five bivalent transgenic soybean line swas identified using the hypocotyls inoculation technique. The lines were the T2 of the transgenic soybean which were transformed with kidney bean chitinase gene and barley ribosome inactivating protein gene, and were positive by Southern Blot analysis. The resistance difference was studied through comparing the death percentage of transgenic soybean with the control. The results showed that four lines were more resistant to P. sojae, whereas other one had no significant difference in comparison with the control. These transgenic soybean lines with enhanced resistance to P. sojae will be useful in soybean resistance breeding.

  3. 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.

  4. 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

  5. Numerous clones resistant to Phytophthora palmivora in the "Guiana" genetic group of Theobroma cacao L.

    Directory of Open Access Journals (Sweden)

    Jean-Marc Thevenin

    Full Text Available Cocoa black pod rot, a disease caused by Stramenopiles of the genus Phytophthora, and particularly by the pan-tropical species P. palmivora, causes serious production losses worldwide. In order to reduce the impact of these pests and diseases, preference is given to genetic control using resistant varieties and, to that end, breeders seek sources of resistance in wild cocoa trees. For instance, surveys of spontaneous cocoa trees in French Guiana between 1985 and 1995 led to the collection of abundant plant material forming a particular genetic group (the "Guiana" group. Following numerous one-off studies demonstrating the merits of this group as a source of resistance to Phytophthora, this article presents the results of a comprehensive study assessing the resistance of 186 "Guiana" clones in relation to the Guianan strain (GY 27 of P. palmivora. This study, undertaken in French Guiana, using an efficient methodology (ten series of tests and a statistical test adapted to the ordinal nature of the data confirmed that the "Guiana" genetic group does indeed constitute an important source of resistance to P. palmivora, though with some variations depending on the demes of origin. Numerous clones (59 proved to be as resistant as the SCAVINA 6 resistance control, whilst nine were statistically more resistant. The "Resistant" and "Moderately Resistant" Guianan clones totalled 108 (58% of the total tested. Some of the clones more resistant than SCAVINA 6 could be incorporated into numerous cocoa breeding programmes, particularly those that also display other notable qualities. The same applies for numerous other clones equivalent to SCAVINA 6, especially the "elite"' clones GU 134-B, GU 139-A and GU 285-A.

  6. Colonization of Barley by the Broad-Host Hemibiotrophic Pathogen Phytophthora palmivora Uncovers a Leaf Development-Dependent Involvement of Mlo.

    Science.gov (United States)

    Le Fevre, Ruth; O'Boyle, Bridget; Moscou, Matthew J; Schornack, Sebastian

    2016-05-01

    The discovery of barley Mlo demonstrated that filamentous pathogens rely on plant genes to achieve entry and lifecycle completion in barley leaves. While having a dramatic effect on foliar pathogens, it is unclear whether overlapping or distinct mechanisms affect filamentous pathogen infection of roots. To remove the bias connected with using different pathogens to understand colonization mechanisms in different tissues, we have utilized the aggressive hemibiotrophic oomycete pathogen Phytophthora palmivora. P. palmivora colonizes root as well as leaf tissues of barley (Hordeum vulgare). The infection is characterized by a transient biotrophy phase with formation of haustoria. Barley accessions varied in degree of susceptibility, with some accessions fully resistant to leaf infection. Notably, there was no overall correlation between degree of susceptibility in roots compared with leaves, suggesting that variation in different genes influences host susceptibility above and below ground. In addition, a developmental gradient influenced infection, with more extensive colonization observed in mature leaf sectors. The mlo5 mutation attenuates P. palmivora infection but only in young leaf tissues. The barley-P. palmivora interaction represents a simple system to identify and compare genetic components governing quantitative colonization in diverse barley tissue types.

  7. 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...

  8. 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...

  9. Identification of Phytophthora Species Parasiting on Pricklyash%花椒疫霉病菌种的鉴定

    Institute of Scientific and Technical Information of China (English)

    谢宁; 曹支敏; 梁超琼; 苗颖; 王楠

    2013-01-01

    依据菌落特征、无性与有性繁殖体形态、rDNA-ITS系统发育及病菌的致病性,将分离自陕西、甘肃花椒树干基部腐烂病斑上的疫霉菌(Phytophthora spp.)6个菌系鉴定为3个种:采自甘肃陇南菌系Pwm、Pwb和陕西凤县菌系Pfs2均属于多寄主疫霉(P.multivoraP.M.Scott & T.Jung),陕西凤县菌系PfP和甘肃秦安菌系Pqy为柑橘褐腐疫霉(Phytophthora citrophthora R.E.Sm.& E.H.Sm.),采自陕西凤县的疫霉菌菌系Pfs1为苎麻疫霉(Phytophthora boehmeriae Sawada).各疫霉菌系的形态学鉴定及致病性测定结果与其rDNN-ITS系统发育分析基本一致.%Based on colonial characteristics,asexual and sexual morphology,rDND-ITS phylogeny and path-ogenicity,6 isolates of Phythophthora collected from pricklyash in Shaanxi and Gansu provinces were identified as three species: Phytophthora multivora P. M. Scott & T. Jung included isolates Pwm,Pwb and P fs 2,collected from Wudu, Wenxian in Gansu and Fengxian in Shaanxi respectively,P. Citrophthora R. E. Sm. & E. H. Sm comprised isolates P f p from Fengxian in Shaanxi and Pqy from Qinan in Gansu,and isolate P fs 1 from Fengxian in Shaanxi identified as P. Boehmeriae Sawada. The morphologic classification of these Phythophthora isolates basically was in accordance with their molecular phylogeny cluste.

  10. 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...

  11. 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...

  12. 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.

  13. Touchdown nested multiplex PCR detection of Phytophthora cinnamomi and P. cambivora from French and English chestnut grove soils.

    Science.gov (United States)

    Langrell, Stephen R H; Morel, Olivier; Robin, Cécile

    2011-07-01

    Soil borne Phytophthora cinnamomi and Phytophthora cambivora are considered the most pathogenic species associated with chestnut (Castanea sativa) decline in Europe. Mapping their incidence and distribution from nursery and plantation soils may offer valuable information for limiting spread. As conventional biological baiting and taxonomic confirmation is generally time consuming, labour, logistically and space intensive, we have focused on the development of a specific touchdown nested multiplex Polymerase Chain Reaction (PCR) approach for the simultaneous detection of both species direct from soil. Pre-existing and novel primers, based on Internal Transcribed Spacer (ITS) sequences, have been evaluated for their specificity and use in a multiplex capacity in various combinations. Coupled to this we have modified a mechanical lysis procedure for DNA extraction from up to 10 g of chestnut under storey soils (ranging from 0.5 to 25 μg DNA g(-1)fresh soil). Using serial dilutions and/or polyvinylpolypyrrolidone chromatography purification, both species have been successfully detected, in artificially and naturally infected soils. Levels of assay detection are comparable to other Phytophthora species where PCR based diagnostic systems have been reported. A qualitative evaluation of this approach against conventional baiting is presented.

  14. 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

  15. Expresión diferencial durante la interacción Solanum tuberosum - Phytophthora infestans

    Directory of Open Access Journals (Sweden)

    Zulma Isabel Monsalve-Fonnegra

    2013-02-01

    Full Text Available Normal 0 21 false false false ES-CO X-NONE X-NONE MicrosoftInternetExplorer4 Título en ingles: Differential expression during Solanum tuberosum- Phytophthora infestans interactionResumen: La papa (Solanum tuberosum L. es el cuarto cultivo más importante a nivel mundial y es el producto agrícola con mayor demanda de fungicidas, insecticidas y fertilizantes químicos. Las pérdidas mundiales ocasionadas por Phytophthora infestans (Mont. de Bary en este cultivo, ascienden a 6,7 billones de dólares al año y su control químico genera un aumento en los costos, perjudica la salud humana y el ambiente. Todo esto justifica la búsqueda constante de mecanismos alternativos para el control de la enfermedad, entre ellos la obtención de variedades resistentes mediante cisgenesis usando genotipos silvestres. Como un aporte en este sentido, y dada la falta de conocimiento de lo que controla y constituye la diferencia entre una respuesta compatible e incompatible, en el presente estudio se compararon los perfiles de expresión génica obtenidos mediante Despliegue Diferencial de variedades resistentes y susceptibles durante su interacción con P. infestans. Los resultados evidenciaron diferencias en la expresión génica, tanto a distintos tiempos post-inoculación como en el tipo de cambio de expresión, incluyendo la presencia y ausencia de bandas diferenciales y el aumento o disminución en su intensidad. Al analizar las secuencias de fragmentos diferencialmente expresados, se encontró que algunos fragmentos sobre-expresados en las variedades susceptibles, tenían homología con secuencias que codifican para una serina-acetiltranferasa y para la subunidad β de la RNA polimerasa. Por su parte, fragmentos sobre-expresados en la variedad resistente, tenían homología con una secuencia codificante para un dominio transmembranal. Palabras claves: pastusa suprema;  diacol-capiro; parda pastusa; despliegue diferencial Abstract: Potato (Solanum tuberosum

  16. 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

  17. 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.

  18. 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.

  19. Influence of climatic conditions on white tip disease (Phytophthora porri) in leek (Allium porrum).

    Science.gov (United States)

    De Jonghe, K; Keirsebilck, D; Martens, K; Buysens, S; Höfte, M

    2002-01-01

    In leek, one of the major vegetable crops in Belgium, Phytophthora porri causes the so-called white tip disease. During the growing seasons of 1999, 2000 and 2001 the incidence of the white tip disease and the role of environmental conditions in the appearance were investigated on several non-treated leek fields in Flanders (Belgium). The first symptoms of white tip disease on leek where recorded in July and the disease progressed until March. Lesions appeared after an incubation period of 91 to 204 DD (degree days above -3 degrees C) (t0) and were diagnostic at 120 DD. The obtained data confirmed a disease increase corresponding with an amount of rainfall of more than 20 l/m2 in 4 days in the period t = t0-92 to t = t0-154 DD. A good correlation was found between the daily disease increase on one hand and the leaf wetness, relative humidity and temperature (negative correlation) on the other hand. Daily disease increase only weakly correlated with rainfall. Based on these results recommendations can be made (for further studies) to develop a model, combining several of the climatic factors, to predict infection periods with high risk on disease increase in the production of leek.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. A method to quantify infection and colonization of holm oak (Quercus ilex roots by Phytophthora cinnamomi

    Directory of Open Access Journals (Sweden)

    Ruiz-Gómez Francisco J

    2012-09-01

    Full Text Available Abstract Phytophthora cinnamomi Rands. is an important root rot pathogen widely distributed in the north hemisphere, with a large host range. Among others diseases, it is known to be a principal factor in the decline of holm oak and cork oak, the most important tree species in the “dehesa” ecosystem of south-western Spain. Previously, the focus of studies on P. cinnamomi and holm oak have been on molecular tools for identification, functional responses of the host, together with other physiological and morphological host variables. However, a microscopic index to describe the degree of infection and colonization in the plant tissues has not yet been developed. A colonization or infection index would be a useful tool for studies that examine differences between individuals subjected to different treatments or to individuals belonging to different breeding accessions, together with their specific responses to the pathogen. This work presents a methodology based on the capture and digital treatment of microscopic images, using simple and accessible software, together with a range of variables that quantify the infection and colonization process.

  5. A method to quantify infection and colonization of holm oak (Quercus ilex) roots by Phytophthora cinnamomi.

    Science.gov (United States)

    Ruiz-Gómez, Francisco J; Sánchez-Cuesta, Rafael; Navarro-Cerrillo, Rafael M; Pérez-de-Luque, Alejandro

    2012-01-01

    Phytophthora cinnamomi Rands. is an important root rot pathogen widely distributed in the north hemisphere, with a large host range. Among others diseases, it is known to be a principal factor in the decline of holm oak and cork oak, the most important tree species in the "dehesa" ecosystem of south-western Spain. Previously, the focus of studies on P. cinnamomi and holm oak have been on molecular tools for identification, functional responses of the host, together with other physiological and morphological host variables. However, a microscopic index to describe the degree of infection and colonization in the plant tissues has not yet been developed. A colonization or infection index would be a useful tool for studies that examine differences between individuals subjected to different treatments or to individuals belonging to different breeding accessions, together with their specific responses to the pathogen. This work presents a methodology based on the capture and digital treatment of microscopic images, using simple and accessible software, together with a range of variables that quantify the infection and colonization process.

  6. 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.

  7. GENETIC STABILITY ANALYSIS OF RB GENE IN GENETICALLY MODIFIED POTATO LINES TOLERANT TO Phytophthora infestans

    Directory of Open Access Journals (Sweden)

    Edy Listanto

    2016-02-01

    Full Text Available Development of potato cultivars with high levels of broad spectrum resistance is a key long-term management strategy against late blight disease caused by Phytophthora infestans. Six progeny lines of hybridization between transgenic potato Katahdin SP951 with non-transgenic Granola and Atlantic were selected based on agronomical characteristics and resistance to late blight disease. The study aimed to analyze the number of insertions and stability of inserted RB gene in the transgenic potato lines. The research was carried out through plant DNA extraction, southern blot analysis and polymerase chain reaction (PCR. Southern blot analysis was used to detect the number of inserts integrated into potato genome, while PCR analysis was used to detect stability of RB gene from generation to generation. The results showed that the progenies obtained from hybridization between Atlantic and transgenic Katahdin SP951 (lines No. 20 and 27 and between Granola and transgenic Katahdin SP951 (line No. 69 contained one copy number of RB gene, according to the probing of nptII. The result is similar to that of inserted RB gene found in the parental transgenic Katahdin SP951. The presence of RB gene in four different generations (G0, G1, G2 and G3 showed stable integration of the gene into the plant genome. The single copy number of RB gene will repress the occurrence of silencing gene expression. The stability analysis of RB gene can determine that the gene is still present in plant genome after several generations.

  8. 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.

  9. 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.

  10. 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.

  11. Development of a multiplex assay for genus- and species-specific detection of Phytophthora based on differences in mitochondrial gene order.

