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Sample records for characterize phytophthora capsici

  1. Cloning, characterization and expression of a novel laccase gene Pclac2 from Phytophthora capsici

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    Bao Zhen Feng

    2014-01-01

    Full Text Available Laccases are blue copper oxidases (E.C. 1.10.3.2 that catalyze the one-electron oxidation of phenolics, aromatic amines, and other electron-rich substrates with the concomitant reduction of O2 to H2O. A novel laccase gene pclac2 and its corresponding full-length cDNA were cloned and characterized from Phytophthora capsici for the first time. The 1683 bp full-length cDNA of pclac2 encoded a mature laccase protein containing 560 amino acids preceded by a signal peptide of 23 amino acids. The deduced protein sequence of PCLAC2 showed high similarity with other known fungal laccases and contained four copper-binding conserved domains of typical laccase protein. In order to achieve a high level secretion and full activity expression of PCLAC2, expression vector pPIC9K with the Pichia pastoris expression system was used. The recombinant PCLAC2 protein was purified and showed on SDS-PAGE as a single band with an apparent molecular weight ca. 68 kDa. The high activity of purified PCLAC2, 84 U/mL, at the seventh day induced with methanol, was observed with 2,2'-azino-di-(3-ethylbenzothialozin-6-sulfonic acid (ABTS as substrate. The optimum pH and temperature for ABTS were 4.0 and 30 ºC, respectively . The reported data add a new piece to the knowledge about P. Capsici laccase multigene family and shed light on potential function about biotechnological and industrial applications of the individual laccase isoforms in oomycetes.

  2. 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.

  3. 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.

  4. Variation in capsidiol sensitivity between Phytophthora infestans and Phytophthora capsici is consistent with their host range.

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    Artemis Giannakopoulou

    Full Text Available Plants protect themselves against a variety of invading pathogenic organisms via sophisticated defence mechanisms. These responses include deployment of specialized antimicrobial compounds, such as phytoalexins, that rapidly accumulate at pathogen infection sites. However, the extent to which these compounds contribute to species-level resistance and their spectrum of action remain poorly understood. Capsidiol, a defense related phytoalexin, is produced by several solanaceous plants including pepper and tobacco during microbial attack. Interestingly, capsidiol differentially affects growth and germination of the oomycete pathogens Phytophthora infestans and Phytophthora capsici, although the underlying molecular mechanisms remain unknown. In this study we revisited the differential effect of capsidiol on P. infestans and P. capsici, using highly pure capsidiol preparations obtained from yeast engineered to express the capsidiol biosynthetic pathway. Taking advantage of transgenic Phytophthora strains expressing fluorescent markers, we developed a fluorescence-based method to determine the differential effect of capsidiol on Phytophtora growth. Using these assays, we confirm major differences in capsidiol sensitivity between P. infestans and P. capsici and demonstrate that capsidiol alters the growth behaviour of both Phytophthora species. Finally, we report intraspecific variation within P. infestans isolates towards capsidiol tolerance pointing to an arms race between the plant and the pathogens in deployment of defence related phytoalexins.

  5. Variation in Capsidiol Sensitivity between Phytophthora infestans and Phytophthora capsici Is Consistent with Their Host Range

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    Giannakopoulou, Artemis; Schornack, Sebastian; Bozkurt, Tolga O.; Haart, Dave; Ro, Dae-Kyun; Faraldos, Juan A.; Kamoun, Sophien; O’Maille, Paul E.

    2014-01-01

    Plants protect themselves against a variety of invading pathogenic organisms via sophisticated defence mechanisms. These responses include deployment of specialized antimicrobial compounds, such as phytoalexins, that rapidly accumulate at pathogen infection sites. However, the extent to which these compounds contribute to species-level resistance and their spectrum of action remain poorly understood. Capsidiol, a defense related phytoalexin, is produced by several solanaceous plants including pepper and tobacco during microbial attack. Interestingly, capsidiol differentially affects growth and germination of the oomycete pathogens Phytophthora infestans and Phytophthora capsici, although the underlying molecular mechanisms remain unknown. In this study we revisited the differential effect of capsidiol on P. infestans and P. capsici, using highly pure capsidiol preparations obtained from yeast engineered to express the capsidiol biosynthetic pathway. Taking advantage of transgenic Phytophthora strains expressing fluorescent markers, we developed a fluorescence-based method to determine the differential effect of capsidiol on Phytophtora growth. Using these assays, we confirm major differences in capsidiol sensitivity between P. infestans and P. capsici and demonstrate that capsidiol alters the growth behaviour of both Phytophthora species. Finally, we report intraspecific variation within P. infestans isolates towards capsidiol tolerance pointing to an arms race between the plant and the pathogens in deployment of defence related phytoalexins. PMID:25203155

  6. Variation in capsidiol sensitivity between Phytophthora infestans and Phytophthora capsici is consistent with their host range.

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    Giannakopoulou, Artemis; Schornack, Sebastian; Bozkurt, Tolga O; Haart, Dave; Ro, Dae-Kyun; Faraldos, Juan A; Kamoun, Sophien; O'Maille, Paul E

    2014-01-01

    Plants protect themselves against a variety of invading pathogenic organisms via sophisticated defence mechanisms. These responses include deployment of specialized antimicrobial compounds, such as phytoalexins, that rapidly accumulate at pathogen infection sites. However, the extent to which these compounds contribute to species-level resistance and their spectrum of action remain poorly understood. Capsidiol, a defense related phytoalexin, is produced by several solanaceous plants including pepper and tobacco during microbial attack. Interestingly, capsidiol differentially affects growth and germination of the oomycete pathogens Phytophthora infestans and Phytophthora capsici, although the underlying molecular mechanisms remain unknown. In this study we revisited the differential effect of capsidiol on P. infestans and P. capsici, using highly pure capsidiol preparations obtained from yeast engineered to express the capsidiol biosynthetic pathway. Taking advantage of transgenic Phytophthora strains expressing fluorescent markers, we developed a fluorescence-based method to determine the differential effect of capsidiol on Phytophtora growth. Using these assays, we confirm major differences in capsidiol sensitivity between P. infestans and P. capsici and demonstrate that capsidiol alters the growth behaviour of both Phytophthora species. Finally, we report intraspecific variation within P. infestans isolates towards capsidiol tolerance pointing to an arms race between the plant and the pathogens in deployment of defence related phytoalexins.

  7. Genetic transformation of the plant pathogens Phytophthora capsici and Phytophthora parasitica.

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    Bailey, A M; Mena, G L; Herrera-Estrella, L

    1991-08-11

    Phytophthora capsici and P.parasitica were transformed to hygromycin B resistance using plasmids pCM54 and pHL1, which contain the bacterial hygromycin B phosphotransferase gene (hph) fused to promoter elements of the Ustilago maydis heat shock hsp70 gene. Enzymes Driselase and Novozyme 234 were used to generate protoplasts which were then transformed following exposure to plasmid DNA and polyethylene glycol 6000. Transformation frequencies of over 500 transformants per micrograms of DNA per 1 x 10(6) protoplasts were obtained. Plasmid pCM54 appears to be transmitted in Phytophthora spp. as an extra-chromosomal element through replication, as shown by Southern blot hybridization and by the loss of plasmid methylation. In addition, transformed strains retained their capacity of infecting Serrano pepper seedlings and Mc. Intosh apple fruits, the host plants for P.capsici and P.parasitica, respectively.

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

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

  9. 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.

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

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    Mee Kyung Sang

    2013-06-01

    Full Text Available We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107 among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05 reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05 reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

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

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    Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

    2013-06-01

    We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

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

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    Xuemin LIU; Yanling ZHOU; Lijun LI

    2008-01-01

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

  13. 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.

  14. Resistance in tomato and wild relatives to crown and root rot caused by Phytophthora capsici.

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    Quesada-Ocampo, L M; Hausbeck, M K

    2010-06-01

    Phytophthora capsici causes root, crown, and fruit rot of tomato, a major vegetable crop grown worldwide. The objective of this study was to screen tomato cultivars and wild relatives of tomato for resistance to P. capsici. Four P. capsici isolates were individually used to inoculate 6-week-old seedlings (1 g of P. capsici-infested millet seed per 10 g of soilless medium) of 42 tomato cultivars and wild relatives of tomato in a greenhouse. Plants were evaluated daily for wilting and death. All P. capsici isolates tested caused disease in seedlings but some isolates were more pathogenic than others. A wild relative of cultivated tomato, Solanum habrochaites accession LA407, was resistant to all P. capsici isolates tested. Moderate resistance to all isolates was identified in the host genotypes Ha7998, Fla7600, Jolly Elf, and Talladega. P. capsici was frequently recovered from root and crown tissue of symptomatic inoculated seedlings but not from leaf tissue or asymptomatic or control plants. The phenotype of the recovered isolate matched the phenotype of the inoculum. Pathogen presence was confirmed in resistant and moderately resistant tomato genotypes by species-specific polymerase chain reaction of DNA from infected crown and root tissue. Amplified fragment length polymorphisms of tomato genotypes showed a lack of correlation between genetic clusters and susceptibility to P. capsici, indicating that resistance is distributed in several tomato lineages. The results of this study create a baseline for future development of tomato cultivars resistant to P. capsici.

  15. 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.

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

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

    2014-01-21

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

  17. Antagonism of antifungal metabolites from Streptomyces griseus H7602 against Phytophthora capsici.

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    Nguyen, Xuan Hoa; Naing, Kyaw Wai; Lee, Young Seong; Kim, Yong Hwan; Moon, Jae Hak; Kim, Kil Yong

    2015-01-01

    In this study, evidences for antagonism were established by production of antifungal metabolites from Streptomyces griseus H7602, which were active to inhibit mycelial growth of Phytophthora capsici in the in vitro assays. Mycelial growth and zoosporangia formation of P. capsici was strongly inhibited in the medium containing the cell free culture filtrate of S. griseus H7602. Antifungal metabolites from the cell free culture filtrate of S. griseus H7602 showed substantial antagonistic effects on P. capsici. In addition, a purified antifungal compound was separated from the antifungal metabolites of S. griseus H7602 and identified to be 1H-pyrrole-2-carboxylic acid (PCA) by spectra analyses. PCA showed strong antifungal activity and was evaluated for the first time for its antagonism against P. capsici under in vitro conditions. Minimum inhibitory concentration (MIC) value of PCA was low (4 µg ml(-1)), and the mycelial growth of P. capsici was almost inhibited at concentration of 64 µg ml(-1). This study suggests that the PCA may be useful as biofungicides against P. capsici, and the prominent antagonism of antifungal metabolites from S. griseus H7602 highlights it as a candidate for biocontrol of P. capsici.

  18. Asexual Reproduction of Phytophthora capsici as Affected by Extracts from Agricultural and Nonagricultural Soils.

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    Sanogo, S

    2007-07-01

    ABSTRACT Formation of sporangia and zoospores in species of Phytophthora is known to be influenced by soil microbial and chemical composition. In Phytophthora capsici, the study of the relationship of soil chemical composition to production of sporangia and zoospores has been limited. P. capsici is a soilborne pathogen of a wide array of vegetable crops, including chile pepper (Capsicum annuum) in New Mexico. Production of sporangia and zoospores by P. capsici was evaluated in extracts of soils from three different environments in New Mexico: (i) agricultural environments with a long history of chile pepper cropping and occurrence of P. capsici (CP), (ii) agricultural environments with no history of chile pepper cropping and no occurrence of P. capsici (Non-CP), and (iii) nonagricultural environments consisting of forests and rangelands (Non-Ag). There was a significant difference in production of P. capsici asexual propagules, expressed as natural log (number of sporangia x number of zoospores), among the three environments (P = 0.0298). Production of propagules was 9 to 13% greater in Non-Ag than in CP or Non-CP environments. Stepwise multiple discriminant analysis and canonical discriminant analysis identified the edaphic variables Na, pH, P, organic matter content, and asexual propagule production as contributing the most to the separation of the three environments. Two significant (P < 0.0001) canonical discriminant functions were derived with the first function, accounting for approximately 75% of the explained variance. Based on the two discriminant functions, approximately 93, 86, and 89% of observations in CP, Non-CP, and Non-Ag environments, respectively, were classified correctly. Soils from agricultural and nonagricultural environments differentially influence production of sporangia and zoospores in P. capsici, and soil samples could be effectively classified into agricultural and nonagricultural environments based on soil chemical properties and the

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

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    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.

  20. 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.

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

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    Yong Wang

    2016-06-01

    Full Text Available 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.

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

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    Dunn, Amara R; Smart, Christine D

    2015-10-01

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

  3. 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.

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

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    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.

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

    Science.gov (United States)

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

    2013-01-01

    Phytophthora species secrete a large array of effectors during infection of their host plants. The Crinkler (CRN) gene family encodes a ubiquitous but understudied class of effectors with possible but as of yet unknown roles in infection. To appreciate CRN effector function in Phytophthora, we devised a simple Crn gene identification and annotation pipeline to improve effector prediction rates. We predicted 84 full-length CRN coding genes and assessed CRN effector domain diversity in sequenced Oomycete genomes. These analyses revealed evidence of CRN domain innovation in Phytophthora and expansion in the Peronosporales. We performed gene expression analyses to validate and define two classes of CRN effectors, each possibly contributing to infection at different stages. CRN localisation studies revealed that P. capsici CRN effector domains target the nucleus and accumulate in specific sub-nuclear compartments. Phenotypic analyses showed that few CRN domains induce necrosis when expressed in planta and that one cell death inducing effector, enhances P. capsici virulence on Nicotiana benthamiana. These results suggest that the CRN protein family form an important class of intracellular effectors that target the host nucleus during infection. These results combined with domain expansion in hemi-biotrophic and necrotrophic pathogens, suggests specific contributions to pathogen lifestyles. This work will bolster CRN identification efforts in other sequenced oomycete species and set the stage for future functional studies towards understanding CRN effector functions. PMID:23536880

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

    Directory of Open Access Journals (Sweden)

    Remco Stam

    Full Text Available Phytophthora species secrete a large array of effectors during infection of their host plants. The Crinkler (CRN gene family encodes a ubiquitous but understudied class of effectors with possible but as of yet unknown roles in infection. To appreciate CRN effector function in Phytophthora, we devised a simple Crn gene identification and annotation pipeline to improve effector prediction rates. We predicted 84 full-length CRN coding genes and assessed CRN effector domain diversity in sequenced Oomycete genomes. These analyses revealed evidence of CRN domain innovation in Phytophthora and expansion in the Peronosporales. We performed gene expression analyses to validate and define two classes of CRN effectors, each possibly contributing to infection at different stages. CRN localisation studies revealed that P. capsici CRN effector domains target the nucleus and accumulate in specific sub-nuclear compartments. Phenotypic analyses showed that few CRN domains induce necrosis when expressed in planta and that one cell death inducing effector, enhances P. capsici virulence on Nicotiana benthamiana. These results suggest that the CRN protein family form an important class of intracellular effectors that target the host nucleus during infection. These results combined with domain expansion in hemi-biotrophic and necrotrophic pathogens, suggests specific contributions to pathogen lifestyles. This work will bolster CRN identification efforts in other sequenced oomycete species and set the stage for future functional studies towards understanding CRN effector functions.

  7. Response of U.S. Bottle Gourd (Lagenaria siceraria) Plant Introductions (PI) to Crown Rot caused by Phytophthora Capsici

    Science.gov (United States)

    Phytophthora capsici can cause severe damage to cucurbit crops grown in open fields in the southeast regions of US. In recent years, there has been a growing interest in the US in grafting watermelon plants onto various cucurbit rootstocks including bottle gourds for managing soil borne diseases. ...

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

    Directory of Open Access Journals (Sweden)

    Moens, M.

    1986-01-01

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

  9. Influence of the toxin of Phytophthora capsici for the microconstruction of pumpkin leaves%南瓜疫病菌(Phytophthora capsici)毒素对寄主叶片超微结构的影响

    Institute of Scientific and Technical Information of China (English)

    马丽艳; 张俊华; 崔崇士

    2006-01-01

    文章对南瓜疫病菌(Phytophthora capsici)进行了毒素提取,并用该毒素处理南瓜幼苗,然后观察南瓜叶片超微结构变化.Phytophthora capsici毒素处理后,随着其浓度的增加和处理时间的延长,细胞质壁分离严重,质膜断裂;叶绿体膨胀严重,膜消失,基粒片层紊乱;线粒体膜、脊被破坏;核膜不均一.

  10. 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

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

    Science.gov (United States)

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

    2016-01-01

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

  12. 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.

  13. 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.

  14. Recognition of an Avr3a homologue plays a major role in mediating nonhost resistance to Phytophthora capsici in Nicotiana species.

    Science.gov (United States)

    Vega-Arreguín, Julio C; Jalloh, Abubakar; Bos, Jorunn I; Moffett, Peter

    2014-08-01

    Nonhost resistance is a commonly occurring phenomenon wherein all accessions or cultivars of a plant species are resistant to all strains of a pathogen species and is likely the manifestation of multiple molecular mechanisms. Phytophthora capsici is a soil-borne oomycete that causes Phytophthora blight disease in many solanaceous and cucurbitaceous plants worldwide. Interest in P. capsici has increased considerably with the sequencing of its genome and its increasing occurrence in multiple crops. However, molecular interactions between P. capsici and both its hosts and its nonhosts are poorly defined. We show here that tobacco (Nicotiana tabacum) acts like a nonhost for P. capsici and responds to P. capsici infection with a hypersensitive response (HR). Furthermore, we have found that a P. capsici Avr3a-like gene (PcAvr3a1) encoding a putative RXLR effector protein produces a HR upon transient expression in tobacco and several other Nicotiana species. This HR response correlated with resistance in 19 of 23 Nicotiana species and accessions tested, and knock-down of PcAvr3a1 expression by host-induced gene silencing allowed infection of resistant tobacco. Our results suggest that many Nicotiana species have the capacity to recognize PcAvr3a1 via the products of endogenous disease resistance (R) genes and that this R gene-mediated response is a major component of nonhost resistance to P. capsici.

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

    Science.gov (United States)

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

    2015-09-01

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

  16. Non-host Plant Resistance against Phytophthora capsici Is Mediated in Part by Members of the I2 R Gene Family in Nicotiana spp.

    Science.gov (United States)

    Vega-Arreguín, Julio C.; Shimada-Beltrán, Harumi; Sevillano-Serrano, Jacobo; Moffett, Peter

    2017-01-01

    The identification of host genes associated with resistance to Phytophthora capsici is crucial to developing strategies of control against this oomycete pathogen. Since there are few sources of resistance to P. capsici in crop plants, non-host plants represent a promising source of resistance genes as well as excellent models to study P. capsici – plant interactions. We have previously shown that non-host resistance to P. capsici in Nicotiana spp. is mediated by the recognition of a specific P. capsici effector protein, PcAvr3a1 in a manner that suggests the involvement of a cognate disease resistance (R) genes. Here, we have used virus-induced gene silencing (VIGS) and transgenic tobacco plants expressing dsRNA in Nicotiana spp. to identify candidate R genes that mediate non-host resistance to P. capsici. Silencing of members of the I2 multigene family in the partially resistant plant N. edwardsonii and in the resistant N. tabacum resulted in compromised resistance to P. capsici. VIGS of two other components required for R gene-mediated resistance, EDS1 and SGT1, also enhanced susceptibility to P. capsici in N. edwardsonii, as well as in the susceptible plants N. benthamiana and N. clevelandii. The silencing of I2 family members in N. tabacum also compromised the recognition of PcAvr3a1. These results indicate that in this case, non-host resistance is mediated by the same components normally associated with race-specific resistance. PMID:28261255

  17. Estrategias para el control de Phytophthora capsici Leo. y Fusarium solani Mart. en el cultivo del chile (Capsicum annuum L.).

    OpenAIRE

    Santos Juárez, Pedro

    2010-01-01

    Phytophthora capsici, Fusarium sp. y Rhizoctonia solani son los principales agentes causales de la marchitez del chile que disminuye el rendimiento del cultivo, lo cual ha originado la sustitución de cultivos y abandono de tierras. Con el fin de coadyuvar al manejo de esta enfermedad en el presente trabajo se evaluaron 51 accesiones de chile (árbol, copi y soledad) para buscar fuentes de resistencia; se probó metalaxyl, fosetil aluminio y tiabendazol para evaluar la sensibilidad de un aislami...

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

    Directory of Open Access Journals (Sweden)

    Fernando Cesar Sala

    2004-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Lidieth Uribe-Lor\\u00EDo

    2014-01-01

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

  20. Detection of gene expression changes in Capsicum annuum L. leaf foliar blight caused by Phytophthora capsici Leon. using qRT-PCR and leaf discs

    Science.gov (United States)

    Phytophthora capsici is responsible for multiple disease syndromes of Capsicum annuum but the resistance mechanism is still unknown. Evaluating gene expression during foliar blight can be used to identify expression patterns associated with resistance in Capsicum species. This study reports a direct...

  1. 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.

  2. Exocarp Properties and Transcriptomic Analysis of Cucumber (Cucumis sativus) Fruit Expressing Age-Related Resistance to Phytophthora capsici.

    Science.gov (United States)

    Ando, Kaori; Carr, Kevin M; Colle, Marivi; Mansfeld, Ben N; Grumet, Rebecca

    2015-01-01

    Very young cucumber (Cucumis sativus) fruit are highly susceptible to infection by the oomycete pathogen, Phytophthora capsici. As the fruit complete exponential growth, at approximately 10-12 days post pollination (dpp), they transition to resistance. The development of age-related resistance (ARR) is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown. Peel sections from cucumber fruit harvested at 8 dpp (susceptible) and 16 dpp (resistant) showed equivalent responses to inoculation as did whole fruit, indicating that the fruit surface plays an important role in defense against P. capsici. Exocarp from 16 dpp fruit had thicker cuticles, and methanolic extracts of peel tissue inhibited growth of P. capsici in vitro, suggesting physical or chemical components to the ARR. Transcripts specifically expressed in the peel vs. pericarp showed functional differentiation. Transcripts predominantly expressed in the peel were consistent with fruit surface associated functions including photosynthesis, cuticle production, response to the environment, and defense. Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001) for response to stress, signal transduction, and extracellular and transport functions. Specific transcripts included genes associated with potential physical barriers (i.e., cuticle), chemical defenses (flavonoid biosynthesis), oxidative stress, penetration defense, and molecular pattern (MAMP)-triggered or effector-triggered (R-gene mediated) pathways. The developmentally regulated changes in gene expression between peels from susceptible- and resistant- age fruits suggest programming for increased defense as the organ reaches full size.

  3. Phytophthora capsici homologue of the cell cycle regulator SDA1 is required for sporangial morphology, mycelial growth and plant infection.

    Science.gov (United States)

    Zhu, Chunyuan; Yang, Xiaoyan; Lv, Rongfei; Li, Zhuang; Ding, Xiaomeng; Tyler, Brett M; Zhang, Xiuguo

    2016-04-01

    SDA1 encodes a highly conserved protein that is widely distributed in eukaryotic organisms. SDA1 is essential for cell cycle progression and organization of the actin cytoskeleton in yeasts and humans. In this study, we identified a Phytophthora capsici orthologue of yeast SDA1, named PcSDA1. In P. capsici, PcSDA1 is strongly expressed in three asexual developmental states (mycelium, sporangia and germinating cysts), as well as late in infection. Silencing or overexpression of PcSDA1 in P. capsici transformants affected the growth of hyphae and sporangiophores, sporangial development, cyst germination and zoospore release. Phalloidin staining confirmed that PcSDA1 is required for organization of the actin cytoskeleton. Moreover, 4',6-diamidino-2-phenylindole (DAPI) staining and PcSDA1-green fluorescent protein (GFP) fusions revealed that PcSDA1 is involved in the regulation of nuclear distribution in hyphae and sporangia. Both silenced and overexpression transformants showed severely diminished virulence. Thus, our results suggest that PcSDA1 plays a similar role in the regulation of the actin cytoskeleton and nuclear division in this filamentous organism as in non-filamentous yeasts and human cells.

  4. Exocarp Properties and Transcriptomic Analysis of Cucumber (Cucumis sativus Fruit Expressing Age-Related Resistance to Phytophthora capsici.

    Directory of Open Access Journals (Sweden)

    Kaori Ando

    Full Text Available Very young cucumber (Cucumis sativus fruit are highly susceptible to infection by the oomycete pathogen, Phytophthora capsici. As the fruit complete exponential growth, at approximately 10-12 days post pollination (dpp, they transition to resistance. The development of age-related resistance (ARR is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown. Peel sections from cucumber fruit harvested at 8 dpp (susceptible and 16 dpp (resistant showed equivalent responses to inoculation as did whole fruit, indicating that the fruit surface plays an important role in defense against P. capsici. Exocarp from 16 dpp fruit had thicker cuticles, and methanolic extracts of peel tissue inhibited growth of P. capsici in vitro, suggesting physical or chemical components to the ARR. Transcripts specifically expressed in the peel vs. pericarp showed functional differentiation. Transcripts predominantly expressed in the peel were consistent with fruit surface associated functions including photosynthesis, cuticle production, response to the environment, and defense. Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001 for response to stress, signal transduction, and extracellular and transport functions. Specific transcripts included genes associated with potential physical barriers (i.e., cuticle, chemical defenses (flavonoid biosynthesis, oxidative stress, penetration defense, and molecular pattern (MAMP-triggered or effector-triggered (R-gene mediated pathways. The developmentally regulated changes in gene expression between peels from susceptible- and resistant- age fruits suggest programming for increased defense as the organ reaches full size.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. 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

    2014-03-06

    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.

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

    Science.gov (United States)

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

    2014-05-01

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

  8. SOIL MYCOFLORA OF BLACK PEPPER RHIZOSPHERE IN THE PHILIPPINES AND THEIR IN VITRO ANTAGONISM AGAINST Phytophthora capsici L.

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    Rita Noveriza

    2016-10-01

    Full Text Available Foot rot disease of black pepper caused by Phytophthora capsici had been reported in Batangas and Laguna, Philippines. The plant was recovered following the application of crop residue (organic substrate and intercropping with other crops. This study was aimed to isolate, identify, and determine the soil mycoflora from the rhizosphere of black pepper grown on various cropping patterns in Batangas and Laguna. Antagonistic activity of mycoflora isolates was tested against P. capsici using dual culture technique. The result showed that 149 colonies of soil mycoflora isolated were belonging to 14 genera; three of them, i.e. Penicillium, Paecilomyces and Aspergillus, were the most dominant. All of the mycoflora isolates were able to inhibit the growth of the pathogen. Eighteen of them were the most promising antagonists, based on their inhibition growth of more than 60%. It is suggested that antagonistic mechanism of Mucor isolate (1001, Trichoderma (125, 170, 171, 179, 180, 181, Gliocladium (109, Cunninghamella (165, 168, Mortierella (177, and Aspergillus (106 was space competitor (competition for nutrient since they rapidly overgrew the pathogen. Aspergillus (67, 79, 81, 83, 108, and 202 isolates inhibited the pathogen apparently by producing antibiotic, whereas Trichoderma (125, 170, 171, 179, 180, and 181 isolates were able to penetrate the hyphae of the pathogen. The organic matter percentage in the soil was significantly correlated with the number of antagonistic mycoflora in rhizosphere (R2 = 0.1094, but the cropping pattern was negatively correlated. This study suggests that organic matter increased antagonistic mycoflora in black pepper rhizosphere, which will reduce severity of the disease.

  9. 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.

  10. 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.

  11. Genetic analysis of environmental strains of the plant pathogen Phytophthora capsici reveals heterogeneous repertoire of effectors and possible effector evolution via genomic island.

    Science.gov (United States)

    Iribarren, María Josefina; Pascuan, Cecilia; Soto, Gabriela; Ayub, Nicolás Daniel

    2015-11-01

    Phytophthora capsici is a virulent oomycete pathogen of many vegetable crops. Recently, it has been demonstrated that the recognition of the RXLR effector AVR3a1 of P. capsici (PcAVR3a1) triggers a hypersensitive response and plays a critical role in mediating non-host resistance. Here, we analyzed the occurrence of PcAVR3a1 in 57 isolates of P. capsici derived from globe squash, eggplant, tomato and bell pepper cocultivated in a small geographical area. The occurrence of PcAVR3a1 in environmental strains of P. capsici was confirmed by PCR in only 21 of these pathogen isolates. To understand the presence-absence pattern of PcAVR3a1 in environmental strains, the flanking region of this gene was sequenced. PcAVR3a1 was found within a genetic element that we named PcAVR3a1-GI (PcAVR3a1 genomic island). PcAVR3a1-GI was flanked by a 22-bp direct repeat, which is related to its site-specific recombination site. In addition to the PcAVR3a1 gene, PcAVR3a1-GI also encoded a phage integrase probably associated with the excision and integration of this mobile element. Exposure to plant induced the presence of an episomal circular intermediate of PcAVR3a1-GI, indicating that this mobile element is functional. Collectively, these findings provide evidence of PcAVR3a1 evolution via mobile elements in environmental strains of Phytophthora.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. DISMINUCIÓN DE LA MARCHITEZ DEL CHILE (Phytophthora capsici Leo) CON COMPLEJIDAD ASCENDENTE DE ANTAGONISTAS EN EL SUSTRATO DE GERMINACIÓN DEL CHILE (Capsicum annuum L.)

    OpenAIRE

    Juliana Bautista-Calles; Roberto García-Espinosa; Emma Zavaleta-Mejía; Jesús Pérez-Moreno; Roberto Montes-Belmont; Ronald Ferrera-Cerrato; Manuel Huerta-Lara

    2010-01-01

    Debido a que, en términos generales, el control biológico de fitopatógenos con origen en el suelo no ha mostrado ser eficiente en campo cuando se ha intentado la reintroducción de sólo un aislamiento de determinado antagonista en cantidades aumentadas al suelo, en este trabajo se intentó la reintroducción al suelo de consorcios de antagonistas a Phytophthora capsici con complejidad ascendente (con 8, 16, 24 y 32 aislamientos), mediante el sustrato de germinación del chile (Capsicum annuum) pa...

  15. 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.

  16. 8种生物杀菌剂对南瓜疫病菌的室内毒力测定%Toxicity Test of Several Bio-fungicides to Phytophthora capsici

    Institute of Scientific and Technical Information of China (English)

    王中业; 张俊华; 奚启新; 杨明秀; 潘春清

    2011-01-01

    采用菌丝生长速率法和孢子萌发法进行了8种生物杀菌剂对南瓜疫病菌(Phytophthora capsici)的毒力测定.结果表明,供试8种生物杀菌剂对南瓜疫病菌菌丝生长和孢子萌发均具有一定的抑制效果,其中1%申嗪霉素悬乳剂对南瓜疫病菌菌丝生长的抑制作用最强,2%宁南霉素次之,5%井冈霉素水剂最弱.%The toxicity of eight bio-fungicides to Phytophthora capsici was tested by mycelia growth inhibition and sporangia germination control method. The result showed that all 8 bio-fungicides inhibited mycelia growth and sporangia germination of Phytophthora capsici. Among the bio-fungicides tested, the highest inhibition effect to mycelia growth and sporangia germination of phytophthora capsici is observed with 1% phenazino-1-carboxylic,followed by 2% ningnanmycin,and Validamycin A had lowest effect.

  17. 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.

  18. 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.

  19. 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.

  20. Use of PCR-RFLP marker to detect Phytophthora capsici in squash%运用PCR-RFLP标记检测南瓜疫病菌

    Institute of Scientific and Technical Information of China (English)

    秦旭升; 刘学敏; 于荣利

    2003-01-01

    用1对特异引物对南瓜疫霉菌(Phytophthora capsici)及疫霉属(Phytophthora)部分真菌和常见土传真菌12个种的14个菌株的18 s rDNA(即Small Subunit Ribosomal DNA)进行扩增,用4种限制性内切酶(EooR Ⅰ、HaeⅢ、HhaⅠ、HinfⅠ)酶切PCR扩增产物,分析各菌株间的DNA限制性片段多态性,首次建立了南瓜疫霉菌的PCR-RFLP检测程序.并运用该PCR-RFLP检测程序对染病南瓜植株进行检测,成功地在南瓜植株发病茎病健交界处、发病叶病健交界处、发病果病健交界处、接种24 h的叶和接种P.capsici 12 h的茎上快速、准确地检测到了南瓜疫病菌的存在.