    Science.gov (United States)

    Bilodeau, Guillaume J; Martin, Frank N; Coffey, Michael D; Blomquist, Cheryl L

    2014-07-01

    A molecular diagnostic assay for Phytophthora spp. that is specific, sensitive, has both genus- and species-specific detection capabilities multiplexed, and can be used to systematically develop markers for detection of a wide range of species would facilitate research and regulatory efforts. To address this need, a marker system was developed based on the high copy sequences of the mitochondrial DNA utilizing gene orders that were highly conserved in the genus Phytophthora but different in the related genus Pythium and plants to reduce the importance of highly controlled annealing temperatures for specificity. An amplification primer pair designed from conserved regions of the atp9 and nad9 genes produced an amplicon of ≈340 bp specific for the Phytophthora spp. tested. The TaqMan probe for the genus-specific Phytophthora test was designed from a conserved portion of the atp9 gene whereas variable intergenic spacer sequences were used for designing the species-specific TaqMan probes. Specific probes were developed for 13 species and the P. citricola species complex. In silico analysis suggests that species-specific probes could be developed for at least 70 additional described and provisional species; the use of locked nucleic acids in TaqMan probes should expand this list. A second locus spanning three tRNAs (trnM-trnP-trnM) was also evaluated for genus-specific detection capabilities. At 206 bp, it was not as useful for systematic development of a broad range of species-specific probes as the larger 340-bp amplicon. All markers were validated against a test panel that included 87 Phytophthora spp., 14 provisional Phytophthora spp., 29 Pythium spp., 1 Phytopythium sp., and 39 plant species. Species-specific probes were validated further against a range of geographically diverse isolates to ensure uniformity of detection at an intraspecific level, as well as with other species having high levels of sequence similarity to ensure specificity. Both diagnostic

  12. Efecto de distintas fertilizaciones de fósforo en la resistencia de brinzales de encina y alcornoque a "Phytophthora cinnamomi" Rands

    OpenAIRE

    Fernández Rebollo, Pilar; Sánchez Hernández, Esperanza; Trapero Casas, Antonio; Navarro Cerrillo, Rafael M.; Gallo Ibáñez, L.

    2004-01-01

    El factor de contribución más virulento en el proceso de decaimiento forestal en el sur de la península ibérica es el Oomiceto Phytophthora cinnamomi Rands. Recientes investigaciones avalan el uso de fertilizaciones fosfóricas y fosfitos como fungicida contra Phytophthora cinnamomi. El objetivo general de este trabajo es estudiar el efecto de la fertilización fosfórica en brinzales de Quercus ilex y Q. suber sobre la resistencia a la podredumbre radical producida por P. cinnamomi. Se realizó ...

  13. 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...

  14. 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

  15. 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

  16. 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.

  17. Identification of stable resistance to Phytophthora infestans in potato genotypes evaluated in field experiments in Peru

    DEFF Research Database (Denmark)

    Wulff, Ednar Gadelha; Pérez, W.; Nelson, R.J.;

    2007-01-01

    Abstract: In this study, genotype by environment (G x E) interactions and phenotypic stability of resistance to Phytophthora infestans, the cause of late blight, were analysed in Peru lot 13 potato genotypes, using additive main effects and multiplicative interaction (AMMI) analysis and Huehn's non...... was stable under field conditions for all the genotypes tested. The first two principal components (PCA1 and PCA2) of the AMMI analysis explained 54%. of the G x E interaction sum of squares. A biplot of the two principal components demonstrated a strong year effect in the G x E interaction. By plotting...

  18. 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...

  19. 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...

  20. 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.

  1. 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.

  2. 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

  3. Population genetic analysis infers migration pathways of Phytophthora ramorum in US nurseries.

    Directory of Open Access Journals (Sweden)

    Erica M Goss

    2009-09-01

    Full Text Available Recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. However, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. Phytophthora ramorum is the exotic pathogen, discovered in the late 1990s, that is responsible for sudden oak death in California forests and ramorum blight of common ornamentals. The nursery trade has moved this pathogen from source populations on the West Coast to locations across the United States, thus risking introduction to other native forests. We examined the genetic diversity of P. ramorum in United States nurseries by microsatellite genotyping 279 isolates collected from 19 states between 2004 and 2007. Of the three known P. ramorum clonal lineages, the most common and genetically diverse lineage in the sample was NA1. Two eastward migration pathways were revealed in the clustering of NA1 isolates into two groups, one containing isolates from Connecticut, Oregon, and Washington and the other isolates from California and the remaining states. This finding is consistent with trace forward analyses conducted by the US Department of Agriculture's Animal and Plant Health Inspection Service. At the same time, genetic diversities in several states equaled those observed in California, Oregon, and Washington and two-thirds of multilocus genotypes exhibited limited geographic distributions, indicating that mutation was common during or subsequent to migration. Together, these data suggest that migration, rapid mutation, and genetic drift all play a role in structuring the genetic diversity of P. ramorum in US nurseries. This work demonstrates that fast-evolving genetic markers can be used to examine the evolutionary processes acting on recently introduced pathogens and to infer their putative migration patterns, thus showing promise for the application of

  4. 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

  5. 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.

  6. Survival potential of Phytophthora infestans sporangia in relation to environmental factors and late blight occurrence

    Directory of Open Access Journals (Sweden)

    Modesto Olanya Ocen

    2016-01-01

    Full Text Available Potato is an important crop globally and late blight (Phytophthora infestans often results in severe crop loss. The cost for late blight control can be in excess of $210 million in the United States. We utilised a non-parametric density distribution analysis of local temperature (T and relative humidity (RH, from 2005 to 2009, to assess and validate sporangia survival potential using survival model and late blight risks during the potato cropping season at Presque Isle, in the northern part of the state of Maine, USA. Modelbased analyses showed that ambient temperatures of 3−30°C and RH values of 45−100% were conducive for sporangia survival. Disease outbreaks and risk periods coincided with a high sporangia survival probability (15−35%. Due to the omission of solar radiation (SR in the computation of survival potential in previous research, we applied a Cox proportional model to estimate the probability of sporangia survival [i.e. hazard at a specific time H(t] as a function of baseline hazard (H0 and the influencing parameters. The model is: H(t = H0(t × exp(0.067ET + 0.138T + 0.083RH + 0.001SR where ET is exposure time. The survival model indicated that RH (β = 0.083 and T (β = 0.138 were significant (p < 0.05 factors in sporangia survival in comparison to SR (β = 0.001. The hazard ratio, indicative of sporangia survival risk, varied with the predictors. For the unit increase of T, sporangia survival hazard increased by 1.148 times. The Cox model and sporangia hazard probabilities can be used for short-term disease forecasts based on the risk period most conducive for pathogen survival and targeted fungicide applications for optimum late blight management.

  7. Incidence of Phytophthora infestans (Mont. de Bary on potato and tomato in Maine, 2006–2010

    Directory of Open Access Journals (Sweden)

    Olanya Ocen Modesto

    2015-01-01

    Full Text Available Late blight, caused by Phytophthora infestans (Mont. de Bary, is a devastating disease which is found worldwide. In Maine, United States (US, we recorded late blight on potato and tomato during the 2006-2009 cropping seasons. From 2006 to 2008, over 90% of the diseased samples were collected in potato fields from northern and central Aroostook County in Northern Maine, US. Then, in 2009, an unprecedented influx of inoculum on infected tomato transplants shipped to retail garden centers throughout the Northeast US significantly changed the late blight infection patterns. In 2009, 43% of diseased samples obtained were from tomato, and 57% from potato, and disease was found to occur all over the state. Moran’s index and spatial autocorrelation analysis of disease occurrence, geographical locations, host factors, and infection levels from previous years, were not statistically significant (p > 0.05. Therefore, random distributions of late blight incidences were recorded across locations and years. Nearest neighbor analysis revealed that mean spatial distances for late blight occurrence ranged from 1.51 to 71.4 km from 2006 to 2008, and 7.4 to 126.5 km in 2009. The frequency and locations of late blight outbreaks in 2009 were substantially greater than in 2006, 2007, and 2008, as affected by the influx of inoculum and movement of infected tomato seedlings as well as conducive environmental conditions. All were contributing factors for late blight occurrence in Maine. In 2010, few disease samples were collected, indicating that the influx of inoculum in 2009 did not persist to cause widespread disease in 2010. The reduction of inocula sources, fungicide protection of susceptible hosts, and the removal and destruction of infected tomato seedlings and potato cull piles or volunteer plants, can greatly reduce late blight occurrences and improve potato production. These actions should be considered as an integral part of late blight management

  8. 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.

  9. Molecular genetic studies in Fragaria species: Agrobacterium-mediated transformation and fine mapping of the Phytophthora fragariae resistance gene Rpf1.

    NARCIS (Netherlands)

    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

  10. 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.

  11. Relationship between occurrence of Phytophthora cambivora on plants in hardy ornamental nursery stocks and detection of the pathogen from water ponds.

    Science.gov (United States)

    Ptaszek, M; Orlikowski, L B; Trzewik, A; Orlikowska, T; Sadowski, C

    2010-01-01

    Phytophthora cambivora was isolated from rooted bases and roots of Castanea sativa, Chamaecyparis lawsoniana and Cotoneaster spp. as well as from water ponds Located in HNS. In the laboratory trials the species colonised leaf blades and stem parts of 3 tested plant species. Differentiated reaction of tested plant species on P. cambivora was observed.

  12. Role of the cyclic lipopeptide massetolide A in biological control of Phytophthora infestans and in colonization of tomato plants by Pseudomonas fluorescens

    NARCIS (Netherlands)

    Tran, H.; Ficke, A.; Asiimwe, T.; Höfte, M.; Raaijmakers, J.M.

    2007-01-01

    Pseudomonas strains have shown promising results in biological control of late blight caused by Phytophthora infestans. However, the mechanism(s) and metabolites involved are in many cases poorly understood. Here, the role of the cyclic lipopeptide massetolide A of Pseudomonas fluorescens SS101 in b

  13. 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

  14. 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...

  15. 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...

  16. 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...

  17. Increased difficulties to control late blight in Tunisia are caused by a genetically diverse Phytophthora infestans population next to the clonal lineage NA-01

    NARCIS (Netherlands)

    Harbaoui, K.; Hamada, W.; Li, Y.; Vleeshouwers, V.G.A.A.; Lee, van der T.A.J.

    2014-01-01

    In Tunisia, late blight caused by Phytophthora infestans is a serious threat to potato and tomato. The Mediterranean weather conditions can be conducive to infection in all seasons and the host crops, tomato and potato, are grown year round. Potato is planted and harvested in two to four overlapping

  18. 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

  19. 杀菌剂对大豆疫霉菌生长的抑制作用%The inhibitive effect of fungicide to Phytophthora sojae growth

    Institute of Scientific and Technical Information of China (English)

    左豫虎; 薛春生; 刘惕若

    2002-01-01

    几种供试杀菌剂对大豆疫霉菌(Phytophthora sojae)茵丝生长、孢子囊形成均有明显抑制作用,对游动孢子形成没有影响,其中以甲霜灵(metalaxyD对P.sojae的抑制作用最强.

  20. Actividad inhibitoria del aceite esencial de Lippia origanoides H.B.K sobre el crecimiento de Phytophthora infestans

    Directory of Open Access Journals (Sweden)

    óscar Arango Bedoya

    2015-04-01

    Full Text Available Phytophthora infestans (Mont. de Bary es el fitopatógeno más perjudicial de la papa (Solanum tuberosum al causar la enfermedad conocida como ‘gota o tizón tardío’. El objetivo de este trabajo fue evaluar la actividad in vitro del aceite esencial obtenido de una especie de orégano silvestre (Lippia origanoides H.B.K. sobre Phytophthora infestans. Para el efecto se evaluaron diferentes concentraciones de este aceite esencial (10, 50, 100, 150, 200, 250 µg/ml y de un fungicida comercial usado como testigo. La actividad antifúngica se determinó con base en la evaluación del crecimiento del micelio mediante el método de dilución en agar tomate. A partir de una concentración de aceite de 150 µg/ml se inhibió completamente el crecimiento del patógeno, por lo que ésta fue considerada como la concentración letal. Este estudio demostró que el aceite esencial de orégano silvestre del Alto Patía, Colombia, es un potencial agente antifúngico que podría ser usado en sistemas de control integrado de P. infestans.

  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. Study on the quarantine fumigation technology of Phytophthora sojae%大豆疫霉检疫熏蒸处理技术初探

    Institute of Scientific and Technical Information of China (English)

    李丽; 刘涛; 张凡华; 任放; 王跃进

    2013-01-01

    Soybean Phytophthora root rot (PPR) that cause by Phytophthora sojae is one of the most serious diseases in the main soybean production area all over the world. In this manuscript, we analyzed the fungitoxicity of methyl bromide, propylene oxide, methyl iodide and carbonyl sulfide, their influences on the quality of soybean were also determined. Our results confirmed the efficacy of the four fumigants against Phytophthora sojae, their EC99 values were methyl bromide 21.24mg/L, propylene oxide 33.21 mg/L, methyl iodide 4.64 mg/L and carbonyl sulfide 46. 73mg/L for 24h fumigation at 20℃. Moreover, quality analysis results showed that there were not significant differences between untreated and treated soybeans after 30d storage, indicating that fumigation with tested fumigants would be the candidates for control of Phytophthora sojae, especially methyl iodide.%大豆疫霉根腐病(Soybean Phytophthora root rot,简称PPR)由大豆疫霉(Phytophthora sojae Kaufmann&Gerdemann)引发,在世界大豆主产区广泛发生,危害严重.为有效防控大豆疫霉根腐病跨境传播,本文测定了溴甲烷、环氧丙烷、碘甲烷和氧硫化碳4种熏蒸剂对大豆疫霉的毒力及其致死剂量对大豆品质的影响.结果表明,20℃下,4种熏蒸剂均有一定杀菌效果,熏蒸24h的EC99分别为:溴甲烷21.24mg/L、环氧丙烷33.21 mg/L、碘甲烷4.64 mg/L、氧硫化碳46.73 mg/L.大豆品质测定结果表明,致死剂量的4种熏蒸剂熏蒸后,大豆粗脂肪、粗蛋白等等主要品质指标无显著变化.本研究为进境大豆携带大豆疫霉的检疫处理提供了候选技术,碘甲烷在带菌大豆检疫处理中的应用前景值得关注.

  3. Biological characteristics of strain F603 of Epicoccom sp.,an antagonistic fungus for controlling Phytophthora infestans

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaoyun; HU Tongle; CAO Keqiang

    2007-01-01

    Factors influencing vegetative growth and spore germination of strain F603 of Epicoccom sp.,an antagonistic fungus for Phytophthora infestans (Mont) de Bary,were studied.Among the different growth media tested,Rye agar was the best medium for its vegetative growth.The range of temperature and pH value for mycelial growth was 5-35℃ and 2-12,respectively,with the optimum 25℃ and 6-9,respectively.The fungus grew better in Czapek medium with maltose and dextrose as carbon sources and peptone,KNO3,and NaNO3 as nitrogen sources.The range of temperature for spore germination of strain F603 was 5-35℃,the optimum was 20℃.The range of temperature for sporulation was 10-30℃,and the optimum was 15-18℃.