  1. Study on Resistance of Phytophthora capsici to Chemicals and Screen of New Chemicals to Prevent Phytophthora Blight%辣椒疫病菌的抗药性和新药剂的筛选研究

    Institute of Scientific and Technical Information of China (English)

    何允波; 唐丽萍; 张宝国

    2004-01-01

    辣椒疫病是由辣椒疫霉(Phytophthora capsici L.)引起的重要植物病害,化学药剂是目前防治该病害最有效的途径之一.为此,对辣椒疫病的发生特点、化学药剂防治的抗性问题和新化学防治药剂的筛选进行了研究.

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

    Science.gov (United States)

    Lewis Ivey, M L; Miller, S A

    2013-09-01

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

  3. Cucumis sativus L-type lectin receptor kinase (CsLecRK) gene family response to Phytophthora melonis, Phytophthora capsici and water immersion in disease resistant and susceptible cucumber cultivars.

    Science.gov (United States)

    Wu, Tingquan; Wang, Rui; Xu, Xiaomei; He, Xiaoming; Sun, Baojuan; Zhong, Yujuan; Liang, Zhaojuan; Luo, Shaobo; Lin, Yu'e

    2014-10-10

    L-type lectin receptor kinase (LecRK) proteins are an important family involved in diverse biological processes such as pollen development, senescence, wounding, salinity and especially in innate immunity in model plants such as Arabidopsis and tobacco. Till date, LecRK proteins or genes of cucumber have not been reported. In this study, a total of 25 LecRK genes were identified in the cucumber genome, unequally distributed across its seven chromosomes. According to similarity comparison of their encoded proteins, the Cucumis sativus LecRK (CsLecRK) genes were classified into six major clades (from Clade I to CladeVI). Expression of CsLecRK genes were tested using QRT-PCR method and the results showed that 25 CsLecRK genes exhibited different responses to abiotic (water immersion) and biotic (Phytophthora melonis and Phytophthora capsici inoculation) stresses, as well as that between disease resistant cultivar (JSH) and disease susceptible cultivar (B80). Among the 25 CsLecRK genes, we found CsLecRK6.1 was especially induced by P. melonis and P. capsici in JSH plants. All these results suggested that CsLecRK genes may play important roles in biotic and abiotic stresses.

  4. 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

  5. 嘧菌酯和丙森锌复配对辣椒疫霉菌的抑制活性%Inhibitory Effect of Azoxystrobin and Propineb Synergistic Fungicides to Phytophthora capsici

    Institute of Scientific and Technical Information of China (English)

    王惟萍; 石延霞; 李宝聚

    2011-01-01

    [Aims] The control effect of azoxystrobin and propineb mixed fungicides on Phytophthora capsici were studied to provide guide for controlling Phytophthora capsici. [Methods] The two fungicides were mixed at different ratio and diluted into seven concentration, then inoculated Phytophthora capsici on leaves and the control effect was observed. [Results] The EC50 of the mixture with 1:6 ratio of azoxystrobin and propineb was 21.21 mg/L, which was lower than the two single components. [Conclusions] The bioactivity on Phytophthora capsici was different between the mixtures with different ratio. The best ratio of the two fungicides was 1:6, which indicated strong synergistic action with the co-toxicity index of 791.11.%[目的]研究嘧菌酯和丙森锌复配对辣椒疫霉菌的抑制活性,对防治辣椒疫病具指导意义.[方法]采用活体组织法测定,将两者按不同比例复配后稀释成7个质量浓度喷施于辣椒叶片上,后接种疫霉菌菌片,观测其抑制效果.[结果]嘧菌酯:丙森锌按1:6(质量比)复配后EC50值为21.21 mg/L低于2个单剂.[结论]两者以不同比例复配后对疫霉菌的生物活性存在差异.嘧菌酯:丙森锌为1:6比例复配的共毒系数为791.11,表现出明显的增效作用,为最适配比.

  6. 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.

  7. 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

  8. Reaction of Phytophthora fruit rot resistant germplasm lines to a broad range of Phytophthora capsici isolates from across the United States of America

    Science.gov (United States)

    Phytophthora fruit rot limits watermelon production in most states in the Southeastern US (FL, GA, SC, NC and VA). It has also become a serious problem in recent years in northern states (IN, MD, DE). About 50% of the US watermelons are grown in the southeastern states where environmental conditions...

  9. Isolation and identification of Phytophthora capsici in Guangdong Province and measurement of their pathogenicity and physiological race differentiation

    Institute of Scientific and Technical Information of China (English)

    LI Zhijun; LONG Weiping; ZHENG Jinrong; LEI Jianjun

    2007-01-01

    Five isolates collected from different peppercropping regions in Guangdong Province,China were determined.Based on their morphological characteristics and symptoms after being re-inoculated to pepper,these isolates were identified as Phytophythora capsici Leonian.The sporangia induced on carrot medium (CA) were morphologically similar and most of their shapes were ovate or elliptic,and obviously papillate.The mean size of the sporangium was 40.8-45.9 (l) μm×23.2-30.9 (b) μm,with l/b ratio 1.4-1.8.There were evident differences in mycelial growth rate,productivity of sporangia and pathogenicity to pepper among the isolates.A test of physiological characteristics showed that one isolate was determined as Race 1,and the other four isolates belonged to Race 3.It is concluded that Race 3 is most likely to be the predominent race in Guangdong Province,China.

  10. 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.

  11. 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

  12. 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

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

    Science.gov (United States)

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

  14. 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

  15. 圆滑番荔枝叶乙醇提取物不同萃取组分对胡椒瘟病菌的抑菌活性测定%Determination of the Antifungal Activity of Ethanol Extracts from Annona glabra Leaf against Phytophthora capsici

    Institute of Scientific and Technical Information of China (English)

    苟亚峰; 孙世伟; 高圣风; 桑利伟; 刘爱勤

    2014-01-01

    Annona glabra leaf ethanol extracts were extracted by liquid -liquid partition method. Getting different petroleum ether, trichloromethane, ethyl acetate extract components. Testing the different components antifungal activity against Phytophthora capsici with growth rate method. The results showed that the ethyl acetate extract components had high inhibition rate against Phytophthora capsici mycelium growth. When the concentration was 20 mg/mL, the inhibition rate reached to 74.43%.%采用液-液分配法对圆滑番荔枝叶乙醇提取物进行萃取分离,得到石油醚、三氯甲烷、乙酸乙酯等不同萃取组分。采用生长速率法测定不同萃取组分对胡椒瘟病菌的抑制作用。结果表明:乙酸乙酯萃取组分对胡椒瘟病菌的抑制作用最强,其中20 mg/mL乙酸乙酯萃取组分对胡椒瘟病菌菌丝生长的抑制率达到74.43%,具有较好的抑菌效果。

  16. Fungicide rotation schemes for managing Phytophthora fruit rot of watermelon across Southeastern United States (NC, SC, and GA)

    Science.gov (United States)

    Phytophthora capsici has been documented as a pathogen on a wide variety of vegetable crops in the family Solanaceae, Cucurbitaceae, Fabaceae, and plants belonging to 23 other families. Phytophthora fruit rot of watermelons caused by P. capsici is particularly severe in southeastern U.S where optima...

  17. 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.

  18. 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

  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. 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.

  1. Phytophthora viruses.

    Science.gov (United States)

    Cai, Guohong; Hillman, Bradley I

    2013-01-01

    Phytophthora sp. is a genus in the oomycetes, which are similar to filamentous fungi in morphology and habitat, but phylogenetically more closely related to brown algae and diatoms and fall in the kingdom Stramenopila. In the past few years, several viruses have been characterized in Phytophthora species, including four viruses from Phytophthora infestans, the late blight pathogen, and an endornavirus from an unnamed Phytophthora species from Douglas fir. Studies on Phytophthora viruses have revealed several interesting systems. Phytophthora infestans RNA virus 1 (PiRV-1) and PiRV-2 are likely the first members of two new virus families; studies on PiRV-3 support the establishment of a new virus genus that is not affiliated with established virus families; PiRV-4 is a member of Narnaviridae, most likely in the genus Narnavirus; and Phytophthora endornavirus 1 (PEV1) was the first nonplant endornavirus at the time of reporting. Viral capsids have not been found in any of the above-mentioned viruses. PiRV-1 demonstrated a unique genome organization that requires further examination, and PiRV-2 may have played a role in late blight resurgence in 1980s-1990s.

  2. 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...

  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. 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.

  5. Influence of fruit age on Phytophthora fruit rot development on susceptible and resistant watermelon germplasm

    Science.gov (United States)

    Phytophthora fruit rot of watermelon caused by Phytophthora capsici is an emerging disease in the southeastern United States. The disease has resulted in severe losses to watermelon growers in GA, SC, and NC, and is considered a top-research priority by the National Watermelon Association. We releas...

  6. Fruit age and development of Phytophthora fruit rot on resistant and susceptible watermelon lines

    Science.gov (United States)

    Phytophthora fruit rot caused by Phytophthora capsici is an emerging disease in most watermelon producing regions of Southeast U.S. and has resulted in severe losses to watermelon growers especially in GA, SC, and NC. We recently released four germplasm lines (USVL203-PFR, USVL020-PFR, USVL782-PFR,...

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

    Science.gov (United States)

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

  8. Levels of Polyamines and Kinetic Characterization of Their Uptake in the Soybean Pathogen Phytophthora sojae

    OpenAIRE

    Chibucos, M. Constantine; Paul F Morris

    2006-01-01

    Polyamines are ubiquitous biologically active aliphatic cations that are at least transiently available in the soil from decaying organic matter. Our objectives in this study were to characterize polyamine uptake kinetics in Phytophthora sojae zoospores and to quantify endogenous polyamines in hyphae, zoospores, and soybean roots. Zoospores contained 10 times more free putrescine than spermidine, while hyphae contained only 4 times as much free putrescine as spermidine. Zoospores contained no...

  9. Genome-wide identification of laccase gene family in three Phytophthora species.

    Science.gov (United States)

    Feng, Baozhen; Li, Peiqian

    2012-12-01

    Phytophthora spp. is a primary pathogen in oomycete, causing economically and environmentally devastating epidemics of plants. Laccases have been found in all domains of life but have not been reported in oomycte. In this paper, laccase genes of Phytophthora spp. were identified in three genomes (Phytophthora capsici, Phytophthora sojae and Phytophthora ramorum). 18 laccase genes were identified in total, including four in P. capsici genome, six in P. sojae genome and eight in P. ramorum genome. Most of the predicted gene models shared typical fungal laccase character, possessing three conserved positions with one cysteine and ten histidine residues at these positions. Phylogenetic analysis illustrated that laccases from Phytophthora clustered into four clades, while fungal laccases clustered together. The results provided the theoretical ground for new hypotheses about the roles laccases in oomycetes and may guide the future research of these enzymes.

  10. Study on The Cultivation and Distraction Method of P.capsici Toxin%辣椒疫霉菌产毒培养方式和提取方法的研究

    Institute of Scientific and Technical Information of China (English)

    李海燕; 赵伟全; 于秀梅; 刘惕若

    2004-01-01

    研究表明,采用Plich's培养液在振荡培养的方式下,辣椒疫霉菌(Phytophthora capsici)产毒量最高.大量快速提出Phytophthora capsici毒素的最佳方法为硫酸铵沉淀法,聚乙二醇法不适宜提取Phytophthora capsici毒素.

  11. Analysis of different squash cultivars' isozyme in interaction with p.capsici%不同抗性南瓜品种感染Phytophthora capsici病菌后几种酶同工酶谱分析

    Institute of Scientific and Technical Information of China (English)

    张俊华; 崔崇士; 张耀伟

    2003-01-01

    采用电泳分离法,对不同抗性南瓜品种感染Phytophthora capsici病菌后几种酶同工酶谱分析.结果表明,感病品种接种后与健康植株相比,POD、PPO酶带几乎没有增加,抗病品种接种后与健康植株相比,增加2条POD酶带(Rf=0.6308,0.7077),增加3条PPO酶带(Rf=0.3,0.6286,0.7429).抗感品种健康植株POD、PPO酶带数基本相同,接种后抗病品种比感病品种多3条POD酶带(Rf=0.2615,0.6308,0.7077)和3条PPO酶带(Rf=0.3,0.6286,0.7429).

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

    Science.gov (United States)

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

  13. 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.

  14. Arabidopsis Lectin Receptor Kinases LecRK-IX.1 and LecRK-IX.2 Are Functional Analogs in Regulating Phytophthora Resistance and Plant Cell Death.

    Science.gov (United States)

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

    2015-09-01

    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 showing additive susceptibility. Overexpression of LecRK-IX.1 or LecRK-IX.2 in Arabidopsis and transient expression in Nicotiana benthamiana increased Phytophthora resistance but also induced cell death. Phytophthora resistance required both the lectin domain and kinase activity, but for cell death, the lectin domain was not needed. Silencing of the two closely related mitogen-activated protein kinase genes NbSIPK and NbNTF4 in N. benthamiana completely abolished LecRK-IX.1-induced cell death but not Phytophthora resistance. Liquid chromatography-mass spectrometry analysis of protein complexes coimmunoprecipitated in planta with LecRK-IX.1 or LecRK-IX.2 as bait, resulted in the identification of the N. benthamiana ABC transporter NbPDR1 as a potential interactor of both LecRK. The closest homolog of NbPDR1 in Arabidopsis is ABCG40, and coimmunoprecipitation experiments showed that ABCG40 associates with LecRK-IX.1 and LecRK-IX.2 in planta. Similar to the LecRK mutants, ABCG40 mutants showed compromised Phytophthora resistance. This study shows that LecRK-IX.1 and LecRK-IX.2 are Phytophthora resistance components that function independent of each other and independent of the cell-death phenotype. They both interact with the same ABC transporter, suggesting that they exploit similar signal transduction pathways.

  15. Genomic Characterization of a South American Phytophthora Hybrid Mandates Reassessment of the Geographic Origins of Phytophthora infestans.

    Science.gov (United States)

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

    2016-02-01

    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 outbreak remains disputed, as does the New World center of origin of the species itself. Both Mexico and South America have been proposed, generating considerable controversy. Here, we readdress the pathogen's origins using a genomic data set encompassing 71 globally sourced modern and historical samples of P. infestans and the hybrid species P. andina, a close relative known only from the Andean highlands. Previous studies have suggested that the nuclear DNA lineage behind the initial outbreaks in Europe in 1845 is now extinct. Analysis of P. andina's phased haplotypes recovered eight haploid genome sequences, four of which represent a previously unknown basal lineage of P. infestans closely related to the famine-era lineage. Our analyses further reveal that clonal lineages of both P. andina and historical P. infestans diverged earlier than modern Mexican lineages, casting doubt on recent claims of a Mexican center of origin. Finally, we use haplotype phasing to demonstrate that basal branches of the clade comprising Mexican samples are occupied by clonal isolates collected from wild Solanum hosts, suggesting that modern Mexican P. infestans diversified on Solanum tuberosum after a host jump from a wild species and that the origins of P. infestans are more complex than was previously thought.

  16. Evaluation of fungicide rotations for management of Phytophthora fruit rot of watermelon, 2015

    Science.gov (United States)

    The experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC. The soil was Yonges loamy fine sand. For the past 6 years, the field has been infested with Phytophthora capsici. The experimental design was a randomized complete block with four replications. Five-week-old seedli...

  17. 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.

  18. 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...

  19. Identification and characterization of differentially expressed genes from Fagus sylvatica roots after infection with Phytophthora citricola.

    Science.gov (United States)

    Schlink, Katja

    2009-05-01

    Phytophthora species are major plant pathogens infecting herbaceous and woody plants including European beech, the dominant or co-dominant tree in temperate Europe and an economically important species. For the analysis of the interaction of Phytophthora citricola with Fagus sylvatica suppression subtractive hybridization was used to isolate transcripts induced during infection and 1,149 sequences were generated. Hybridizations with driver and tester populations demonstrated differential expression in infected roots as compared to controls and verify efficient enrichment of these cDNAs during subtraction. Up regulation of selected genes during pathogenesis demonstrated using RT-PCR is consistent with these results. Pathogenesis-related proteins formed the largest group among functionally categorized transcripts. Cell wall proteins and protein kinases were also frequently found. Several transcription factors were isolated that are reactive to pathogens or wounding in other plants. The library contained a number of jasmonic acid, salicylic acid and ethylene responsive genes as well as genes directly involved in signaling pathways. Besides a mechanistic interconnection among signaling pathways another factor explaining the activation of different pathways could be the hemibiotrophic life style of Phytophthora triggering different signals in both stages.

  20. 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.

  1. 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.

  2. 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...

  3. Characterization of three novel desaturases involved in the delta-6 desaturation pathways for polyunsaturated fatty acid biosynthesis from Phytophthora infestans.

    Science.gov (United States)

    Sun, Quanxi; Liu, Jiang; Zhang, Qin; Qing, Xiaohe; Dobson, Gary; Li, Xinzheng; Qi, Baoxiu

    2013-09-01

    Phytophthora infestans is the causative agent of potato blight that resulted in the great famine in Ireland in the nineteenth century. This microbe can release large amounts of the C20 very long-chain polyunsaturated fatty acids arachidonic acid (ARA; 20:4Δ(5, 8, 11, 14)) and eicosapentaenoic acid (EPA; 20:5Δ(5, 8, 11, 14, 17)) upon invasion that is known to elicit a hypersensitive response to their host plant. In order to identify enzymes responsible for the biosynthesis of these fatty acids, we blasted the recently fully sequenced P. infestans genome and identified three novel putatively encoding desaturase sequences. These were subsequently functionally characterized by expression in Saccharomyces cerevisiae and confirmed that they encode desaturases with Δ12, Δ6 and Δ5 activity, designated here as PinDes12, PinDes6 and PinDes5, respectively. This, together with the combined fatty acid profiles and a previously identified Δ6 elongase activity, implies that the ARA and EPA are biosynthesized predominantly via the Δ6 desaturation pathways in P. infestans. Elucidation of ARA and EPA biosynthetic mechanism may provide new routes to combating this potato blight microbe directly or by means of conferring resistance to important crops.

  4. Characterization of Phytophthora hybrids from ITS clade 6 associated with riparian ecosystems in South Africa and Australia.

    Science.gov (United States)

    Nagel, Jan H; Gryzenhout, Marieka; Slippers, Bernard; Wingfield, Michael J; Hardy, Giles E St J; Stukely, Michael J C; Burgess, Treena I

    2013-05-01

    Surveys of Australian and South African rivers revealed numerous Phytophthora isolates residing in clade 6 of the genus, with internal transcribed spacer (ITS) gene regions that were either highly polymorphic or unsequenceable. These isolates were suspected to be hybrids. Three nuclear loci, the ITS region, two single copy loci (antisilencing factor (ASF) and G protein alpha subunit (GPA)), and one mitochondrial locus (cytochrome oxidase c subunit I (coxI)) were amplified and sequenced to test this hypothesis. Abundant recombination within the ITS region was observed. This, combined with phylogenetic comparisons of the other three loci, confirmed the presence of four different hybrid types involving the three described parent species Phytophthora amnicola, Phytophthora thermophila, and Phytophthora taxon PgChlamydo. In all cases, only a single coxI allele was detected, suggesting that hybrids arose from sexual recombination. All the hybrid isolates were sterile in culture and all their physiological traits tended to resemble those of the maternal parents. Nothing is known regarding their host range or pathogenicity. Nonetheless, as several isolates from Western Australia were obtained from the rhizosphere soil of dying plants, they should be regarded as potential threats to plant health. The frequent occurrence of the hybrids and their parent species in Australia strongly suggests an Australian origin and a subsequent introduction into South Africa.

  5. 不同抗性南瓜品种感染Phytophthora capsici病菌后几种酶活性测定%Bioassay of different squash cultivars' the activity of POD,PPO and PAL in interaction with P.capsici

    Institute of Scientific and Technical Information of China (English)

    张俊华

    2003-01-01

    采用酶活性测定法,对不同抗性南瓜品种感染Phytophthora capsici病菌后几种酶活性测定.结果表明,过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)活性与品种抗疫病性呈正相关.抗感品种健康植株的多酚氧化酶、过氧化物酶的活性差异不显著,苯丙氨酸解氨酶活性差异显著.抗感品种接种后POD的活性变化分别在36,48,60 h出现3次高峰,PPO的活性变化分别在30 h,42 h出现2次高峰,PAL的活性变化分别在30,48 h出现2次高峰.

  6. Characterization of PPMUCL1/2/3, three members of a new oomycete-specific mucin-like protein family residing in Phytophthora parasitica biofilm.

    Science.gov (United States)

    Larousse, Marie; Govetto, Benjamin; Séassau, Aurélie; Etienne, Catherine; Industri, Benoit; Theodorakopoulos, Nicolas; Deleury, Emeline; Ponchet, Michel; Panabières, Franck; Galiana, Eric

    2014-05-01

    The plant pathogen Phytophthora parasitica forms a biofilm on the host surface. The biofilm transcriptome is characterized by the expression of PPMUCL1/2/3 (PHYTOPHTHORA PARASITICA MUCIN-LIKE) genes, which we report here to be members of a new, large mucin-like gene family restricted to the oomycete lineage. These genes encode secreted proteins organized into two domains. The NH2-terminal domain is highly conserved, but of unknown function. The second domain is a mucin-like domain enriched in threonine and serine residues, with a large number of putative O-glycosylation sites and a repeated motif defining 15 subgroups among the 315 members of the family. The second domain was found to be glycosylated in the recombinant rPPMUCL1 and rPPMUCL2 proteins. An analysis of PPMUCL1/2/3 gene expression indicated that these genes were expressed in a specific and coordinated manner in the biofilm. A novel cis-motif (R) bound to nuclear proteins, suggesting a possible role in PPMUCL1/2/3 gene regulation. Immunohistochemical staining revealed that the PPMUCL1/2 proteins were secreted and accumulated on the surface of the biofilm. Our data demonstrate that PPMUCL1/2/3 belong to a new oomycete-specific family of mucin-like proteins playing a structural role in the biofilm extracellular matrix.

  7. Phytophthora borealis and Phytophthora riparia, new species in Phytophthora ITS Clade 6.

    Science.gov (United States)

    Hansen, Everett M; Reeser, Paul W; Sutton, Wendy

    2012-01-01

    Phytophthora borealis and Phytophthora riparia, identified in recent Phytophthora surveys of forest streams in Oregon, California and Alaska, are described as new species in Phytophthora ITS Clade 6. They are similar in growth form and morphology to P. gonapodyides and are predominantly sterile. They present unique DNA sequences, however, and differ in temperature/growth relations and geographic distribution.

  8. 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.

  9. 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...

  10. Friend or foe: genetic and functional characterization of plant endophytic Pseudomonas aeruginosa

    NARCIS (Netherlands)

    Kumar, A.; Munder, A.; Aravind, R.; Eapen, S.J.; Tümmler, B.; Raaijmakers, J.M.

    2013-01-01

    Endophytic Pseudomonas aeruginosa strain BP35 was originally isolated from black pepper grown in the rain forest in Kerala, India. Strain PaBP35 was shown to provide significant protection to black pepper against infections by Phytophthora capsici and Radopholus similis. For registration and impleme

  11. 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.

  12. Phytophthora beyond agriculture.

    Science.gov (United States)

    Hansen, Everett M; Reeser, Paul W; Sutton, Wendy

    2012-01-01

    Little is known about indigenous Phytophthora species in natural ecosystems. Increasing evidence, however, suggests that a diverse, trophically complex Phytophthora community is important in many forests. The number of described species has steadily increased, with a dramatic spike in recent years as new species have been split from old and new species have been discovered through exploration of new habitats. Forest soil, streams, and the upper canopies of trees are now being explored for Phytophthora diversity, and a new appreciation for the ecological amplitude of the genus is emerging. Ten to twenty species are regularly identified in temperate forest surveys. Half or more of this Phytophthora diversity comes from species described since 2000. Taxa in internal transcribed spacer (ITS) Clade 6 are especially numerous in forest streams and may be saprophytic in this habitat. Three ecological assemblages of forest Phytophthora species are hypothesized: aquatic opportunists, foliar pathogens, and soilborne fine-root and canker pathogens. Aggressive invasive species are associated with all three groups.

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

    Science.gov (United States)

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

    2015-01-01

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

  14. Fighting phytophthora in blueberries

    Science.gov (United States)

    Phytophthora cinnamomi Rands is a ubiquitous soilborne pathogen associated with root rot in many woody perennial plant species, including highbush blueberry (Vaccinium sp.). To identify genotypes with resistance to the pathogen, cultivars and advanced selections of highbush blueberry were grown in a...

  15. The genus Phytophthora anno 2012.

    Science.gov (United States)

    Kroon, Laurens P N M; Brouwer, Henk; de Cock, Arthur W A M; Govers, Francine

    2012-04-01

    Plant diseases caused by Phytophthora species will remain an ever increasing threat to agriculture and natural ecosystems. Phytophthora literally means plant destroyer, a name coined in the 19th century by Anton de Bary when he investigated the potato disease that set the stage for the Great Irish Famine. Phytophthora infestans, the causal agent of potato late blight, was the first species in a genus that at present has over 100 recognized members. In the last decade, the number of recognized Phytophthora species has nearly doubled and new species are added almost on a monthly basis. Here we present an overview of the 10 clades that are currently distinguished within the genus Phytophthora with special emphasis on new species that have been described since 1996 when Erwin and Ribeiro published the valuable monograph 'Phytophthora diseases worldwide' (35).

  16. Mapping of a Novel Race Specific Resistance Gene to Phytophthora Root Rot of Pepper (Capsicum annuum) Using Bulked Segregant Analysis Combined with Specific Length Amplified Fragment Sequencing Strategy.

    Science.gov (United States)

    Xu, Xiaomei; Chao, Juan; Cheng, Xueli; Wang, Rui; Sun, Baojuan; Wang, Hengming; Luo, Shaobo; Xu, Xiaowan; Wu, Tingquan; Li, Ying

    2016-01-01

    Phytophthora root rot caused by Phytophthora capsici (P. capsici) is a serious limitation to pepper production in Southern China, with high temperature and humidity. Mapping PRR resistance genes can provide linked DNA markers for breeding PRR resistant varieties by molecular marker-assisted selection (MAS). Two BC1 populations and an F2 population derived from a cross between P. capsici-resistant accession, Criollo de Morelos 334 (CM334) and P. capsici-susceptible accession, New Mexico Capsicum Accession 10399 (NMCA10399) were used to investigate the genetic characteristics of PRR resistance. PRR resistance to isolate Byl4 (race 3) was controlled by a single dominant gene, PhR10, that was mapped to an interval of 16.39Mb at the end of the long arm of chromosome 10. Integration of bulked segregant analysis (BSA) and Specific Length Amplified Fragment sequencing (SLAF-seq) provided an efficient genetic mapping strategy. Ten polymorphic Simple Sequence Repeat (SSR) markers were found within this region and used to screen the genotypes of 636 BC1 plants, delimiting PhR10 to a 2.57 Mb interval between markers P52-11-21 (1.5 cM away) and P52-11-41 (1.1 cM). A total of 163 genes were annotated within this region and 31 were predicted to be associated with disease resistance. PhR10 is a novel race specific gene for PRR, and this paper describes linked SSR markers suitable for marker-assisted selection of PRR resistant varieties, also laying a foundation for cloning the resistance gene.

  17. 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.

  18. Vroegtijdig Phytophthora opsporen met biosensor

    NARCIS (Netherlands)

    Jansen, R.M.C.

    2003-01-01

    Phytophthora kan vroegtijdig worden opgespoord met biosensoren. Bij de Leerstoelgroep Agrarische Bedrijfstechnologie van Wageningen Universiteit wordt verder gekeken naar praktische toepassingen van deze techniek

  19. 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...

  20. Draft genome sequences of Phytophthora kernoviae and Phytophthora ramorum lineage EU2 from Scotland

    OpenAIRE

    Christine Sambles; Alexandra Schlenzig; Paul O'Neill; Murray Grant; Studholme, David J.

    2015-01-01

    Newly discovered Phytophthora species include invasive pathogens that threaten trees and shrubs. We present draft genome assemblies for three isolates of Phytophthora kernoviae and one isolate of the EU2 lineage of Phytophthora ramorum, collected from outbreak sites in Scotland.

  1. Small homologous blocks in phytophthora genomes do not point to an ancient whole-genome duplication.

    Science.gov (United States)

    van Hooff, Jolien J E; Snel, Berend; Seidl, Michael F

    2014-05-01

    Genomes of the plant-pathogenic genus Phytophthora are characterized by small duplicated blocks consisting of two consecutive genes (2HOM blocks) and by an elevated abundance of similarly aged gene duplicates. Both properties, in particular the presence of 2HOM blocks, have been attributed to a whole-genome duplication (WGD) at the last common ancestor of Phytophthora. However, large intraspecies synteny-compelling evidence for a WGD-has not been detected. Here, we revisited the WGD hypothesis by deducing the age of 2HOM blocks. Two independent timing methods reveal that the majority of 2HOM blocks arose after divergence of the Phytophthora lineages. In addition, a large proportion of the 2HOM block copies colocalize on the same scaffold. Therefore, the presence of 2HOM blocks does not support a WGD at the last common ancestor of Phytophthora. Thus, genome evolution of Phytophthora is likely driven by alternative mechanisms, such as bursts of transposon activity.

  2. 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.

  3. 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.

  4. Phytophthora sojae: Diversity among and within Populations

    Science.gov (United States)

    Soybean production is increasing around the world and, to no surprise, so are the reports of soybean diseases caused by Phytophthora sojae, including Phytophthora seed, root, and stem rot. Phytophthora sojae is a diploid oomycete, which is homothallic and is limited to primarily one host: the soybe...

  5. Intracellular and extracellular phosphatidylinositol 3-phosphate produced by Phytophthora species is important for infection.

    Science.gov (United States)

    Lu, Shan; Chen, Linlin; Tao, Kai; Sun, Nannan; Wu, Yuren; Lu, Xiaoxue; Wang, Yuanchao; Dou, Daolong

    2013-09-01

    RxLR effectors produced by Phytophthora pathogens have been proposed to bind to phosphatidylinositol 3-phosphate (PtdIns(3)P) to mediate their translocation into host cells and/or to increase their stability in planta. Since the levels of PtdIns(3)P in plants are low, we examined whether Phytophthora species may produce PtdIns(3)P to promote infection. We observed that PtdIns(3)P-specific GFP biosensors could bind to P. parasitica and P. sojae hyphae during infection of Nicotiana benthamiana leaves transiently secreting the biosensors, suggesting that the hyphae exposed PtdIns(3)P on their plasma membrane and/or secreted PtdIns(3)P. Silencing of the phosphatidylinositol 3-kinases (PI3K) genes, treatment with LY294002, or expression of PtdIns(3)P-binding proteins by P. sojae reduced the virulence of the pathogen on soybean, indicating that pathogen-synthesized PtdIns(3)P was required for full virulence. Secretion of PtdIns(3)P-binding proteins or of a PI3P-5-kinase by N. benthamiana leaves significantly increased the level of resistance to infection by P. parasitica and P. capsici. Together, our results support the hypothesis that Phytophthora species produce external PtdIns(3)P to aid in infection, such as to promote entry of RxLR effectors into host cells. Our results derived from P. sojae RxLR effector Avr1b confirm that both the N-terminus and the C-terminus of this effector can bind PtdIns(3)P.

  6. Phytophthora infestans, een dynamische ziekteverwekker

    NARCIS (Netherlands)

    Govers, F.

    2010-01-01

    Samenvatting van de inaugurele rede van Francine Govers op 11 juni 2009. Dit artikel beschrijft de stand van zaken in het onderzoek aan oömyceten en in het bijzonder aan Phytophthora infestans, de veroorzaker van de aardappelziekte. Er wordt ingegaan op ziektebestrijding en resistentieveredeling, de

  7. Draft genome sequences of Phytophthora kernoviae and Phytophthora ramorum lineage EU2 from Scotland

    Directory of Open Access Journals (Sweden)

    Christine Sambles

    2015-12-01

    Full Text Available Newly discovered Phytophthora species include invasive pathogens that threaten trees and shrubs. We present draft genome assemblies for three isolates of Phytophthora kernoviae and one isolate of the EU2 lineage of Phytophthora ramorum, collected from outbreak sites in Scotland.

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

    OpenAIRE

    Juliana Bautista-Calles; Manuel Huerta-Lara; Roberto García-Espinoza

    2014-01-01

    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 ...

  9. 辣椒疫病(Phytophthora capsici Leonian)药剂防治试验示范报告

    Institute of Scientific and Technical Information of China (English)

    鲁占魁; 李建如

    1997-01-01

    分别用64%杀毒矾和70%代森锰锌可湿性粉剂每亩1kg,播种前土壤施药;生长期500倍药液灌根3次,防治效果为65.5%和42.9%,净产值增长率为81.1%和94.5%。

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

    Science.gov (United States)

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

    2016-07-01

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

  11. Variation in Phytophthora infestans: sources and implications

    NARCIS (Netherlands)

    Flier, W.G.

    2002-01-01

    Uitgebreide samenvatting van de dissertatie van Wilbert G. Flier over de oömyceet Phytophthora infestans (Monst.) de Bary, de veroorzaker van 'het kwaad' ofwel de aardappelziekte in de teelt van aardappelen en tomaten

  12. Pathogenic diversity of Phytophthora sojae and breeding strategies to develop Phytophthora-resistant soybeans

    Science.gov (United States)

    Phytophthora stem and root rot disease, caused by Phytophthora sojae, is one of the most destructive diseases of soybean (Glycine max (L.) Merr.), and has been increasing in several soybean-producing areas around the world. This disease induces serious limitations on soybean production, with yield l...

  13. 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...

  14. 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...... Phytophthora-arter, så dette er en skadegjører juletredyrkere må være på vakt overfor...

  15. Pea Broth Enhances the Biocontrol Efficacy of Lysobacter capsici AZ78 by Triggering Cell Motility Associated with Biogenesis of Type IV Pilus.

    Science.gov (United States)

    Tomada, Selena; Puopolo, Gerardo; Perazzolli, Michele; Musetti, Rita; Loi, Nazia; Pertot, Ilaria

    2016-01-01

    Bacterial cells can display different types of motility, due to the presence of external appendages such as flagella and type IV pili. To date, little information on the mechanisms involved in the motility of the Lysobacter species has been available. Recently, L. capsici AZ78, a biocontrol agent of phytopathogenic oomycetes, showed the ability to move on jellified pea broth. Pea broth medium improved also the biocontrol activity of L. capsici AZ78 against Plasmopara viticola under greenhouse conditions. Noteworthy, the quantity of pea residues remaining on grapevine leaves fostered cell motility in L. capsici AZ78. Based on these results, this unusual motility related to the composition of the growth medium was investigated in bacterial strains belonging to several Lysobacter species. The six L. capsici strains tested developed dendrite-like colonies when grown on jellified pea broth, while the development of dendrite-like colonies was not recorded in the media commonly used in motility assays. To determine the presence of genes responsible for biogenesis of the flagellum and type IV pili, the genome of L. capsici AZ78 was mined. Genes encoding structural components and regulatory factors of type IV pili were upregulated in L. capsici AZ78 cells grown on the above-mentioned medium, as compared with the other tested media. These results provide new insight into the motility mechanism of L. capsici members and the role of type IV pili and pea compounds on the epiphytic fitness and biocontrol features of L. capsici AZ78.

  16. Pea broth enhances the biocontrol efficacy of Lysobacter capsici AZ78 by triggering cell motility associated with biogenesis of type IV pilus

    Directory of Open Access Journals (Sweden)

    Selena Tomada

    2016-07-01

    Full Text Available Bacterial cells can display different types of motility, due to the presence of external appendages such as flagella and type IV pili. To date, little information on the mechanisms involved in the motility of the Lysobacter species has been available. Recently, L. capsici AZ78, a biocontrol agent of phytopathogenic oomycetes, showed the ability to move on jellified pea broth. Pea broth medium improved also the biocontrol activity of L. capsici AZ78 against Plasmopara viticola under greenhouse conditions. Noteworthy, the quantity of pea residues remaining on grapevine leaves fostered cell motility in L. capsici AZ78. Based on these results, this unusual motility related to the composition of the growth medium was investigated in bacterial strains belonging to several Lysobacter species. The six L. capsici strains tested developed dendrite-like colonies when grown on jellified pea broth, while the development of dendrite-like colonies was not recorded in the media commonly used in motility assays. To determine the presence of genes responsible for biogenesis of the flagellum and type IV pili, the genome of L. capsici AZ78 was mined. Genes encoding structural components an d regulatory factors of type IV pili were upregulated in L. capsici AZ78 cells grown on the above-mentioned medium, as compared with the other tested media. These results provide new insight into the motility mechanism of L. capsici members and the role of type IV pili and pea compounds on the epiphytic fitness and biocontrol features of L. capsici AZ78.

  17. 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.

  18. PHYTOPHTHORA INFESTANS POPULATION STRUCTURE: A WORLDWIDE SCALE

    Directory of Open Access Journals (Sweden)

    MARTHA CÁRDENAS

    2012-01-01

    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 (Peptidase, 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.

  19. Diagnostics of Tree Diseases Caused by Phytophthora austrocedri Species.

    Science.gov (United States)

    Mulholland, Vincent; Elliot, Matthew; Green, Sarah

    2015-01-01

    We present methods for the detection and quantification of four Phytophthora species which are pathogenic on trees; Phytophthora ramorum, Phytophthora kernoviae, Phytophthora lateralis, and Phytophthora austrocedri. Nucleic acid extraction methods are presented for phloem tissue from trees, soil, and pure cultures on agar plates. Real-time PCR methods are presented and include primer and probe sets for each species, general advice on real-time PCR setup and data analysis. A method for sequence-based identification, useful for pure cultures, is also included.

  20. 广州地区茄疫病的发生及疫霉种鉴定%On the Occurrence and the Identification of Eggplant's Phytophthora Disease in Guangzhou Region

    Institute of Scientific and Technical Information of China (English)

    成家壮; 韦小燕

    2002-01-01

    1987~1999年,从广州地区茄的果实、茎、叶及根上分离得到疫霉菌,根据形态特征、培养性状及生理特性等方面研究结果,鉴定出4个种,其中以辣椒疫霉Phytophthora capsici Leon较为普遍,烟草疫霉P.nicotianae Van Breda de Haan次之, 掘氏疫霉P.drechsleri Tucker较少出现,致病疫霉P.infestans (Montagne) de Bary 仅见于春季;此外,种群分布与前作及不同季节有关.

  1. 75 FR 44936 - Notice of Request for Extension of Approval of an Information Collection; Phytophthora Ramorum...

    Science.gov (United States)

    2010-07-30

    ...; Phytophthora Ramorum; Quarantine and Regulations AGENCY: Animal and Plant Health Inspection Service, USDA... regulations for the interstate movement of regulated articles to prevent the spread of Phytophthora ramorum... of Phytophthora ramorum, contact Mr. Prakash Hebbar, Program Manager, Emergency and Domestic...

  2. Pudrición basal causada por Phytophthora capcisi en plantas de chile tratadas con vermicompost

    Directory of Open Access Journals (Sweden)

    Lidieth Uribe-Lorío

    2014-07-01

    Full Text Available 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.

  3. Phytophthora aquimorbida sp. nov. and Phytophthora taxon 'aquatilis' recovered from irrigation reservoirs and a stream in Virginia, USA.

    Science.gov (United States)

    Hong, Chuanxue; Richardson, Patricia A; Hao, Wei; Ghimire, Sita R; Kong, Ping; Moorman, Gary W; Lea-Cox, John D; Ross, David S

    2012-01-01

    Two distinct subgroups (L2 and A(-2)) were recovered from irrigation reservoirs and a stream in Virginia, USA. After molecular, morphological and physiological examinations, the L2 subgroup was named Phytophthora aquimorbida and the A(-2) designated as Phytophthora taxon 'aquatilis'. Both taxa are homothallic. P. aquimorbida is characterized by its noncaducous and nonpapillate sporangia, catenulate and radiating hyphal swellings and thick-walled plerotic oospores formed in globose oogonia mostly in the absence of an antheridium. P. taxon 'aquatilis' produces plerotic oospores in globose oogonia mostly with a paragynous antheridium. It has semi-papillate, caducous sporangia with variable pedicels, but it does not have hyphal swelling. Analyses of ITS, CO1, β-tubulin and NADH1 sequences revealed that P. aquimorbida is closely related to P. hydropathica, P. irrigata and P. parsiana, and P. taxon 'aquatilis' is related to P. multivesiculata. The optimum temperature for culture growth is 30 and 20 C for P. aquimorbida and P. taxon 'aquatilis' respectively. Both taxa were pathogenic to rhododendron plants and caused root discoloration, pale leaves, wilting, tip necrosis and dieback. Their plant biosecurity risk also is discussed.

  4. 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

  5. Variation in Phytophthora infestans : sources and implications

    NARCIS (Netherlands)

    Flier, W.

    2001-01-01

    The oomycete pseudofungus Phytophthora infestans (Mont.) de Bary, the causal organism of late blight, is considered to be one of the most devastating pathogens affecting potatoes and tomatoes worldwide. In Europe, the pathogen caused severe epidemics on potatoes after its introduction in 1845. Late

  6. Tomato late blight (Phytophthora infestans) in Uganda

    NARCIS (Netherlands)

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

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lamour, Kurt H [ORNL; McDonald, W Hayes [ORNL; Savidor, Alon [ORNL

    2006-01-01

    Genome sequences of the soybean pathogen, Phytophthora sojae, and the sudden oak death pathogen, Phytophthora ramorum, suggest a photosynthetic past and reveal recent massive expansion and diversification of potential pathogenicity gene families. Abstract: Draft genome sequences of the soybean pathogen, Phytophthora sojae, and the sudden oak death pathogen, Phytophthora ramorum, have been determined. O mycetes 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 support 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 o mycete avirulence genes.

  8. 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.

  9. 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.

  10. Pathogenicity of Phytophthora isolates originating from several woody hosts in Bulgaria and Poland

    Directory of Open Access Journals (Sweden)

    Lyubenova Aneta B.

    2016-09-01

    Full Text Available Our aim was to examine the virulence of eight Phytophthora isolates belonging to three species (Phytophthora cryptogea, Phytophthora plurivora and Phytophthora quercina obtained from diverse European ecosystems (in Bulgaria, Poland and Germany towards three forest tree hosts – English oak (Quercus robur L., Turkey oak (Quercus cerris L. and European beech (Fagus sylvatica L..

  11. The aspartic proteinase family of three Phytophthora species

    NARCIS (Netherlands)

    Kay, J.; Meijer, H.J.G.; Have, ten A.; Kan, van J.A.L.

    2011-01-01

    Background - Phytophthora species are oomycete plant pathogens with such major social and economic impact that genome sequences have been determined for Phytophthora infestans, P. sojae and P. ramorum. Pepsin-like aspartic proteinases (APs) are produced in a wide variety of species (from bacteria to

  12. 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...

  13. Development of new polymorphic microsatellite markers for three closely related plant-pathogenic Phytophthora species using 454-pyrosequencing and their potential applications.

    Science.gov (United States)

    Schoebel, Corine N; Jung, Esther; Prospero, Simone

    2013-10-01

    Phytophthora spp. (oomycetes) are causal agents of devastating diseases on a high number of crops, ornamentals, and native plants worldwide. Neutral molecular markers are increasingly being used to investigate the genetic population structure and possible pathways of spread of different plant pathogens, including Phytophthora spp. In this study, polymorphic microsatellite markers were developed for three species of the former Phytophthora citricola species complex-namely, P. multivora, P. plurivora, and P. pini (P. citricola I)-using the 454-pyrosequencing technique. In total, 35 polymorphic microsatellite loci were found and further characterized: 11 for P. plurivora, 16 for P. multivora, and 8 for P. pini. Microsatellites with dinucleotide motifs repeated 6 to 10 times were the most common for all three species. On average, 65 alleles per species and 5.3 alleles per locus were detected. Most loci were characterized by a low observed heterozygosity, which might be due to the homothallic mating system of the three Phytophthora spp. targeted. Cross amplification of the newly developed markers was tested on 17 Phytophthora spp. belonging to five different internal transcribed spacer clades. Transferability success was generally low and decreased with increasing genetic distance from the species to the three target species. A set of four loci was selected to easily discriminate P. plurivora, P. multivora, and P. pini on the basis of presence or absence of a polymerase chain reaction amplicon on an agarose gel.

  14. 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.

  15. 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.

  16. 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

  17. 辣椒定位于叶绿体的13-脂氧合酶基因(CaLOX2)克隆及表达分析%Cloning and Expression Characterization of Chloroplast-targeted 13-lipoxygenase Gene(CaLOX2) in Capsicum annuum L.

    Institute of Scientific and Technical Information of China (English)

    贾庆利; 巩振辉; 李大伟

    2012-01-01

    (GenBank accession number: JQ219046) was isolated using in silico cloning from Capsicum annuum L. and characterized by RT-PCR. The length of the gene was 2 843 bp, which contained a 2 730 bp long open reading frame (ORF), coding a 910 animo acid polypeptide. Th e deduced amino acid sequence of the gene contained the typical domain of lipoxygenase and putative transit peptides for chloroplast import. Phylogenetic analysis revealed that CaL0X2 clustered together with well-characterized plastidic type II 13-LOXs genes from tomato (Solatium lycopersicum) TomLOXD, potato (Solarium tuberosum) StLOXH3 and tobacco (Nicotiana attenuate) NaL0X3. Real-time quantitative PCR analysis showed that CaL0X2 transcripts were expressed in all tissues of pepper, however the expression patterns of the gene had tissue specificity, the transcripts were most abundantly expressed in the leaf but much less in flower; the expression level of the CaL0X2 mRNA could be up-regulated significantly after inoculation with zoospores of Phytophthora capsici in both incompatible and compatible interaction. But, its expression level was much higher and earlier at time point in the incompatible interaction than that in the compatible interaction., which indicated CaL0X2 was involed in race-specific resistance to Phytophthora capsici in pepper. The gene expression patterns differed in different pepper organs, its expression level was much higher but later at time point in the leaves than that in the roots after inoculated with Phytophthora capsici race phi. The expression of CaL0X2 was up-regulated after treatment with mechanical wounding and NaCl stress, but down-regulated by low temperature. This gene was highly induced by H2O2, salicylic acid (SA), and methyjasmonic acid (MeJA). The comparison of CaLOX2 with the well-studied LOXs from other plant species in phylogenetic analysis and expression patterns indicated that the most likely biochemical function of CaL0X2 was in the biosynthesis of JA through

  18. Survey and analysis of microsatellites from transcript sequences in Phytophthora species: frequency, distribution, and potential as markers for the genus

    Directory of Open Access Journals (Sweden)

    Barreto Emiliano

    2006-09-01

    Full Text Available Abstract Background Members of the genus Phytophthora are notorious pathogens with world-wide distribution. The most devastating species include P. infestans, P. ramorum and P. sojae. In order to develop molecular methods for routinely characterizing their populations and to gain a better insight into the organization and evolution of their genomes, we used an in silico approach to survey and compare simple sequence repeats (SSRs in transcript sequences from these three species. We compared the occurrence, relative abundance, relative density and cross-species transferability of the SSRs in these oomycetes. Results The number of SSRs in oomycetes transcribed sequences is low and long SSRs are rare. The in silico transferability of SSRs among the Phytophthora species was analyzed for all sets generated, and primers were selected on the basis of similarity as possible candidates for transferability to other Phytophthora species. Sequences encoding putative pathogenicity factors from all three Phytophthora species were also surveyed for presence of SSRs. However, no correlation between gene function and SSR abundance was observed. The SSR survey results, and the primer pairs designed for all SSRs from the three species, were deposited in a public database. Conclusion In all cases the most common SSRs were trinucleotide repeat units with low repeat numbers. A proportion (7.5% of primers could be transferred with 90% similarity between at least two species of Phytophthora. This information represents a valuable source of molecular markers for use in population genetics, genetic mapping and strain fingerprinting studies of oomycetes, and illustrates how genomic databases can be exploited to generate data-mining filters for SSRs before experimental validation.

  19. DMPP-enhanced control efficacy of chili pepper Phytophthora blight using ammonium bicarbonate:Action effects and mechanisms%DMPP 增强碳酸氢铵防控辣椒疫病的效果与机制

    Institute of Scientific and Technical Information of China (English)

    曹云; 王光飞; 郭德杰; 马艳; 罗德旭; 孙玉东; 汪国莲

    2016-01-01

    Phytophthora blight of chili pepper, caused by oomycetes of Phytophthora capsici, has been reported to be a key limiting factor of chili pepper production worldwide. Increased public interest in protecting the environment and human health has prompted research in agronomic strategies that reduce the use of fungicides. Alternative control methods with high efficacy, low cost and limited environmental effect are high-priority research areas for sustainable agriculture. Under the same incubation conditions (soil moisture of 60% of field capacity, temperature of 25 ℃ and inoculation concentration of P. capsici of 500 CFU·g-1), DMPP (1% applied pure N) and ammonium bicarbonate (AB) [100 mg(N)·kg-1] were added tofluvo-aquic soil and incubated for 15 d. Soil without any addition of DMPP and/or AB was set as the control. After incubation, DMPP or AB-treated soil was used to grow chili pepper in a pot experiment for 28 d. The effect of DMPP and AB application on disease incidence of Phytophthora blight of chili pepper was then compared. The soil physio-chemical and microbial responses (soil pH, electric conductivity, concentrations of different forms of nitrogen; numbers of total bacteria, fungi, P. capsici and ammonia-oxidizing bacteria) to the addition of DMPP and AB were determined. The relationship between Phytophthora blight disease incidence and soil phyiso-chemical and microbial characteristics was evaluated. The aim of the study was to investigate the control effects of DMPP-enhanced ammonium biocarbonate on Phytophthora blight of chili pepper and correlation with soil physio-chemical properties, and provided technological support for control of Phytophthora blight of chili pepper of greenhouse. The results suggested that compared with the control, the contents of soil ammonium nitrogen in DMPP and DMPP+AB treatments were higher, and the contents of nitrate and nitrite nitrogen significantly lower. The application of DMPP for 15 d decreased copied gene numbers

  20. Genetic analysis and identification of DNA markers linked to a novel Phytophthora sojae resistance gene in the Japanese soybean cultivar Waseshiroge

    Science.gov (United States)

    Glycine max (L.) Merr. cv. Waseshiroge is considered to be strongly resistant to several races of Phytophthora sojae in Japan. In order to characterize the inheritance of Waseshiroge resistance to P. sojae isolates, 42 F2 progeny plants and 94 F7:8 families were produced from crosses between the sus...

  1. Distinctive Nuclear Localization Signals in the Oomycete Phytophthora sojae.

    Science.gov (United States)

    Fang, Yufeng; Jang, Hyo Sang; Watson, Gregory W; Wellappili, Dulani P; Tyler, Brett M

    2017-01-01

    To date, nuclear localization signals (NLSs) that target proteins to nuclei in oomycetes have not been defined, but have been assumed to be the same as in higher eukaryotes. Here, we use the soybean pathogen Phytophthora sojae as a model to investigate these sequences in oomycetes. By establishing a reliable in vivo NLS assay based on confocal microscopy, we found that many canonical monopartite and bipartite classical NLSs (cNLSs) mediated nuclear import poorly in P. sojae. We found that efficient localization of P. sojae nuclear proteins by cNLSs requires additional basic amino acids at distal sites or collaboration with other NLSs. We found that several representatives of another well-characterized NLS, proline-tyrosine NLS (PY-NLS) also functioned poorly in P. sojae. To characterize PY-NLSs in P. sojae, we experimentally defined the residues required by functional PY-NLSs in three P. sojae nuclear-localized proteins. These results showed that functional P. sojae PY-NLSs include an additional cluster of basic residues for efficient nuclear import. Finally, analysis of several highly conserved P. sojae nuclear proteins including ribosomal proteins and core histones revealed that these proteins exhibit a similar but stronger set of sequence requirements for nuclear targeting compared with their orthologs in mammals or yeast.

  2. Distinctive Nuclear Localization Signals in the Oomycete Phytophthora sojae

    Science.gov (United States)

    Fang, Yufeng; Jang, Hyo Sang; Watson, Gregory W.; Wellappili, Dulani P.; Tyler, Brett M.

    2017-01-01

    To date, nuclear localization signals (NLSs) that target proteins to nuclei in oomycetes have not been defined, but have been assumed to be the same as in higher eukaryotes. Here, we use the soybean pathogen Phytophthora sojae as a model to investigate these sequences in oomycetes. By establishing a reliable in vivo NLS assay based on confocal microscopy, we found that many canonical monopartite and bipartite classical NLSs (cNLSs) mediated nuclear import poorly in P. sojae. We found that efficient localization of P. sojae nuclear proteins by cNLSs requires additional basic amino acids at distal sites or collaboration with other NLSs. We found that several representatives of another well-characterized NLS, proline-tyrosine NLS (PY-NLS) also functioned poorly in P. sojae. To characterize PY-NLSs in P. sojae, we experimentally defined the residues required by functional PY-NLSs in three P. sojae nuclear-localized proteins. These results showed that functional P. sojae PY-NLSs include an additional cluster of basic residues for efficient nuclear import. Finally, analysis of several highly conserved P. sojae nuclear proteins including ribosomal proteins and core histones revealed that these proteins exhibit a similar but stronger set of sequence requirements for nuclear targeting compared with their orthologs in mammals or yeast. PMID:28210240

  3. PsVPS1, a Dynamin-Related Protein, Is Involved in Cyst Germination and Soybean Infection of Phytophthora sojae

    OpenAIRE

    Delong Li; Zhijian Zhao; Yidan Huang; Zhaojun Lu; Meng Yao; Yujuan Hao; Chunhua Zhai; Yuanchao Wang

    2013-01-01

    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-si...

  4. Phytophthora species, new threats to the plant health in Korea.

    Science.gov (United States)

    Hyun, Ik-Hwa; Choi, Woobong

    2014-12-01

    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 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.

  5. De rol van heterotrimere G-eiwitten in de ontwikkeling en virulentie van Phytophthora infestans

    NARCIS (Netherlands)

    Latijnhouwers, M.

    2003-01-01

    Onderzoek naar de ziekteverwekker Phytophthora infestans die de aardappelziekte veroorzaakt. Samenvatting van het proefschrift van Maita J.M. Latijnhouwers getiteld: 'The role of heterotrimeric G-proteins in development and virulence of Phytophthora infestans'

  6. Voetsporen van evolutie: de dynamiek van effectorgenen in het Phytophthora-genoom

    NARCIS (Netherlands)

    Jiang, R.H.Y.

    2007-01-01

    Het geslacht Phytophthora omvat meer dan 65 verwoestende plantenpathogene soorten die ernstige schade toebrengen aan landbouwgewassen en aan planten, struiken en bomen in de natuur. Economisch belangrijke pathogenen zijn onder andere Phytophthora infestans, de veroorzaker van de aardappelziekte, Phy

  7. 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

  8. 78 FR 58993 - Notice of Request for Extension of Approval of an Information Collection; Phytophthora Ramorum...

    Science.gov (United States)

    2013-09-25

    ... Collection; Phytophthora Ramorum; Quarantine and Regulations AGENCY: Animal and Plant Health Inspection... Phytophthora ramorum. DATES: We will consider all comments that we receive on or before November 25, 2013... of regulated articles to prevent the spread of Phytophthora ramorum, contact Dr. Prakash K....

  9. 40 CFR 180.1057 - Phytophthora palmivora; exemption from requirement of tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Phytophthora palmivora; exemption from... From Tolerances § 180.1057 Phytophthora palmivora; exemption from requirement of tolerance. Phytophthora palmivora is exempted from the requirement of a tolerance in or on the raw agricultural...

  10. 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.

  11. Evidence for homoploid speciation in Phytophthora alni supports taxonomic reclassification in this species complex.

    Science.gov (United States)

    Husson, C; Aguayo, J; Revellin, C; Frey, P; Ioos, R; Marçais, B

    2015-04-01

    Alder decline has been a problem along European watercourses since the early 1990s. Hybridization was identified as the main cause of this emerging disease. Indeed, the causal agent, a soil-borne pathogen named Phytophthora alni subsp. alni (Paa) is the result of interspecific hybridization between two taxa, Phytophthora alni subsp. multiformis (Pam) and Phytophthora alni subsp. uniformis (Pau), initially identified as subspecies of Paa. The aim of this work was to characterize the ploidy level within the P. alni complex that is presently poorly understood. For that, we used two complementary approaches for a set of 31 isolates of Paa, Pam and Pau: (i) quantification of allele copy number of three single-copy nuclear genes using allele-specific real-time PCR and (ii) comparison of the genome size estimated by flow cytometry. Relative quantification of alleles of the three single-copy genes showed that the copy number of a given allele in Paa was systematically half that of its parents Pau or Pam. Moreover, DNA content estimated by flow cytometry in Paa was equal to half the sum of those in Pam and Pau. Our results therefore suggest that the hybrid Paa is an allotriploid species, containing half of the genome of each of its parents Pam and Pau, which in turn are considered to be allotetraploid and diploid, respectively. Paa thus results from a homoploid speciation process. Based on published data and on results from this study, a new formal taxonomic name is proposed for the three taxa Paa, Pam and Pau which are raised to species status and renamed P. ×alni, P. ×multiformis and P. uniformis, respectively.

  12. A molecular method to assess Phytophthora diversity in environmental samples.

    Science.gov (United States)

    Scibetta, Silvia; Schena, Leonardo; Chimento, Antonio; Cacciola, Santa O; Cooke, David E L

    2012-03-01

    Current molecular detection methods for the genus Phytophthora are specific to a few key species rather than the whole genus and this is a recognized weakness of protocols for ecological studies and international plant health legislation. In the present study a molecular approach was developed to detect Phytophthora species in soil and water samples using novel sets of genus-specific primers designed against the internal transcribed spacer (ITS) regions. Two different rDNA primer sets were tested: one assay amplified a long product including the ITS1, 5.8S and ITS2 regions (LP) and the other a shorter product including the ITS1 only (SP). Both assays specifically amplified products from Phytophthora species without cross-reaction with the related Pythium s. lato, however the SP assay proved the more sensitive and reliable. The method was validated using woodland soil and stream water from Invergowrie, Scotland. On-site use of a knapsack sprayer and in-line water filters proved more rapid and effective than centrifugation at sampling Phytophthora propagules. A total of 15 different Phytophthora phylotypes were identified which clustered within the reported ITS-clades 1, 2, 3, 6, 7 and 8. The range and type of the sequences detected varied from sample to sample and up to three and five different Phytophthora phylotypes were detected within a single sample of soil or water, respectively. The most frequently detected sequences were related to members of ITS-clade 6 (i.e. P. gonapodyides-like). The new method proved very effective at discriminating multiple species in a given sample and can also detect as yet unknown species. The reported primers and methods will prove valuable for ecological studies, biosecurity and commercial plant, soil or water (e.g. irrigation water) testing as well as the wider metagenomic sampling of this fascinating component of microbial pathogen diversity.

  13. Survival of Phytophthora infestans in Surface Water.

    Science.gov (United States)

    Porter, Lyndon D; Johnson, Dennis A

    2004-04-01

    ABSTRACT Coverless petri dishes with water suspensions of sporangia and zoospores of Phytophthora infestans were embedded in sandy soil in eastern Washington in July and October 2001 and July 2002 to quantify longevity of spores in water under natural conditions. Effects of solar radiation intensity, presence of soil in petri dishes (15 g per dish), and a 2-h chill period on survival of isolates of clonal lineages US-8 and US-11 were investigated. Spores in water suspensions survived 0 to 16 days under nonshaded conditions and 2 to 20 days under shaded conditions. Mean spore survival significantly increased from 1.7 to 5.8 days when soil was added to the water. Maximum survival time of spores in water without soil exposed to direct sunlight was 2 to 3 days in July and 6 to 8 days in October. Mean duration of survival did not differ significantly between chilled and nonchilled sporangia, but significantly fewer chilled spores survived for extended periods than that of nonchilled spores. Spores of US-11 and US-8 isolates did not differ in mean duration of survival, but significantly greater numbers of sporangia of US-8 survived than did sporangia of US-11 in one of three trials.

  14. 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.

  15. 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.

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

    NARCIS (Netherlands)

    Zwankhuizen, M.J.

    1998-01-01

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

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

    Science.gov (United States)

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

  18. 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

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

    DEFF Research Database (Denmark)

    Cvitanich, Cristina; Judelson, Howard S.

    2003-01-01

    Germinated asexual sporangia, zoospores, and mycelia of Phytophthora infestans were transformed to G418-resistance by microprojectile bombardment. After optimization, an average of 14 transformants/shot were obtained, using 10(6) germinated sporangia and gold particles coated with 1 microg...

  20. Susceptibility of highbush blueberry cultivars to Phytophthora root rot

    Science.gov (United States)

    Phytophthora cinnamomi Rands is a ubiquitous soilborne pathogen associated with root rot in many woody perennial plant species, including highbush blueberry (Vaccinium sp.). To identify genotypes with resistance to the pathogen, cultivars and advanced selections of highbush blueberry were grown in a...

  1. 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...

  2. Carbohydrate-related enzymes of important Phytophthora plant pathogens.

    Science.gov (United States)

    Brouwer, Henk; Coutinho, Pedro M; Henrissat, Bernard; de Vries, Ronald P

    2014-11-01

    Carbohydrate-Active enZymes (CAZymes) form particularly interesting targets to study in plant pathogens. Despite the fact that many CAZymes are pathogenicity factors, oomycete CAZymes have received significantly less attention than effectors in the literature. Here we present an analysis of the CAZymes present in the Phytophthora infestans, Ph. ramorum, Ph. sojae and Pythium ultimum genomes compared to growth of these species on a range of different carbon sources. Growth on these carbon sources indicates that the size of enzyme families involved in degradation of cell-wall related substrates like cellulose, xylan and pectin is not always a good predictor of growth on these substrates. While a capacity to degrade xylan and cellulose exists the products are not fully saccharified and used as a carbon source. The Phytophthora genomes encode larger CAZyme sets when compared to Py. ultimum, and encode putative cutinases, GH12 xyloglucanases and GH10 xylanases that are missing in the Py. ultimum genome. Phytophthora spp. also encode a larger number of enzyme families and genes involved in pectin degradation. No loss or gain of complete enzyme families was found between the Phytophthora genomes, but there are some marked differences in the size of some enzyme families.

  3. Phytophthora ramorum causes cryptic bole cankers in Canyon line Oak

    Science.gov (United States)

    Unusual mortality of large canyon live oaks was observed in natural stands in San Mateo, California starting in 2007. A survey of affected stands showed that symptomatic trees were spatially associated with California bay, the primary source of Phytophthora ramorum spores in this forest type. Trunk ...

  4. 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

  5. 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

  6. 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...