  4. 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

  5. A simple method for extracting DNA from rhododendron plants infected with Phytophthora spp. for use in PCR

    Directory of Open Access Journals (Sweden)

    Trzewik Aleksandra

    2016-01-01

    Full Text Available Among the numerous protocols that describe the extraction of DNA, those relating to the isolation of DNA from infected plants, are rare. This study describes a rapid and reliable method of extracting a high quality and quantity of DNA from rhododendron leaves artificially infected with Phytophthora cactorum, P. cambivora, P. cinnamomi, P. citrophthora, and P. plurivora. The use of the modified Doyle and Doyle protocol (1987 allowed us to obtain high quantity and quality DNA (18.26 μg from 100 mg of the fresh weight of infected leaves at the ratios of A260/280 and A260/230 - 1.83 and 1.72, respectively, suitable for conventional polymerase chain reaction (PCR and real-time PCR amplifications.

  6. 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

  7. 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...... was not detectable on gels from cysts. In addition, one spot was significantly down-regulated and another spot not detectable on the gels from appressoria. The corresponding proteins to 13 of these spots were identified with high confidence using tandem mass spectrometry and database searches. The functions...

  8. 泰国榴莲上棕榈疫霉的分离和鉴定%Isolation and Identification of Phytophthora palmivora from Imported Thailand Durian

    Institute of Scientific and Technical Information of China (English)

    赵旭东; 张慧丽

    2013-01-01

    The pathogenic fungus was isolated from imported Thialand Durian, which could infect Durian fruit and made the fruit black and rot. According to the morphological characteristics and the neighbor-joining tree based on ITS sequence analysis, the isolated strain was finally identified as Phytophthora palmivora.%在对来自泰国的榴莲检验中分离到1株引起榴莲果皮和果肉变色、软腐的病原真菌。通过形态鉴定和核糖体ITS区DNA序列测定以及系统发育分析,最终将该病菌鉴定为棕榈疫霉(Phytophthora palmivora)。

  9. 大豆疫霉根腐病的几种实验室检验方法%Several Lab. Quarantine Methods of Soybean Phytophthora Root Rot

    Institute of Scientific and Technical Information of China (English)

    肖迪; 葛红霞; 肖威

    2006-01-01

    大豆疫霉根腐病(Soybean Phytophthora Root Rot)是我国一类检疫对象.近年,大豆疫霉根腐病的检验技术研究也相继开展起来,本文综述了大豆疫霉根腐病的土壤检测、病植检测、种子检测等几种实验室检测方法.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. Plant-plant-microbe mechanisms involved in soil-borne disease suppression on a maize and pepper intercropping system.

    Directory of Open Access Journals (Sweden)

    Min Yang

    Full Text Available BACKGROUND: Intercropping systems could increase crop diversity and avoid vulnerability to biotic stresses. Most studies have shown that intercropping can provide relief to crops against wind-dispersed pathogens. However, there was limited data on how the practice of intercropping help crops against soil-borne Phytophthora disease. PRINCIPAL FINDINGS: Compared to pepper monoculture, a large scale intercropping study of maize grown between pepper rows reduced disease levels of the soil-borne pepper Phytophthora blight. These reduced disease levels of Phytophthora in the intercropping system were correlated with the ability of maize plants to form a "root wall" that restricted the movement of Phytophthora capsici across rows. Experimentally, it was found that maize roots attracted the zoospores of P. capsici and then inhibited their growth. When maize plants were grown in close proximity to each other, the roots produced and secreted larger quantities of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H-one (DIMBOA and 6-methoxy-2-benzoxazolinone (MBOA. Furthermore, MBOA, benzothiazole (BZO, and 2-(methylthio-benzothiazole (MBZO were identified in root exudates of maize and showed antimicrobial activity against P. capsici. CONCLUSIONS: Maize could form a "root wall" to restrict the spread of P. capsici across rows in maize and pepper intercropping systems. Antimicrobe compounds secreted by maize root were one of the factors that resulted in the inhibition of P. capsici. These results provide new insights into plant-plant-microbe mechanisms involved in intercropping systems.

  16. 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.

  17. Soil properties linked to Phytophthora cinnamomi presence and oak decline in Iberian dehesas

    Science.gov (United States)

    Moreno, G.; Vivas, M.; Pérez, A.; Cubera, E.; Madeira, M.; Solla, A.

    2009-04-01

    symptomatic (declined) trees, at surface, 50, 100 and 150 cm depths. Soil texture, redox potential, mineral N, and the presence of Phytophthora cinnamomi were determined. Soil bulk density was measured at the surface, and soil compactness was measured through a digital penetrometer at 0-40 cm depth. In the stream banks, fine-textured soils were significantly more common under declined trees than under healthy ones, while in slopes the contrary trend occurred. Differences were clearly observed at layers located at 100 and 150 cm depth. Soil bulk density was moderate, with mean values of 1.05 and 1.07 g cm-3 (0-5 cm depth), and 1.28 and 1.30 g cm-3 (5-10 cm) for healthy and declined oaks, respectively. Regarding soil resistance to penetration, values under declined oaks were significantly (p=0.012) higher below 20 cm depth, probably due to compaction caused by old cultivation practices. Most of the soil samples analyzed showed a high level of oxidation (superoxic and manoxic), 28% were suboxic and only 0.7% were anoxic, with a possible limitation of root growth. Although not significant, soils trended to be more reduced under declined oaks at stream banks, with a contrary tendency at slopes (Table 1). The presence of P. cinammomi in soil was positively related to oak decline in stream banks (p=0.011), but not in slopes, and associated to more compacted soils (p=0.05). The presence of P. cinammomi in roots was positively correlated with oak decay (p=0.01), being more abundant among 50-100 cm depth in slopes, and among 100-150 cm depth in the stream banks, but in both cases was mostly associated to fine-textured soils. In conclusion, Q. ilex decline was not related with anoxic conditions limiting root growth, but with soil properties leading to restricted water availability for trees in slopes, and with soil conditions favorable for P. cinnamomi root-infections in the stream banks.

  18. Ectomycorrhizal community structure in a healthy and a Phytophthora-infected chestnut (Castanea sativa Mill.) stand in central Italy.

    Science.gov (United States)

    Blom, Jan Maarten; Vannini, Andrea; Vettraino, Anna Maria; Hale, Michael D; Godbold, Douglas L

    2009-11-01

    Ink disease caused by Phytophthora cambivora is a major disease of sweet chestnut (Castanea sativa). In two C. sativa stands in central Italy, one (Montesanti) that is infected with P. cambivora and the trees showing symptoms of ink disease and another healthy stand (Puzzella), the ectomycorrhizal (ECM) community structure was investigated. On the roots of the surviving trees of the diseased stand, 29 different ECM species were determined compared to 23 in the healthy stand. Eleven ECM species were common to both stands; however, a number of species were unique to one of the stands. Cenococcum geophilum was dominant at both sites, but the percentage colonisation was much higher at Montesanti (40.8%) compared to Puzzella (27.2%). There was a switch in species from Russula vesca, Russula lepida and Russula azurea at Puzzella to Russula nigricans, R. lepida and Russula delica at Montesanti. Both R. vesca and R. azurea were found only at the Puzzella site. At the diseased site, the ECMs formed had a smaller root tip diameter, and the ECM at the healthy site had more abundant extramatrical hyphae.

  19. Identification of avocado (Persea americana) root proteins induced by infection with the oomycete Phytophthora cinnamomi using a proteomic approach.

    Science.gov (United States)

    Acosta-Muñiz, Carlos H; Escobar-Tovar, Lina; Valdes-Rodríguez, Silvia; Fernández-Pavia, Silvia; Arias-Saucedo, Luis J; de la Cruz Espindola Barquera, Maria; Gómez Lim, Miguel Á

    2012-01-01

    Avocado root rot, caused by Phytophthora cinnamomi, is the most important disease that limits avocado production. A proteomic approach was employed to identify proteins that are upregulated by infection with P. cinnamomi. Different proteins were shown to be differentially expressed after challenge with the pathogen by two-dimensional (2-D) gel electrophoresis. A densitometric evaluation of protein expression indicated differential regulation during the time-course analyzed. Some proteins induced in response to the infection were identified by standard peptide mass fingerprinting using matrix-assisted laser desorption/ionization-time of flight-mass spectrometry and sequencing by MALDI LIFT-TOF/TOF tandem mass spectrometry. Of the 400 protein spots detected on 2-D gels, 21 seemed to change in abundance by 3 hours after infection. Sixteen proteins were upregulated, 5 of these were only detected in infected roots and 11 showed an increased abundance. Among the differentially expressed proteins identified are homologs to isoflavone reductase, glutathione S-transferase, several abscisic acid stress-ripening proteins, cinnamyl alcohol dehydrogenase, cinnamoyl-CoA reductase, cysteine synthase and quinone reductase. A 17.3-kDa small heat-shock protein and a glycine-rich RNA-binding protein were identified as downregulated. Our group is the first to report on gene induction in response to oomycete infection in roots from avocado, using proteomic techniques.

  20. Rainfall and temperatures changes have confounding impacts on Phytophthora cinnamomi occurrence risk in the southwestern USA under climate change scenarios.

    Science.gov (United States)

    Thompson, Sally E; Levin, Simon; Rodriguez-Iturbe, Ignacio

    2014-04-01

    Global change will simultaneously impact many aspects of climate, with the potential to exacerbate the risks posed by plant pathogens to agriculture and the natural environment; yet, most studies that explore climate impacts on plant pathogen ranges consider individual climatic factors separately. In this study, we adopt a stochastic modeling approach to address multiple pathways by which climate can constrain the range of the generalist plant pathogen Phytophthora cinnamomi (Pc): through changing winter soil temperatures affecting pathogen survival; spring soil temperatures and thus pathogen metabolic rates; and changing spring soil moisture conditions and thus pathogen growth rates through host root systems. We apply this model to the southwestern USA for contemporary and plausible future climate scenarios and evaluate the changes in the potential range of Pc. The results indicate that the plausible range of this pathogen in the southwestern USA extends over approximately 200,000 km(2) under contemporary conditions. While warming temperatures as projected by the IPCC A2 and B1 emissions scenarios greatly expand the range over which the pathogen can survive winter, projected reductions in spring rainfall reduce its feasible habitat, leading to spatially complex patterns of changing risk. The study demonstrates that temperature and rainfall changes associated with possible climate futures in the southwestern USA have confounding impacts on the range of Pc, suggesting that projections of future pathogen dynamics and ranges should account for multiple pathways of climate-pathogen interaction.

  1. Four potato (Solanum tuberosum) ABCG transporters and their expression in response to abiotic factors and Phytophthora infestans infection.

    Science.gov (United States)

    Ruocco, Michelina; Ambrosino, Patrizia; Lanzuise, Stefania; Woo, Sheridan Lois; Lorito, Matteo; Scala, Felice

    2011-12-15

    Pleiotropic drug resistant (PDR/ABCG) genes are involved in plant response to biotic and abiotic stresses. In this work, we cloned, from Solanum tuberosum, four PDR/ABCG transporter genes named StPDR1, StPDR2, StPDR3 and StPDR4, which were differentially expressed in plant tissues and cell cultures. A number of different chemically unrelated compounds were found to regulate the transcript levels of the four genes in cultured cells. In particular, StPDR2 was highly up-regulated in the presence of Botrytis cinerea cell walls, NaCl, 2,4-dichlorophenol, sclareol and α-solanin and biological compounds. The expression of the genes was also investigated by real time RT-PCR during infection by Phytophthora infestans. StPDR1 and StPDR2 were up-regulated about 13- and 37-fold at 48 h post-infection (hpi), StPDR3 was expressed (4-5-fold) at 24 and 48 hpi and then rapidly decreased, while StPDR4 RNA accumulation was stimulated (about 4-fold) at 12 and 24 hpi, decreased at 48 hpi and increased again at 96 hpi. We discuss the role of StPDR1-4 genes in response to pathogens and abiotic stresses.

  2. A Myb transcription factor of Phytophthora sojae, regulated by MAP kinase PsSAK1, is required for zoospore development.

    Directory of Open Access Journals (Sweden)

    Meng Zhang

    Full Text Available PsSAK1, a mitogen-activated protein (MAP kinase from Phytophthora sojae, plays an important role in host infection and zoospore viability. However, the downstream mechanism of PsSAK1 remains unclear. In this study, the 3'-tag digital gene expression (DGE profiling method was applied to sequence the global transcriptional sequence of PsSAK1-silenced mutants during the cysts stage and 1.5 h after inoculation onto susceptible soybean leaf tissues. Compared with the gene expression levels of the recipient P. sojae strain, several candidates of Myb family were differentially expressed (up or down in response to the loss of PsSAK1, including of a R2R3-type Myb transcription factor, PsMYB1. qRT-PCR indicated that the transcriptional level of PsMYB1 decreased due to PsSAK1 silencing. The transcriptional level of PsMYB1 increased during sporulating hyphae, in germinated cysts, and early infection. Silencing of PsMYB1 results in three phenotypes: a no cleavage of the cytoplasm into uninucleate zoospores or release of normal zoospores, b direct germination of sporangia, and c afunction in zoospore-mediated plant infection. Our data indicate that the PsMYB1 transcription factor functions downstream of MAP kinase PsSAK1 and is required for zoospore development of P. sojae.

  3. Comparative analyses of fungicide sensitivity and SSR marker variations indicate a low risk of developing azoxystrobin resistance in Phytophthora infestans.