  7. Multi-scale modelling of infection pressure from Phytophthora infestans

    NARCIS (Netherlands)

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

    2007-01-01

    Management of potato late blight could benefit from prediction of the risk posed to potato fields from external inoculum sources of Phytophthora infestans. Influx of inoculum depends on a complex interplay of population biological, atmospheric and spore survival processes, and is difficult to predic

  8. The Effect of Potassium Nitrate on the Reduction of Phytophthora Stem Rot Disease of Soybeans, the Growth Rate and Zoospore Release of Phytophthora Sojae

    Science.gov (United States)

    The effects of potassium nitrate (KNO3) application on Phytophthora stem rot disease reduction of Glycine max (L.) Merr. cvs. Chusei-Hikarikuro and Sachiyutaka, and fungal growth and zoospore release of a Phytophthora sojae isolate were investigated under laboratory conditions. The application of 4-...

  9. Two novel species representing a new clade and cluster of Phytophthora.

    Science.gov (United States)

    Yang, Xiao; Copes, Warren E; Hong, Chuanxue

    2014-01-01

    Phytophthora stricta sp. nov. and Phytophthora macilentosa sp. nov. are described based on morphological, physiological and molecular characters in this study. Phytophthora stricta represents a previously unknown clade in the rRNA internal transcribed spacer (ITS)-based phylogeny. Phytophthora macilentosa, along with nine other species, consistently forms a high temperature-tolerant cluster within ITS clade 9. These observations are supported by the sequence analysis of the mitochondrial cytochrome c oxidase 1 gene. Both species are heterothallic and all examined isolates are A1 mating type. Phytophthora stricta produces nonpapillate and slightly caducous sporangia. This species is named after its characteristic constrictions on sporangiophores. Phytophthora macilentosa produces nonpapillate and noncaducous sporangia, which are mostly elongated obpyriform with a high length to breadth ratio. Both species were recovered from irrigation water of an ornamental plant nursery in Mississippi, USA and P. stricta was also recovered from stream water in Virginia, USA.

  10. Genomic analyses of dominant U.S. clonal lineages of Phytophthora infestans reveals a shared common ancestry for clonal lineages US11 and US18 and a lack of recently shared ancestry among all other U.S. lineages

    Science.gov (United States)

    The populations of the potato and tomato late blight pathogen, Phytophthora infestans, in the US are well known for emerging repeatedly as novel clonal lineages. These successions of dominant clones have historically been named US1-US24, in order of appearance, since their first characterization usi...

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

    OpenAIRE

    1998-01-01

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

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

    OpenAIRE

    1997-01-01

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

  13. A universal microarray detection method for identification of multiple Phytophthora spp. using padlock probes.

    Science.gov (United States)

    Sikora, Katarzyna; Verstappen, Els; Mendes, Odette; Schoen, Cor; Ristaino, Jean; Bonants, Peter

    2012-06-01

    The genus Phytophthora consists of many species that cause important diseases in ornamental, agronomic, and forest ecosystems worldwide. Molecular methods have been developed for detection and identification of one or several species of Phytophthora in single or multiplex reactions. In this article, we describe a padlock probe (PLP)-based multiplex method of detection and identification for many Phytophthora spp. simultaneously. A generic TaqMan polymerase chain reaction assay, which detects all known Phytophthora spp., is conducted first, followed by a species-specific PLP ligation. A 96-well-based microarray platform with colorimetric readout is used to detect and identify the different Phytophthora spp. PLPs are long oligonucleotides containing target complementary sequence regions at both their 5' and 3' ends which can be ligated on the target into a circular molecule. The ligation is point mutation specific; therefore, closely related sequences can be differentiated. This circular molecule can then be detected on a microarray. We developed 23 PLPs to economically important Phytophthora spp. based upon internal transcribed spacer-1 sequence differences between individual Phytophthora spp. Tests on genomic DNA of many Phytophthora isolates and DNA from environmental samples showed the specificity and utility of PLPs for Phytophthora diagnostics.

  14. 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.

  15. 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

  16. 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

  17. Occurrence of Phytophthora plurivora and other Phytophthora species in oak forests of southern Poland and their association with site conditions and the health status of trees.

    Science.gov (United States)

    Jankowiak, R; Stępniewska, H; Bilański, P; Kolařík, M

    2014-11-01

    Phytophthora plurivora and other Phytophthora species are known to be serious pathogens of forest trees. Little is known, however, about the presence of P. plurivora in Polish oak forests and their role in oak decline. The aims of this study were to identify P. plurivora in healthy and declining Quercus robur stands in southern Poland and to demonstrate the relationship between different site factors and the occurrence of P. plurivora. In addition, the virulence of P. plurivora and other Phytophthora species was evaluated through inoculations using 2-year-old oak seedlings. Rhizosphere soil was investigated from 39 oak stands representing different healthy tree statuses. The morphology and DNA sequences of the internal transcribed spacer regions (ITS) of the ribosomal DNA and the mitochondrial cox1 gene were used for identifications. P. plurivora, an oak fine root pathogen, was isolated from rhizosphere soil samples in 6 out of 39 stands. Additionally, Phytophthora cambivora, Phytophthora polonica and Phytophthora rosacearum-like were also obtained from several stands. The results showed a significant association between the presence of P. plurivora and the health status of oak trees. Similar relationships were also observed for all identified Phytophthora species. In addition, there was evidence for a connection between the presence of all identified Phytophthora species and some site conditions. Phytophthora spp. occurred more frequently in declining stands and in silt loam and sandy loam soils with pH ≥ 3.66. P. plurivora and P. cambivora were the only species capable of killing whole plants, producing extensive necrosis on seedling stems.

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

    Science.gov (United States)

    Fleischmann, F; Raidl, S; Osswald, W F

    2010-04-01

    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(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(2)-treatment, whereas elevated CO(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(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.

  19. Identification of Phytophthora fragariae var. rubi by PCR.

    Science.gov (United States)

    Schlenzig, Alexandra

    2009-01-01

    The following chapter describes a PCR method for the identification of the raspberry root rot pathogen Phytophthora fragariae var. rubi. Furthermore, a nested PCR suitable for the detection of the pathogen in infected raspberry roots and validated against the "Duncan bait test" (EPPO Bull 35:87-91, 2005) is explained. Protocols for different DNA extraction methods are given which can be transferred to other fungal pathogens.

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

    OpenAIRE

    Ik-Hwa Hyun; Woobong Choi

    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 ...

  1. Evaluation of biorational products for management of Phytophthora blight of bell pepper transplants

    Science.gov (United States)

    Several commercially available biopesticides and phosphonate-containing products were selected and tested for their efficacy in controlling Phytopthora capsici on bell pepper at various inoculum and fertility levels. The effects of concentration, application method and frequency of application on t...

  2. Molecular profiling of the Phytophthora plurivora secretome: a step towards understanding the cross-talk between plant pathogenic oomycetes and their hosts.

    Science.gov (United States)

    Severino, Valeria; Farina, Annarita; Fleischmann, Frank; Dalio, Ronaldo J D; Di Maro, Antimo; Scognamiglio, Monica; Fiorentino, Antonio; Parente, Augusto; Osswald, Wolfgang; Chambery, Angela

    2014-01-01

    The understanding of molecular mechanisms underlying host-pathogen interactions in plant diseases is of crucial importance to gain insights on different virulence strategies of pathogens and unravel their role in plant immunity. Among plant pathogens, Phytophthora species are eliciting a growing interest for their considerable economical and environmental impact. Plant infection by Phytophthora phytopathogens is a complex process coordinated by a plethora of extracellular signals secreted by both host plants and pathogens. The characterization of the repertoire of effectors secreted by oomycetes has become an active area of research for deciphering molecular mechanisms responsible for host plants colonization and infection. Putative secreted proteins by Phytophthora species have been catalogued by applying high-throughput genome-based strategies and bioinformatic approaches. However, a comprehensive analysis of the effective secretome profile of Phytophthora is still lacking. Here, we report the first large-scale profiling of P. plurivora secretome using a shotgun LC-MS/MS strategy. To gain insight on the molecular signals underlying the cross-talk between plant pathogenic oomycetes and their host plants, we also investigate the quantitative changes of secreted protein following interaction of P. plurivora with the root exudate of Fagus sylvatica which is highly susceptible to the root pathogen. We show that besides known effectors, the expression and/or secretion levels of cell-wall-degrading enzymes were altered following the interaction with the host plant root exudate. In addition, a characterization of the F. sylvatica root exudate was performed by NMR and amino acid analysis, allowing the identification of the main released low-molecular weight components, including organic acids and free amino acids. This study provides important insights for deciphering the extracellular network involved in the highly susceptible P. plurivora-F. sylvatica interaction.

  3. 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

  4. Phytophthora andina sp nov., a newly identified heterothallic pathogen of solanaceous hosts in the Andean highlands

    NARCIS (Netherlands)

    Oliva, R.F.; Kroon, L.P.N.M.; Chacon, G.; Flier, W.G.; Ristaino, J.B.; Forbes, G.A.

    2010-01-01

    A blight disease on fruits and foliage of wild and cultivated Solanum spp. was found to be associated with a new species of Phytophthora. The proposed novel species is named Phytophthora andina Adler & Flier, sp. nov. based on morphological characteristics, pathogenicity assays, mitochondrial DN

  5. Phylogenetic Analysis of Phytophthora Species Based on Mitochondrial and Nuclear DNA Sequences

    NARCIS (Netherlands)

    Kroon, L.P.N.M.; Bakker, F.T.; Bosch, van den G.B.M.; Bonants, P.J.M.; Flier, W.G.

    2004-01-01

    A molecular phylogenetic analysis of the genus Phytophthora was performed, 113 isolates from 48 Phytophthora species were included in this analysis. Phylogenetic analyses were performed on regions of mitochondrial (cytochrome c oxidase subunit 1; NADH dehydrogenase subunit 1) and nuclear gene sequen

  6. 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

  7. Phytophthora megakarya, a causal agent of black pod rot in Africa

    Science.gov (United States)

    In most parts of the world where Theobroma cacao is grown, Phytophthora palmivora is the major concern for causing black pod rot (BPR). Phytophthora megakarya, on the other hand, occurs only in Africa, but represents a major threat to cacao production, the countries of West Africa being the largest ...

  8. 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...

  9. The interplay between a Phytophthora RXLR effector and an Arabidopsis lectin receptor kinase

    NARCIS (Netherlands)

    Bouwmeester, K.

    2010-01-01

    Phytophthora infestans – the causal agent of potato late blight – secretes a plethora of effector proteins to facilitate plant infection. The central subject of this thesis is ipiO, one of the first cloned Phytophthora genes with a putative function in pathogenicity as was anticipated based on its i

  10. 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...

  11. 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...

  12. 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

  13. Multiplex-detectie van Phytophthora: "padlock-based Universal Multiplex detection Array" (pUMA)

    NARCIS (Netherlands)

    Gaszczyk, K.; Mendes, O.; Verstappen, E.C.P.; Bonants, P.J.M.; Schoen, C.D.

    2010-01-01

    Plant Research International heeft een diagnostische methode ontwikkeld die toe te passen is 'in planta', en ook de meest recent beschreven (quarantaine-) soorten omvat. De methode omvat de ontwikkeling van een generieke Phytophthora-methode gevolgd door een Phytophthora-identificatie.

  14. 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.

  15. Diversity of Phytophthora Species from Declining Mediterranean Maquis Vegetation, including Two New Species, Phytophthora crassamura and P. ornamentata sp. nov.

    Science.gov (United States)

    Scanu, Bruno; Linaldeddu, Benedetto T.; Deidda, Antonio; Jung, Thomas

    2015-01-01

    The Mediterranean basin is recognized as a global biodiversity hotspot accounting for more than 25,000 plant species that represent almost 10% of the world’s vascular flora. In particular, the maquis vegetation on Mediterranean islands and archipelagos constitutes an important resource of the Mediterranean plant diversity due to its high rate of endemism. Since 2009, a severe and widespread dieback and mortality of Quercus ilex trees and several other plant species of the Mediterranean maquis has been observed in the National Park of La Maddalena archipelago (northeast Sardinia, Italy). Infected plants showed severe decline symptoms and a significant reduction of natural regeneration. First studies revealed the involvement of the highly invasive wide-host range pathogen Phytophthora cinnamomi and several fungal pathogens. Subsequent detailed research led to a better understanding of these epidemics showing that multiple Phytophthora spp. were involved, some of them unknown to science. In total, nine Phytophthora species were isolated from rhizosphere soil samples collected from around symptomatic trees and shrubs including Asparagus albus, Cistus sp., Juniperus phoenicea, J. oxycedrus, Pistacia lentiscus and Rhamnus alaternus. Based on morphological characters, growth-temperature relations and sequence analysis of the ITS and cox1 gene regions, the isolates were identified as Phytophthora asparagi, P. bilorbang, P. cinnamomi, P. cryptogea, P. gonapodyides, P. melonis, P. syringae and two new Clade 6 taxa which are here described as P. crassamura sp. nov. and P. ornamentata sp. nov. Pathogenicity tests supported their possible involvement in the severe decline that is currently threatening the Mediterranean maquis vegetation in the La Maddalena archipelago. PMID:26649428

  16. Diversity of Phytophthora Species from Declining Mediterranean Maquis Vegetation, including Two New Species, Phytophthora crassamura and P. ornamentata sp. nov.

    Directory of Open Access Journals (Sweden)

    Bruno Scanu

    Full Text Available The Mediterranean basin is recognized as a global biodiversity hotspot accounting for more than 25,000 plant species that represent almost 10% of the world's vascular flora. In particular, the maquis vegetation on Mediterranean islands and archipelagos constitutes an important resource of the Mediterranean plant diversity due to its high rate of endemism. Since 2009, a severe and widespread dieback and mortality of Quercus ilex trees and several other plant species of the Mediterranean maquis has been observed in the National Park of La Maddalena archipelago (northeast Sardinia, Italy. Infected plants showed severe decline symptoms and a significant reduction of natural regeneration. First studies revealed the involvement of the highly invasive wide-host range pathogen Phytophthora cinnamomi and several fungal pathogens. Subsequent detailed research led to a better understanding of these epidemics showing that multiple Phytophthora spp. were involved, some of them unknown to science. In total, nine Phytophthora species were isolated from rhizosphere soil samples collected from around symptomatic trees and shrubs including Asparagus albus, Cistus sp., Juniperus phoenicea, J. oxycedrus, Pistacia lentiscus and Rhamnus alaternus. Based on morphological characters, growth-temperature relations and sequence analysis of the ITS and cox1 gene regions, the isolates were identified as Phytophthora asparagi, P. bilorbang, P. cinnamomi, P. cryptogea, P. gonapodyides, P. melonis, P. syringae and two new Clade 6 taxa which are here described as P. crassamura sp. nov. and P. ornamentata sp. nov. Pathogenicity tests supported their possible involvement in the severe decline that is currently threatening the Mediterranean maquis vegetation in the La Maddalena archipelago.

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

    Directory of Open Access Journals (Sweden)

    Leónides Castellanos González

    2016-03-01

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

  18. Ovicidal activity of lactic acid produced by Lysobacter capsici YS1215 on eggs of root-knot nematode, Meloidogyne incognita.

    Science.gov (United States)

    Lee, Yong Seong; Naning, Kyaw Wai; Nguyen, Xuan Hoa; Kim, Sun Bae; Moon, Jae Hak; Kim, Kil Yong

    2014-11-28

    Lysobacter capsici YS1215 isolated from soil previously showed nematicidal potential for biological control of the root-knot nematode. In this study, lactic acid, a nematicidal compound, was isolated from culture filtrate of YS1215, and its ovicidal activity was investigated. Purification and identification of lactic acid were performed by a series of column chromatographies and identified by (1)H and (13)C NMR spectra and GC-MS analysis. Our results showed that bacterial culture filtrate containing lactic acid significantly inhibited egg hatching. The lowest egg hatch rate (5.9%) was found at a high concentration (25 μl/ml) of lactic acid at 5 days after incubation, followed by 20 (15.2%), 15 (23.7%), 10 (29.8%), and 5 (36.4%) μl/ml, while egg hatching in the control (sterile distilled water) was 44.5%. This is the first report of lactic acid as an ovicidal compound, and it may be considered as an alternative of chemical pesticide against root-knot nematodes.

  19. 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}

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Rhizobium capsici sp. nov., isolated from root tumor of a green bell pepper (Capsicum annuum var. grossum) plant.

    Science.gov (United States)

    Lin, Shih-Yao; Hung, Mei-Hua; Hameed, Asif; Liu, You-Cheng; Hsu, Yi-Han; Wen, Cheng-Zhe; Arun, A B; Busse, Hans-Jürgen; Glaeser, Stefanie P; Kämpfer, Peter; Young, Chiu-Chung

    2015-03-01

    A novel, Gram-staining-negative, rod-shaped, aerobic and motile bacterium, designated strain CC-SKC2(T), was isolated from the root tumor of a green bell pepper (Capsicum annuum var. grossum) plant in Taiwan. Cells were positive for oxidase and catalase activities and exhibited growth at 25-37 °C, pH 4.0-9.0 and tolerated NaCl concentrations up to 4.0 % (w/v). Strain CC-SKC2(T) is able to trigger nodulation in soybean (Glycine max Merr.), but not in Capsicum annuum var. grossum, red bean (Vigna angularis), sesbania (Sesbania roxburghii Merr.) or alfalfa (Medicago varia Martin.). The novel strain shared highest 16S rRNA gene sequence similarity to Rhizobium rhizoryzae KCTC 23652(T) and Rhizobium straminoryzae CC-LY845(T) (both 97.5 %) followed by Rhizobium lemnae L6-16(T) (97.3 %), Rhizobium pseudoryzae KCTC 23294(T) (97.1 %), and Rhizobium paknamense NBRC 109338(T) (97.0 %), whereas other Rhizobium species shared Rhizobium species. The major fatty acids in strain CC-SKC2(T) were C16:0, C19:0 cyclo ω8c, C14:0 3-OH and/or C16:1 iso I and C18:1 ω7c and/or C18:1 ω6c. The polyamine pattern showed predominance of spermidine and moderate amounts of sym-homospermidine. The predominant quinone system was ubiquinone (Q-10) and the DNA G+C content was 60.5 mol%. On the basis of polyphasic taxonomic evidence presented here, strain CC-SKC2(T) is proposed to represent a novel species within the genus Rhizobium, for which the name Rhizobium capsici sp. nov. is proposed. The type strain is CC-SKC2(T) (=BCRC 80699(T) = JCM 19535(T)).

  5. 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

  6. Slow sand filters effectively reduce Phytophthora after a pathogen switch from Fusarium and a simulated pump failure.

    Science.gov (United States)

    Lee, Eric; Oki, Lorence R

    2013-09-15

    Slow sand filtration has been shown to effectively reduce Phytophthora zoospores in irrigation water. This experiment tested the reduction of Phytophthora colony forming units (CFUs) by slow sand filtration systems after switching the pathogen contaminating plant leachate from Fusarium to Phytophthora and the resilience of the system to a short period without water, as might be caused by a pump failure. The slow sand filtration system greatly reduced Phytophthora CFUs and transmission after switching the pathogens. In addition, Phytophthora reduction by the slow sand filter was equally effective before and after the simulated pump failure. Reduction of Fusarium was not seen by the SSFs, before or after the simulated pump failure. The results suggest that slow sand filters are effective at reducing larger organisms, such as Phytophthora zoospores, even after a pump failure or a change in pathogens.

  7. Phytophthora gemini sp. nov., a new species isolated from the halophilic plant Zostera marina in the Netherlands.

    Science.gov (United States)

    Man in 't Veld, Willem A; Rosendahl, Karin C H M; Brouwer, Henk; de Cock, Arthur W A M

    2011-08-01

    Eight strains belonging to the Oomycete genus Phytophthora were isolated from Zostera marina (seagrass) in The Netherlands over the past 25 y. Based on morphology, isozymes, temperature-growth relationships and ITS sequences, these strains were found to belong to two different Phytophthora species. Five strains, four of them isolated from rotting seeds and one isolated from decaying plants, could not be assigned to a known species and hence belong to a new species for which we propose the name Phytophthora gemini sp. nov. Three strains were isolated from decaying plants and were identified as Phytophthora inundata, thereby expanding the known habitat range of this species from fresh to brackish-saline areas. The possible role of both Phytophthora species in the decline of Z. marina in The Netherlands and the evolutionary significance of the presence of Phytophthora species in marine environments are discussed.

  8. Rapid isothermal detection of Phytophthora species on plant samples using recombinase polymerase amplification

    Science.gov (United States)

    Recently several isothermal amplification techniques have been developed that are extremely tolerant towards inhibitors present in many plant extracts. Recombinase polymerase amplification (RPA) assays for the genus Phytophthora have been developed which provide a simple and rapid method to macerate...

  9. 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

  10. Beleidsondersteunend Onderzoek Plantgezondheid BO-06 Resultaten 2009 : Phytophthora infestans (BO-06-008)

    NARCIS (Netherlands)

    Boonekamp, P.M.

    2010-01-01

    Een verzameling artikelen of rapporten over plantgezondheid. Het thema is Phytophthora infestans. Het plantgezondheidsonderzoek richt zich nog veel op het optimaliseren van bestaande methoden en technieken en korte termijnsuccesjes, vindt Piet Boonekamp. Voor een wezenlijke verduurzaming van plantge

  11. Phytophthora terminalis sp. nov. and Phytophthora occultans sp. nov., two invasive pathogens of ornamental plants in Europe.

    Science.gov (United States)

    Man In 't Veld, Willem A; Rosendahl, Karin C H M; van Rijswick, Patricia C J; Meffert, Johan P; Westenberg, Marcel; van de Vossenberg, Bart T L H; Denton, Geoff; van Kuik, Fons A J

    2015-01-01

    In the past decade several Phytophthora strains were isolated from diseased Pachysandra terminalis plants suffering stem base and root rot, originating from the Netherlands and Belgium. All isolates were homothallic and had a felt-like colony pattern, produced semi-papillate sporangia, globose oogonia and had a maximum growth at ~ 27 C. Several additional Phytophthora strains were isolated from diseased Buxus sempervirens plants, originating from the Netherlands and Belgium, which had sustained stem base and root rot; similar strains also were isolated from Acer palmatum, Choisya ternata and Taxus in the United Kingdom. All isolates were homothallic and had a stellate colony pattern, produced larger semi-papillate sporangia and smaller globose oogonia than the isolates from Pa. terminalis and had a maximum growth temperature of ~ 30 C. Phylogenetic analyses of both species using the internal transcribed spacer region of the nuc rDNA (ITS), mt cytochrome oxidases subunit I gene (CoxI) and nuc translation elongation factor 1-α gene (TEF1α) revealed that all sequences of each species were identical at each locus and unique to that species, forming two distinct clusters in subclade 2a. Sequence analysis of partial β-tubulin genes showed that both taxa share an identical sequence that is identical to that of Ph. himalsilva, a species originating from Asia, suggesting a common Asian origin. Pathogenicity trials demonstrated disease symptoms on their respective hosts, and re-isolation and re-identification of the inoculated pathogens confirmed Koch's postulates.

  12. Pyrosequencing of environmental soil samples reveals biodiversity of the Phytophthora resident community in chestnut forests.

    Science.gov (United States)

    Vannini, Andrea; Bruni, Natalia; Tomassini, Alessia; Franceschini, Selma; Vettraino, Anna Maria

    2013-09-01

    Pyrosequencing analysis was performed on soils from Italian chestnut groves to evaluate the diversity of the resident Phytophthora community. Sequences analysed with a custom database discriminated 15 pathogenic Phytophthoras including species common to chestnut soils, while a total of nine species were detected with baiting. The two sites studied differed in Phytophthora diversity and the presence of specific taxa responded to specific ecological traits of the sites. Furthermore, some species not previously recorded were represented by a discrete number of reads; among these species, Phytophthora ramorum was detected at both sites. Pyrosequencing was demonstrated to be a very sensitive technique to describe the Phytophthora community in soil and was able to detect species not easy to be isolated from soil with standard baiting techniques. In particular, pyrosequencing is an highly efficient tool for investigating the colonization of new environments by alien species, and for ecological and adaptive studies coupled with biological detection methods. This study represents the first application of pyrosequencing for describing Phytophthoras in environmental soil samples.

  13. Membrane-based oligonucleotide array developed from multiple markers for the detection of many Phytophthora species.

    Science.gov (United States)

    Chen, Wen; Djama, Zeinab Robleh; Coffey, Michael D; Martin, Frank N; Bilodeau, Guillaume J; Radmer, Lorien; Denton, Geoff; Lévesque, C André

    2013-01-01

    Most Phytophthora spp. are destructive plant pathogens; therefore, effective monitoring and accurate early detection are important means of preventing potential epidemics and outbreaks of diseases. In the current study, a membrane-based oligonucleotide array was developed that can detect Phytophthora spp. reliably using three DNA regions; namely, the internal transcribed spacer (ITS), the 5' end of cytochrome c oxidase 1 gene (cox1), and the intergenic region between cytochrome c oxidase 2 gene (cox2) and cox1 (cox2-1 spacer). Each sequence data set contained ≈250 sequences representing 98 described and 15 undescribed species of Phytophthora. The array was validated with 143 pure cultures and 35 field samples. Together, nonrejected oligonucleotides from all three markers have the ability to reliably detect 82 described and 8 undescribed Phytophthora spp., including several quarantine or regulated pathogens such as Phytophthora ramorum. Our results showed that a DNA array containing signature oligonucleotides designed from multiple genomic regions provided robustness and redundancy for the detection and differentiation of closely related taxon groups. This array has the potential to be used as a routine diagnostic tool for Phytophthora spp. from complex environmental samples without the need for extensive growth of cultures.

  14. Inheritance of Biological Characteristics of Phytophthora capsici Metalaxyl-resistant mutants in Asexual Reproduction%辣椒疫霉抗甲霜灵菌株若干生物学性状的无性遗传研究

    Institute of Scientific and Technical Information of China (English)

    戚仁德; 汪涛; 李萍; 丁建成

    2008-01-01

    [目的]为了探索辣椒疫霉抗甲霜灵菌株Mtr的遗传规律.[方法]在实验室条件下,研究了该病菌的若干生物学性状在无性世代中的遗传特点.[结果]辣椒疫霉Mtr突变株的生长速率、菌落形态以及对甲霜灵的抗性等性状在其游动孢子后代中未发生变异.[结论]这些性状在无性繁殖中能稳定遗传.

  15. 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...

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

    Directory of Open Access Journals (Sweden)

    Ah-Fong Audrey MV

    2010-12-01

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

  17. 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.

  18. Five Reasons to Consider Phytophthora infestans a Reemerging Pathogen.

    Science.gov (United States)

    Fry, W E; Birch, P R J; Judelson, H S; Grünwald, N J; Danies, G; Everts, K L; Gevens, A J; Gugino, B K; Johnson, D A; Johnson, S B; McGrath, M T; Myers, K L; Ristaino, J B; Roberts, P D; Secor, G; Smart, C D

    2015-07-01

    Phytophthora infestans has been a named pathogen for well over 150 years and yet it continues to "emerge", with thousands of articles published each year on it and the late blight disease that it causes. This review explores five attributes of this oomycete pathogen that maintain this constant attention. First, the historical tragedy associated with this disease (Irish potato famine) causes many people to be fascinated with the pathogen. Current technology now enables investigators to answer some questions of historical significance. Second, the devastation caused by the pathogen continues to appear in surprising new locations or with surprising new intensity. Third, populations of P. infestans worldwide are in flux, with changes that have major implications to disease management. Fourth, the genomics revolution has enabled investigators to make tremendous progress in terms of understanding the molecular biology (especially the pathogenicity) of P. infestans. Fifth, there remain many compelling unanswered questions.

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

    Science.gov (United States)

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

    2014-08-01

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

  20. Structural and functional profile of the carbohydrate esterase gene complement in Phytophthora infestans.

    Science.gov (United States)

    Ospina-Giraldo, Manuel D; McWalters, Jessica; Seyer, Lauren

    2010-12-01

    The plant cell cuticle is the first obstacle for penetration of the host by plant pathogens. To breach this barrier, most pathogenic fungi employ a complex assortment of cell wall-degrading enzymes including carbohydrate esterases, glycoside hydrolases, and polysaccharide lyases. We characterized the full complement of carbohydrate esterase-coding genes in three Phytophthora species and analyzed the expression of cutinase in vitro and in planta; we also determined the cutinase allele distribution in multiple isolates of P. infestans. Our investigations revealed that there are 49, 21, and 37 esterase homologs in the P. infestans, P. ramorum, and P. sojae genomes, respectively, with a considerable number predicted to be extracellular. Four cutinase gene copies were found in both the P. infestans and P. ramorum genomes, while 16 copies were found in P. sojae. Transcriptional analyses of cutinase in P. infestans revealed that its expression level during infection is significantly upregulated at all time points compared to that of the same gene in mycelium grown in vitro. Expression achieves maximum values at 15 hpi, declining at subsequent time points. These results may suggest, therefore, that cutinase most likely plays a role in P. infestans pathogenicity.

  1. 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.

  2. 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.

  3. 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.

  4. Infection of Phytophthora palmivora from Soil in Cocoa Plantation

    Directory of Open Access Journals (Sweden)

    Agus Purwantara

    2008-12-01

    Full Text Available Phytophthora palmivora causes serious losses on cocoa in Indonesia and world-wide. The research aimed to assess the potential of soil as source of inocula for Phytophthora diseases in cocoa. Soil samples were baited using a healthy cocoa pod tissue, and the pathogen was isolated for morphological and molecular identification. Baiting technique was successfully used to detect the presence of P. palmivora in soil samples, and this was confirmed by morphological and molecular identification. P. palmivora can be detected in soil in all year around in wet areas indicating that soil is a massive and consistent source of inocula. Surveys conducted on the soil of Amazonian, Amelonado and Trinitario blocks of various ages showed that P. palmivora can be found in old and young cocoa blocks, even as young as 3 or 4 years. P. palmivora infection from soil to the pods appears to be mainly through contact or rain splash. Baiting with whole healthy pods exposed at different heights above undisturbed litter and above bare soil showed that the infection still occurred at 100 cm above the soil, even though it decreased gradually with the height. Infection from litter was not different to that from bare soil, indicating that the litter layer is not acting physically as a shield preventing rain from splashing the inocula up from wet soil to the pods. However, in tests for the possibility of P. palmivora carried through air convection, no pod was found to be infected, suggesting that the pathogen was not carried through convective accend of aerosol droplets from soil surface up to pods in the canopy.Key words : Theobroma cacao, pod rot, stem canker, baiting.

  5. Two previously unknown Phytophthora species associated with brown rot of Pomelo (Citrus grandis) fruits in Vietnam

    Science.gov (United States)

    Schena, Leonardo; Jung, Thomas; Evoli, Maria; Pane, Antonella; Van Hoa, Nguyen; Van Tri, Mai; Wright, Sandra; Ramstedt, Mauritz; Olsson, Christer; Faedda, Roberto; Magnano di San Lio, Gaetano

    2017-01-01

    Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis), a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI) as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana) rootstocks grafted with ‘King’ mandarin (Citrus nobilis) and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch’s postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi), sweet orange (Citrus x sinensis) and bergamot (Citrus x bergamia) as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on ‘Carrizo’ citrange (C. sinensis ‘Washington Navel’ x Poncirus trifoliata). This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity. PMID:28208159

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

    Directory of Open Access Journals (Sweden)

    Martens Cindy

    2010-06-01

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

  7. The Arabidopsis lectin receptor kinase LecRK-I.9 enhances resistance to Phytophthora infestans in Solanaceous plants

    NARCIS (Netherlands)

    Bouwmeester, K.; Han, M.; Blanco-Portales, R.; Song, W.; Weide, R.; Guo, L.Y.; Vossen, van der E.A.G.; Govers, F.

    2014-01-01

    Phytophthora species are notorious plant pathogens which cause a variety of devastating crop diseases. Phytophthora pathogens secrete a plethora of effector proteins, several of which are known to interact with receptors in the host cell thereby either activating or suppressing defense responses. Un

  8. 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

  9. Phytophthora ipomoeae, a new homothallic species causing leaf blight on Ipomoea longipedunculata in the Toluca Valley of central Mexico

    NARCIS (Netherlands)

    Flier, W.G.; Grunwald, N.J.; Kroon, L.P.N.M.; Bosch, van den G.B.M.; Garay-Serrano, E.; Lozoya-Saldan, H.; Bonants, P.J.M.; Turkensteen, L.J.

    2002-01-01

    A Phytophthora species was found on blighted foliage of Ipomoea longipedunculata, a morning glory native to the highlands of central Mexico. Based on host range, morphology, allozymes, mitochondrial DNA haplotype and rDNA sequences it is concluded that a new Phytophthora species, P. ipomoeae sp. nov

  10. 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...

  11. Effects of Phytophthora cinnamomi isolate, inoculum delivery method, flood, and drought on vigor, disease severity and mortality of blueberry plants

    Science.gov (United States)

    Four studies evaluated the effect of Phytophthora cinnamomi isolates, inoculum delivery methods, and flood and drought conditions on vigor, disease severity scores, and survival of blueberry plants grown in pots in the greenhouse. Phytophthora cinnamomi isolates were obtained from blueberry plants ...

  12. 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...

  13. 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...

  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. Activation of defense against Phytophthora infestans in potato by down-regulation of syntaxin gene expression.

    Science.gov (United States)

    Eschen-Lippold, Lennart; Landgraf, Ramona; Smolka, Ulrike; Schulze, Sebastian; Heilmann, Mareike; Heilmann, Ingo; Hause, Gerd; Rosahl, Sabine

    2012-03-01

    The oomycete Phytophthora infestans is the causal agent of late blight, the most devastating disease of potato. The importance of vesicle fusion processes and callose deposition for defense of potato against Phytophthora infestans was analyzed. Transgenic plants were generated, which express RNA interference constructs targeted against plasma membrane-localized SYNTAXIN-RELATED 1 (StSYR1) and SOLUBLE N-ETHYLMALEIMIDE-SENSITIVE FACTOR ADAPTOR PROTEIN 33 (StSNAP33), the potato homologs of Arabidopsis AtSYP121 and AtSNAP33, respectively. Phenotypically, transgenic plants grew normally, but showed spontaneous necrosis and chlorosis formation at later stages. In response to infection with Phytophthora infestans, increased resistance of StSYR1-RNAi plants, but not StSNAP33-RNAi plants, was observed. This increased resistance correlated with the constitutive accumulation of salicylic acid and PR1 transcripts. Aberrant callose deposition in Phytophthora infestans-infected StSYR1-RNAi plants coincided with decreased papilla formation at penetration sites. Resistance against the necrotrophic fungus Botrytis cinerea was not significantly altered. Infiltration experiments with bacterial solutions of Agrobacterium tumefaciens and Escherichia coli revealed a hypersensitive phenotype of both types of RNAi lines. The enhanced defense status and the reduced growth of Phytophthora infestans on StSYR1-RNAi plants suggest an involvement of syntaxins in secretory defense responses of potato and, in particular, in the formation of callose-containing papillae.

  16. The Irish potato famine pathogen Phytophthora infestans originated in central Mexico rather than the Andes.

    Science.gov (United States)

    Goss, Erica M; Tabima, Javier F; Cooke, David E L; Restrepo, Silvia; Fry, William E; Forbes, Gregory A; Fieland, Valerie J; Cardenas, Martha; Grünwald, Niklaus J

    2014-06-17

    Phytophthora infestans is a destructive plant pathogen best known for causing the disease that triggered the Irish potato famine and remains the most costly potato pathogen to manage worldwide. Identification of P. infestan's elusive center of origin is critical to understanding the mechanisms of repeated global emergence of this pathogen. There are two competing theories, placing the origin in either South America or in central Mexico, both of which are centers of diversity of Solanum host plants. To test these competing hypotheses, we conducted detailed phylogeographic and approximate Bayesian computation analyses, which are suitable approaches to unraveling complex demographic histories. Our analyses used microsatellite markers and sequences of four nuclear genes sampled from populations in the Andes, Mexico, and elsewhere. To infer the ancestral state, we included the closest known relatives Phytophthora phaseoli, Phytophthora mirabilis, and Phytophthora ipomoeae, as well as the interspecific hybrid Phytophthora andina. We did not find support for an Andean origin of P. infestans; rather, the sequence data suggest a Mexican origin. Our findings support the hypothesis that populations found in the Andes are descendants of the Mexican populations and reconcile previous findings of ancestral variation in the Andes. Although centers of origin are well documented as centers of evolution and diversity for numerous crop plants, the number of plant pathogens with a known geographic origin are limited. This work has important implications for our understanding of the coevolution of hosts and pathogens, as well as the harnessing of plant disease resistance to manage late blight.

  17. Metabarcoding Analysis of Phytophthora Diversity Using Genus-Specific Primers and 454 Pyrosequencing.

    Science.gov (United States)

    Prigigallo, Maria I; Abdelfattah, Ahmed; Cacciola, Santa O; Faedda, Roberto; Sanzani, Simona M; Cooke, David E L; Schena, L

    2016-03-01

    A metabarcoding method based on genus-specific primers and 454 pyrosequencing was utilized to investigate the genetic diversity of Phytophthora spp. in soil and root samples of potted plants, from eight nurseries. Pyrosequencing enabled the detection of 25 Phytophthora phylotypes distributed in seven different clades and provided a much higher resolution than a corresponding cloning/Sanger sequencing approach. Eleven of these phylotypes, including P. cactorum, P. citricola s.str., P. palmivora, P. palmivora-like, P. megasperma or P. gonapodyides, P. ramorum, and five putative new Phytophthora species phylogenetically related to clades 1, 2, 4, 6, and 7 were detected only with the 454 pyrosequencing approach. We also found an additional 18 novel records of a phylotype in a particular nursery that were not detected with cloning/Sanger sequencing. Several aspects confirmed the reliability of the method: (i) many identical sequence types were identified independently in different nurseries, (ii) most sequence types identified with 454 pyrosequencing were identical to those from the cloning/Sanger sequencing approach and/or perfectly matched GenBank deposited sequences, and (iii) the divergence noted between sequence types of putative new Phytophthora species and all other detected sequences was sufficient to rule out sequencing errors. The proposed method represents a powerful tool to study Phytophthora diversity providing that particular attention is paid to the analysis of 454 pyrosequencing raw read sequences and to the identification of sequence types.

  18. Phytophthora community structure analyses in Oregon nurseries inform systems approaches to disease management.

    Science.gov (United States)

    Parke, Jennifer L; Knaus, Brian J; Fieland, Valerie J; Lewis, Carrie; Grünwald, Niklaus J

    2014-10-01

    Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to the development of integrated systems approaches. Four horticultural nurseries in Oregon were sampled every 2 months for 4 years to determine the identity and community structure of Phytophthora spp. associated with different sources and stages in the nursery production cycle. Plants, potting media, used containers, water, greenhouse soil, and container yard substrates were systematically sampled from propagation to the field. From 674 Phytophthora isolates recovered, 28 different species or taxa were identified. The most commonly isolated species from plants were Phytophthora plurivora (33%), P. cinnamomi (26%), P. syringae (19%), and P. citrophthora (11%). From soil and gravel substrates, P. plurivora accounted for 25% of the isolates, with P. taxon Pgchlamydo, P. cryptogea, and P. cinnamomi accounting for 18, 17, and 15%, respectively. Five species (P. plurivora, P. syringae, P. taxon Pgchlamydo, P. gonapodyides, and P. cryptogea) were found in all nurseries. The greatest diversity of taxa occurred in irrigation water reservoirs (20 taxa), with the majority of isolates belonging to internal transcribed spacer clade 6, typically including aquatic opportunists. Nurseries differed in composition of Phytophthora communities across years, seasons, and source within the nursery. These findings suggest likely contamination hazards and target critical control points for management of Phytophthora disease using a systems approach.

  19. Multiple Phytophthora species associated with a single riparian ecosystem in South Africa.

    Science.gov (United States)

    Nagel, Jan H; Slippers, Bernard; Wingfield, Michael J; Gryzenhout, Marieka

    2015-01-01

    The diversity of Phytophthora spp. in rivers and riparian ecosystems has received considerable international attention, although little such research has been conducted in South Africa. This study determined the diversity of Phytophthora spp. within a single river in Gauteng province of South Africa. Samples were collected over 1 y including biweekly river baiting with Rhododendron indicum leaves. Phytophthora isolates were identified with phylogenetic analyses of sequences for the internal transcribed spacer (ITS) region of the ribosomal DNA and the mitochondrial cytochrome oxidase c subunit I (coxI) gene. Eight Phytophthora spp. were identified, including a new taxon, P. taxon Sisulu-river, and two hybrid species from Cooke's ITS clade 6. Of these, species from Clade 6 were the most abundant, including P. chlamydospora and P. lacustris. Species residing in Clade 2 also were encountered, including P. multivora, P. plurivora and P. citrophthora. The detection of eight species in this investigation of Phytophthora diversity in a single riparian river ecosystem in northern South Africa adds to the known diversity of this genus in South Africa and globally.

  20. 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.

  1. [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.

  2. FIRST REPORT OF Phytophthora nicotianae CAUSING ROOT ROT OF SOURSOP IN NORTHEASTERN BRAZIL

    Directory of Open Access Journals (Sweden)

    JAQUELINE FIGUEREDO DE OLIVEIRA COSTA

    Full Text Available ABSTRACT In 2013, soursop trees showing symptoms of root rot were observed in a field in Maceió, state of Alagoas, Brazil. It was isolated Phytophthora sp. which pathogenicity was confirmed in the host seedlings. Morphological and physiological characteristics in carrot-agar modified medium were consistent with Phytophthora nicotianae description. The PCR sequences products obtained with ITS1/ITS4 primers were compared to sequences of ribosomal DNA of Phytophthora species from the GenBank database observing high identity with other P. nicotianae isolates. A phylogenetic tree was performed to compare the isolate with other sequences of P. nicotianae, which clustering has been verified with 99% of bootstrap, confirming the morphophysiological studies. This is the first report of this pathogen on annonaceous plants in the Northeastern Brazil.

  3. 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

  4. Phytophthora species recovered from the Connecticut River Valley in Massachusetts, USA.

    Science.gov (United States)

    Brazee, Nicholas J; Wick, Robert L; Hulvey, Jonathan P

    2016-01-01

    Little is currently known about the assemblage of Phytophthora species in northeastern North America, representing a gap in our understanding of species incidence. Therefore, Phytophthora species were surveyed at 20 sites in Massachusetts, with 16 occurring in the Connecticut River Valley. Many of the sampled waterways were adjacent to active agricultural lands, yet were buffered by mature floodplain forests composed of Acer, Platanus, Populus and Ulmus. Isolates were recovered with three types of baits (rhododendron leaves, pear, green pepper) in 2013 and water filtration in 2014. Overall, 457 isolates of Phytophthora were recovered and based on morphological characters and rDNA internal transcribed spacer (ITS), β-tubulin (β-tub) and cytochrome oxidase c subunit I (cox1) sequences, 18 taxa were identified, including three new species: P. taxon intercalaris, P. taxon caryae and P. taxon pocumtuck. In addition, 49 isolates representing five species of Phytopythium also were identified. Water filtration captured a greater number of taxa (18) compared to leaf and fruit baits (12). Of the three bait types rhododendron leaves yielded the greatest number of isolates and taxa, followed by pear and green pepper, respectively. Despite the proximity to agricultural lands, none of the Phytophthora species baited are considered serious pathogens of vegetable crops in the region. However, many of the recovered species are known woody plant pathogens, including four species in the P. citricola s.l. complex that were identified: P. plurivora, P. citricola III, P. pini and a putative novel species, referred to here as P. taxon caryae. An additional novel species, P. taxon pocumtuck, is a close relative of P. borealis based on cox1 sequences. The results illustrate a high level of Phytophthora species richness in the Connecticut River Valley and that major rivers can serve as a source of inoculum for pathogenic Phytophthora species in the northeast.

  5. 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.

  6. 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.

  7. Strain Specific Factors Control Effector Gene Silencing in Phytophthora sojae.

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    Sirjana Devi Shrestha

    Full Text Available The Phytophthora sojae avirulence gene Avr3a encodes an effector that is capable of triggering immunity on soybean plants carrying the resistance gene Rps3a. P. sojae strains that express Avr3a are avirulent to Rps3a plants, while strains that do not are virulent. To study the inheritance of Avr3a expression and virulence towards Rps3a, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 X P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F5 generation. However, test-crosses of F1 progeny (ACR10 X P7076 with strain P6497 result in the release of silencing of Avr3a. Expression of Avr3a in the progeny is variable and correlates with the phenotypic penetrance of the avirulence trait. The F1 progeny from a direct cross of P6497 X ACR10 segregate for inheritance for Avr3a expression, a result that could not be explained by parental imprinting or heterozygosity. Analysis of small RNA arising from the Avr3a gene sequence in the parental strains and hybrid progeny suggests that the presence of small RNA is necessary but not sufficient for gene silencing. Overall, we conclude that inheritance of the Avr3a gene silenced phenotype relies on factors that are variable among P. sojae strains.

  8. Strain Specific Factors Control Effector Gene Silencing in Phytophthora sojae.

    Science.gov (United States)

    Shrestha, Sirjana Devi; Chapman, Patrick; Zhang, Yun; Gijzen, Mark

    2016-01-01

    The Phytophthora sojae avirulence gene Avr3a encodes an effector that is capable of triggering immunity on soybean plants carrying the resistance gene Rps3a. P. sojae strains that express Avr3a are avirulent to Rps3a plants, while strains that do not are virulent. To study the inheritance of Avr3a expression and virulence towards Rps3a, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 X P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F5 generation. However, test-crosses of F1 progeny (ACR10 X P7076) with strain P6497 result in the release of silencing of Avr3a. Expression of Avr3a in the progeny is variable and correlates with the phenotypic penetrance of the avirulence trait. The F1 progeny from a direct cross of P6497 X ACR10 segregate for inheritance for Avr3a expression, a result that could not be explained by parental imprinting or heterozygosity. Analysis of small RNA arising from the Avr3a gene sequence in the parental strains and hybrid progeny suggests that the presence of small RNA is necessary but not sufficient for gene silencing. Overall, we conclude that inheritance of the Avr3a gene silenced phenotype relies on factors that are variable among P. sojae strains.

  9. Four phenotypically and phylogenetically distinct lineages in Phytophthora lateralis.

    Science.gov (United States)

    Brasier, Clive M; Franceschini, Selma; Vettraino, Anna Maria; Hansen, Everett M; Green, Sarah; Robin, Cecile; Webber, Joan F; Vannini, Andrea

    2012-12-01

    Until recently Phytophthora lateralis was known only as the cause of dieback and mortality of Chamaecyparis lawsoniana in its native range in the Pacific Northwest (PNW). Since the 1990s however disease outbreaks have occurred increasingly on ornamental C. lawsoniana in Europe; and in 2007 the pathogen was discovered in soil around old growth Chamaecyparis obtusa in Taiwan, where it may be endemic. When the phenotypes of over 150 isolates of P. lateralis from Taiwan, across the PNW (British Columbia to California) and from France, the Netherlands and the UK were compared three growth rate groups were resolved: one slow growing from Taiwan, one fast growing from the PNW and Europe, and one of intermediate growth from a small area of the UK. Within these growth groups distinct subtypes were identified based on colony patterns and spore metrics and further discriminated in a multivariate analysis. The assumption that the three main growth groups represented phylogenetic units was tested by comparative sequencing of two mitochondrial and three nuclear genes. This assumption was confirmed. In addition two phenotype clusters within the Taiwan growth group were also shown to be phylogenetically distinct. These four phenotypically and genotypically unique populations are informally designated as the PNW lineage, the UK lineage, the Taiwan J lineage, and the Taiwan K lineage. Their characteristics and distribution are described and their evolution, taxonomic, and plant health significance is discussed.

  10. Production of gametangia by Phytophthora ramorum in vitro.

    Science.gov (United States)

    Brasier, Clive; Kirk, Susan

    2004-07-01

    Until now gametangia have not been obtained between paired European A1 and American A2 isolates of Phytopthora ramorum in vitro. Their production in artificial culture relies on interspecific pairings. Using P. drechsleri and P. cambivora testers, 51 of 110 P. ramorum isolates from across Europe were all shown to be A1s; while 32 of 38 American isolates from across California and southwest Oregon were shown to be A2s. However, these interspecific pairings are complex, unusually slow and unpredictable. A range of culture media and conditions are described that were tested, unsuccessfully, with a view to enhancing the efficiency of the interspecific pairings. In further tests, gametangia were obtained between A1 and A2 isolates of P. ramorum when juvenile, pre-chlamydospore producing mycelia were mixed together on carrot agar. The gametangia formed in 3-10 d, sparsely to frequently, initially only within the boundaries of the mixed inocula but subsequently in the extended mycelial growth. Chlamydospores were also produced. This inoculum-mixing method, though again sometimes unpredictable, should enhance efficiency of testing for compatibility types and facilitate further studies on whether the sexual outcrossing system of P. ramorum is functional. Differences between sexual reproduction of P. ramorum and that of other heterothallic Phytophthora species are discussed.

  11. 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.

  12. 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.

  13. 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.

  14. A Novel Phytophthora sojae Resistance Rps12 Gene Mapped to a Genomic Region That Contains Several Rps Genes

    Science.gov (United States)

    Sahoo, Dipak K.; Abeysekara, Nilwala S.; Cianzio, Silvia R.; Robertson, Alison E.

    2017-01-01

    Phytophthora sojae Kaufmann and Gerdemann, which causes Phytophthora root rot, is a widespread pathogen that limits soybean production worldwide. Development of Phytophthora resistant cultivars carrying Phytophthora resistance Rps genes is a cost-effective approach in controlling this disease. For this mapping study of a novel Rps gene, 290 recombinant inbred lines (RILs) (F7 families) were developed by crossing the P. sojae resistant cultivar PI399036 with the P. sojae susceptible AR2 line, and were phenotyped for responses to a mixture of three P. sojae isolates that overcome most of the known Rps genes. Of these 290 RILs, 130 were homozygous resistant, 12 heterzygous and segregating for Phytophthora resistance, and 148 were recessive homozygous and susceptible. From this population, 59 RILs homozygous for Phytophthora sojae resistance and 61 susceptible to a mixture of P. sojae isolates R17 and Val12-11 or P7074 that overcome resistance encoded by known Rps genes mapped to Chromosome 18 were selected for mapping novel Rps gene. A single gene accounted for the 1:1 segregation of resistance and susceptibility among the RILs. The gene encoding the Phytophthora resistance mapped to a 5.8 cM interval between the SSR markers BARCSOYSSR_18_1840 and Sat_064 located in the lower arm of Chromosome 18. The gene is mapped 2.2 cM proximal to the NBSRps4/6-like sequence that was reported to co-segregate with the Phytophthora resistance genes Rps4 and Rps6. The gene is mapped to a highly recombinogenic, gene-rich genomic region carrying several nucleotide binding site-leucine rich repeat (NBS-LRR)-like genes. We named this novel gene as Rps12, which is expected to be an invaluable resource in breeding soybeans for Phytophthora resistance. PMID:28081566

  15. A Recent Expansion of the RXLR Effector Gene Avrblb2 Is Maintained in Global Populations of Phytophthora infestans Indicating Different Contributions to Virulence.

    Science.gov (United States)

    Oliva, Ricardo F; Cano, Liliana M; Raffaele, Sylvain; Win, Joe; Bozkurt, Tolga O; Belhaj, Khaoula; Oh, Sang-Keun; Thines, Marco; Kamoun, Sophien

    2015-08-01

    The introgression of disease resistance (R) genes encoding immunoreceptors with broad-spectrum recognition into cultivated potato appears to be the most promising approach to achieve sustainable management of late blight caused by the oomycete pathogen Phytophthora infestans. Rpi-blb2 from Solanum bulbocastanum shows great potential for use in agriculture based on preliminary potato disease trials. Rpi-blb2 confers immunity by recognizing the P. infestans avirulence effector protein AVRblb2 after it is translocated inside the plant cell. This effector belongs to the RXLR class of effectors and is under strong positive selection. Structure-function analyses revealed a key polymorphic amino acid (position 69) in AVRblb2 effector that is critical for activation of Rpi-blb2. In this study, we reconstructed the evolutionary history of the Avrblb2 gene family and further characterized its genetic structure in worldwide populations. Our data indicate that Avrblb2 evolved as a single-copy gene in a putative ancestral species of P. infestans and has recently expanded in the Phytophthora spp. that infect solanaceous hosts. As a consequence, at least four variants of AVRblb2 arose in P. infestans. One of these variants, with a Phe residue at position 69, evades recognition by the cognate resistance gene. Surprisingly, all Avrblb2 variants are maintained in pathogen populations. This suggests a potential benefit for the pathogen in preserving duplicated versions of AVRblb2, possibly because the variants may have different contributions to pathogen fitness in a diversified solanaceous host environment.

  16. Phytophthora suppressor of RNA silencing 2 is a conserved RxLR effector that promotes infection in soybean and Arabidopsis thaliana.

    Science.gov (United States)

    Xiong, Qin; Ye, Wenwu; Choi, Duseok; Wong, James; Qiao, Yongli; Tao, Kai; Wang, Yuanchao; Ma, Wenbo

    2014-12-01

    The genus Phytophthora consists of notorious and emerging pathogens of economically important crops. Each Phytophthora genome encodes several hundreds of cytoplasmic effectors, which are believed to manipulate plant immune response inside the host cells. However, the majority of Phytophthora effectors remain functionally uncharacterized. We recently discovered two effectors from the soybean stem and root rot pathogen Phytophthora sojae with the activity to suppress RNA silencing in plants. These effectors are designated Phytophthora suppressor of RNA silencing (PSRs). Here, we report that the P. sojae PSR2 (PsPSR2) belongs to a conserved and widespread effector family in Phytophthora. A PsPSR2-like effector produced by P. infestans (PiPSR2) can also suppress RNA silencing in plants and promote Phytophthora infection, suggesting that the PSR2 family effectors have conserved functions in plant hosts. Using Agrobacterium rhizogenes-mediated hairy roots induction, we demonstrated that the expression of PsPSR2 rendered hypersusceptibility of soybean to P. sojae. Enhanced susceptibility was also observed in PsPSR2-expressing Arabidopsis thaliana plants during Phytophthora but not bacterial infection. These experiments provide strong evidence that PSR2 is a conserved Phytophthora effector family that performs important virulence functions specifically during Phytophthora infection of various plant hosts.

  17. The in vitro culture of Phytophthora infestans isolates occurring on the tomato - their pathogenicity and usefulness for artificial inoculations

    Directory of Open Access Journals (Sweden)

    Elżbieta Horodecka

    2013-12-01

    Full Text Available In investigations on the fungus, Phytophthora infestans, isolated from open air, field-grown tomatoes, particular attention was paid to the pathogenicity of 32 isolates and the suitability of 10 kinds of natural media. It is concluded that Phytophthora races in Poland have highly varied pathogenicities and that they belong to race 0 or 1. The races were divided into subgroups of various aggressiveness. It was found that the best medium to obtain an inoculum was the agar-oat medium without vitamin B1. Vitamin B1 as well as tomatine added to agar media stimulated growth, but inhibited sporulation of Phytophthora infestans.

  18. 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.

  19. 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.

  20. Effector genomics accelerates discovery and functional profiling of potato disease resistance and phytophthora infestans avirulence genes.

    Directory of Open Access Journals (Sweden)

    Vivianne G A A Vleeshouwers

    Full Text Available Potato is the world's fourth largest food crop yet it continues to endure late blight, a devastating disease caused by the Irish famine pathogen Phytophthora infestans. Breeding broad-spectrum disease resistance (R genes into potato (Solanum tuberosum is the best strategy for genetically managing late blight but current approaches are slow and inefficient. We used a repertoire of effector genes predicted computationally from the P. infestans genome to accelerate the identification, functional characterization, and cloning of potentially broad-spectrum R genes. An initial set of 54 effectors containing a signal peptide and a RXLR motif was profiled for activation of innate immunity (avirulence or Avr activity on wild Solanum species and tentative Avr candidates were identified. The RXLR effector family IpiO induced hypersensitive responses (HR in S. stoloniferum, S. papita and the more distantly related S. bulbocastanum, the source of the R gene Rpi-blb1. Genetic studies with S. stoloniferum showed cosegregation of resistance to P. infestans and response to IpiO. Transient co-expression of IpiO with Rpi-blb1 in a heterologous Nicotiana benthamiana system identified IpiO as Avr-blb1. A candidate gene approach led to the rapid cloning of S. stoloniferum Rpi-sto1 and S. papita Rpi-pta1, which are functionally equivalent to Rpi-blb1. Our findings indicate that effector genomics enables discovery and functional profiling of late blight R genes and Avr genes at an unprecedented rate and promises to accelerate the engineering of late blight resistant potato varieties.

  1. MiR1918 enhances tomato sensitivity to Phytophthora infestans infection.

    Science.gov (United States)

    Luan, Yushi; Cui, Jun; Wang, Weichen; Meng, Jun

    2016-10-25

    Late blight of tomato is caused by the oomycete pathogen Phytophthora infestans. In our previous work, we identified and characterized a miR1918 in P. infestans (pi-miR1918), and showed that its sequence is similar to the sequence of tomato miR1918 (sly-miR1918). In this study, we used Arabidopsis thaliana pre-miR159a as a backbone to synthesize pi-miR1918 via PCR and mutagenesis. The artificial pi-miR1918 was used to investigate the role of miR1918 in tomato-P. infestans interaction. Trangenic tomato plants that overexpressed the artificial pi-miR1918 displayed more serious disease symptoms than wild-type tomato plants after infection with P. infestans, as shown by increased number of necrotic cells, lesion sizes and number of sporangia per leaf. The target genes of pi-miR1918 and sly-miR1918 were also predicted for tomato and P. infestans, respectively. qPCR analysis of these targets also performed during tomato-P. infestans interaction. The expression of target gene, RING finger were negatively correlated with miR1918 in the all Lines of transgenic tomato plants. In addition, we used the 5' RACE to determine the cleavage site of miR1918 to RING finger. These results suggested that miR1918 might be involved in the silencing of target genes, thereby enhancing the susceptibility of tomato to P. infestans infection.

  2. Interspecific somatic hybrids Solanum villosum (+) S. tuberosum, resistant to Phytophthora infestans.

    Science.gov (United States)

    Tarwacka, Justyna; Polkowska-Kowalczyk, Lidia; Kolano, Bożena; Śliwka, Jadwiga; Wielgat, Bernard

    2013-11-15

    The interspecific somatic hybrids 4x S. villosum (+) 2x S. tuberosum clone DG 81-68 (VT hybrids) were obtained and characterized molecularly and cytogenetically. The morphology of fusion-derived plants was intermediate in relation to the parental species. The expected ploidy level of the regenerants was 6x for the VT hybrids, but the real ploidy of the hybrids varied, with some of them being euploids, and others - aneuploids. The hybridity of the regenerants was verified by random amplified polymorphic DNA (RAPD) analysis. Despite the variation in ploidy, the RAPD patterns of the hybrids were mostly uniform, suggesting similarity of the genotypes of the VT clones. Genomic in situ hybridization (GISH) analysis discriminated between the chromosomes of both parental genomes in VT somatic hybrids and also confirmed their hybridity. The resistance of VT somatic hybrids to Phytophthora infestans was evaluated and all of the hybrids proved to be highly resistant. In search of the mechanisms involved in resistance of the Solanum species to P. infestans, the biochemical reactions occurring early after elicitor treatment were studied. The production of reactive oxygen species (ROS), as one of the earliest reactions induced by pathogens or their elicitors, was examined in the resistant wild species S. villosum, susceptible S. tuberosum clone DG 81-68 and in the VT hybrid, resistant to P. infestans. After treatment of the leaves with elicitor, the relative increase in ROS production was higher in leaves of the susceptible potato clone than in the resistant plants of S. villosum and the somatic hybrid.

  3. Gene flow analysis demonstrates that Phytophthora fragariae var. rubi constitutes a distinct species, Phytophthora rubi comb. nov.

    Science.gov (United States)

    Man in 't Veld, Willem A

    2007-01-01

    Isozyme analysis and cytochrome oxidase sequences were used to examine whether differentiation of P. fragariae var. fragariae and P. fragariae var. rubi at the variety level is justified. In isozyme studies six strains of both P. fragariae varieties were analyzed with malate dehydrogenase (MDH), glucose phosphate isomerase (GPI), aconitase (ACO), isocitrate dehydrogenase (IDH) and phosphogluconate dehydrogenase (PGD), comprising altogether seven putative loci. Five unique alleles (Mdh-1(A), Mdh-2(B), Gpi(A), Aco(B) and Idh-1(B)) were found in strains of P. fragariae var. fragariae, whereas five unique alleles (Mdh-1(B), Mdh-2(A), Gpi(B), Aco(A) and Idh-1(A)) were present in strains of P. fragariae var. rubi. It was inferred from these data that there is no gene flow between the two P. fragariae varieties. Cytochrome oxidase I (Cox I) sequences showed consistent differences at 15 positions between strains of Fragaria and Rubus respectively. Based on isozyme data, cytochrome oxidase I sequences, and previously published differences in restyriction enzyme patterns of mitochondrial DNA, sequences of nuclear and mitochondrial genes, AFLP patterns and pathogenicity, it was concluded that both specific pathogenic varieties of P. fragariae are reproductively isolated and constitute a distinct species. Consequently strains isolated from Rubus idaeus are assigned to Phytophthora rubi comb. nov.

  4. 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.

  5. The plant pathogen Phytophthora andina emerged via hybridization of an unknown Phytophthora species and the Irish potato famine pathogen, P. infestans.

    Science.gov (United States)

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

    2011-01-01

    Emerging plant pathogens have largely been a consequence of the movement of pathogens to new geographic regions. Another documented mechanism for the emergence of plant pathogens is hybridization between individuals of different species or subspecies, which may allow rapid evolution and adaptation to new hosts or environments. Hybrid plant pathogens have traditionally been difficult to detect or confirm, but the increasing ease of cloning and sequencing PCR products now makes the identification of species that consistently have genes or alleles with phylogenetically divergent origins relatively straightforward. We investigated the genetic origin of Phytophthora andina, an increasingly common pathogen of Andean crops Solanum betaceum, S. muricatum, S. quitoense, and several wild Solanum spp. It has been hypothesized that P. andina is a hybrid between the potato late blight pathogen P. infestans and another Phytophthora species. We tested this hypothesis by cloning four nuclear loci to obtain haplotypes and using these loci to infer the phylogenetic relationships of P. andina to P. infestans and other related species. Sequencing of cloned PCR products in every case revealed two distinct haplotypes for each locus in P. andina, such that each isolate had one allele derived from a P. infestans parent and a second divergent allele derived from an unknown species that is closely related but distinct from P. infestans, P. mirabilis, and P. ipomoeae. To the best of our knowledge, the unknown parent has not yet been collected. We also observed sequence polymorphism among P. andina isolates at three of the four loci, many of which segregate between previously described P. andina clonal lineages. These results provide strong support that P. andina emerged via hybridization between P. infestans and another unknown Phytophthora species also belonging to Phytophthora clade 1c.

  6. 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.

  7. 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.

  8. Incidence of Phytophthora infestans (Mont.) de Bary on potato and tomato in Maine, 2006-2010

    Science.gov (United States)

    Late blight, caused by Phytophthora infestans, is a devastating disease globally. In Maine, we recorded late blight on potato and tomato during the 2006-2010 cropping seasons. From 2006 to 2008, over 90% of diseased samples were collected in potato fields from northern and central Aroostook County i...

  9. Understanding the molecular basis of the resistance of Phytophthora infestans to fungicides by functional genomics

    Science.gov (United States)

    Development of resistance to fungicides is a major concern in managing potato late blight disease caused by Phytophthora infestans. The problem is P. infestans is capable of sexual recombination contributing to increased strain variability and high adaptability that hastens the development of resis...