    Science.gov (United States)

    Qin, Chun-Fang; He, Meng-Han; Chen, Feng-Ping; Zhu, Wen; Yang, Li-Na; Wu, E-Jiao; Guo, Zheng-Liang; Shang, Li-Ping; Zhan, Jiasui

    2016-01-01

    Knowledge of the evolution of fungicide resistance is important in securing sustainable disease management in agricultural systems. In this study, we analyzed and compared the spatial distribution of genetic variation in azoxystrobin sensitivity and SSR markers in 140 Phytophthora infestans isolates sampled from seven geographic locations in China. Sensitivity to azoxystrobin and its genetic variation in the pathogen populations was measured by the relative growth rate (RGR) at four fungicide concentrations and determination of the effective concentration for 50% inhibition (EC50). We found that all isolates in the current study were sensitive to azoxystrobin and their EC50 was similar to that detected from a European population about 20 years ago, suggesting the risk of developing azoxystrobin resistance in P. infestans populations is low. Further analyses indicate that reduced genetic variation and high fitness cost in resistant mutations are the likely causes for the low evolutionary likelihood of developing azoxystrobin resistance in the pathogen. We also found a negative correlation between azoxystrobin tolerance in P. infestans populations and the mean annual temperature of collection sites, suggesting that global warming may increase the efficiency of using the fungicide to control the late blight. PMID:26853908

  4. Comparative analyses of fungicide sensitivity and SSR marker variations indicate a low risk of developing azoxystrobin resistance in Phytophthora infestans.

    Science.gov (United States)

    Qin, Chun-Fang; He, Meng-Han; Chen, Feng-Ping; Zhu, Wen; Yang, Li-Na; Wu, E-Jiao; Guo, Zheng-Liang; Shang, Li-Ping; Zhan, Jiasui

    2016-01-01

    Knowledge of the evolution of fungicide resistance is important in securing sustainable disease management in agricultural systems. In this study, we analyzed and compared the spatial distribution of genetic variation in azoxystrobin sensitivity and SSR markers in 140 Phytophthora infestans isolates sampled from seven geographic locations in China. Sensitivity to azoxystrobin and its genetic variation in the pathogen populations was measured by the relative growth rate (RGR) at four fungicide concentrations and determination of the effective concentration for 50% inhibition (EC50). We found that all isolates in the current study were sensitive to azoxystrobin and their EC50 was similar to that detected from a European population about 20 years ago, suggesting the risk of developing azoxystrobin resistance in P. infestans populations is low. Further analyses indicate that reduced genetic variation and high fitness cost in resistant mutations are the likely causes for the low evolutionary likelihood of developing azoxystrobin resistance in the pathogen. We also found a negative correlation between azoxystrobin tolerance in P. infestans populations and the mean annual temperature of collection sites, suggesting that global warming may increase the efficiency of using the fungicide to control the late blight.

  5. Pseudomonas strains naturally associated with potato plants produce volatiles with high potential for inhibition of Phytophthora infestans.

    Science.gov (United States)

    Hunziker, Lukas; Bönisch, Denise; Groenhagen, Ulrike; Bailly, Aurélien; Schulz, Stefan; Weisskopf, Laure

    2015-02-01

    Bacteria emit volatile organic compounds with a wide range of effects on bacteria, fungi, plants, and animals. The antifungal potential of bacterial volatiles has been investigated with a broad span of phytopathogenic organisms, yet the reaction of oomycetes to these volatile signals is largely unknown. For instance, the response of the late blight-causing agent and most devastating oomycete pathogen worldwide, Phytophthora infestans, to bacterial volatiles has not been assessed so far. In this work, we analyzed this response and compared it to that of selected fungal and bacterial potato pathogens, using newly isolated, potato-associated bacterial strains as volatile emitters. P. infestans was highly susceptible to bacterial volatiles, while fungal and bacterial pathogens were less sensitive. Cyanogenic Pseudomonas strains were the most active, leading to complete growth inhibition, yet noncyanogenic ones also produced antioomycete volatiles. Headspace analysis of the emitted volatiles revealed 1-undecene as a compound produced by strains inducing volatile-mediated P. infestans growth inhibition. Supplying pure 1-undecene to P. infestans significantly reduced mycelial growth, sporangium formation, germination, and zoospore release in a dose-dependent manner. This work demonstrates the high sensitivity of P. infestans to bacterial volatiles and opens new perspectives for sustainable control of this devastating pathogen.

  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. Sweets for the foe - effects of nonstructural carbohydrates on the susceptibility of Quercus robur against Phytophthora quercina.

    Science.gov (United States)

    Angay, Oguzhan; Fleischmann, Frank; Recht, Sabine; Herrmann, Sylvie; Matyssek, Rainer; Oßwald, Wolfgang; Buscot, François; Grams, Thorsten E E

    2014-09-01

    The root-rot pathogen Phytophthora quercina is a key determinant of oak decline in Europe. The susceptibility of pedunculate oak (Quercus robur) to this pathogen has been hypothesized to depend on the carbon availability in roots as an essential resource for defense. Microcuttings of Q. robur undergo an alternating rhythm of root and shoot growth. Inoculation of mycorrhizal (Piloderma croceum) and nonmycorrhizal oak roots with P. quercina was performed during both growth phases, that is, root flush (RF) and shoot flush (SF). Photosynthetic and morphological responses as well as concentrations of nonstructural carbohydrates (NSC) were analyzed. Infection success was quantified by the presence of pathogen DNA in roots. Concentrations of NSC in roots depended on the alternating root/shoot growth rhythm, being high and low during RF and SF, respectively. Infection success was high during RF and low during SF, resulting in a significantly positive correlation between pathogen DNA and NSC concentration in roots, contrary to the hypothesis. The alternating growth of roots and shoots plays a crucial role for the susceptibility of lateral roots to the pathogen. NSC availability in oak roots has to be considered as a benchmark for susceptibility rather than resistance against P. quercina.

  8. Laboratory model of the potential role of fungi (Phytophthora spp. ) in the decomposition of red mangrove (Rhizophora mangle) leaf litter

    Energy Technology Data Exchange (ETDEWEB)

    Fell, J.W.; Master, I.M.; Newell, S.Y.

    1977-01-01

    Field studies of quantitative changes in carbon, nitrogen and dry weight of decomposing mangrove leaves demonstrated similar net weight and carbon losses irrespective of station location or time of year. In contrast, rates differed and percent change in nitrogen content varied from no gain to 78% increase. A laboratory model was designed to examine the field responses. Because of variation between leaves, a split leaf technique was developed in which one half of the leaf was used to predict the original carbon, nitrogen and dry weight of the other, experimental, half leaf. Nitrogen immobilization, in the laboratory studies, required the presence of microorganisms, such as fungi of the genus Phytophthora, and the addition of inorganic N. The final amount of nitrogen in the leaf was directly related to the original amount, however, change in nitrogen was inversely related to original nitrogen. Weight loss was inversely related to the dry weight:fresh weight ratio of the leaves, possibly due to the high fiber content of the high ratio leaves. A discussion is presented of the field results, as interpreted by the laboratory model. 28 references, 15 figures, 1 table.

  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. Quantification of induced resistance against Phytophthora species expressing GFP as a vital marker: beta-aminobutyric acid but not BTH protects potato and Arabidopsis from infection.

    Science.gov (United States)

    Si-Ammour, Azeddine; Mauch-Mani, Brigitte; Mauch, Felix

    2003-07-01

    SUMMARY Induced resistance was studied in the model pathosystem Arabidopsis-Phytophthora brassicae (formerly P. porri) in comparison with the agronomically important late blight disease of potato caused by Phytophthora infestans. For the quantification of disease progress, both Phytophthora species were transformed with the vector p34GFN carrying the selectable marker gene neomycine phosphotransferase (nptII) and the reporter gene green fluorescent protein (gfp). Eighty five per cent of the transformants of P. brassicae and P. infestans constitutively expressed GFP at high levels at all developmental stages both in vitro and in planta. Transformants with high GFP expression and normal in vitro growth and virulence were selected to quantify pathogen growth by measuring the in planta emitted GFP fluorescence. This non-destructive monitoring of the infection process was applied to analyse the efficacy of two chemical inducers of disease resistance, a functional SA-analogue, benzothiadiazole (BTH), and beta-aminobutyric acid (BABA) which is involved in priming mechanisms of unknown nature. BABA pre-treatment (300 microm) via soil drench applied 24 h before inoculation completely protected the susceptible Arabidopsis accession Landsberg erecta (Ler) from infection with P. brassicae. A similar treatment with BTH (330 microm) did not induce resistance. Spraying the susceptible potato cultivar Bintje with BABA (1 mm) 2 days before inoculation resulted in a phenocopy of the incompatible interaction shown by the resistant potato cultivar Matilda while BTH (1.5 mm) did not protect Bintje from severe infection. Thus, in both pathosystems, the mechanisms of induced resistance appeared to be similar, suggesting that the Arabidopsis-P. brassicae pathosystem is a promising model for the molecular analysis of induced resistance mechanisms of potato against the late blight disease.

  11. Overexpression of GmERF5, a new member of the soybean EAR motif-containing ERF transcription factor, enhances resistance to Phytophthora sojae in soybean.

    Science.gov (United States)

    Dong, Lidong; Cheng, Yingxin; Wu, Junjiang; Cheng, Qun; Li, Wenbin; Fan, Sujie; Jiang, Liangyu; Xu, Zhaolong; Kong, Fanjiang; Zhang, Dayong; Xu, Pengfei; Zhang, Shuzhen

    2015-05-01

    Phytophthora root and stem rot of soybean [Glycine max (L.) Merr.], caused by Phytophthora sojae Kaufmann and Gerdemann, is a destructive disease throughout the soybean planting regions in the world. Here, we report insights into the function and underlying mechanisms of a novel ethylene response factor (ERF) in soybean, namely GmERF5, in host responses to P. sojae. GmERF5-overexpressing transgenic soybean exhibited significantly enhanced resistance to P. sojae and positively regulated the expression of the PR10, PR1-1, and PR10-1 genes. Sequence analysis suggested that GmERF5 contains an AP2/ERF domain of 58 aa and a conserved ERF-associated amphiphilic repression (EAR) motif in its C-terminal region. Following stress treatments, GmERF5 was significantly induced by P. sojae, ethylene (ET), abscisic acid (ABA), and salicylic acid (SA). The activity of the GmERF5 promoter (GmERF5P) was upregulated in tobacco leaves with ET, ABA, Phytophthora nicotianae, salt, and drought treatments, suggesting that GmERF5 could be involved not only in the induced defence response but also in the ABA-mediated pathway of salt and drought tolerance. GmERF5 could bind to the GCC-box element and act as a repressor of gene transcription. It was targeted to the nucleus when transiently expressed in Arabidopsis protoplasts. GmERF5 interacted with a basic helix-loop-helix transcription factor (GmbHLH) and eukaryotic translation initiation factor (GmEIF) both in yeast cells and in planta. To the best of our knowledge, GmERF5 is the first soybean EAR motif-containing ERF transcription factor demonstrated to be involved in the response to pathogen infection. PMID:25779701

  12. 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.

  13. Interacção in vitro entre macrofungos micorrízicos de Castanea sativa e o patógeno Phytophthora cinnamomi

    OpenAIRE

    Rodrigues, Paula; Martins, Anabela

    2006-01-01

    Nas últimas décadas, o controlo biológico de doenças das plantas tem vindo a ganhar importância no sentido de reduzir os custos económicos e ambientais resultantes da aplicação sucessiva de produtos químicos. Pisolithus tinctorius é um importante macrofungo ectomicorrízico de Castanea sativa, frequentemente referido como tendo um efeito positivo no controlo de Phytophthora cinnamomi. No entanto, os mecanismos subjacentes a este efeito não são conhecidos. O presente estudo teve como objectivo ...

  14. 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

  15. Diversity of Phytophthora sojae in soil of Heilongjiang Province%黑龙江省土壤中大豆疫霉菌(Phytophthora sojae)的多样性

    Institute of Scientific and Technical Information of China (English)

    李爽; 文景芝

    2012-01-01

    In order to understand the diversity of Phytophthora sojae in different types of soil, we used gene postulation method and amplified fragment length polymorphism (AFLP) markers to analyze the avirulent genes and genetic diversity of 176 P. sojae isolates gained from 5 different types of soil in Heilongjiang Province. Results showed that there were differences in avirulent genes, avirulent gene types, avirulent gene combinations and patho-genicity among P. sojae populations from different types of soil. The P. sojae populations from black soil, albic soil and meadow soil were relatively rich in diversity of avirulent genes, avirulent gene types and avirulent gene combinations, and were lower pathogenic. The P. sojae populations from saline soil were low in diversity of avirulent genes, avirulent gene types and avirulent gene combinations, and were highly pathogenic. No isolate was found in sandy soil. AFLP cluster analysis showed that the 176 isolates were divided into 6 groups with dissimilarity distance of 0. 76. The genetic diversities of P. sojae population in black soil and albic soil were richer than that in meadow soil and saline soil. Comprehensive analysis showed that the avirulent genes and genetic diversity of P. sojae populations in Heilongjiang Province were rich and correlated with soil types.%为探究不同类型土壤中大豆疫霉菌(Phytophthora sojae)的多样性,以分离自5种不同类型土壤的176株P.sojae为研究对象,利用基因推导法和AFLP分子标记技术进行多样性分析.结果表明,不同类型土壤中P.sojae 无毒基因型、无毒基因种类、无毒基因组合和群体致病力均表现出差异性,其中黑土、白浆土和草甸土中的P.sojae无毒基因型、无毒基因种类和无毒基因组合多样性相对丰富,群体致病力中等偏弱;盐碱土中的P.sojae无毒基因型、无毒基因种类和无毒基因组合多样性丰富度较低,群体致病力相对较强;风沙土中没有分离

  16. Distribución de Phytophthora cactorum en el perfil de un suelo cultivado con frutilla (Fragaria x ananassa

    Directory of Open Access Journals (Sweden)

    María Josefina Iribarren

    2012-03-01

    Full Text Available Phytophthora cactorum es el agente causal de la podredumbre seca que produce importantes pérdidas en los cultivos de frutilla (Fragaria x ananassa. Este patógeno persiste como oosporas formadas principalmente en los frutos afectados, los que quedan en la superficie del suelo. En un lote representativo de los cultivos de frutillas de la zona noreste de la provincia de Buenos Aires, Argentina, y después de haberse levantado la plantación y labrado el suelo, se buscó establecer la distribución espacial de las oosporas de P. cactorum remanentes. El muestreo se realizó en tres bloques ubicados a lo largo de una transecta diagonal al terreno y a dos profundidades en el perfil del suelo. También se caracterizó la topografía del terreno y parámetros físicos del suelo de interés. La detección de P. cactorum se realizó mediante el empleo de cebos. No se encontraron diferencias significativas en cuanto a la presencia del patógeno en los distintos puntos muestreados sobre el terreno, a la escala de análisis. Sólo se observó una pequeña tendencia a la disminución del inóculo en profundidad. El número de recuentos positivos en las profundidades A y AB/BA fueron respectivamente 30 y 22 en un total de 72 muestras. Tampoco hubo diferencias significativas en densidad aparente, humedad equivalente y macroporosidad del suelo. Si bien la distribución en superficie de P. cactorum pudo deberse fundamentalmente a procesos naturales, la labranza del suelo posibilitó la dispersión de oosporas viables en profundidad.