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

    Science.gov (United States)

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

  11. Tuber blight development in potato cultivars in response to different genotypes of Phytophthora infestans

    Science.gov (United States)

    Potato late blight, caused by Phytophthora infestans, is one of the most devastating diseases in potatoes, causing significant loses under disease-conducive conditions. Migrations or introduction of new genotypes to a specific region impose a different set of criteria for consideration for potato gr...

  12. Survival potential of Phytophthora infestans sporangia in relation to meteorological factors

    Science.gov (United States)

    Assessment of meteorological factors coupled with sporangia survival curves may enhance effective management of potato late blight, caused by Phytophthora infestans. We utilized a non-parametric density estimation approach to evaluate the cumulative probability of occurrence of temperature and relat...

  13. Doseringsverlaging op basis van loof- en knolresistentie tegen Phytophthora infestans in aardappel

    NARCIS (Netherlands)

    Spits, H.G.

    2007-01-01

    Een mogelijkheid om het middelengebruik omlaag te krijgen is een bestrijdingsstrategie te ontwikkelen waarbij de gevoeligheid van het ras gebruikt wordt bij de beheersing van de aardappelziekte. Bij zo’n strategie zou een ras dat weinig gevoelig is voor Phytophthora met een lagere dosering net zo go

  14. Molecular determinants of resistance activation and suppression by Phytophthora infestans effector IPI-O

    Science.gov (United States)

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

  15. Variability in virulence and the race concept in Phytophthora infestans (Mont. de Bary

    Directory of Open Access Journals (Sweden)

    Ludwik S. Sujkowski

    2014-08-01

    Full Text Available Variability in virulence and aggressiveness was studied in 102 single zoospore isolates originating from 4 field isolates of Phytophthora infestans. Field isolates appeared to be mixtures of a wide spectrum of phenotypes differing in both characters as mentioned above. Race concept in P. infestans has been discussed.

  16. Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans

    NARCIS (Netherlands)

    Haas, B.J.; Kamoun, S.; Zody, M.C.; Jiang, R.H.Y.; Handsaker, R.E.; Cano, L.M.; Grabherr, M.; Kodira, C.D.; Raffaele, S.; Torto-Alalibo, T.; Bozkurt, T.O.; Ah-Fong, A.M.V.; Alvarado, L.; Anderson, V.L.; Armstrong, M.R.; Avrova, A.; Baxter, L.; Beynon, J.; Boevink, P.C.; Bollmann, S.R.; Bos, J.I.B.; Bulone, V.; Cai, G.; Cakir, C.; Carrington, J.C.; Chawner, M.; Conti, L.; Costanzo, S.; Ewan, R.; Fahlgren, N.; Fischbach, M.A.; Fugelstad, J.; Gilroy, E.M.; Gnerre, S.; Green, P.J.; Grenville-Briggs, L.J.; Griffith, J.; Grunwald, N.J.; Horn, K.; Horner, N.R.; Hu, C.H.; Huitema, E.; Jeong, D.H.; Jones, A.M.E.; Jones, J.D.G.; Jones, R.W.; Karlsson, E.K.; Kunjeti, S.G.; Lamour, K.; Liu, Z.; Ma, L.; Maclean, D.; Chibucos, M.C.; McDonald, H.; McWalters, J.; Meijer, H.J.G.; Morgan, W.; Morris, P.F.; Munro, C.A.; O'Neill, K.; Ospina-Giraldo, M.; Pinzon, A.; Pritchard, L.; Ramsahoye, B.; Ren, Q.; Restrepo, S.; Roy, S.; Sadanandom, A.; Savidor, A.; Schornack, S.; Schwartz, D.C.; Schumann, U.D.; Schwessinger, B.; Seyer, L.; Sharpe, T.; Silvar, C.; Song, J.; Studholme, D.J.; Sykes, S.; Thines, M.; Vondervoort, van de P.J.I.; Phuntumart, V.; Wawra, S.; Weide, R.; Win, J.; Young, C.; Zhou, S.; Fry, W.; Meyers, B.C.; West, van P.; Ristaino, J.; Govers, F.; Birch, P.R.J.; Whisson, S.C.; Judelson, H.S.; Nusbaum, C.

    2009-01-01

    Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans ha

  17. '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

  18. Population structure of Phytophthora infestans in the Toluca Valley region of Central Mexico

    NARCIS (Netherlands)

    Grünwald, N.J.; Flier, W.G.; Sturbaum, A.K.; Garay-Serrano, E.; Bosch, van den G.B.M.; Smart, C.D.; Matuszak, J.M.; Turkensteen, L.J.; Fry, W.E.

    2001-01-01

    We tested the hypothesis that the population of Phytophthora infestans in the Toluca valley region is genetically differentiated according to habitat. Isolates were sampled in three habitats from (i) wild Solanum spp. (WILD), (ii) land-race varieties in low-input production systems (RURAL), and (iii

  19. A Rapid Diagnostic Test to Distinguish Between American and European Populations of Phytophthora ramorum

    NARCIS (Netherlands)

    Kroon, L.P.N.M.; Verstappen, E.C.P.; Kox, L.F.F.; Flier, W.G.; Bonants, P.J.M.

    2004-01-01

    A new devastating disease in the United States, commonly known as Sudden Oak Death, is caused by Phytophthora ramorum. This pathogen, which previously was described attacking species of Rhododendron and Viburnum in Germany and the Netherlands, has established itself in forests on the central coast o

  20. Epidemiological importance of Solanum sisymbriifolium, S. nigrum and S. dulcamara as alternative hosts for Phytophthora infestans

    NARCIS (Netherlands)

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

    2003-01-01

    Lesions of Phytophthora infestans were found on woody nightshade (Solanum dulcamara), black nightshade (S. nigrum) and S. sisymbriifolium during a nationwide late blight survey in the Netherlands in 1999 and 2000. Pathogenicity and spore production of P. infestans isolates collected from potato (S.

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

    Science.gov (United States)

    Potato is an important crop globally and late blight (Phytophthora infestans) often results in severe crop loss. The cost for late blight control can be in excess of $210 million in the United States. We utilized a non-parametric density distribution analysis of local temperature (Temp) and relative...

  2. Anaerobic soil disinfestation reduces survival and infectivity of Phytophthora nicotianae chlamydospores in pepper

    Science.gov (United States)

    Phytophthora nicotianae is the principal causal agent of root and crown rot disease of pepper plants in Extremadura (western Spain), a spring-summer crop in this region. Preplant soil treatment by anaerobic soil disinfestation (ASD) may effectively control plant pathogens in many crop production sys...

  3. Management of Phytophthora cinnamomi root rot disease of blueberry with gypsum and compost

    Science.gov (United States)

    Root rot disease of blueberry caused by Phytophthora cinnamomi is becoming more prevalent as a consequence of widespread adoption of drip irrigation. This creates higher moisture content in the root zone more conducive for the pathogen. Options for disease control under organic management are limi...

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

    Science.gov (United States)

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

  5. Differentiating Phytophthora ramorum and P. kernoviae from other species isolated from foliage of rhododendrons

    Science.gov (United States)

    Phytophthora species are among plant pathogens that are the most threatening to agriculture. After the discovery of P. ramorum, surveys have identified new species and new reports on Rhododendrons. Based upon propagule production and characteristics and colony growth, a dichotomous key was produce...

  6. Draft genome sequences of seven isolates of Phytophthora ramorum EU2 from Northern Ireland

    Directory of Open Access Journals (Sweden)

    Lourdes de la Mata Saez

    2015-12-01

    Full Text Available Here we present draft-quality genome sequence assemblies for the oomycete Phytophthora ramorum genetic lineage EU2. We sequenced genomes of seven isolates collected in Northern Ireland between 2010 and 2012. Multiple genome sequences from P. ramorum EU2 will be valuable for identifying genetic variation within the clonal lineage that can be useful for tracking its spread.

  7. Lineage, Temperature, and Host Species Have Interacting Effects on Lesion Development in Phytophthora Ramorum

    Science.gov (United States)

    There are four recognized clonal lineages of the pathogen Phytophthora ramorum. The two major lineages present in North America are NA1 and NA2. With a few exceptions, NA1 is found in natural forest ecosystems and nurseries, and NA2 is generally restricted to nurseries. Isolates from the NA1 and NA2...

  8. Phytophthora effector targets a novel component of small RNA pathway in plants to promote infection.

    Science.gov (United States)

    Qiao, Yongli; Shi, Jinxia; Zhai, Yi; Hou, Yingnan; Ma, Wenbo

    2015-05-05

    A broad range of parasites rely on the functions of effector proteins to subvert host immune response and facilitate disease development. The notorious Phytophthora pathogens evolved effectors with RNA silencing suppression activity to promote infection in plant hosts. Here we report that the Phytophthora Suppressor of RNA Silencing 1 (PSR1) can bind to an evolutionarily conserved nuclear protein containing the aspartate-glutamate-alanine-histidine-box RNA helicase domain in plants. This protein, designated PSR1-Interacting Protein 1 (PINP1), regulates the accumulation of both microRNAs and endogenous small interfering RNAs in Arabidopsis. A null mutation of PINP1 causes embryonic lethality, and silencing of PINP1 leads to developmental defects and hypersusceptibility to Phytophthora infection. These phenotypes are reminiscent of transgenic plants expressing PSR1, supporting PINP1 as a direct virulence target of PSR1. We further demonstrate that the localization of the Dicer-like 1 protein complex is impaired in the nucleus of PINP1-silenced or PSR1-expressing cells, indicating that PINP1 may facilitate small RNA processing by affecting the assembly of dicing complexes. A similar function of PINP1 homologous genes in development and immunity was also observed in Nicotiana benthamiana. These findings highlight PINP1 as a previously unidentified component of RNA silencing that regulates distinct classes of small RNAs in plants. Importantly, Phytophthora has evolved effectors to target PINP1 in order to promote infection.

  9. Development of a loop-mediated isothermal amplification assay for detection of Phytophthora sojae.

    Science.gov (United States)

    Dai, Ting-Ting; Lu, Chen-Chen; Lu, Jing; Dong, SuoMeng; Ye, WenWu; Wang, YuanChao; Zheng, XiaoBo

    2012-09-01

    Phytophthora sojae is a devastating pathogen that causes soybean Phytophthora root rot. This study reports the development of a loop-mediated isothermal amplification (LAMP) assay targeting the A3aPro element for visual detection of P. sojae. The A3aPro-LAMP assay efficiently amplified the target element in Phytophthora spp., Pythium spp., and true fungi isolates. Magnesium pyrophosphate resulting from the LAMP of P. sojae could be detected by real-time measurement of turbidity. Phytophthora sojae DNA products were visualized as a ladder-like banding pattern on 2% gel electrophoresis. A positive colour (sky blue) was only observed in the presence of P. sojae with the addition of hydroxynaphthol blue prior to amplification, whereas none of other isolates showed a colour change. The detection limit of the A3aPro-specific LAMP assay for P. sojae was 10 pg μL(-1) of genomic DNA per reaction. The assay also detected P. sojae from diseased soybean tissues and residues. These results suggest that the A3aPro-LAMP assay reported here can be used for the visual detection of P. sojae in plants and production fields.

  10. 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, ...

  11. The Phytophthora species assemblage and diversity in riparian alder ecosystems of western Oregon, USA.

    Science.gov (United States)

    Sims, Laura Lee; Sutton, Wendy; Reeser, Paul; Hansen, Everett M

    2015-01-01

    Phytophthora species were systematically sampled, isolated, identified and compared for presence in streams, soil and roots of alder (Alnus species) dominated riparian ecosystems in western Oregon. We describe the species assemblage and evaluate Phytophthora diversity associated with alder. We recovered 1250 isolates of 20 Phytophthora species. Only three species were recovered from all substrates (streams, soil, alder roots): P. gonapodyides, the informally described "P. taxon Pgchlamydo", and P. siskiyouensis. P. alni ssp. uniformis along with five other species not previously recovered in Oregon forests are included in the assemblage: P.citricola s.l., P. gregata, P. gallica, P. nicotianae and P. parsiana. Phytophthora species diversity was greatest in downstream riparian locations. There was no significant difference in species diversity comparing soil and unwashed roots (the rhizosphere) to stream water. There was a difference between the predominating species from the rhizosphere compared to stream water. The most numerous species was the informally described "P. taxon Oaksoil", which was mainly recovered from, and most predominant in, stream water. The most common species from riparian forest soils and alder root systems was P. gonapodyides.

  12. Roles of small RNAs in soybean defense against Phytophthora sojae infection.

    Science.gov (United States)

    Wong, James; Gao, Lei; Yang, Yang; Zhai, Jixian; Arikit, Siwaret; Yu, Yu; Duan, Shuyi; Chan, Vicky; Xiong, Qin; Yan, Jun; Li, Shengben; Liu, Renyi; Wang, Yuanchao; Tang, Guiliang; Meyers, Blake C; Chen, Xuemei; Ma, Wenbo

    2014-09-01

    The genus Phytophthora consists of many notorious pathogens of crops and forestry trees. At present, battling Phytophthora diseases is challenging due to a lack of understanding of their pathogenesis. We investigated the role of small RNAs in regulating soybean defense in response to infection by Phytophthora sojae, the second most destructive pathogen of soybean. Small RNAs, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), are universal regulators that repress target gene expression in eukaryotes. We identified known and novel small RNAs that differentially accumulated during P. sojae infection in soybean roots. Among them, miR393 and miR166 were induced by heat-inactivated P. sojae hyphae, indicating that they may be involved in soybean basal defense. Indeed, knocking down the level of mature miR393 led to enhanced susceptibility of soybean to P. sojae; furthermore, the expression of isoflavonoid biosynthetic genes was drastically reduced in miR393 knockdown roots. These data suggest that miR393 promotes soybean defense against P. sojae. In addition to miRNAs, P. sojae infection also resulted in increased accumulation of phased siRNAs (phasiRNAs) that are predominantly generated from canonical resistance genes encoding nucleotide binding-leucine rich repeat proteins and genes encoding pentatricopeptide repeat-containing proteins. This work identifies specific miRNAs and phasiRNAs that regulate defense-associated genes in soybean during Phytophthora infection.

  13. 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...

  14. 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

  15. 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

  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. 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...

  18. Resistance to Phytophthora infestans in Solanum tuberosum and wild Solanum species

    NARCIS (Netherlands)

    Colon, L.T.

    1994-01-01

    Resistance to Phytophthora infestans , the causal agent of late blight, is present in the potato, Solanum tuberosum , and in many wild relatives of this crop. The resistance of S. tuberosum is partial and, though helpful in reducing the use of fungicides, is not sufficient to fully solve the problem

  19. 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

  20. Towards the development of integrated cultural control of tomato late blight (Phytophthora infestans) in Uganda

    NARCIS (Netherlands)

    Tumwine, J.

    1999-01-01

    Tomato ( Lycopersicon esculentum ) is a major vegetable crop in Uganda. Moneymaker, Marglobe, Heinz and Roma are the major commercial varieties grown in the country, the first two being the most popular. Late blight ( Phytophthora infestans ) is the most important disease of Ugandan tomatoes. Tomato

  1. 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...

  2. 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...

  3. Bescherming van nieuwe groei tegen Phytophthora in de teelt van aardappelen

    NARCIS (Netherlands)

    Kalkdijk, J.R.; Schepers, H.T.A.M.; Evenhuis, A.

    2005-01-01

    Onderzoek naar de werking van fungiciden tijdens de teelt van poot- en consumptieaardappelen. Tijdens de periode dat het loof snel groeit zijn er delen van de plant onbeschermd tegen Phytophthora. De werking van fungiciden op de bescherming van de nieuwe groei is in biotoetsen regelmatig getoetst. E

  4. 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...

  5. A Multiplexed, Probe-Based Quantitative PCR Assay for DNA of Phytophthora sojae

    Science.gov (United States)

    Phytophthora sojae (Kaufm. & Gerd.) causes seed rot, pre- and post-emergence damping off, and sometimes foliar blight in soybean (Glycine max). Crop loss may approach 100% with susceptible cultivars. We report here the development of a unique quantitative PCR assay specific to DNA of P. sojae, and a...

  6. Multi-Year Evaluation of Commercial Soybean Cultivars for Resistance to Phytophthora sojae

    Science.gov (United States)

    Phytophthora sojae causes damping off, root rot, and stem rot of soybean, particularly in poorly drained soils. The use of resistance has been one of the primary management tools used to control this disease, with the most commonly used genes being Rps1c and Rps1k, followed by Rps1a. The Varietal In...

  7. Correlation of isozyme profiles with genomic sequences of Phytophthora ramorum and its P. sojae orthologues

    NARCIS (Netherlands)

    Man in 't Veld, W.A.; Govers, F.; Meijer, H.J.G.

    2007-01-01

    A correct interpretation of isozyme patterns can be seriously hampered by the lack of supporting genetic data. The availability of the complete genome sequence of Phytophthora ramorum, enabled us to correlate isozyme profiles with the gene models predicted for these enzymes. Thirty-nine P. ramorum s

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

    DEFF Research Database (Denmark)

    Skottrup, Peter Durand; 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 sporangi...

  10. A combined mitochondrial and nuclear multilocus phylogeny of the genus Phytophthora

    Science.gov (United States)

    The most recent phylogenetic analysis of the genus Phytophthora was completed in 2008 (Blair et al. 2008) and utilized 8.1 kb of sequence data from seven nuclear loci. Given the large number of species that have recently been described, this study was undertaken to broaden the available information...

  11. 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

  12. The effect of salinity on the growth, sporulation and infection of Phytophthora ramorum

    Science.gov (United States)

    Phytophthora ramorum, a threat to Eastern U.S. forests, has been found in waterways outside the boundaries of infested ornamental nurseries. Very little is known about what factors are conducive to its survival and sporulation in water. This study examined the effect of salt on growth, sporulation,...

  13. 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,...

  14. Biologically active Phytophthora mating hormone prepared by catalytic asymmetric total synthesis

    NARCIS (Netherlands)

    Harutyunyan, S.R.; Zhao, Z.; Hartog, den T.; Bouwmeester, K.; Minnaard, A.J.; Feringa, B.L.; Govers, F.

    2008-01-01

    A Phytophthora mating hormone with an array of 1,5-stereogenic centers has been synthesized by using our recently developed methodology of catalytic enantioselective conjugate addition of Grignard reagents. We applied this methodology in a diastereo- and enantioselective iterative route and obtained

  15. Biologically active Phytophthora mating hormone prepared by catalytic asymmetric total synthesis

    NARCIS (Netherlands)

    Harutyunyan, Syuzanna R.; Zhao, Zhijian; den Hartog, Tim; Bouwmeester, Klaas; Minnaard, Adriaan J.; Feringa, Ben L.; Govers, Francine

    2008-01-01

    A Phytophthora mating hormone with an array of 11,5-stereogenic centers has been synthesized by using our recently developed methodology of catalytic enantioselective conjugate addition of Grignard reagents. We applied this methodology in a diastereo-and enantioselective iterative route and obtained

  16. Identification and validation of polymorphic microsatellite loci for the analysis of Phytophthora nicotianae populations

    Science.gov (United States)

    A large number of SSR loci were screened in the genomic assemblies of 14 different isolates of Phytophthora nicotianae and primers were developed for amplification of 17 markers distributed among different contigs. These loci were highly polymorphic and amplified from genetically distant isolates of...

  17. Evaluation of watermelon varieties for tolerance to powdery mildew and Phytophthora fruit rot, 2014

    Science.gov (United States)

    This experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC. The soil was Yonges loamy fine sand. This study was undertaken to determine the performance of seeded and seedless commercial watermelon varieties for tolerance to powdery mildew (PM) and Phytophthora fruit rot as...

  18. Differential expression of G protein alpha and ß subunit genes during development of Phytophthora infestans

    NARCIS (Netherlands)

    Laxalt, A.M.; Latijnhouwers, M.; Hulten, van M.; Govers, F.

    2002-01-01

    A G protein subunit gene (pigpa1) and a G protein subunit gene (pigpb1) were isolated from the oomycete Phytophthora infestans, the causal agent of potato late blight. Heterotrimeric G proteins are evolutionary conserved GTP-binding proteins that are composed of ,, and subunits and participate in di

  19. 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

  20. 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

  1. Genetic mapping of resistance factors to Phytophthora palmivora in cocoa.

    Science.gov (United States)

    Flament, M H; Kebe, I; Clément, D; Pieretti, I; Risterucci, A M; N'Goran, J A; Cilas, C; Despréaux, D; Lanaud, C

    2001-02-01

    Phytophthora palmivora causes pod rot, a serious disease on cocoa widespread throughout the producing regions. In order to ascertain the genetic determination of cocoa resistance to P. palmivora, a study was carried out on two progenies derived from crosses between a heterozygous, moderately resistant Forastero clone, T60/887, and two closely related and highly susceptible Forastero clones, one completely homozygous, IFC2, and one partially heterozygous, IFC5. The cumulative size of both progenies was 112 individuals. Plants were subjected to natural and artificial inoculation of P. palmivora in C te d'Ivoire. The genetic maps of T60/887 and of IFC5 were constructed using amplified fragment length polymorphism (AFLP) markers and microsatellites. The map of T60/887 comprised 198 markers assembled in 11 linkage groups and representing a total length of 793 cM. The map of IFC5 comprised 55 AFLP markers that were assembled into six linkage groups for a total length of 244 cM. Ratio of rotten over total number of fruit under natural infection was measured for each tree over two harvests. Artificial inoculations were performed on leaves and pods. These tests were weakly correlated with the pod rot rate in the field. Five quantitative trait loci (QTLs) of resistance were detected for T60/887 but none were common between the three traits measured. Stability and reliability of the experimental procedures are discussed and revealed the difficult use of these artificial tests on adult trees for a good prediction of field resistance.

  2. 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.

  3. 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

  4. Development of Rapid Isothermal Amplification Assays for Detection of Phytophthora spp. in Plant Tissue.

    Science.gov (United States)

    Miles, Timothy D; Martin, Frank N; Coffey, Michael D

    2015-02-01

    Several isothermal amplification techniques recently have been developed that are tolerant of inhibitors present in many plant extracts, which can reduce the need for obtaining purified DNA for running diagnostic assays. One such commercially available technique that has similarities with real-time polymerase chain reaction (PCR) for designing primers and a labeled probe is recombinase polymerase amplification (RPA). This technology was used to develop two simple and rapid approaches for detection of Phytophthora spp.: one genus-specific assay multiplexed with a plant internal control and the other species-specific assays for Phytophthora ramorum and P. kernoviae. All assays were tested for sensitivity (ranging from 3 ng to 1 fg of DNA) and specificity using DNA extracted from more than 136 Phytophthora taxa, 21 Pythium spp., 1 Phytopythium sp., and a wide range of plant species. The lower limit of linear detection using purified DNA was 200 to 300 fg of DNA in all pathogen RPA assays. Six different extraction buffers were tested for use during plant tissue maceration and the assays were validated in the field by collecting 222 symptomatic plant samples from over 50 different hosts. Only 56 samples were culture positive for Phytophthora spp. whereas 91 were positive using the Phytophthora genus-specific RPA test and a TaqMan real-time PCR assay. A technique for the generation of sequencing templates from positive RPA amplifications to confirm species identification was also developed. These RPA assays have added benefits over traditional technologies because they are rapid (results can be obtained in as little as 15 min), do not require DNA extraction or extensive training to complete, use less expensive portable equipment than PCR-based assays, and are significantly more specific than current immunologically based methods. This should provide a rapid, field-deployable capability for pathogen detection that will facilitate point-of-sample collection processing

  5. SNP-based differentiation of Phytophthora infestans clonal lineages using locked nucleic acid probes and high resolution melt analysis

    Science.gov (United States)

    Phytophthora infestans, the cause of the devastating late blight disease of potato and tomato, exhibits a clonal reproductive lifestyle in North America. Phenotypes such as fungicide sensitivity and host preference are conserved among individuals within clonal lineages, while substantial phenotypic ...

  6. 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

  7. Analysis of the tomato leaf transcriptome during successive hemibiotrophic stages of a compatible interaction with the oomycete pathogen Phytophthora infestans.

    Science.gov (United States)

    Zuluaga, Andrea P; Vega-Arreguín, Julio C; Fei, Zhangjun; Matas, Antonio J; Patev, Sean; Fry, William E; Rose, Jocelyn K C

    2016-01-01

    The infection of plants by hemibiotrophic pathogens involves a complex and highly regulated transition from an initial biotrophic, asymptomatic stage to a later necrotrophic state, characterized by cell death. Little is known about how this transition is regulated, and there are conflicting views regarding the significance of the plant hormones jasmonic acid (JA) and salicylic acid (SA) in the different phases of infection. To provide a broad view of the hemibiotrophic infection process from the plant perspective, we surveyed the transcriptome of tomato (Solanum lycopersicum) during a compatible interaction with the hemibiotrophic oomycete Phytophthora infestans during three infection stages: biotrophic, the transition from biotrophy to necrotrophy, and the necrotrophic phase. Nearly 10 000 genes corresponding to proteins in approximately 400 biochemical pathways showed differential transcript abundance during the three infection stages, revealing a major reorganization of plant metabolism, including major changes in source-sink relations, as well as secondary metabolites. In addition, more than 100 putative resistance genes and pattern recognition receptor genes were induced, and both JA and SA levels and associated signalling pathways showed dynamic changes during the infection time course. The biotrophic phase was characterized by the induction of many defence systems, which were either insufficient, evaded or suppressed by the pathogen.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. The Loricrin-Like Protein (LLP) of Phytophthora infestans Is Required for Oospore Formation and Plant Infection

    Science.gov (United States)

    Guo, Ting; Wang, Xiao-Wen; Shan, Kun; Sun, Wenxian; Guo, Li-Yun

    2017-01-01

    Loricrin-like protein (LLP) is characterized by a high content of glycine residues and is a major component of plant cell wall. Here, we identified a Phytophthora infestans ortholog of plant LLP, named PiLLP. In P. infestans, PiLLP is strongly expressed in asexual and sexual developmental stages, including in sporangia, zoospores and germinating cysts, and during oospore formation, as well as in the early stages of infection and during hydrogen peroxide stress. Compared with the wild type, the PiLLP-silenced transformants were defective in oospore formation, had slower colony expansion rates, produced less sporangia with lower germination and zoospore-release rates, and were more sensitive to hydrogen peroxide. Moreover, Nile red staining, and PiLLP-red fluorescent protein fusions indicated that PiLLP is involved in oogonia formation. The silenced transformants also had severely diminished virulence levels that could be partially restored with diphenyleneiodium treatments. The analysis of catalase activity showed a decrease of catalase activity in silenced transformants. Thus, PiLLP is important for sexual and asexual reproduction, and is required for oxidative stress tolerance and plant infection. PMID:28232841

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

    Science.gov (United States)

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

    2015-06-01

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

  15. The dihydrolipoyl acyltransferase gene BCE2 participates in basal resistance against Phytophthora infestans in potato and Nicotiana benthamiana.

    Science.gov (United States)

    Wang, Hongyang; Sun, Chunlian; Jiang, Rui; He, Qin; Yang, Yu; Tian, Zhejuan; Tian, Zhendong; Xie, Conghua

    2014-07-01

    Dihydrolipoyl acyltransferase (EC 2.3.1.12), a branched-chain α-ketoacid dehydrogenase E2 subunit (BCE2), catalyzes the transfer of the acyl group from the lipoyl moiety to coenzyme A. However, the role of BCE2 responding to biotic stress in plant is not clear. In this study, we cloned and characterized a BCE2 gene from potato, namely StBCE2, which was previously suggested to be involved in Phytophthora infestans-potato interaction. We found that the expression of StBCE2 was strongly induced by both P. infestans isolate HB09-14-2 and salicylic acid. Besides, when the homolog of StBCE2 in Nicotiana benthamiana named NbBCE2 was silenced, plants showed increased susceptibility to P. infestans and reduced accumulation of hydrogen peroxide (H2O2). Furthermore, we found that a marker gene NbrbohB involved in the production of reactive oxygen species, was also suppressed in NbBCE2-silenced plants. However, silencing of NbBCE2 had no significant effect on the hypersensitive responses trigged by INF1, R3a-AVR3a(KI) pair or Rpi-vnt1.1-AVR-vnt1.1 pair. Our results suggest that BCE2 is associated with the basal resistance to P. infestans by regulating H2O2 production.

  16. 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.

  17. 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.

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

    Science.gov (United States)

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

    2014-05-01

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

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

    Science.gov (United States)

    Li, Delong; Zhao, Zhijian; Huang, Yidan; Lu, Zhaojun; Yao, Meng; Hao, Yujuan; Zhai, Chunhua; Wang, Yuanchao

    2013-01-01

    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.

  20. Race Structure and Distribution of Phytophthora infestans in the Investigated Areas of China

    Institute of Scientific and Technical Information of China (English)

    ZHU Jie-hua; YANG Zhi-hui; SHAO Tie-mei; TIAN Shi-min; ZHANG Zhi-ming

    2003-01-01

    Ninety isolates collected from five different provinces and cities (Hebei, Yunan, Sichuan,Chongqing, Inner Mongolia ) during 1997 -1998 were tested with potato clones possessed 8 dominant mono-genes R1, R3, R4, R6, R7, R9, R10, R11 and the combination of R1-R4 of the international late blight dif-ferential host. It concluded that: (1) in the 90 isolates tested 21 different races were detected, of which the 1.3. 4. 7. 9. 10. 11 was very common with frequency of 32.2%, followed by 1. 3. 4. 6. 7. 9. 10. 11 and 3.4. 7. 9. 11 with frequency of 10.0%; (2) all tested resistant genes were compatible to the virulent gene of iso-lates of Phytophthora infestans assayed, which indicated that the virulent genes were very common in thetested population of Phytophthora infestans.

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

    Directory of Open Access Journals (Sweden)

    Ptaszek Magdalena

    2015-09-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  3. Identification of Phytophthora Species on Phytophthora Blight of Vanilla%香草兰疫病疫霉菌种的鉴定

    Institute of Scientific and Technical Information of China (English)

    曾会才; 张开明; 李锐; 贺春萍

    2000-01-01

    从云南西双版纳的景洪、勐腊两地的热带作物园香草兰疫病果荚、茎节、叶片上分离到10个疫霉分离菌,根据孢子囊、厚垣孢子、藏卵器、雄器形态、菌落形态及主要生长温度,鉴定为烟草疫霉(寄生疫霉)Phytophthora nicotianae(P.parasitice)10个分离菌株均属于A1交配型.

  4. The Phytophthora mating hormone α2 is an antagonist of the counterhormone α1.

    Science.gov (United States)

    Zhang, Li; Yajima, Arata; Ojika, Makoto

    2016-06-01

    The crop destroyer Phytophthora uses mating hormones α1 and α2 to commence its sexual reproduction. The α1-induced sexual reproduction of the A2 mating type was unexpectedly found to be interfered with by the counterhormone α2 that the A2 type itself produces to induce the sexual reproduction of the A1 type. A plausible mechanism is proposed based on structure-activity relationships.

  5. Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans

    OpenAIRE

    Haas, Brian J.; Kamoun, Sophien; Michael C Zody; Jiang, Rays H.Y.; Handsaker, Robert E.; Liliana M Cano; Grabherr, Manfred; Kodira, Chinnappa D.; Raffaele, Sylvain; Torto-Alalibo, Trudy; Bozkurt, Tolga O.; Ah-Fong, Audrey M. V.; Alvarado, Lucia; Anderson, Vicky L.; Armstrong, Miles R.

    2009-01-01

    Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on human history, resulting in famine and population displacement(1). To this day, it affects world agriculture by causing the most destructive disease of potato, the four...

  6. The use of genus-specific amplicon pyrosequencing to assess phytophthora species diversity using eDNA from soil and water in Northern Spain.

    Science.gov (United States)

    Català, Santiago; Pérez-Sierra, Ana; Abad-Campos, Paloma

    2015-01-01

    Phytophthora is one of the most important and aggressive plant pathogenic genera in agriculture and forestry. Early detection and identification of its pathways of infection and spread are of high importance to minimize the threat they pose to natural ecosystems. eDNA was extracted from soil and water from forests and plantations in the north of Spain. Phytophthora-specific primers were adapted for use in high-throughput Sequencing (HTS). Primers were tested in a control reaction containing eight Phytophthora species and applied to water and soil eDNA samples from northern Spain. Different score coverage threshold values were tested for optimal Phytophthora species separation in a custom-curated database and in the control reaction. Clustering at 99% was the optimal criteria to separate most of the Phytophthora species. Multiple Molecular Operational Taxonomic Units (MOTUs) corresponding to 36 distinct Phytophthora species were amplified in the environmental samples. Pyrosequencing of amplicons from soil samples revealed low Phytophthora diversity (13 species) in comparison with the 35 species detected in water samples. Thirteen of the MOTUs detected in rivers and streams showed no close match to sequences in international sequence databases, revealing that eDNA pyrosequencing is a useful strategy to assess Phytophthora species diversity in natural ecosystems.

  7. Fine Mapping of a Phytophthora Resistance Gene RpsWY in Soybean (Glycine max L.) by High-Throughput Genome-Wide Sequencing

    Science.gov (United States)

    Phytophthora root rot (PRR) caused by Phytophthora sojae is one of the most important soil-borne diseases in many soybean-production regions in the world. Identification of resistant gene(s) is an effective way for breeding to prevent soybean from being harmed by this disease. Here, two soybean popu...

  8. 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.

  9. Mitochondrial genome sequences reveal evolutionary relationships of the Phytophthora 1c clade species.

    Science.gov (United States)

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

    2015-11-01

    Phytophthora infestans is one of the most destructive plant pathogens of potato and tomato globally. The pathogen is closely related to four other Phytophthora species in the 1c clade including P. phaseoli, P. ipomoeae, P. mirabilis and P. andina that are important pathogens of other wild and domesticated hosts. P. andina is an interspecific hybrid between P. infestans and an unknown Phytophthora species. We have sequenced mitochondrial genomes of the sister species of P. infestans and examined the evolutionary relationships within the clade. Phylogenetic analysis indicates that the P. phaseoli mitochondrial lineage is basal within the clade. P. mirabilis and P. ipomoeae are sister lineages and share a common ancestor with the Ic mitochondrial lineage of P. andina. These lineages in turn are sister to the P. infestans and P. andina Ia mitochondrial lineages. The P. andina Ic lineage diverged much earlier than the P. andina Ia mitochondrial lineage and P. infestans. The presence of two mitochondrial lineages in P. andina supports the hybrid nature of this species. The ancestral state of the P. andina Ic lineage in the tree and its occurrence only in the Andean regions of Ecuador, Colombia and Peru suggests that the origin of this species hybrid in nature may occur there.

  10. Phytophthora parasitica elicitor-induced reactions in cells of Petroselinum crispum.

    Science.gov (United States)

    Fellbrich, G; Blume, B; Brunner, F; Hirt, H; Kroj, T; Ligterink, W; Romanski, A; Nürnberger, T

    2000-06-01

    Cultured parsley (Petroselinum crispum) cells respond to treatment with elicitors derived from different species of the genus Phytophthora with transcript accumulation of defense-associated genes and the production of furanocoumarin phytoalexins. Pep-25, an oligopeptide fragment of a Phytophthora sojae 42-kDa cell wall protein, and a cell wall elicitor preparation derived from Phytophthora parasitica (Pp-elicitor) stimulate accumulation of the same gene transcripts and formation of the same pattern of furanocoumarins. Treatment of cultured cells and protoplasts with proteinase-digested Pp-elicitor identified proteinaceous constituents as active eliciting compounds in parsley. Similar to Pep- 25, Pp-elicitor induced effluxes of K+ and Cl- and influxes of protons and Ca2+. Concomitantly, as monitored in aequorin-transgenic parsley cell lines both elicitors induced an immediate increase in the cytoplasmic Ca2+ concentration up to sustained levels of 175 nM (Pp-elicitor) or 300 nM (Pep-25), respectively. The signature of the Ca2+ response differed greatly between the two elicitors tested. Extracellular Ca2+ proved essential for activation of an oxidative burst, MAP kinase activity and phytoalexin production by either elicitor. While Pp-elicitor induced a qualitatively similar spectrum of defense responses as did Pep-25, elicitor-specific quantitative differences in response intensity and kinetics suggest activation of a conserved signaling cascade through separate ligand binding sites.

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

    Science.gov (United States)

    Stong, Rachel A; Kolodny, Eli; Kelsey, Rick G; González-Hernández, M P; Vivanco, Jorge M; Manter, Daniel K

    2013-06-01

    Elicitin-mediated acquisition of plant sterols is required for growth and sporulation of Phytophthora spp. This study examined the interactions between elicitins, sterols, and tannins. Ground leaf tissue, sterols, and tannin-enriched extracts were obtained from three different plant species (California bay laurel, California black oak, and Oregon white oak) in order to evaluate the effect of differing sterol/tannin contents on Phytophthora ramorum growth. For all three species, high levels of foliage inhibited P. ramorum growth and sporulation, with a steeper concentration dependence for the two oak samples. Phytophthora ramorum growth and sporulation were inhibited by either phytosterols or tannin-enriched extracts. High levels of sterols diminished elicitin gene expression in P. ramorum; whereas the tannin-enriched extract decreased the amount of 'functional' or ELISA-detectable elicitin, but not gene expression. Across all treatment combinations, P. ramorum growth and sporulation correlated strongly with the amount of ELISA-detectable elicitin (R (2) = 0.791 and 0.961, respectively).

  12. Cross-species global proteomics reveals conserved and unique processes in Phytophthora sojae and P. ramorum

    Energy Technology Data Exchange (ETDEWEB)

    Savidor, Alon [ORNL; Donahoo, Ryan S [ORNL; Hurtado-Gonzales, Oscar [University of Tennessee, Knoxville (UTK); Land, Miriam L [ORNL; Shah, Manesh B [ORNL; Lamour, Kurt H [ORNL; McDonald, W Hayes [ORNL

    2008-08-01

    Phytophthora ramorum and Phytophthora sojae are destructive plant pathogens. Phytophthora sojae has a narrow host range whereas P. ramorum has a wide host range. A global proteomic comparison of the vegetative (mycelium) and infective (germinating-cyst) life-stages of P. sojae and P. ramorum was conducted to identify candidate proteins involved in host range, early infection and vegetative growth. Sixty-two candidates for early infection, 26 candidates for vegetative growth, and numerous proteins that may be involved in defining host specificity were identified. In addition, common life stage proteomic trends between the organisms were observed. In mycelia, proteins involved in transport and metabolism of amino acids, carbohydrates and other small molecules were up-regulated. In the germinating cysts, up-regulated proteins associated with lipid transport and metabolism, cytoskeleton and protein synthesis were observed. It appears that the germinating cyst catabolizes lipid reserves through the -oxidation pathway to drive the extensive protein synthesis necessary to produce the germ tube and initiate infection. Once inside the host, the pathogen switches to vegetative growth, where energy is derived from glycolysis and utilized for synthesis of amino acids and other molecules that assist survival in the plant tissue.

  13. Morphological and molecular identification of phytophthora species from maple trees in Serbia

    Directory of Open Access Journals (Sweden)

    Milenković Ivan

    2014-01-01

    Full Text Available The paper presents the results of the study performed with aims to determine the presence and diversity of Phytophthora species on maple trees in Serbia. Due to high aggressiveness and their multicyclic nature, presence of these pathogens is posing significant threat to forestry and biodiversity. In total, 29 samples of water, soil and tissues were taken from 10 different localities, and six different maple hosts were tested. After the isolation tests, 17 samples from five different maple hosts were positive for the presence of Phytophthora spp., and 31 isolates were obtained. After the detailed morphological and physiological classification, four distinct groups of isolates were separated. DNA was extracted from selected representative isolates and molecular identification with sequencing of ITS region was performed. Used ITS4 and ITS6 primers successfully amplified the genomic DNA of chosen isolates and morphological identification of obtained isolates was confirmed after the sequencing. Four different Phytophthora species were detected, including P. cactorum, P. gonapodyides, P. plurivora and P. lacustris. The most common isolated species was homothallic, and with very variable and semipapillate sporangia, P. plurivora with 22 obtained isolates. This is the first report of P. plurivora and P. gonapodyides on A. campestre, P. plurivora and P. lacustris on Acer heldreichii and first report of P. lacustris on A. pseudoplatanus and A. tataricum in Serbia. [Projekat Ministarstva nauke Republike Srbije, br. TR 37008

  14. Copper treatment during storage reduces Phytophthora and Halophytophthora infection of Zostera marina seeds used for restoration

    Science.gov (United States)

    Govers, Laura L.; van der Zee, Els M.; Meffert, Johan P.; van Rijswick, Patricia C. J.; Man in ‘t Veld, Willem A.; Heusinkveld, Jannes H. T.; van der Heide, Tjisse

    2017-01-01

    Restoration is increasingly considered an essential tool to halt and reverse the rapid decline of vital coastal ecosystems dominated by habitat-forming foundation species such as seagrasses. However, two recently discovered pathogens of marine plants, Phytophthora gemini and Halophytophthora sp. Zostera, can seriously hamper restoration efforts by dramatically reducing seed germination. Here, we report on a novel method that strongly reduces Phytophthora and Halophytophthora infection of eelgrass (Zostera marina) seeds. Seeds were stored in seawater with three different copper sulphate concentrations (0.0, 0.2, 2.0 ppm) crossed with three salinities (0.5, 10.0, 25.0 ppt). Next to reducing seed germination, infection significantly affected cotyledon colour: 90% of the germinated infected seeds displayed a brown cotyledon upon germination that did not continue development into the seedling stage, in contrast to only 13% of the germinated non-infected seeds. Copper successfully reduced infection up to 86% and the 0.2 ppm copper sulphate treatment was just as successful as the 2.0 ppm treatment. Infection was completely eliminated at low salinities, but green seed germination was also dramatically lowered by 10 times. We conclude that copper sulphate treatment is a suitable treatment for disinfecting Phytophthora or Halophytophthora infected eelgrass seeds, thereby potentially enhancing seed-based restoration success. PMID:28225072

  15. Signatures of selection and host-adapted gene expression of the Phytophthora infestans RNA silencing suppressor PSR2.

    Science.gov (United States)

    de Vries, Sophie; von Dahlen, Janina K; Uhlmann, Constanze; Schnake, Anika; Kloesges, Thorsten; Rose, Laura E

    2017-01-01

    Phytophthora infestans is a devastating pathogen in agricultural systems. Recently, an RNA silencing suppressor (PSR2, 'Phytophthora suppressor of RNA silencing 2') has been described in P. infestans. PSR2 has been shown to increase the virulence of Phytophthora pathogens on their hosts. This gene is one of the few effectors present in many economically important Phytophthora species. In this study, we investigated: (i) the evolutionary history of PSR2 within and between species of Phytophthora; and (ii) the interaction between sequence variation, gene expression and virulence. In P. infestans, the highest PiPSR2 expression was correlated with decreased symptom expression. The highest gene expression was observed in the biotrophic phase of the pathogen, suggesting that PSR2 is important during early infection. Protein sequence conservation was negatively correlated with host range, suggesting host range as a driver of PSR2 evolution. Within species, we detected elevated amino acid variation, as observed for other effectors; however, the frequency spectrum of the mutations was inconsistent with strong balancing selection. This evolutionary pattern may be related to the conservation of the host target(s) of PSR2 and the absence of known corresponding R genes. In summary, our study indicates that PSR2 is a conserved effector that acts as a master switch to modify plant gene regulation early during infection for the pathogen's benefit. The conservation of PSR2 and its important role in virulence make it a promising target for pathogen management.

  16. 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.

  17. Antagonistic in vitro activity of Trichoderma spp. isolates to the fungi Phytophthora citrophthora / Atividade antagônica in vitro de isolados de Trichoderma spp. ao fungo Phytophthora citrophthora

    Directory of Open Access Journals (Sweden)

    Cleiton Gredson Sabin Benett

    2008-07-01

    Full Text Available Gummosis is among the main fungal diseases of the citrus. It is caused by Phytophthora sp. and usually shows up in the lap of the plant, provoking rottenness and gum exudation, and expands causing the plant death for constrictions in the cambium or phloem which interrupts the descending fow of sap. The objective of this work was to evaluate the antagonistic in vitro activity of Trichoderma spp. to the fungi Phytophthora citrophthora. Phytophthora citrophthora was exposed to fve environments of antagonism (without antagonist and with four strains of Trichoderma viride, T. virens, T. harzianu and T. stromaticum. The in vitro essay was accomplished through the method of paired cultures. A completely randomized desing was used with fve treatments and three replications, and each plot was represented by three petri dishes. The isolates of Trichoderma demonstrated signifcant effect in the inhibition of the mycelial growth of the fungi Phytophthora citrophthora, and the fungi Trichoderma stromaticum presented larger antagonism to the fungi P. citrophthora while the T. harzianum presented antagonism smaller.A citricultura nacional apresenta inúmeras pragas e doenças que limitam sua produção dentre as principais doenças fúngicas da cultura dos citros pode se destacar a gomose. A gomose causada por Phytophthora sp. geralmente se manifesta no colo da planta, provocando podridão e exsudação de goma, podendo expandir-se ocasionando a morte da planta por estrangulamento devido ao ataque do cambio ou foema, o que interrompe o fuxo descendente de seiva. Este trabalho foi realizado com o objetivo de se avaliar a atividade antagônica in vitro, de isolados de Trichoderma spp. ao fungo Phytophthora citrophthora. O fator em estudo foi um patógeno (Phytophthora citrophthora em cinco ambientes de antagonismo (sem antagonista e com os isolados de Trichoderma viride, T. virens, T. harzianu e T. stromaticum. O ensaio in vitro foi realizado por meio do m

  18. Pathogen-associated molecular pattern-triggered immunity and resistance to the root pathogen Phytophthora parasitica in Arabidopsis.

    Science.gov (United States)

    Larroque, Mathieu; Belmas, Elodie; Martinez, Thomas; Vergnes, Sophie; Ladouce, Nathalie; Lafitte, Claude; Gaulin, Elodie; Dumas, Bernard

    2013-09-01

    The cellulose binding elicitor lectin (CBEL) of the genus Phytophthora induces necrosis and immune responses in several plant species, including Arabidopsis thaliana. However, the role of CBEL-induced responses in the outcome of the interaction is still unclear. This study shows that some of CBEL-induced defence responses, but not necrosis, required the receptor-like kinase BAK1, a general regulator of basal immunity in Arabidopsis, and the production of a reactive oxygen burst mediated by respiratory burst oxidases homologues (RBOH). Screening of a core collection of 48 Arabidopsis ecotypes using CBEL uncovered a large variability in CBEL-induced necrotic responses. Analysis of non-responsive CBEL lines Ws-4, Oy-0, and Bla-1 revealed that Ws-4 and Oy-0 were also impaired in the production of the oxidative burst and expression of defence genes, whereas Bla-1 was partially affected in these responses. Infection tests using two Phytophthora parasitica strains, Pp310 and Ppn0, virulent and avirulent, respectively, on the Col-0 line showed that BAK1 and RBOH mutants were susceptible to Ppn0, suggesting that some immune responses controlled by these genes, but not CBEL-induced cell death, are required for Phytophthora parasitica resistance. However, Ws-4, Oy-0, and Bla-1 lines were not affected in Ppn0 resistance, showing that natural variability in CBEL responsiveness is not correlated to Phytophthora susceptibility. Overall, the results uncover a BAK1- and RBOH-dependent CBEL-triggered immunity essential for Phytophthora resistance and suggest that natural quantitative variation of basal immunity triggered by conserved general elicitors such as CBEL does not correlate to Phytophthora susceptibility.

  19. Cohnella capsici sp. nov., a novel nitrogen-fixing species isolated from Capsicum annuum rhizosphere soil, and emended description of Cohnella plantaginis.

    Science.gov (United States)

    Wang, Li-Ying; Wang, Tian-Shu; Chen, San-Feng

    2015-01-01

    A novel bacterial strain designated YN-59(T) was isolated from Capsicum annuum rhizosphere soil in China. The isolate was found to be aerobic, Gram-positive, rod-shaped and to form ellipsoidal or oval spores positioned centrally in swollen sporangia. On the basis of 16S rRNA gene sequence analysis, the isolated strain YN-59 was determined to be related to members of genus Cohnella. High levels of 16S rRNA gene sequence similarity were found between strain YN-59 and Cohnella plantaginis DSM 25424(T) (98.5 %) and Cohnella ginsengisoli DSM18997(T) (97.3 %); the 16S rRNA gene sequence similarities between strain YN-59 and the other strains recognized members of the genus Cohnella were below 97 %. The DNA-DNA hybridization values of strain YN-59 with C. plantaginis DSM 25424(T) and C. ginsengisoli DSM18997(T) were 44.2 ± 8.4 and 28.8 ± 5.8 %, respectively. The DNA G + C content of strain YN-59(T) was determined to be 59.32 mol %. The major isoprenoid quinone was identified as MK-7 and the predominant fatty acids as anteiso-C15:0 (45.32 %), iso-C16:0 (19.19 %), iso-C15:0 (9.65 %) and C16:0 (8.91 %). The polar lipids of strain YN-59(T) were found to consist of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol; several unidentified phospholipids were also detected. The diagnostic diamino acid in the cell wall was identified as meso-diaminopimelic. On the basis of its phenotypic and genotypic characteristics and levels of DNA-DNA hybridization, strain YN-59(T) is considered to represent a novel species of the genus Cohnella, for which the name Cohnella capsici sp. nov. (type strain YN-59(T) = CGMCC 1.12046(T) = JCM 19168(T)) is proposed.

  20. 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

  1. 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

  2. Phytophthora have distinct endogenous small RNA populations that include short interfering and microRNAs.

    Directory of Open Access Journals (Sweden)

    Noah Fahlgren

    Full Text Available In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. Each species produces two distinct populations of small RNAs that are predominantly 21- or 25-nucleotides long. The 25-nucleotide small RNAs were primarily derived from loci encoding transposable elements and we propose that these small RNAs define a pathway of short-interfering RNAs that silence repetitive genetic elements. The 21-nucleotide small RNAs were primarily derived from inverted repeats, including a novel microRNA family that is conserved among the three species, and several gene families, including Crinkler effectors and type III fibronectins. The Phytophthora microRNA is predicted to target a family of amino acid/auxin permeases, and we propose that 21-nucleotide small RNAs function at the post-transcriptional level. The functional significance of microRNA-guided regulation of amino acid/auxin permeases and the association of 21-nucleotide small RNAs with Crinkler effectors remains unclear, but this work provides a framework for testing the role of small RNAs in Phytophthora biology and pathogenesis in future work.

  3. Phytophthora have distinct endogenous small RNA populations that include short interfering and microRNAs.

    Science.gov (United States)

    Fahlgren, Noah; Bollmann, Stephanie R; Kasschau, Kristin D; Cuperus, Josh T; Press, Caroline M; Sullivan, Christopher M; Chapman, Elisabeth J; Hoyer, J Steen; Gilbert, Kerrigan B; Grünwald, Niklaus J; Carrington, James C

    2013-01-01

    In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. Each species produces two distinct populations of small RNAs that are predominantly 21- or 25-nucleotides long. The 25-nucleotide small RNAs were primarily derived from loci encoding transposable elements and we propose that these small RNAs define a pathway of short-interfering RNAs that silence repetitive genetic elements. The 21-nucleotide small RNAs were primarily derived from inverted repeats, including a novel microRNA family that is conserved among the three species, and several gene families, including Crinkler effectors and type III fibronectins. The Phytophthora microRNA is predicted to target a family of amino acid/auxin permeases, and we propose that 21-nucleotide small RNAs function at the post-transcriptional level. The functional significance of microRNA-guided regulation of amino acid/auxin permeases and the association of 21-nucleotide small RNAs with Crinkler effectors remains unclear, but this work provides a framework for testing the role of small RNAs in Phytophthora biology and pathogenesis in future work.

  4. 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.

  5. Analysis on Genotypic Differentiation of Phytophthora infestans by Using Random Amplified Polymorphic DNA (RAPD)

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A total of 104 isolates including two Korean isolates and three Japanese isolates of Phytophthora infestans collected from Heilongjiang and Jilin Provinces from 2006 to 2008 were used to determine their mating types,metalaxyl resistance,and RAPD genotypes.All the isolates of P.infestans collected from Heilongjiang and Jilin Provinces belonged to A 1 mating type,and no A 2 mating type was detected.Frequencies of metalaxyl resistant isolates were 94.4%,47.8% and 75.0% in 2006,2007 and 2008,respectively.Accord...

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

    Directory of Open Access Journals (Sweden)

    Leszek B. Orlikowski

    2014-08-01

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

  7. Phytophthora tropicalis on Hedera helix and Epipremnum aureum in Polish greenhouses.

    Science.gov (United States)

    Orlikowski, L B; Trzewik, A; Wiejacha, K

    2006-01-01

    Phytophthora tropicalis was isolated from Hedera helix and Epipremnum aureum showing discoloration of leaves, necrosis of shoot base, spread upwards and on roots. The species was detected from 7/8 plants of Hedera and 3/4 of Epipremnum. Additionally Botrytis cinerea, Fusarium avenaceum and Rhizoctonia solani were recovered from some of diseased plants. P. tropicalis caused leaf necrosis of 13 plant species and tomato seedlings. The quickest spread of necrosis was observed on leaves of Peperomia magnoliaefolia, Pelargonium zonale and Phalaenopsis x hybridum. The disease developed at temperature ranged from 10 degrees to 32.5 degrees C with optimum 30 degrees C.

  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. 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

    Eight genes that are upregulated during sexual development in the heterothallic oomycete, Phytophthora infestans, were identified by suppression subtractive hybridization. Two genes showed very low but detectable expression in vegetative hyphae and became induced about 40- to >100-fold early...... in mating, before gametangial initials appeared. The remaining six loci were not induced until later in mating, coincident with the formation of gametangia and oospores, with induction levels ranging from 60- to >100-fold. Five genes were single copy, and three were members of families. Sequence analysis...

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  11. 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

  12. Assessment of SIMBLIGHT1, SIMPHYT1, and NOBLIGHT models for predicting Phytophthora infestans in the northeastern U.S.

    Science.gov (United States)

    Accurate prediction of Phytophthora infestans outbreaks is crucial for effective late blight management. The SIMBLIGHT1, SIMPHYT1, and modified SIMPHYT1 models were assessed for predicting late blight outbreaks relative to the NOBLIGHT model using climatic data from field experiments at Presque Isle...

  13. Genetic variation within clonal lineages of Phytophthora infestans revealed through genotyping-by-sequencing, and implications for late blight epidemiology

    Science.gov (United States)

    Genotyping-by-sequencing (GBS) was performed on 257 Phytophthora infestans isolates belonging to four clonal lineages to study within-lineage diversity. The four lineages used in the study included US-8 (n=28), US-11 (n=27), US-23 (n=166), and US-24 (n=36), with isolates originating from 23 of the U...

  14. Effectiveness of SIMBLIGHT1 and SIMPHYT1 models for predicting Phytophthora infestans in the Northeastern United States

    Science.gov (United States)

    Accurate prediction of Phytophthora infestans outbreaks is crucial for effective late blight management. The SIMBLIGHT1, SIMPHYT1, and modified SIMPHYT1 models were assessed for predicting late blight outbreaks relative to the NOBLIGHT model using climatic data from field experiments at Presque Isle...

  15. Fungicide sensitivity of US genotypes of Phytophthora infestans (Mont.) de Bary to six oomycete-targeted compounds.

    Science.gov (United States)

    Phytophthora infestans (Mont.) de Bary causes potato late blight, an important and costly disease of potato and tomato crops. The baseline sensitivity of recent clonal lineages of P. infestans was tested for six oomycete-targeted fungicides. Forty five isolates collected between 2004 and 2012 were t...

  16. Determination of virulence contributions from Phytophthora infestans effectors IPI-O1 and IPI-O4

    Science.gov (United States)

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

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

    Science.gov (United States)

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

  18. 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. Pyrosequencing as a tool for the detection of Phytophthora species: error rate and risk of false Molecular Operational Taxonomic Units

    NARCIS (Netherlands)

    Vettraino, A.M.; Bonants, P.J.M.; Tomassini, A.; Bruni, N.; Vannini, A.

    2012-01-01

    Aims: To evaluate the accuracy of pyrosequencing for the description of Phytophthora communities in terms of taxa identification and risk of assignment for false Molecular Operational Taxonomic Units (MOTUs). Methods and Results: Pyrosequencing of Internal Transcribed Spacer 1 (ITS1) amplicons was u

  20. 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

  1. COST action FP801- established and emerging Phytophthora: incresasing threats to woodland and forest ecosystems in Europe

    NARCIS (Netherlands)

    Woodward, S.; Vannini, A.; Werres, S.; Osswald, W.; Bonants, P.J.M.; Jung, T.

    2011-01-01

    With the rapidly growing international trade in plants and ongoing impacts of climate change, impacts of plant pathogens in the genus Phytophthora are increasing, threatening the biodiversity and sustainability of European forest ecosystems. Through the European Cooperation in Science and Technology

  2. Formation, production and viability of oospores of Phytophthora infestans from potato and Solanum demissum in the Toluca Valley, central Mexico

    NARCIS (Netherlands)

    Flier, W.G.; Grünwald, N.J.; Fry, W.E.; Turkensteen, L.J.

    2001-01-01

    Aspects of the ecology of oospores of Phytophthora infestans were studied in the highlands of central Mexico. From an investigation of a random sample of strains, it was found that isolates differed in their average capability to form oospores when engaged in compatible pairings. Most crosses produc

  3. Downstream targets of the Phytophthora infestans G alpha subunit PiGPA1 revealed by cDNA-AFLP

    NARCIS (Netherlands)

    Dong, W.; Latijnhouwers, M.; Jiang, R.H.Y.; Meijer, H.J.G.; Govers, F.

    2004-01-01

    In many plant pathogens heterotrimeric G-proteins are essential signalling components involved in development and pathogenicity. In the late blight oomycete pathogen Phytophthora infestans the G-protein (x subunit PiGPA1 controls zoospore motility and is required for virulence. To identify G-protein

  4. 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...

  5. Gene duplication and fragment recombination drive functional diversification of a superfamily of cytoplasmic effectors in Phytophthora sojae.

    Science.gov (United States)

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

    2013-01-01

    Phytophthora and other oomycetes secrete a large number of putative host cytoplasmic effectors with conserved FLAK motifs following signal peptides, termed crinkling and necrosis inducing proteins (CRN), or Crinkler. Here, we first investigated the evolutionary patterns and mechanisms of CRN effectors in Phytophthora sojae and compared them to two other Phytophthora species. The genes encoding CRN effectors could be divided into 45 orthologous gene groups (OGG), and most OGGs unequally distributed in the three species, in which each underwent large number of gene gains or losses, indicating that the CRN genes expanded after species evolution in Phytophthora and evolved through pathoadaptation. The 134 expanded genes in P. sojae encoded family proteins including 82 functional genes and expressed at higher levels while the other 68 genes encoding orphan proteins were less expressed and contained 50 pseudogenes. Furthermore, we demonstrated that most expanded genes underwent gene duplication or/and fragment recombination. Three different mechanisms that drove gene duplication or recombination were identified. Finally, the expanded CRN effectors exhibited varying pathogenic functions, including induction of programmed cell death (PCD) and suppression of PCD through PAMP-triggered immunity or/and effector-triggered immunity. Overall, these results suggest that gene duplication and fragment recombination may be two mechanisms that drive the expansion and neofunctionalization of the CRN family in P. sojae, which aids in understanding the roles of CRN effectors within each oomycete pathogen.

  6. 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...

  7. Effect of cultural practices and fungicide treatments on the severity of Phytophthora root rot of blueberries grown in Mississippi

    Science.gov (United States)

    Phytophthora root rot is an important disease of blueberries, especially those grown in areas with poor drainage. Reliable cultural and chemical management strategies are needed for control of this disease. Two studies were conducted to evaluate the effects of cultural practices and fungicide treat...

  8. A review of research advances in Phytophthora boehmeriae%苎麻疫霉研究进展

    Institute of Scientific and Technical Information of China (English)

    高智谋

    2007-01-01

    In this paper, the advances in the study on Phytophthora boehmeriae,including geographical distribution, host range, morphology, biology, ecology, detection, control etc,are reviewed to provide a useful information for the integrated management of the diseases caused by the oomycete and for the related research.

  9. Phytophthora species recovered from irrigation reservoirs in Mississippi and Alabama nurseries and pathogenicity of three new species

    Science.gov (United States)

    From a survey of containment ponds for Phytophthora spp. at one nursery each in Alabama and Mississippi, eight species and one taxon were recovered with P. gonapodyides dominant in cooler months and P. hydropathica in warmer months, accounting for 39.6% and 46.6% overall recovery, respectively. Amo...

  10. First report of the EU1 clonal lineage of Phytophthora ramorum on tanoak in an Oregon forest

    Science.gov (United States)

    Initially reported in California as the causal agent of sudden oak death (SOD), efforts to limit spread of Phytophthora ramorum in Oregon natural forests have concentrated on quarantine regulations and eradication of the pathogen from infested areas. P. ramorum has four clonal lineages NA1, NA2, EU1...

  11. Gene duplication and fragment recombination drive functional diversification of a superfamily of cytoplasmic effectors in Phytophthora sojae.

    Directory of Open Access Journals (Sweden)

    Danyu Shen

    Full Text Available Phytophthora and other oomycetes secrete a large number of putative host cytoplasmic effectors with conserved FLAK motifs following signal peptides, termed crinkling and necrosis inducing proteins (CRN, or Crinkler. Here, we first investigated the evolutionary patterns and mechanisms of CRN effectors in Phytophthora sojae and compared them to two other Phytophthora species. The genes encoding CRN effectors could be divided into 45 orthologous gene groups (OGG, and most OGGs unequally distributed in the three species, in which each underwent large number of gene gains or losses, indicating that the CRN genes expanded after species evolution in Phytophthora and evolved through pathoadaptation. The 134 expanded genes in P. sojae encoded family proteins including 82 functional genes and expressed at higher levels while the other 68 genes encoding orphan proteins were less expressed and contained 50 pseudogenes. Furthermore, we demonstrated that most expanded genes underwent gene duplication or/and fragment recombination. Three different mechanisms that drove gene duplication or recombination were identified. Finally, the expanded CRN effectors exhibited varying pathogenic functions, including induction of programmed cell death (PCD and suppression of PCD through PAMP-triggered immunity or/and effector-triggered immunity. Overall, these results suggest that gene duplication and fragment recombination may be two mechanisms that drive the expansion and neofunctionalization of the CRN family in P. sojae, which aids in understanding the roles of CRN effectors within each oomycete pathogen.

  12. 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

  13. Phytophthora infestans isolates lacking class I ipiO variants are virulent on Rpi-blb1 potato

    NARCIS (Netherlands)

    Champouret, N.; Bouwmeester, K.; Rietman, H.; Lee, van der T.; Maliepaard, C.A.; Heupink, A.; Vondervoort, van de P.J.I.; Jacobsen, E.; Visser, R.G.F.; Vossen, van der E.A.G.; Govers, F.; Vleeshouwers, V.G.A.A.