  17. 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.

  18. 致病疫霉拮抗真菌研究进展%Advances of antagonistic fungi against Phytophthora infestans

    Institute of Scientific and Technical Information of China (English)

    蒋继志; 郭俊亭; 李丽艳

    2012-01-01

    Phytophthora infestans (Mont. ) de Bary causes late blight of potato and tomato, and is the first important factor limiting sustainability for potato and tomato production all over the world. Current resistant varieties, agricultural cultivations, and chemical fungicides could not completely and effectively control the late blight since P. Infestans has evident physiological differentiation and quick hereditary vari ation. To explore antagonistic fungi and develop safe and high effective microbial pesticide against P. In festans is one of the main study fields at present. In order to carry out biological control of potato and tomato late blight, the progress on antagonistic fungi to P. Infestans in recent years were reviewed, and some problems existing in this field and research highlight were pointed out.%致病疫霉主要引起马铃薯和番茄的晚疫病,是严重制约马铃薯和番茄生产可持续发展的首要因素.生产中可利用的措施主要有选育和利用抗病品种、农业栽培措施和化学农药,但因病菌生理分化明显、遗传变异迅速,现有措施难以完全有效控制该病,发掘致病疲霉拮抗微生物并研发安全高效的微生物农药是当前的主要研究方向之一.综述了近年来对于致病疫霉拮抗真菌的研究进展,并指出了在该领域中存在的一些问题和今后的研究重点,以期对马铃薯晚疫病的生物防治发挥推进作用.

  19. 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.

  20. Dissection of two soybean QTL conferring partial resistance to Phytophthora sojae through sequence and gene expression analysis

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    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. 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.

  2. 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

  3. Synthesis and Antifungal Activities of New Type β-Methoxyacrylate-Based StrobUurin Analogues

    Institute of Scientific and Technical Information of China (English)

    张翔; 刘慧君; 高永鑫; 王会利; 郭宝元; 李建中

    2012-01-01

    Strobilurins have become one of the most important classes of agricultural fungicides. To discover new strobilurin derivatives with high activity against resistant pathogens, a series of novel fl-methoxyacrylate analogues were designed and synthesized by integrating substituted pyrimidine with a strobilurin pharmacophore. The compounds were confirmed and characterized by infrared, 1H nuclear magnetic resonance, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds 1 exhibited potent antifungal activity against Colletotrichum orbiculare, Botrytis cinerea Pers and Phytophthora capsici Leonian at the concentration of 50 μg/mL. Exhilaratingly, compound 1 a (R= methyl) showed better antifungal activity against all the tested fungi than the commercial strobilurin fungicide azoxystrobin.

  4. 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

  5. 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

  6. Paromomycin Derived from Streptomyces sp. AG-P 1441 Induces Resistance against Two Major Pathogens of Chili Pepper.

    Science.gov (United States)

    Balaraju, Kotnala; Kim, Chang-Jin; Park, Dong-Jin; Nam, Ki-Woong; Zhang, Kecheng; Sang, Mee Kyung; Park, Kyungseok

    2016-09-28

    This is the first report that paromomycin, an antibiotic derived from Streptomyces sp. AG-P 1441 (AG-P 1441), controlled Phytophthora blight and soft rot diseases caused by Phytophthora capsici and Pectobacterium carotovorum, respectively, in chili pepper (Capsicum annum L.). Chili pepper plants treated with paromomycin by foliar spray or soil drenching 7 days prior to inoculation with P. capsici zoospores showed significant (p chili pepper. Furthermore, the treatment slightly promoted growth; this growth was supported by increased chlorophyll content in paromomycin-treated chili pepper plants. Additionally, paromomycin likely induced resistance as confirmed by the expression of pathogenesis-related (PR) genes: PR-1, β-1,3-glucanase, chitinase, PR-4, peroxidase, and PR-10, which enhanced plant defense against P. capsici in chili pepper. This finding indicates that AG-P 1441 plays a role in pathogen resistance upon the activation of defense genes, by secretion of the plant resistance elicitor, paromomycin. PMID:27291677

  7. Screening of antagonistic bacteria for biological control of nursery wilt of black pepper (Piper nigrum).

    Science.gov (United States)

    Anith, K N; Radhakrishnan, N V; Manomohandas, T P

    2003-01-01

    Bacterial antagonists of Phytophthora capsici were isolated from underground shoot portions of rooted cuttings of black pepper. Initially isolates were screened by dual culture on potato dextrose agar and carrot agar. Further, a screening was done on black pepper shoots for supression of lesion caused by the pathogen. Most of the antagonists showed varying levels of antagonism in the dual culture and the shoot assay. Isolate PN-026, showing the highest suppression of lesion development in the shoot assay was found to be the most efficient antagonist in reducing Phytophthora capsici induced nursery wilt of black pepper. This screening involving the host, pathogen, and the antagonist, performed on black pepper shoot (the planting material for this vegetatively propagated crop), could be used as a rapid and reliable method for the isolation of efficient bacterial antagonists of P. capsici.

  8. 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.

  9. 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

  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. 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...... 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 this region, as noted for other members of the family. Expression of M90 was measured by using RNA blots....... Potential roles for a translational regulator during both sexual development and asexual sporulation are discussed....

  12. Microscopic observations on oospore germination of Phytophthora sojae%大豆疫病卵孢子萌发的显微观察

    Institute of Scientific and Technical Information of China (English)

    罗加风; 黄国明

    2001-01-01

    @@ 大豆疫病Phytophthora sojae Kaufmann&Gerdemann作为典型的土传真菌病害,随病土远距离传播的卵孢子是病菌扩散的主要来源.国内外许多专家都认为该病不能种传,周肇蕙和严进发现:通过人工接种大豆疫霉可以得到有卵孢子的病种子,认为该病可以种传[1~2],但种子中卵孢子的活性测定仍未解决.

  13. 大豆疫霉菌对大豆幼苗的侵染特性%The infections characteristics of Phytophthora sojae to soybean seedlings

    Institute of Scientific and Technical Information of China (English)

    左豫虎; 薛春生; 韩文革; 刘惕若

    2002-01-01

    @@ 大豆疫病由大豆疫霉菌Phytophthora sojae引致.20世纪50年代在美国曾大面积发生,成为当时美国大豆能否继续种植的关键因素.1991年以来,此病先在我国东北发现并且分离到了病原菌[1~2],近几年该病有逐年加重的趋势.该病引起的苗期死株率轻则10%,重则80%~90%,甚至造成局部地块绝产,对大豆生产造成严重威胁.为此,作者对P. sojae的侵染特性进行了初步研究.

  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. 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.

  16. 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

  17. 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

  18. 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

  19. 大豆疫霉根腐病的发生和防治研究进展%Progress in the studies on the occurr ence of Phytophthora sojae and its control

    Institute of Scientific and Technical Information of China (English)

    朱振东

    2002-01-01

    @@ 由大豆疫霉菌(Phytophthora sojae Kaufmann &Gerdemann,异名P.megasperma var.sojae Hildebrand,P.megasperma f.sp.glycinea Kuan and Erwin,P.sojae f.sp.glycinea Faris et al.)引起的大豆疫霉根腐病是严重影响大豆生产的毁灭性病害之一.

  20. 野生大豆接种大豆疫霉根腐病菌后过氧化物酶(POD)活性变化%Response of POD Activity in Glycine soja Inoculated by Phytophthora sojae

    Institute of Scientific and Technical Information of China (English)

    程鹏; 徐鹏飞; 范素杰; 靳立梅; 吴俊江; 王金生; 张淑珍

    2013-01-01

    对大豆疫霉菌胁迫下抗感不同野生大豆根、茎、叶中过氧化物酶(peroxidase,POD)活性的变化进行了初步研究.结果表明:抗病野生大豆接种后叶中POD活性在病程的大部分阶段高于感病野生大豆,同时高于未接种植株;而根和茎中的POD酶活性在病程的大部分阶段有所增加,但变化幅度不大.%Phytophthora root and stem rot caused by Phytophthora sojae is a world wide destructive soybean disease,it may attack plants at any growth stage,causing root and stem rot. The principle of POD activity changes in roots,stems and leaves of soybean varieties with different resistance to Phytophthora sojae and the effect of POD on resistance to this disease were researched. The results showed that the POD activities of leaves in resistant soybean varieties increased compared with the susceptible soybean varieties at most of the pathogenicity stages,and it was also higher than that of control. The reaction of POD in roots and stems increased at most of the pathogenicity stages, however, the change extent was relatively low.

  1. 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.)

    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...

  2. 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.

  3. 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.

  4. 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.)

  5. 木醋液对马铃薯晚疫病菌的抑制作用%Inhibition Effects of Wood Vinegar on Phytophthora infestans

    Institute of Scientific and Technical Information of China (English)

    马骏; 刘霞; 王洪洋; 杨艳丽

    2011-01-01

    The inhibition effects of wood vinegar on Phytophthora infestans were studied by adding different concentrations of wood vinegar in the rye culture medium. The results showed that the mycelia growth rate was inhibited by over 2% wood vinegar concentrations, however, the mycelia growth and sporangia formation were promoted by 0.1% concentration of wood vinegar. The sporangia formation was promoted by 0.2% wood vinegar concentrations, but for the mycelia growth, the difference was not significant.%通过在黑麦培养基中添加不同浓度的木醋液,研究木醋液对马铃薯晚疫病菌的抑菌作用。结果表明,2%以上浓度的木醋液对菌丝生长有明显的抑制作用,而0.1%浓度的木醋液反而对菌丝生长和孢子囊的形成有促进作用,0.2%浓度的木醋液虽然对菌丝生长影响不显著,但对孢子囊的形成仍然有促进作用。

  6. 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.

  7. 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.

  8. A Phytophthora sojae gene of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) induced in host infection and its anti-oxidative function in yeast

    Institute of Scientific and Technical Information of China (English)

    ZENG Juan; WANG Yuanchao; SHEN Gui; ZHENG Xiaobo

    2006-01-01

    Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional protein well defined in eukaryotes, especially in mammalian and Saccharomyces cerevisiae. Using the method of suppression subtractive hybridization (SSH), we identified a Phytophthora sojae cDNA coding GAPDH, which was up-regulated during the early stage of soybean infection. The termed PsGapdh gene possessed three copies in the P. sojae genome. Its amino acid sequence harbored overall conserved domain of GADPH, homologous closest to GapC1 of Achlya bisexualis (oomycete) and adjoined to GapC2s of Odontella sinensis and Phaeodactylum tricornutum (diatom), on the C-Ⅱbranch of subfamily GapC in phylogeny tree of GAPDH. The transcriptional level of PsGapdh was up-regulated throughout early infection. Heterogenous expression of PsGapdh in the yeast tdh1-deleted mutant could rescue growth arrest under continuous exposure to H2O2. These results indicated active roles of PsGapdh in pathogen-host interaction and anti-oxidation.

  9. A Field Experiment on Control Effects of Six Chemicals on Vanilla Phytophthora nicotianae%6种药剂防治香草兰疫病田间药效试验

    Institute of Scientific and Technical Information of China (English)

    刘爱勤; 桑利伟; 孙世伟; 苟亚峰; 刘向阳

    2012-01-01

    The control effects of six chemicals 68% Metalaxyl-M mancozeb WDG, 50% dimethomorph WP, 25% metalaxyl propamocarb WP, 69% dimethomorph mancozeb WP, 36% cymoxanil mancozeb WP and 70% Aliette Mn .Zn WP on Phytophthora nicotianae in vanilla were tested using field experiment. The results showed that 68% Metalaxyl-M mancozeb WDG, 50% dimethomorph WP and 25% metalaxyl propamocarb WP had better control effect to vanilla Phytophthora nicotianae. Three of them could be applied alternately to control Phytophthora nicotianae in vanilla production.%为筛选出防治香草兰疫病的最佳药剂,采用田间小区试验方法.测定68%精甲霜·锰锌WDG(水份散粒剂)、50%烯酰吗啉WP(可湿性粉剂)、25%甲霜·霜霉威WP、69%烯酰吗啉·锰锌WP、36%霜脲锰锌WP和70%乙磷铝锰锌WP等6种不同使用浓度药剂对香草兰疫病的防治效果。结果表明:68%精甲霜·锰锌WDG1000倍液、50%烯酰吗啉WP1000倍液及36%霜脲锰锌WP1000倍液对香草兰疫病大田防效较好。分别为86.6%、81.4%和79.8%。生产上可交替使用这3种药剂来防治香草兰疫病。

  10. Efeito da aplicação foliar de fosfonato potássico na protecção das raízes do castanheiro (Castanea sativa Mill.) inoculadas com Phytophthora cinnamomi Rands

    OpenAIRE

    Gouveia, Eugénia; Coelho, Valentim; Fonseca, Felícia; Nunes, Luís; Monteiro, Maria do Loreto

    2008-01-01

    Phytophthora cinnamomi é um parasita cujo ciclo de vida ocorre integralmente no ambiente solo causando podridões das raízes e colo em muitas espécies vegetais. O castanheiro (Castanea sativa Mill) é muito susceptível às espécies do género Phytophthoro e os sintomas da Doença da Tinta rapidamente se manifestam. Recentemente, verificou-se que as formas aniónicas do acido fosfónico evidenciam elevada eficácia no combate as doenças radiculares associadas a Phytophthoro.

  11. Isolamento de genes de resistência a Phytophthora cinnamoni e definição de um protocolo de transformação genética em Castanea sativa

    OpenAIRE

    Santos, Carmen Sofia Pedro dos, 1987-

    2010-01-01

    Tese de mestrado. Biologia (Biologia Celular e Biotecnologia). Universidade de Lisboa, Faculdade de Ciências, 2010 Castanea sativa pertence à família Fagaceae, tem um importante papel na ecologia, alimentação e economia. C. sativa sofre de uma doença severa, denominada por doença da tinta, causada maioritariamente pelo agente patogénico Phytophthora cinnamomi. A transformação genética surge como uma ferramenta poderosa para o melhoramento de plantas lenhosas como as espécies de castanheiro...

  12. Genome-wide prediction and functional validation of promoter motifs regulating gene expression in spore and infection stages of Phytophthora infestans.

    Directory of Open Access Journals (Sweden)

    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.

  13. Potato NPH3/RPT2-Like Protein StNRL1, Targeted by a Phytophthora infestans RXLR Effector, Is a Susceptibility Factor.

    Science.gov (United States)

    Yang, Lina; McLellan, Hazel; Naqvi, Shaista; He, Qin; Boevink, Petra C; Armstrong, Miles; Giuliani, Licida M; Zhang, Wei; Tian, Zhendong; Zhan, Jiasui; Gilroy, Eleanor M; Birch, Paul R J

    2016-05-01

    Plant pathogens deliver effectors to manipulate host processes. We know little about how fungal and oomycete effectors target host proteins to promote susceptibility, yet such knowledge is vital to understand crop disease. We show that either transient expression in Nicotiana benthamiana, or stable transgenic expression in potato (Solanum tuberosum), of the Phytophthora infestans RXLR effector Pi02860 enhances leaf colonization by the pathogen. Expression of Pi02860 also attenuates cell death triggered by the P. infestans microbe-associated molecular pattern INF1, indicating that the effector suppresses pattern-triggered immunity. However, the effector does not attenuate cell death triggered by Cf4/Avr4 coexpression, showing that it does not suppress all cell death activated by cell surface receptors. Pi02860 interacts in yeast two-hybrid assays with potato NPH3/RPT2-LIKE1 (NRL1), a predicted CULLIN3-associated ubiquitin E3 ligase. Interaction of Pi02860 in planta was confirmed by coimmunoprecipitation and bimolecular fluorescence complementation assays. Virus-induced gene silencing of NRL1 in N. benthamiana resulted in reduced P. infestans colonization and accelerated INF1-mediated cell death, indicating that this host protein acts as a negative regulator of immunity. Moreover, whereas NRL1 virus-induced gene silencing had no effect on the ability of the P. infestans effector Avr3a to suppress INF1-mediated cell death, such suppression by Pi02860 was significantly attenuated, indicating that this activity of Pi02860 is mediated by NRL1. Transient overexpression of NRL1 resulted in the suppression of INF1-mediated cell death and enhanced P. infestans leaf colonization, demonstrating that NRL1 acts as a susceptibility factor to promote late blight disease.

  14. 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

  15. ALTERNATIVAS MICROBIOLÓGICAS PARA EL MANEJO DE Phytophthora cinnamomi Rands., EN Persea americana Mill. BAJO CONDICIONES DE CASA-MALLA

    Directory of Open Access Journals (Sweden)

    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.

  16. 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

    Directory of Open Access Journals (Sweden)

    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.

  17. 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)

  18. 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

  19. 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.

  20. Overexpression of SpWRKY1 promotes resistance to Phytophthora nicotianae and tolerance to salt and drought stress in transgenic tobacco.

    Science.gov (United States)

    Li, Jing-bin; Luan, Yu-shi; Liu, Zhen

    2015-11-01

    WRKY transcription factors are key regulatory components of plant responses to biotic and abiotic stresses. SpWRKY1, a pathogen-induced WRKY gene, was isolated from tomato (Solanum pimpinellifolium L3708) using in silico cloning and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. SpWRKY1 expression was significantly induced following oomycete pathogen infection and treatment with salt, drought, salicylic acid (SA), methyl jasmonate (MeJA) and abscisic acid (ABA). Overexpression of SpWRKY1 in tobacco conferred greater resistance to Phytophthora nicotianae infection, as evidenced by lower malondialdehyde (MDA) content; relative electrolyte leakage (REL); higher chlorophyll content; and higher peroxidase (POD, EC 1.11.1.7), superoxide dismutase (SOD, EC 1.15.1.1) and phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) activities. This resistance was also coupled with enhanced expression of SA- and JA-associated genes (NtPR1, NtPR2, NtPR4, NtPR5 and NtPDF1.2), as well as of various defense-related genes (NtPOD, NtSOD and NtPAL). In addition, transgenic tobacco plants also displayed an enhanced tolerance to salt and drought stresses, mainly demonstrated by the transgenic lines exhibiting lower accumulation of MDA content and higher POD (EC 1.11.1.7), SOD (EC 1.15.1.1) activities, chlorophyll content, photosynthetic rate and stomatal conductance, accompanied by enhanced expression of defense-related genes (NtPOD, NtSOD, NtLEA5, NtP5CS and NtNCED1) under salt and drought stresses. Overall, these findings suggest that SpWRKY1 acts as a positive regulator involved in tobacco defense responses to biotic and abiotic stresses. PMID:25496091

  1. 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

  2. Rapid metabolic profiling of Nicotiana tabacum defence responses against Phytophthora nicotianae using direct infrared laser desorption ionization mass spectrometry and principal component analysis

    Directory of Open Access Journals (Sweden)

    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

  3. 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.

  4. 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.

  5. 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

  6. Mejoramiento Genético de la Papa en Colombia, para Resistencia a la "Gota" Causada por el PhytophthoraInfestans, (Mont. de Bary

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    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

  7. 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.

  8. EVALUACIÓN DE INDICADORES QUE CARACTERIZAN LA ACCIÓN PROTECTORA DEL QUITOSANO EN Nicotiana tabacum L. vs Phytophthora nicotianae BREDA DE HAAN

    Directory of Open Access Journals (Sweden)

    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.

  9. Research progress on antagonistic bacteria against Phytophthora infestans%致病疫霉颉颃细菌研究进展

    Institute of Scientific and Technical Information of China (English)

    黄英菊; 蒋继志; 冯丽娜; 赵偲

    2013-01-01

    致病疫霉可引起马铃薯和番茄晚疫病,常造成巨大损失,生产中主要依靠抗病品种和化学农药防治。但因病菌生理分化明显、遗传变异迅速,已出现能克服现有全部抗病基因的菌株,且抗药性日益突出,致使该病难以完全有效地得到控制。发掘致病疫霉颉颃微生物,并研发安全、高效的微生物农药是当前的研究热点之一。结合笔者开展的研究工作,就近年来国内外对致病疫霉颉颃细菌的筛选、颉颃物质及其作用机制等进行了综述。同时,对该领域当前存在的一些问题和今后的研究重点进行了讨论,以期加快对致病疫霉颉颃细菌的利用。%Phytophthora infestans caused late blight of potato and tomato, often caused a great loss. Resistant varieties and pesticides were current main measures for controlling late blight of potato and tomato. Because of obvious physiological differentiation and quick hereditary variation of P. infestans, some new strains with strong chemicals resistance appeared in many potato production areas could overcome existing resistance genes. Research progress on screening of antagonistic bacteria, active substances and action mechanisms on P. infestans in recent years at home and abroad was reviewed, and some problems in this field and research highlight in future were discussed, which could contribute to its utilizations.

  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. 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....

  12. 大豆疫霉病及其遗传多样性的研究方法%Research Progress in Biology of Phytophthora sojae and its Molecular Approaches for Gene Diversity

    Institute of Scientific and Technical Information of China (English)

    韩丽娟; 刘文洪

    2004-01-01

    本文对大豆疫霉菌(Phytophthora sojae)发生危害概况、侵染特性、菌株分离方法、流行学调查、小种分化与鉴定方法、毒力基因的多态性、基因多态性的分子鉴定、SSR标记在基因多态性研究中的应用等进行了系统综述,讨论了研究P.sojae生理小种遗传多样性的方法,指出应用SSR分子标记进行P.sojae种下分类,确定生理小种间亲缘关系是可行的.

  13. A cultivation method for production of pure vegetative mycelia from Phytophthor sojae%一种大豆疫霉菌(Phytophthora sojae)纯营养菌丝的培养方法

    Institute of Scientific and Technical Information of China (English)

    李岩; 文景芝

    2009-01-01

    比较了胡萝卜琼脂和玻璃纸胡萝卜琼脂培养大豆疫霉菌(Phytophthora sojae)对菌丝生长速度、卵孢子产生、孢子囊产生时间及RNA提取效果的影响.结果表明,玻璃纸胡萝卜琼脂培养的大豆疫霉菌,10 d内不会产生卵孢子,当大豆疫霉菌从玻璃纸上取下时,不会带有培养基,能够提取出高质量的RNA,满足差异显示反转录PCR对RNA质量的要求,是一种适合大豆疫霉菌纯营养菌丝的培养方法.

  14. Ação antagônica de rizobactérias contra Phytophthora parasitica e p. citrophthora e seu efeito no desenvolvimento de plântulas de citros

    Directory of Open Access Journals (Sweden)

    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.

  15. 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

  16. 大豆疫霉拮抗菌株的筛选与鉴定%Screening and Identification of Antagonistic Strain against Phytophthora sojae

    Institute of Scientific and Technical Information of China (English)

    付红梅; 李森; 檀根甲; 王子迎; 赵平生

    2011-01-01

    [ Objective] The paper was to .screen the antagonistic strain against Phytophthora sojae with biocontrol potential, and provide basis for searching control measures and designing new control strategies against P. sojae. [ Method] The rhizosphere soil of soybean was collected from three different places in Heilongiang Province, and various soil microorganisms were isolated. Dual culture method was used to screen the microorganism with antagonistic effect against P. sojae. On this basis, the growth inhibition rate of the microorganism with stronger antagonistic effect against P. sojae was determined, and its control effect against P. sojae was also measured. [ Result ] A strain of bacterium with relatively good antagonistic effect was isolated from soil, and named as strain B048. Dual test showed that the growth inhibition rate of antagonistic bacterium B048 against P. sojae reached 97.5%. Antagonistic endurance tests showed that the width of inhibition zone was still 20.0 mm after dual culture with P. sojae for 21 d. In potting experiment, the control effect of B048 against P. sojae was 100%. The antagonistic bacterium was primarily identified to be Bacillus pumilus through morphology and 16S rDNA sequence analysis. [ Conclusion] The antagonistic bacterium B048 had good prospect to be developed as the biocontrol bacterium against P. sojae.%[目的]筛选具有生防潜力的大豆疫霉拮抗菌,为寻找病害防控措施、设计新的疫病控制策略提供基础.[方法]从黑龙江省3个不同地区采集大豆根围土壤样本并分离各类土壤微生物,采用对峙培养法筛选出对大豆疫霉有拮抗作用的微生物,并在此基础上测定拮抗力较强微生物对大豆疫霉菌的生长抑制率及其对大豆疫病的控制作用.[结果]从土壤中分离得到1株拮抗效果相对较好的细菌,命名为B048菌株.对峙试验结果显示,拮抗细菌B048菌株对大豆疫霉的生长抑制率达97.5%;拮抗持久力测定显示,

  17. Chemical and biological characterization of sclerosin, an antifungal lipopeptide.

    Science.gov (United States)

    Berry, Chrystal L; Brassinga, Ann Karen C; Donald, Lynda J; Fernando, W G Dilantha; Loewen, Peter C; de Kievit, Teresa R

    2012-08-01

    Pseudomonas sp. strain DF41 produces a lipopeptide, called sclerosin that inhibits the fungal pathogen Sclerotinia sclerotiorum . The aim of the current study was to deduce the chemical structure of this lipopeptide and further characterize its bioactivity. Mass spectrometry analysis determined the structure of sclerosin to be CH(3)-(CH(2))(6)-CH(OH)-CH(2)-CO-Dhb-Pro-Ala-Leu/Ile-Ala-Val-Val-Dhb-Thr-Val-Leu/Ile-Dhp-Ala-Ala-Ala-Val-Dhb-Dhb-Ala-Dab-Ser-Val-OH, similar to corpeptins A and B of the tolaasin group, differing by only 3 amino acids in the peptide chain. Subjecting sclerosin to various ring opening procedures revealed no new ions, suggesting that this molecule is linear. As such, sclerosin represents a new member of the tolaasin lipopeptide group. Incubation of S. sclerotinia ascospores and sclerotia in the presence of sclerosin inhibited the germination of both cell types. Sclerosin also exhibited antimicrobial activity against Bacillus species. Conversely, this lipopeptide demonstrated no zoosporicidal activity against the oomycete pathogen Phytophthora infestans . Next, we assessed the effect of DF41 and a lipopeptide-deficient mutant on the growth and development of Caenorhabditis elegans larvae. We discovered that sclerosin did not protect DF41 from ingestion by and degradation in the C. elegans digestive tract. However, another metabolite produced by this bacterium appeared to shorten the life-span of the nematode compared to C. elegans growing on Escherichia coli OP50. PMID:22838838

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. Field resistance of Phytophthora melonis to metalaxyl in South China%华南地区瓜类疫霉对甲霜灵的田间抗药性

    Institute of Scientific and Technical Information of China (English)

    吴永官; 陆少峰; 黄思良; 付岗; 陈亮; 谢大森; 黎起秦; 岑贞陆

    2011-01-01

    [ Objective] Phytophthora melonis is the casual agent of wax gourd and cucumber Phytophthora blight which becomes a constraint for sustainable production of the related crops. Metalaxyl is one of the principal fungicides for controlling the disease now. The objectives of the present study were; ( 1 ) to investigate the baseline sensitivity and field resistance off. Melonis to metalaxyl in South China; (2) to test the occurrence of metalaxyl-resistant mutants from metalaxyl-sensitive wild type strains exposed to the fungicide; and ( 3 ) to monitor the development of metalaxyl resistance in P. Melonis population. [Methods] Over 400 samples of wax gourd and cucumber Phytophthora blight were collected from Guangxi Zhuang Autonomous Region and Guangdong province during 2007-2010, and 193 strains of P. Melonis were isolated and purified. The sensitivity of the isolated strains to metalaxyl was tested using mycelial growth rate method in vitro and floating-leaf-disk method in vivo, respectively. The metalaxyl-sensitive strains were induced on PDA plates containing 10 μg/mL metalaxyl. [Results] The sensitive, moderately resistant and resistant strains were recorded as 29. 0% , 18. 1% and 52. 8% , respectively, among 193 tested strains. The frequency and level of resistance of P. Melonis from Guangdong were higher than that from Guangxi. The strains from cucumber was generally more resistant to metalaxyl than those from wax gourd. The metalaxyl-resistant strains were frequently detected as predominant populations in most of the sampling sites and the highest resistance index (4226. 9) was confirmed. Metalaxyl-resistant (Mtr) mutants could be isolated from approximately 60% of the sensitive wild-type strains. The resistance level of the M' mutants was 189 -407 times higher than that of their sensitive parental strains. The EC50values of 9 sensitive strains from a sampling site without a record of phenylamide fungicide application ranged from 0. 0429 to 0. 5461 μg/mL. Their

  3. 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

  4. 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.

  5. 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.

  6. 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...

  7. Analysis on Genetic Diversity of Phytophthora infestans Based on SRAP in Fujian Province%福建省致病疫霉菌SRAP遗传多样性分析

    Institute of Scientific and Technical Information of China (English)

    兰成忠; 李本金; 陈庆河; 翁启勇

    2011-01-01

    为了解福建省致病疫霉菌的群体遗传结构,为该病原菌的遗传进化提供理论依据,笔者应用SRAP分子标记技术对福建省致病疫霉茵的群体遗传多样性,及不同地区菌株间的关系进行比较分析.利用10个菌株从110对引物组合中筛选出多态性引物10对,对分离自福建省10个不同市(县)的62个致病疫霉菌茵株DNA进行PCR扩增,共产生92条谱带,其中多态性标记90条,多态检测率为97.8%.利用NTSYpc Version2.1软件对供试菌株间的遗传距离进行聚类分析并构建系统树状图.以遗传距离0.57为阈值,可将供试62个菌株划分为4个遗传聚类组,SRAP分组与菌株的地理来源、寄主均无明显相关性.聚类分析结果表明,福建省不同地区的致病疫霉茵整体亲缘关系相近,但各菌株间存在遗传差异.%In order to learn the genetic structure of Phytophthora infestans in Fujian province and provide a theoretical basis for genetic evolution of this pathogen. Sequence related amplified polymorphism (SRAP) analysis was used to detect the genetic variation in populations of Phytophthora infestans in Fujian province.Among 110 combinations of primer pairs screened, 10 primer pairs that amplified consistent polymorphic bands with DNA of 10 isolates were generated. They were further applied to amplfy the genomic DNA of 62 isolates collected from different areas and hosts in Fujian province. In total, 92 SRAP markers were obtained.Among the bands, 90 were polymorphic, which accounted for 97.8%. Based on the genetic distance, a dendrogram was constructed with the software NTSYSpc Version2.1. At genetic distance of 0.57, 62 isolates were divided into 4 SRAP groups. There was no correlation between SRAP group and the geographic origin or their hosts. The analysis showed that some strains from one area closely related to that from another area.Nonetheless, rich genetic variation existed among the tested strains in Fujian province.

  8. 柠檬草精油对烟草黑胫病的抑制活性研究%Antimicrobial Activities of Lemongrass Essential Oil Against Phytophthora parasitica var.nicotianae

    Institute of Scientific and Technical Information of China (English)

    卢敏; 韩智强; 李忠环; 詹莜国; 彭云; 徐云; 姚雷

    2012-01-01

    研究了5种常见植物精油的抗烟草黑胫病活性,确定了植物精油的种类与浓度,为烟草黑胫病防治的精油药剂的开发与应用提供理论依据.采用菌丝生长抑制法和茎秆接种法,分别评价了植物精油对烟草黑胫病的体外和体内抑菌活性.结果表明,在体外条件下,柠檬草精油对烟草黑胫病的抑制效果最好,具有浓度梯度抑制效应,最低抑菌浓度为320 μg/mL;在体内条件下,柠檬草精油640μg/mL时对烟草黑胫病预防与治疗效果最佳,病情指数分别为16.67和56.79,相对诱导效果分别为81.93%和38.44%,与甲霜灵190 μg/mL无显著性差异.柠檬草精油具有优越的体外和体内抗菌活性,是有潜力的生物抗菌剂和杀菌剂,有望在今后的烟草黑胫病菌防治中进一步开发利用.%Antimicrobial activities of five common plant essential oils against Phytophthora parasitica var. Nicotianae were investigated,and the species and concentration of the plant essential oils were determined, which provided a theory basis for the development and application of essential oil fungicide against P. Parasitica var. Nicotianae. Hypha growth inhibition assay and stem inoculation method were used to evaluate the in vitro and in vivo antimicrobial activity of essential oils to P. Parasitica var. Nicotianae. The results showed that, in the selected five essential oils, lemongrass essential oil was most effective against P. Parasitica var. Nicotianae in vitro which inhibited hypha growth in a dose-dependent manner, and totally inhibited mycelia growth with a minimum concentration of 320 μg/mL. In vivo, 640 μg/mL of lemongrass essential oil was most efficient for prevention and treatment of disease with a disease index of 16.67 and 56. 79 and relatively induced efficiency of 81. 93% and 38. 44 %, respectively. No significant difference was found between 640μg/mL of lemongrass essential oil and 190 μg/mL of metalaxyl. This study has demonstrated

  9. 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.

    Science.gov (United States)

    Oh, Sang-Keun; Kwon, Suk-Yoon; Choi, Doil

    2014-09-01

    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.

  10. 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.

  11. 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.

  12. 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.

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    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.

  13. 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.

  14. Molecular Characterization of LjABCG1, an ATP-Binding Cassette Protein in Lotus japonicus.

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    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.

  15. Trichoderma sp Native from Chili Region of Poanas, Durango, Mexico Antagonist against Phytopathogen Fungi

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    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.

  16. 贵州省烟草黑胫病菌对烯酰吗啉的敏感性%Sensitivity of Phytophthora nicotianae var.nicotianae to dimethomorph in Guizhou

    Institute of Scientific and Technical Information of China (English)

    苏凯; 桑维钧; 张新强; 潘滴滴; 王慧

    2013-01-01

    To confirm the sensitivity of Phytophthora nicotianae var. Nicotianae to dimethomorph, forty seven isolates of P. Nicotianae var. Nicotianae were collected from several areas in Guizhou Province, and sensitivity of mycelial growth and zoosporangia formation to dimethomorph were measured. The results showed that dimethomorph could inhibit the mycelial growth and sporangium formation of P. Nicotianae var. Nicotianae, for mycelial growth, with a mean EC50 value of 2. 476 8 μg/mL,ranging from 0. 792 6 μg/mL to 4. 232 7 μg/mL; and for sporangium formation, with a mean EC50 value of 2. 040 0 μg/mL,ranging from 0. 394 5 μg/mL to 4. 232 7 μg/mL. Sensitivity of these isolates to dimethomorph was fitted well with a normal distribution function. There were significant differences in the sensitivity of different strains to dimethomorph, and moreover there was a correlation between strain sensitivity and its geographical origin.%为了明确烟草黑胫病菌对烯酰吗啉的敏感性现状,从贵州省各地采集了47株烟草黑胫病菌株,分别测定了菌丝生长和游动孢子囊形成对烯酰吗啉的敏感性.结果表明,烯酰吗啉对烟草黑胫病菌菌丝生长和孢子囊形成的抑制基本一致,对菌丝EC50范围为0.792 6~4.232 7μg/mL,平均为2.476 8μg/mL;对孢子囊的抑制作用略强,EC50范围为0.394 5~4.625 3μg/mL,平均值为2.040 0 μg/mL.统计分析表明,烟草黑胫病菌47个菌株菌丝生长和孢子萌发对烯酰吗啉的敏感性符合正态分布,不同菌株对烯酰吗啉的敏感性有显著差异,而且菌株对烯酰吗啉的敏感性与其地理来源有一定的相关性.

  17. 三七疫霉病拮抗根际土壤细菌的筛选及初步鉴定%Screening and Preliminarily Identification of Rhizosphere Soil bacterial ControllingPhytophthora Cactorum ofPanax Notoginsing

    Institute of Scientific and Technical Information of China (English)

    杨丽芬; 杨建; 高玲玲; 郭建伟; 洪亮; 程加省; 孔琼; 田学军

    2016-01-01

    为了筛选对环境友好的生防细菌防治三七疫霉病,通过高温处理、稀释涂布法分别从三七健康及患病植株根际土壤分离了21和16株可培养细菌,并以对峙培养法分别筛选到6和7株拮抗菌株,上述13株拮抗菌株经生理生化特征鉴定为芽孢杆菌属。结果表明,健康植株根际土壤有较丰富的可培养细菌,而患病植株根际土壤可培养细菌中的拮抗菌株较丰富,表明健康植株与患病植株根际土壤的拮抗细菌丰度发生了变化。解淀粉芽孢杆菌B1的抑菌带宽达8.5mm,具有一定的潜在生防价值。%To screen eco-friendly bio-control bacteria controlling Phytophthora cactorum of Panax notoginsing, 21 and 16 strains rhizobacteria were separated respectively from healthy and infected Panax notoginsing by thermal processing, tissue crashing method, dilution coating method, additionally 6 and 7 strains antagonistic bacteria among them were respectively selected by confrontation culture method, then total of antagonistic bacteria above were identified as Bacillium spp. through physiological and biochemical characteristics. The results suggested that there were richer cultural bacteria in rhizosphere soil of healthy plants, in contrast that there were relatively richer antagonistic bacteria in rhizosphere soil of infected plants. In another word, the richness of antagonistic bacteria changed in rhizosphere soil of healthy and infected plants. Bacillus amyloliquefaciens B1 identified by physiological and biochemical characteristics, which had a certain potential bio-control value because of inhibition zone width up to 8.5 mm.

  18. Toxicity Test of Six Fungicides in vitro to Phytophthora infestans from Potatoes%6种杀菌剂对马铃薯晚疫病菌的室内毒力测定

    Institute of Scientific and Technical Information of China (English)

    田琴; 杨志辉; 朱杰华

    2012-01-01

    The toxiciUes of six fungicides(Mandipropamid, Famoxadone .cymoxanil, Fluopicolide .propamocab hydro chloride, Dimethomorph@ copper abietate, Propineb @ cymoxanil and Mancozeb) to Phytophthora infestans were determined by the method of growth rate in vitro. These tested fungicides had a better inhibiting effect on mycelial growth of P. infestans, of which Mandipropamid was the best one, with EC50 value being 0.029 μg/mL, followed by Famoxadone.cymoxanil, Propineb. cymoxanil, Dimethomorph .copper abietate, Fluopicolide .propamocab hydrochloride and the worst one was Mancozeb, whose EC50 value was 5.502 μg / mL. Based on the toxicity estimation in vitro and their characteristics, the six tested fungicides could be alternately and reasonably used to control the potato late blight in order to avoid or delay the occurrence of fungicide resistance in potato production.%试验采用生长速率法测定了双炔酰菌胺、恶酮.霜脲氰、氟菌.霜霉威、烯酰.松脂酮、丙森锌.霜脲氰、代森锰锌6种杀菌剂对马铃薯晚疫病菌的毒力。结果表明,供试6种杀菌剂对马铃薯晚疫病菌丝生长都有良好的抑制效果。双炔酰菌胺的毒力最强,其EC50值为0.029μg/mL,恶酮.霜脲氰、丙森锌.霜脲氰、烯酰.松脂酮、氟菌.霜霉威毒力依次减弱,而代森锰锌毒力最差,其EC50值为5.502μg/mL。根据室内毒力测定结果及药剂特性,供试的6种杀菌剂在田间防治上可视病害的发生情况交替或混合应用,做到科学合理搭配,以避免或延缓抗药性的产生。

  19. 我国部分地区大豆疫霉群体遗传分析%Genetic structure analysis of Phytophthora sojae population from several provinces in China

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    唐庆华; 崔林开; 苗苗; 李德龙; 阴伟晓; 郑小波; 王源超

    2011-01-01

    The primary objective of this study was to explore genetic diversity among Chinese Phytophthora sojae isolates. The fingerprints of 79 P. sojae isolates from part of regions of China were determined using 13 simple sequence repeats(SSR) primers. A total of 33 reproducible SSR fragments were scored among 13 primers ,of which 97.0% were polymorphic among the Chinese P. sojae population. The cluster analysis with the unweighted pair group method revealed that the 79 isolates of P. sojae were separated clearly into thirteen clusters(genotypes)in 0.79 dissimilarity distance. The genetic similarity among major of P. sojae isolates was low,indicating that there were abundant genetic diversities among Chinese P. sojae isolates as a result of remarkable genetic variations that occurred in DNA level. The analysis results in this study showed that there is certain correlation between P. sojae isolates genomic DNA polymorphisms and their originations, suggesting the interaction between P. sojae and soybean cultivars with genetical backgrounds may contribute to the wildly distributed genetical diversity among Chinese P. sojae strains.%为探究我国大豆疫霉菌的遗传多样性,使用13对简单重复序列标记(simple sequence repeats,SSR)引物对来自部分地区的79个大豆疫霉菌分离物进行了DNA指纹分析.13对SSR引物共扩增出33条条带,其中多态性条带比例为97.0%.SSR指纹聚类分析表明:当以相异距离0.79为阈值时,可将79个大豆疫霉菌分离物划分为13个遗传聚类组.多数大豆疫霉菌分离物之间遗传相似性较低,表明我国大豆疫霉在DNA水平上发生了显著的遗传变异,从而具有较丰富的遗传多样性.大豆疫霉菌DNA多态性特征与分离物地理来源之间存在一定相关性,说明不同地区的大豆疫霉菌群体与大豆栽培品种之间的互作很可能是引起大豆疫霉菌发生广泛遗传变异的主要原因.

  20. Genetic relationships between Anhui and Heilongjiang populations of Phytophthora sojae assessed by SSR markers%安徽和黑龙江省大豆疫霉群体遗传结构的SSR分析

    Institute of Scientific and Technical Information of China (English)

    王子迎; 王朝霞; 沈洁; 鲁红侠

    2009-01-01

    The genetic diversity of two geographic populations of Phytophthora sojae Kauf. & Gerd. from Anhui and Heilongjiang Provinces was determined using the molecular marker of simple sequence repeats (SSRs). Genetic variation was analyzed for 83 isolates of P. sojae. By using 20 pairs of SSR primers, a total of 109 polymophic bands (alleles) were amplified at an average of 5.5 bands per pair of primers. Genetic similarity analysis showed that there were obvious differences between Helongjiang and Anhui populations. Cluster analysis with an unweighted pair group method revealed that the 83 isolates of P. sojae were clearly separated into seven clustering groups (genotypes) at a level of 80% similarity. We also found that isolates from Heilongjiang had lower genotypic diversity than those of Anhui. In addition, three particular P. sojae genotypes were only found in Anhui population and two particular genotypes were only found in Heilongjiang population. In conclusion, the results in this study do not support the hypothesis that P. sojae in Anhui has immigrated from Heilongjiang.%采用简单重复序列(SSR)的分析方法,对来自安徽和黑龙江省的大豆疫霉群体进行了遗传多样性分析.通过使用20对SSR引物对供试的83株大豆疫霉菌株进行PCR扩增,共得到109个SSR标记,全部为多态性标记,平均每对引物扩增出5.5条带.遗传变异与相似性分析表明,安徽群体具有更高的遗传变异度,安徽群体与黑龙江群体问遗传相似性较低:聚类分析显示,供试菌株在80%的相似性水平上可被区分为7个类群,且安徽群体分布于更多的聚类组中:Shannon-Wiener多样性指数也表明安徽群体的遗传多样性较黑龙江群体丰富.综合分析表明,本研究的结果不支持关于安徽的大豆疫霉可能来源于黑龙江的推测.

  1. 哈茨木霉对辣椒生长的影响%Effects of Biocontrol Agents Trichoderma harzianum on Plant Growth in Capsicum

    Institute of Scientific and Technical Information of China (English)

    刘云龙; 何永宏; 张旭东

    2002-01-01

    在田间用哈茨木霉(Trichoderma harzianum)制剂处理土壤,栽培辣椒,结果表明:哈茨木霉不但对辣椒疫霉(Phytophthora capsici)和尖镰孢(Fusarium oxysporum)引起的根腐病具有一定的防病作用,而且能促进植株生长,提前开花、挂果,提高产量15%左右.

  2. Molecular Cloning of HbPR-1 Gene from Rubber Tree, Expression of HbPR-1 Gene in Nicotiana benthamiana and Its Inhibition of Phytophthora palmivora.

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    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.

  3. Identification and Analysis of Mitochondrial Haplotypes of Phytophthora infestans in Northeast and North China by PCR%利用PCR技术测定东北、华北致病疫霉线粒体单倍型

    Institute of Scientific and Technical Information of China (English)

    贾京珠; 杨志辉; 朱杰华; 赵冬梅; 蒋继志

    2015-01-01

    为了明确东北、华北地区致病疫霉群体的线粒体单倍型组成与多样性,采用PCR的方法对2013年采自两地区5省(区)的163株致病疫霉菌株的线粒体单倍型进行了测定和分析。由高变区HVRi所区分的Ⅰ型菌株所占比例为38.65%,Ⅱ型菌株占61.35%;高变区HVRii所区分的R1型、R2型和R3型菌株所占比例分别为1.85%、4.90%和93.25%。东北和华北两地区的优势线粒体单倍型均为ⅠR3型与ⅡR3型,其在群体中的比例分别为36.81%和56.44%。不同省(区)间致病疫霉线粒体单倍型组成存在一定差异,ⅡR2型菌株仅在河北和辽宁省有少量分布,所占比例仅为4.91%;ⅠR1型菌株仅存在于黑龙江,所占比例仅为1.84%。东北和华北地区致病疫霉线粒体单倍型整体表现一致,不同省(区)之间多态性不同,说明致病疫霉的线粒体单倍型与地理来源之间有很大关系。%To understand the composition and polymorphism of mitochondrial haplotypes of Phytophthora infestans in Northeast and North China,one hundred and sixty three P. infestans isolates were collected from five provinces ( region) of the two areas in 2013 and their mitochondrial haplotypes were identified and analyzed by PCR. The results showed that the percentage of type Ⅰ was 38. 65% and the rest 61. 35% belonged to typeⅡ,which were distinguished by HVRi. The percentages of type R1 ,R2 and R3 , which were distinguished by HVRii,were 1. 85%,4. 90% and 93. 25%,respectively. Haplotypes ⅠR3 and ⅡR3 were dominant and widely distributed in the Northeast and the North China. The percentages of haplotypes ⅠR3 and ⅡR3 were 36. 81% and 56. 44%, respectively. The composition of mitochondrial haplotypes of P. infestans was weakly different in the tested five provinces (region). Only a few strains with ⅡR2 occurred in Hebei and Liaoning provinces,and its percentage was 4. 91%. HaplotypeⅠR1 only distributed in Heilongjiang province,and its percentage was

  4. Sensitivity of Metalaxyl-Resistant Strains of Phytophthora infestans to Five Fungicides%抗甲霜灵致病疫霉菌对5种杀菌剂的敏感性测定

    Institute of Scientific and Technical Information of China (English)

    兰成忠; 陈庆河; 李本金; 赵健; 翁启勇

    2011-01-01

    In order to determine the sensitivity of metalaxyl-resistant strains of Phytophthora infestans to fungicides flumorph, azoxystrobin, pyraclostrobin, dimethomorph and cymoxanil, the toxicity of fungicides to metalaxylsensitive and metalaxyl-resistant strains of P. Infestans were tested by measuring radial growth on agar medium amended with fungicides. The results showed that the five tested fungicides had high inhibitory activity against mycelium growth and sporangia formation of metalaxyl-resistant and metalaxyl-sensitive isolates of P. Infestans. Flumorph exhibited the strongest toxicity to metalaxyl-resistant strains with the mean EC50 of 0. 037 6 μg · mL-1. There was obvious difference in sensitivity of tested isolates to cymoxanil, which ECM values ranged from 0. 008 4 μg · mL-1 to 0. 868 1 μg · mL-1 , the mean EC50 value was 0. 386 6 μg · mL-1 in inhibiting the mycelium growth of metalaxyl-resistant strains. There is high correlation of tested results between in vitro method and the floating-leaf-disk method, and showed that the tested fungicides had no cross-resistance with metalaxyl. These fungicides maybe substitute metalaxyl for controlling potato and tomato late blight disease.%为明确致病疫霉菌甲霜灵抗性菌株对氟吗啉、嘧菌酯、吡唑醚菌酯、烯酰吗啉和霜脲氰的敏感性,采用菌丝生长速度法,并用叶盘漂浮法加以比较,测定了致病疫霉菌甲霜灵抗性菌株和敏感性菌株对供试杀菌剂的敏感性.试验结果表明,供试5种杀菌剂对致病疫霉菌甲霜灵抗性和敏感菌株的菌丝生长、孢子囊的形成都具有明显的抑制作用.对致病疫霉菌甲霜灵抗性菌株毒力最强的杀菌剂是氟吗啉,其平均EC50值为0.037 6μg·mL-1,致病疫霉菌间对霜脲氰的敏感性差异显著,EC50值在0.008 4~0.868 1μg·mL-1之间,其中甲霜灵抗性菌株平均EC50值为0.386 6 μg·mL-1.菌丝生长速率法离体测定表现出与叶盘漂浮法结果具有较

  5. 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

  6. Development of polymorphic SSR markers for Phytophthora sojae and analysis of the genetic diversity%大豆疫霉多态性SSR标记开发及遗传多样性分析

    Institute of Scientific and Technical Information of China (English)

    徐静静; 王晓鸣; 武小菲; 朱振东

    2009-01-01

    Using FastPCR software, 1 234 perfect simple sequence repeats (SSRs) with 2 to 4 bp repeat motif were identified in complete genomic sequences of Phytophthora sojae. 260 SSRs were selected for primer design, and the validity of resulting primer pairs was detected by amplifying 5 isolates of P. Sojae. There were 212 (81.5%) primer pairs amplified characteristic SSR bands and 112 primer pairs (52.8%) amplified polymorphic bands among 5 different P. Sojae isolates. 18 primer pairs were selected to analyze the genetic diversity of 73 P. Sojae isolates came from USA, Heilongjiang Province and Fujian Province of China. On the 18 SSR loci, a total of 112 alleles were detected in 73 isolates. At each locus,4 to 9 alleles were detected with an average of 6.22. The results showed that the selected primer pairs were high polymorphic. There was the closest genetic distance between the P. Sojae populations from Heilongjiang and Fujian, while the populations from USA and Fujian had the farthest genetic distance. 73 P. Sojae isolates could be divided into 6 groups by UPGMA clustering, 8 USA isolates (72.73%) were clustered together with 53 Chinese isolates (85.48%), implicated that Chinese P. Sojae isolates and some USA isolates should have several common ancestors and Chinese isolates could be exotic species.%用FastPCR软件在大豆疫霉全基因组中搜索到1 234个含2~4个重复基元精确SSRs.选择260个SSRs设计引物,经对大豆疫霉5个分离物的基因组DNA检测,有212对(81.5%)有效扩增出SSR特征条带,112对(52.8%)扩增多态性.用18对多态性SSR引物分析了来自美国、中国黑龙江省和福建省大豆疫霉分离物的遗传多样性,在73个分离物中共扩增出112个等位变异,变异范围为4~9,平均为6.22个,表明选择的引物对具有高的多态性.在3个大豆疫霉群体中,黑龙江省和福建省分离物的遗传距离最近,美国和福建省分离物的遗传距离最远.UPGMA聚类将73个分离物划分为6

  7. Phytophthora nicotianae var. nicotianae on tomatoes

    NARCIS (Netherlands)

    Weststeijn, G.

    1973-01-01

    Around 1960 some disorders which initially were considered to be of a physiological nature were found in tomato plants grown in glasshouses in the Netherlands. One complex of symptoms was a brown rot of the lateral roots and the tap root, often followed by decomposition of the stem base tissue and d

  8. 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

  9. 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

  10. 致病疫霉拮抗内生细菌的筛选及离体防病作用%Screening of endophytic bacteria against Phytophthora infestans and prevention of potato late blight

    Institute of Scientific and Technical Information of China (English)

    蒋继志; 张蕾; 刘璇; 郑旭

    2013-01-01

    为了筛选对致病疫霉菌丝有显著抑制作用的植物内生细菌菌株,并测试其在马铃薯离体组织上对晚疫病的预防效果,本试验利用传统的分离培养方法从常见几种茄科植物组织内分离纯化内生细菌,以平板对峙法和滤纸片法分别测试细菌活体、无菌体发酵液和菌液对致病疫霉菌丝生长的抑制作用,在马铃薯块茎切片和离体叶片上测试菌液对晚疫病的预防效果.结果表明,分离纯化的81株内生细菌中,活体菌株对致病疫霉有抑制作用的有63株,抑制率达到50%以上的31株菌,其中以分离自辣椒果实的LJ-6和马铃薯块茎的TD-12菌株的抑制作用最强,抑菌率分别为93.12%和92.24%;同时发现活体菌株抑制率达到50%以上的31株菌的发酵液原液均无明显抑制作用,但这些菌株菌液的抑制作用普遍优于活体菌株;TD-12菌株的菌液在马铃薯块茎切片上对晚疫病具有显著的预防及诱导抗病效果,保护率均在91%以上;在马铃薯离体叶片上对晚疫病的防效为76.23%.这些结果表明TD-12菌株在防治马铃薯晚疫病方面有较大的应用潜力.%The objective of this paper is to obtain some endophytic bacteria inhibiting mycelial growth of Phytophthora infestans and evaluate their prevention effectivities of potato detached tissues from potato late blight. The endophytic bacterial strains were isolated and purified with the traditional method from inside the potato, tomato, eggplant and pepper tissues. The suppression of bacterial livings, fermentation liquids, and bacterial fluids on mycelial growth of P. infestans were tested by dual-culture method and filter paper method. Disease control effects of bacterial fluid on potato tuber slices and leaves were investigated. The results showed that 81 endophytic strains were isolated and purified, 63 of them could significantly restrain mycelial growth of P. infestans, in which the inhibition rates of 31

  11. 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

  12. 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

  13. 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.

  14. 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%。

  15. 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

  16. 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.

  17. 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...

  18. Composites Characterization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose of the Composites Characterization Laboratory is to investigate new and/or modified matrix materials and fibers for advanced composite applications both...

  19. 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

  20. Metric characterizations II

    CERN Document Server

    Blecher, David P

    2012-01-01

    The present paper is a sequel to our paper "Metric characterization of isometries and of unital operator spaces and systems". We characterize certain common objects in the theory of operator spaces (unitaries, unital operator spaces, operator systems, operator algebras, and so on), in terms which are purely linear-metric, by which we mean that they only use the vector space structure of the space and its matrix norms. In the last part we give some characterizations of operator algebras (which are not linear-metric in our strict sense described in the paper).

  1. 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.

  2. A characterization of maximin

    NARCIS (Netherlands)

    Bosmans, K.G.M.; Ooghe, E.

    2013-01-01

    We characterize maximin on the basis of anonymity, continuity, weak Pareto and weak Hammond equity. In contrast to the standard Hammond equity axiom, weak Hammond equity supports only utility transfers that unambiguously diminish overall inequality.

  3. 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.

  4. 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.

  5. 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

  6. 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...

  7. 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.

  8. 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...

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. Tank characterization reference guide

    Energy Technology Data Exchange (ETDEWEB)

    De Lorenzo, D.S.; DiCenso, A.T.; Hiller, D.B.; Johnson, K.W.; Rutherford, J.H.; Smith, D.J. [Los Alamos Technical Associates, Kennewick, WA (United States); Simpson, B.C. [Westinghouse Hanford Co., Richland, WA (United States)

    1994-09-01

    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.

  15. Novel macrocyclic molecules based on 12a-N substituted 16-membered azalides and azalactams as potential antifungal agents.

    Science.gov (United States)

    Wang, Xiaolei; Zhang, Shun; Pang, Yanlong; Yuan, Huihui; Liang, Xiaomei; Zhang, Jianjun; Wang, Daoquan; Wang, Mingan; Dong, Yanhong

    2014-02-12

    Novel macrocyclic molecules comprising sulfonyl and acyl moiety at the position N-12a of 16-membered azalides (6a-n) and azalactams (10a-r) scaffold were synthesized from cyclododecanone 1 as starting material via 5 steps and 4 steps, respectively. The antifungal activity of these compounds against Sclerotinia sclerotiorum, Pyricularia oryzae, Botrytis cinerea, Rhizoctonia solani and Phytophthora capsici were evaluated and found that compounds possessing α-exomethylene (6c, 6d, 6e and 6g) showed antifungal activity comparable to commercial fungicide Chlorothalonil against P. oryzae and compounds possessing p-chlorobenzoyl exhibited enhanced antifungal activity than those with other substituents against S. sclerotiorum, P. oryzae, and B. cinerea. These findings suggested that the α-exomethylene and p-chlorobenzoyl may be two potential pharmacological active groups with antifungal activities. PMID:24469079

  16. 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

  17. 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.

  18. Characterization of Bacillus cereus

    NARCIS (Netherlands)

    Wijnands LM; Dufrenne JB; Leusden FM; MGB

    2002-01-01

    Bacillus cereus is a ubiquitary microorganism that may cause food borne disease. Pathogenicity, however, depends on various characteristics such as the ability to form (entero)-toxin(s) that can not be detected by microbiological methods. Further characterization of pathogenic properties is not only

  19. 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

  20. 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…