    2009-01-01

    A strategy to control the devastating late blight disease is providing potato cultivars with genes that are effective in resistance to a broad spectrum of Phytophthora infestans isolates. Thus far, most late blight resistance (R) genes that were introgressed in potato were quickly defeated. In contr

  14. 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

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

    Science.gov (United States)

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

  16. Large-scale gene discovery in the oomycete Phytophthora infestans reveals likely components of phytopathogenicity shared with true fungi

    NARCIS (Netherlands)

    Randall, T.A.; Dwyer, R.A.; Huitema, E.; Beyer, K.; Cvitanich, C.; Kelkar, H.; Ah Fong, A.M.V.; Gates, K.; Roberts, S.; Yatzkan, E.; Gaffney, T.; Law, M.; Testa, A.; Torto-Alalibo, T.; Zhang Meng,; Zheng Li,; Mueller, E.; Windass, J.; Binder, A.; Birch, P.R.J.; Gisi, U.; Govers, F.; Gow, N.A.; Mauch, F.; West, van P.; Waugh, M.E.; Yu Jun,; Boller, T.; Kamoun, S.; Lam, S.T.; Judelson, H.S.

    2005-01-01

    o overview the gene content of the important pathogen Phytophthora infestans, large-scale cDNA and genomic sequencing was performed. A set of 75,757 high-quality expressed sequence tags (ESTs) from P. infestans was obtained from 20 cDNA libraries representing a broad range of growth conditions, stre

  17. 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

  18. 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...

  19. 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.

  20. 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...

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2015-04-01

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

  3. Efficacy of Chaetomium Species as Biological Control Agents against Phytophthora nicotianae Root Rot in Citrus.

    Science.gov (United States)

    Hung, Phung Manh; Wattanachai, Pongnak; Kasem, Soytong; Poeaim, Supattra

    2015-09-01

    Thailand is one of the largest citrus producers in Southeast Asia. Pathogenic infection by Phytophthora, however, has become one of major impediments to production. This study identified a pathogenic oomycete isolated from rotted roots of pomelo (Citrus maxima) in Thailand as Phytophthora nicotianae by the internal transcribed spacer ribosomal DNA sequence analysis. Then, we examined the in vitro and in vivo effects of Chaetomium globosum, Chaetomium lucknowense, Chaetomium cupreum and their crude extracts as biological control agents in controlling this P. nicotianae strain. Represent as antagonists in biculture test, the tested Chaetomium species inhibited mycelial growth by 50~56% and parasitized the hyphae, resulting in degradation of P. nicotianae mycelia after 30 days. The crude extracts of these Chaetomium species exhibited antifungal activities against mycelial growth of P. nicotianae, with effective doses of 2.6~101.4 µg/mL. Under greenhouse conditions, application of spores and methanol extracts of these Chaetomium species to pomelo seedlings inoculated with P. nicotianae reduced root rot by 66~71% and increased plant weight by 72~85% compared to that in the control. The method of application of antagonistic spores to control the disease was simple and economical, and it may thus be applicable for large-scale, highly effective biological control of this pathogen.

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

    Science.gov (United States)

    MigdaŁ, Wojciech; Orlikowski, Leszek B.; Ptaszek, Magdalena; Gryczka, Urszula

    2012-08-01

    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.

  5. 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

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

    DEFF Research Database (Denmark)

    Martin, Michael David; Garrett Vieira, Filipe Jorge; Ho, Simon Y. W.;

    2016-01-01

    sequences, four of which represent a previously unknown basal lineage of P. infestans closely related to the famine-era lineage. Our analyses further reveal that clonal lineages of both P. andina and historical P. infestans diverged earlier than modern Mexican lineages, casting doubt on recent claims...... of a Mexican center of origin. Finally, we use haplotype phasing to demonstrate that basal branches of the clade comprising Mexican samples are occupied by clonal isolates collected from wild Solanum hosts, suggesting that modern Mexican P. infestans diversified on Solanum tuberosum after a host jump from...

  7. Phylogenetic relationships of Phytophthora andina, a new species from the highlands of Ecuador that is closely related to the Irish potato famine pathogen Phytophthora infestans.

    Science.gov (United States)

    Gómez-Alpizar, Luis; Hu, Chia-Hui; Oliva, Ricardo; Forbes, Gregory; Ristaino, Jean Beagle

    2008-01-01

    Phylogenetic relationships of Phytophthora infestans sensu lato in the Andean highlands of South America were examined. Three clonal lineages (US-1, EC-1, EC-3) and one heterogeneous lineage (EC-2) were found in association with different host species in genus Solanum. The EC-2 lineage includes two mitochondrial (mtDNA) haplotypes, Ia and Ic. Isolates of P. infestans sensu lato EC-2 fit the morphological description of P. infestans but are different from any genotypes of P. infestans described to date. All isolates of P. infestans sensu lato from Ecuador were amplified by a P. infestans specific primer (PINF), and restriction fragment length patterns were identical in isolates amplified with ITS primers 4 and 5. The EC-1 clonal lineage of P. infestans sensu lato from S. andreanum, S. columbianum, S. paucijugum, S. phureja, S. regularifolium, S. tuberosum and S. tuquerense was confirmed to be P. infestans based on sequences of the cytochrome oxidase I (cox I) gene and intron 1 of ras gene. The EC-2 isolates with the Ic haplotype formed a distinct branch in the same clade with P. infestans and P. mirabilis, P. phaseoli and P. ipomoeae for both cox I and ras intron 1 phylogenies and were identified as the newly described species P. andina. Ras intron 1 sequence data suggests that P. andina might have arisen via hybridization between P. infestans and P. mirabilis.

  8. High genotypic diversity found among population of Phytophthora infestans collected in Estonia.

    Science.gov (United States)

    Runno-Paurson, Eve; Kiiker, Riinu; Joutsjoki, Tiina; Hannukkala, Asko

    2016-03-01

    Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is one of the most important diseases of potato worldwide. This is the first study characterising Estonian P. infestans population using the SSR marker genotyping method. 70 P. infestans isolates collected during the growing season in 2004 from eight potato fields in three different regions of Estonia were characterised with nine polymorphic SSR markers. A1 and A2 mating type isolates were detected from every studied field indicating the high potential for sexual reproduction, which raises the genotypic diversity in P. infestans population. Results revealed highly diverse P. infestans population in Estonia resembling the Northern European populations. Most of the multilocus genotypes were detected only once among the collected isolates. Subpopulations collected from different geographical regions of Estonia showed no differentiation from each other but instead formed one highly diverse group.

  9. 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.

  10. Studies on the occurrence and colonisation of plants by Phytophthora ramorum in Poland

    Directory of Open Access Journals (Sweden)

    Leszek Orlikowski

    2014-08-01

    Full Text Available Occurrence of Phytophthora ramorum on Rhododendron, Vaccinium, Viburnum and Quercus species in ornamental nurseris and fores stands in 2001-2002 and necrosis spead on plant parts and seedlings wewe studied. Only P. citricola was isolated from Rhododendron spp. and V.vitis-idaea. Shoot necrosis and dieback symptoms were not observed on Viburnum species in surveyed nurseries. From diseased Quercus trunks among others Armillaria spp. and Fusarium spp. were isolated. Inoculation of leaves and stem parts of Rhododendron cultivars and other ericaceous plants with P. ramorum resulted in the development of leaf and stem rot. The species caused stem necrosis of Fagus sylvatica, Q. rubra and Pseudotsuga menziesii but symptoms developed slowly.

  11. Comparative structural and functional analysis of genes encoding pectin methylesterases in Phytophthora spp.

    Science.gov (United States)

    Mingora, Christina; Ewer, Jason; Ospina-Giraldo, Manuel

    2014-03-15

    We have scanned the Phytophthora infestans, P. ramorum, and P. sojae genomes for the presence of putative pectin methylesterase genes and conducted a sequence analysis of all gene models found. We also searched for potential regulatory motifs in the promoter region of the proposed P. infestans models, and investigated the gene expression levels throughout the course of P. infestans infection on potato plants, using in planta and detached leaf assays. We found that genes located on contiguous chromosomal regions contain similar motifs in the promoter region, indicating the possibility of a shared regulatory mechanism. Results of our investigations also suggest that, during the pathogenicity process, the expression levels of some of the analyzed genes vary considerably when compared to basal expression observed in in vitro cultures of non-sporulating mycelium. These results were observed both in planta and in detached leaf assays.

  12. 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

    -parametric test. The potato genotypes were tested in seven experiments over two years in the vicinity of Comas, Peru, an area used by the International potato Center to screen for resistance to late blight. Results of the two analyses generally correlated and indicated that quantitative resistance to P. infestans......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...... yearly means of the relative area under the disease progress curve (rAUDPC), genotypes could be assigned to one of three resistance categories, resistant, moderately resistant or Susceptible, but the need for a more readily applicable and truly quantitative scale for resistance was noted. Based...

  13. 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.

  14. 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.

  15. General and hybrid correlation nuclear magnetic resonance analysis of phosphorus in Phytophthora palmivora.

    Science.gov (United States)

    Kirwan, Gemma M; Fernandez, David I; Niere, Julie O; Adams, Michael J

    2012-10-01

    Generalized two-dimensional (Gen2D) correlation analysis and hybrid correlation analysis have been applied to a series of dynamic (31)P nuclear magnetic resonance (NMR) spectra to monitor the in vivo metabolic changes of the plant pathogen Phytophthora palmivora in the presence and absence of phosphonate over an 18-h period. Results indicate that phosphonate exposure causes cleavage in organism polyphosphate chains as well as an increase in total sugar phosphates. In the presence of phosphonate, the NMR resonances attributed to terminal polyphosphate phosphorus reduced at a lower rate than those of middle polyphosphate phosphorus, indicating a change in average chain length and suggesting cleavage in the middle of the chain as well as at the ends. The correlation analysis techniques serve to identify and confirm spectral regions undergoing major change in the time-series data and facilitate the analysis of these dynamic changes.

  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. 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.

  18. The Plant Membrane-Associated REMORIN1.3 Accumulates in Discrete Perihaustorial Domains and Enhances Susceptibility to Phytophthora infestans1[W

    Science.gov (United States)

    Bozkurt, Tolga O.; Richardson, Annis; Dagdas, Yasin F.; Mongrand, Sébastien; Kamoun, Sophien; Raffaele, Sylvain

    2014-01-01

    Filamentous pathogens such as the oomycete Phytophthora infestans infect plants by developing specialized structures termed haustoria inside the host cells. Haustoria are thought to enable the secretion of effector proteins into the plant cells. Haustorium biogenesis, therefore, is critical for pathogen accommodation in the host tissue. Haustoria are enveloped by a specialized host-derived membrane, the extrahaustorial membrane (EHM), which is distinct from the plant plasma membrane. The mechanisms underlying the biogenesis of the EHM are unknown. Remarkably, several plasma membrane-localized proteins are excluded from the EHM, but the remorin REM1.3 accumulates around P. infestans haustoria. Here, we used overexpression, colocalization with reporter proteins, and superresolution microscopy in cells infected by P. infestans to reveal discrete EHM domains labeled by REM1.3 and the P. infestans effector AVRblb2. Moreover, SYNAPTOTAGMIN1, another previously identified perihaustorial protein, localized to subdomains that are mainly not labeled by REM1.3 and AVRblb2. Functional characterization of REM1.3 revealed that it is a susceptibility factor that promotes infection by P. infestans. This activity, and REM1.3 recruitment to the EHM, require the REM1.3 membrane-binding domain. Our results implicate REM1.3 membrane microdomains in plant susceptibility to an oomycete pathogen. PMID:24808104

  19. 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.

  20. Spatial Analysis of Phytophthora infestans Genotypes and Late Blight Severity on Tomato and Potato in the Del Fuerte Valley Using Geostatistics and Geographic Information Systems.

    Science.gov (United States)

    Jaime-Garcia, R; Orum, T V; Felix-Gastelum, R; Trinidad-Correa, R; Vanetten, H D; Nelson, M R

    2001-12-01

    ABSTRACT Genetic structure of Phytophthora infestans, the causal agent of potato and tomato late blight, was analyzed spatially in a mixed potato and tomato production area in the Del Fuerte Valley, Sinaloa, Mexico. Isolates of P. infestans were characterized by mating type, allozyme analysis at the glucose-6-phosphate isomerase and peptidase loci, restriction fragment length polymorphism with probe RG57, metalaxyl sensitivity, and aggressiveness to tomato and potato. Spatial patterns of P. infestans genotypes were analyzed by geographical information systems and geo-statistics during the seasons of 1994-95, 1995-96, and 1996-97. Spatial analysis of the genetic structure of P. infestans indicates that geographic substructuring of this pathogen occurs in this area. Maps displaying the probabilities of occurrence of mating types and genotypes of P. infestans, and of disease severity at a regional scale, were presented. Some genotypes that exhibited differences in epidemiologically important features such as metalaxyl sensitivity and aggressiveness to tomato and potato had a restricted spread and were localized in isolated areas. Analysis of late blight severity showed recurring patterns, such as the earliest onset of the disease in the area where both potato and tomato were growing, strengthening the hypothesis that infected potato tubers are the main source of primary inoculum. The information that geostatistical analysis provides might help improve management programs for late blight in the Del Fuerte Valley.

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

    Science.gov (United States)

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

    2014-09-26

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

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

    Directory of Open Access Journals (Sweden)

    Guillaume Saubeau

    2014-09-01

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

  3. The tRNA-Derived Small RNAs Regulate Gene Expression through Triggering Sequence-Specific Degradation of Target Transcripts in the Oomycete Pathogen Phytophthora sojae

    Science.gov (United States)

    Wang, Qinhu; Li, Tingting; Xu, Ke; Zhang, Wei; Wang, Xiaolong; Quan, Junli; Jin, Weibo; Zhang, Meixiang; Fan, Guangjin; Wang, Ming-Bo; Shan, Weixing

    2016-01-01

    Along with the well-studied microRNA (miRNA) and small interfering RNA (siRNA) is a new class of transfer RNA-derived small RNA (tsRNA), which has recently been detected in multiple organisms and is implicated in gene regulation. However, while miRNAs and siRNAs are known to repress gene expression through sequence-specific RNA cleavage or translational repression, how tsRNAs regulate gene expression remains unclear. Here we report the identification and functional characterization of tsRNAs in the oomycete pathogen Phytophthora sojae. We show that multiple tRNAs are processed into abundant tsRNAs, which accumulate in a similar developmental stage-specific manner and are negatively correlated with the expression of predicted target genes. Degradome sequencing and 5′ RLM RACE experiments indicate tsRNAs can trigger degradation of target transcripts. Transient expression assays using GUS sensor constructs confirmed the requirement of sequence complementarity in tsRNA-mediated RNA degradation in P. sojae. Our results show that the tsRNA are a class of functional endogenous sRNAs and suggest that tsRNA regulate gene expression through inducing sequence-specific degradation of target RNAs in oomycetes. PMID:28066490

  4. Down-regulation of defense genes and resource allocation into infected roots as factors for compatibility between Fagus sylvatica and Phytophthora citricola.

    Science.gov (United States)

    Schlink, Katja

    2010-05-01

    Phytophthora citricola is a wide spread and highly aggressive pathogen of Fagus sylvatica. The hemibiotrophic oomycete infects the roots and establishes a compatible interaction with F. sylvatica. To investigate the transcriptional changes associated with P. citricola infection, 68 custom oligo-microarray measurements were conducted. Hierarchical as well as non-hierarchical clustering was carried out to analyze the expression profiles. Experimental setup includes a time scale covering the biotrophic and necrotrophic stages of interaction as well as comparative analyses of the local and systemic responses. The local reaction of F. sylvatica is characterized by a striking lack of defense gene induction leading to the conclusion that P. citricola escapes the main recognition systems and/or suppresses the host's response. The analysis of the systemic reaction revealed a massive shift in gene expression patterns during the biotrophic phase that is interpreted as evidence of resource allocation into the roots to support the increased sink caused by pathogen growth. Defense genes known to be responsive to salicylic acid (effective against biotrophs), jasmonic acid, and ethylene (effective against necrotrophs and herbivores) are represented on the arrays. All significant changes in gene expression measured for salicylic acid responsive genes were down-regulations in roots and leaves while some jasmonic acid responsive genes showed a very late up-regulation only in leaves, probably caused by the desiccation shortly before plant death. Together, these expression changes could explain the success of the pathogen.

  5. 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.

  6. Heterokaryotic nuclear conditions and a heterogeneous nuclear population are observed by flow cytometry in Phytophthora infestans.

    Science.gov (United States)

    Catal, Mursel; King, Louis; Tumbalam, Pavani; Wiriyajitsomboon, Prissana; Kirk, William W; Adams, Gerard C

    2010-08-01

    A simple and reliable method for preparation of whole nuclei of a common oomycete, Phytophthora infestans, is described for laser flow cytometry. The ease of preparation, the absence of detectable debris and aggregates, and the precision in determinations of DNA content per nucleus improve interpretation and understanding of the genetics of the organism. Phytophthora infestans is the pathogen that causes potato and tomato late blight. The genetic flexibility of P. infestans and other oomycete pathogens has complicated understanding of the mechanisms of variation contributing to shifts in race structure and virulence profiles on important agricultural crops. Significant phenotypic and genotypic changes are being reported in the apparent absence of sexual recombination in the field. Laser flow cytometry with propidium iodide is useful in investigating the nuclear condition of the somatic colony of field strains of P. infestans. The majority of the studied strains contain a single population of nuclei in nonreplicated diplophase. However, mean DNA content per nucleus varies considerably among isolates confirming the heterogeneity of the nuclear population in regard to C-value, for field isolates. Nuclear DNA content varies from 1.75x to 0.75x that of nuclei in a standard strain from central Mexico. Some strains contain two to three populations of nuclei with differing DNA contents in the mycelium and are heterokaryons. Such a range in DNA content suggests DNA-aneuploidy, but direct confirmation of aneuploidy will require microscopy of chromosomes. Heterokaryosis and populations of nuclei of differing DNA content necessarily confound standardized assays used worldwide in crop breeding programs for determination of race profiles and virulence phenotypes of this important pathogen.

  7. Modeling climate impact on an emerging disease, the Phytophthora alni-induced alder decline.

    Science.gov (United States)

    Aguayo, Jaime; Elegbede, Fabrice; Husson, Claude; Saintonge, François-Xavier; Marçais, Benoît

    2014-10-01

    Alder decline caused by Phytophthora alni is one of the most important emerging diseases in natural ecosystems in Europe, where it has threatened riparian ecosystems for the past 20 years. Environmental factors, such as mean site temperature and soil characteristics, play an important role in the occurrence of the disease. The objective of the present work was to model and forecast the effect of environment on the severity of alder Phytophthora outbreaks, and to determine whether recent climate change might explain the disease emergence. Two alder sites networks in NE and SW France were surveyed to assess the crown health of trees; the oomycete soil inoculum was also monitored in the NE network. The main factors explaining the temporal annual variation in alder crown decline or crown recovery were the mean previous winter and previous summer temperatures. Both low winter temperatures and high summer temperatures were unfavorable to the disease. Cold winters promoted tree recovery because of poor survival of the pathogen, while hot summer temperature limited the incidence of tree decline. An SIS model explaining the dynamics of the P. alni-induced alder decline was developed using the data of the NE site network and validated using the SW site network. This model was then used to simulate the frequency of declining alder over time with historical climate data. The last 40 years' weather conditions have been generally favorable to the establishment of the disease, indicating that others factors may be implicated in its emergence. The model, however, showed that the climate of SW France was much more favorable for the disease than that of the Northeast, because it seldom limited the overwintering of the pathogen. Depending on the European area, climate change could either enhance or decrease the severity of the alder decline.

  8. Abscisic acid in salt stress predisposition to phytophthora root and crown rot in tomato and chrysanthemum.

    Science.gov (United States)

    Dileo, Matthew V; Pye, Matthew F; Roubtsova, Tatiana V; Duniway, John M; Macdonald, James D; Rizzo, David M; Bostock, Richard M

    2010-09-01

    Plants respond to changes in the environment with complex signaling networks, often under control of phytohormones that generate positive and negative crosstalk among downstream effectors of the response. Accordingly, brief dehydration stresses such as salinity and water deficit, which induce a rapid and transient systemic increase in levels of abscisic acid (ABA), can influence disease response pathways. ABA has been associated with susceptibility of plants to bacteria, fungi, and oomycetes but relatively little attention has been directed at its role in abiotic stress predisposition to root pathogens. This study examines the impact of brief salinity stress on infection of tomato and chrysanthemum roots by Phytophthora spp. Roots of plants in hydroponic culture exposed to a brief episode of salt (sodium chloride) stress prior to or after inoculation were severely diseased relative to nonstressed plants. Tomato roots remained in a predisposed state up to 24 h following removal from the stress. An increase in root ABA levels in tomato preceded or temporally paralleled the onset of stress-induced susceptibility, with levels declining in roots prior to recovery from the predisposed state. Exogenous ABA could substitute for salt stress and significantly enhanced pathogen colonization and disease development. ABA-deficient tomato mutants lacked the predisposition response, which could be restored by complementation of the mutant with exogenous ABA. In contrast, ethylene, which exacerbates disease symptoms in some host-parasite interactions, did not appear to contribute to the predisposition response. Thus, several lines of evidence support ABA as a critical and dominant factor in the salinity-induced predisposition to Phytophthora spp. infection.

  9. 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...... research on P. ramorum across Europe. Regulatory work should keep updated with research results on P. ramorum and further development of the Japanese larch outbreaks....

  10. 疫霉菌无毒基因研究进展%Research progress in phytophthora avirulence gene

    Institute of Scientific and Technical Information of China (English)

    崔林开; 胡艳红; 李永丽

    2012-01-01

    The interaction between pathogen avirulence gene and plant resistance gene follows the gene-for-gene model. Many avirulence genes of phytophthora have been cloned in recent years. In this paper, the plant immune system and the interaction model between avirulence genes and resistance genes were introduced. The basic structure of phytophthora avirulence gene and the function of each part were described in detail. Based on the sequence polymorphism of the avirulence genes, the mechanism for virulence variation in phytophthora were elucidated, and the critical functional sites of phytophthora avirulence gene were emphatically expounded as well.%病原菌的无毒基因与寄主植物的抗病基因之间的互作符合“基因对基因假说”,产生的抗性是植物抗病性的重要形式.近几年,多个疫霉菌的无毒基因被快速克隆出来,使我们对疫霉菌的无毒基因有了较深入的认识.本研究介绍了植物的免疫系统与无毒基因和抗病基因之间的互作模式,详细阐述了已克隆的疫霉菌无毒基因的基本结构及其各部分的功能,结合无毒基因的序列多态性阐明了疫霉菌的毒性变异机制,并对疫霉菌无毒基因关键功能位点进行分析.

  11. The Pectin Methylesterase Gene Complement of Phytophthora sojae: Structural and Functional Analyses, and the Evolutionary Relationships with Its Oomycete Homologs.

    Science.gov (United States)

    Horowitz, Brent B; Ospina-Giraldo, Manuel D

    2015-01-01

    Phytophthora sojae is an oomycete pathogen that causes the disease known as root and stem rot in soybean plants, frequently leading to massive economic damage. Additionally, P. sojae is increasingly being utilized as a model for phytopathogenic oomycete research. Despite the economic and scientific importance of P. sojae, the mechanism by which it penetrates the host roots is not yet fully understood. It has been found that oomycetes are not capable of penetrating the cell wall solely through mechanical force, suggesting that alternative factors facilitate breakdown of the host cell wall. Pectin methylesterases have been suggested to be important for Phytophthora pathogenicity, but no data exist on their role in the P. sojae infection process. We have scanned the newly revised version of the annotated P. sojae genome for the presence of putative pectin methylesterases genes and conducted a sequence analysis of all gene models found. We also searched for potential regulatory motifs in the promoter region of the proposed P. sojae models, and investigated the gene expression levels throughout the early course of infection on soybean plants. We found that P. sojae contains a large repertoire of pectin methylesterase-coding genes and that most of these genes display similar motifs in the promoter region, indicating the possibility of a shared regulatory mechanism. Phylogenetic analyses confirmed the evolutionary relatedness of the pectin methylesterase-coding genes within and across Phytophthora spp. In addition, the gene duplication events that led to the emergence of this gene family appear to have occurred prior to many speciation events in the genus Phytophthora. Our results also indicate that the highest levels of expression occurred in the first 24 hours post inoculation, with expression falling after this time. Our study provides evidence that pectin methylesterases may be important for the early action of the P. sojae infection process.

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

    Institute of Scientific and Technical Information of China (English)

    管理和

    2012-01-01

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

  13. 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.

  14. Development of alternative strategies for the control of the important phytopathogens Phytophthora infestans (Mont.) and Erwinia amylovora (Burrill)

    OpenAIRE

    2007-01-01

    Within the framework of two projects, financed by DBU (Deutsche Bundesstiftung Umwelt) and ProInno ("Förderung der Erhöhung der Innovationskompetenz mittelständischer Unternehmen"), respectively, in co-operation with an industrial partner, alternative phytosanitary compounds from natural sources have been screened. High throughput screening systems were developed and used for testing of large numbers of extracts of Actinomycetes in 96-well multiplates against Phytophthora infestans and Erwini...

  15. 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.

  16. The Arabidopsis lectin receptor kinase LecRK-I.9 enhances resistance to Phytophthora infestans in Solanaceous plants.

    Science.gov (United States)

    Bouwmeester, Klaas; Han, Miao; Blanco-Portales, Rosario; Song, Wei; Weide, Rob; Guo, Li-Yun; van der Vossen, Edwin A G; Govers, Francine

    2014-01-01

    Late blight caused by the plant pathogenic oomycete Phytophthora infestans is known as one of the most destructive potato diseases. Plant breeders tend to employ NB-LRR-based resistance for introducing genetically controlled late blight resistance in their breeding lines. However, P. infestans is able to rapidly escape this type of resistance, and hence, NB-LRR-based resistance in potato cultivars is often not durable. Previously, we identified a novel type of Phytophthora resistance in Arabidopsis. This resistance is mediated by the cell surface receptor LecRK-I.9, which belongs to the family of L-type lectin receptor kinases. In this study, we report that expression of the Arabidopsis LecRK-I.9 gene in potato and Nicotiana benthamiana results in significantly enhanced late blight resistance. Transcriptional profiling showed strong reduction in salicylic acid (SA)-mediated defence gene expression in LecRK-I.9 transgenic potato lines (TPLs). In contrast, transcripts of two protease inhibitor genes accumulated to extreme high levels, suggesting that LecRK-I.9-mediated late blight resistance is relying on a defence response that includes activation of protease inhibitors. These results demonstrate that the functionality of LecRK-I.9 in Phytophthora resistance is maintained after interfamily transfer to potato and N. benthamiana and suggest that this novel type of LecRK-based resistance can be exploited in breeding strategies to improve durable late blight resistance in Solanaceous crops.

  17. Immediate Activation of Respiration in Petroselinum crispum L. in Response to the Phytophthora megasperma f. sp. Glycinea Elicitor.

    Science.gov (United States)

    Norman, E. G.; Walton, A. B.; Turpin, D. H.

    1994-12-01

    Treatment of parsley (Petroselinum crispum L.) cell cultures with the Phytophthora megasperma elicitor isolated from the fungus Phytophthora megasperma f. sp. Glycinea caused an immediate increase in the rate of respiratory CO2 evolution in the dark. The respiratory response was biphasic, showing a rapid enhancement in the first 20 min and then a slower increase until a steady rate was attained 60 min posttreatment. The enhanced rate of CO2 evolution corresponded to the activation of phosphofructokinase and glucose-6-phosphate dehydrogenase, key enzymes in the regulation of carbohydrate flow to glycolysis and the oxidative pentose phosphate (OPP) pathway, respectively. The increased rate of CO2 evolution and the activation of phosphofructokinase and glucose-6-phosphate dehydrogenase were maintained for the duration of the experiments, indicating long-term stimulation of respiration through both glycolysis and the OPP pathway. A 23% decrease in the C6:C1 ratio of 14CO2 evolution from labeled glucose 60 min after the addition of Phytophthora megasperma elicitor is consistent with an increased contribution of the OPP pathway to cellular respiration. Long-term activation of the OPP pathway following elicitation could serve to maintain the pools of substrates necessary during activation of the shikimic acid pathway, leading to the production of defensive compounds.

  18. Efficient disruption and replacement of an effector gene in the oomycete Phytophthora sojae using CRISPR/Cas9.

    Science.gov (United States)

    Fang, Yufeng; Tyler, Brett M

    2016-01-01

    Phytophthora sojae is an oomycete pathogen of soybean. As a result of its economic importance, P. sojae has become a model for the study of oomycete genetics, physiology and pathology. The lack of efficient techniques for targeted mutagenesis and gene replacement have long hampered genetic studies of pathogenicity in Phytophthora species. Here, we describe a CRISPR/Cas9 system enabling rapid and efficient genome editing in P. sojae. Using the RXLR effector gene Avr4/6 as a target, we observed that, in the absence of a homologous template, the repair of Cas9-induced DNA double-strand breaks (DSBs) in P. sojae was mediated by non-homologous end-joining (NHEJ), primarily resulting in short indels. Most mutants were homozygous, presumably as a result of gene conversion triggered by Cas9-mediated cleavage of non-mutant alleles. When donor DNA was present, homology-directed repair (HDR) was observed, which resulted in the replacement of Avr4/6 with the NPT II gene. By testing the specific virulence of several NHEJ mutants and HDR-mediated gene replacements in soybean, we have validated the contribution of Avr4/6 to recognition by soybean R gene loci, Rps4 and Rps6, but also uncovered additional contributions to resistance by these two loci. Our results establish a powerful tool for the study of functional genomics in Phytophthora, which provides new avenues for better control of this pathogen.

  19. The Field Efficacy Trials of Trifloxystrobin · Tebuconazole 75 %WG against CoUetotrichum capsici%肟菌酯·戊唑醇75%WG防治辣椒炭疽病田间药效试验

    Institute of Scientific and Technical Information of China (English)

    张舒; 郭茂胜; 千继红; 吕亮; 常向前; 袁斌

    2011-01-01

    The field efficacy trials of Trifloxystrobin · Tebuconazole 75% WG against pepper anthracnose, Colletotrichum capsici ,were tested. The results show that the control effect against pepper anthracnose were respectively 82.3% and 89. 48% at the concentration of 225 g/ham2 at 2 days and 3 days after treatment, and Significantly better than Tebuconazole 430g/L SC, Difenoconazole 10% WP and Maneozeb 80% WP, Recommended dose was 150 -225g/hm2.%对肟菌酯·戊唑醇75%WG防治辣椒炭疽病(Colletotrichum capsici)的田间防效进行了试验。结果表明,225g/hm2肟菌酯.戊唑醇75%WG药后2d和3d对辣椒炭疽病的防治效果分别达82.3%和89.48%,显著优于对照药剂戊唑醇430g/L SC、苯醚甲环唑10%WP和代森锰锌80%WP;推荐剂量为10~15g/667m2。

  20. 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

  1. 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

  2. The Irish Potato Famine Pathogen Phytophthora infestans Translocates the CRN8 Kinase into Host Plant Cells

    Science.gov (United States)

    van Damme, Mireille; Bozkurt, Tolga O.; Cakir, Cahid; Schornack, Sebastian; Sklenar, Jan; Jones, Alexandra M. E.; Kamoun, Sophien

    2012-01-01

    Phytopathogenic oomycetes, such as Phytophthora infestans, secrete an arsenal of effector proteins that modulate plant innate immunity to enable infection. We describe CRN8, a host-translocated effector of P. infestans that has kinase activity in planta. CRN8 is a modular protein of the CRN effector family. The C-terminus of CRN8 localizes to the host nucleus and triggers cell death when the protein is expressed in planta. Cell death induction by CRN8 is dependent on its localization to the plant nucleus, which requires a functional nuclear localization signal (NLS). The C-terminal sequence of CRN8 has similarity to a serine/threonine RD kinase domain. We demonstrated that CRN8 is a functional RD kinase and that its auto-phosphorylation is dependent on an intact catalytic site. Co-immunoprecipitation experiments revealed that CRN8 forms a dimer or multimer. Heterologous expression of CRN8 in planta resulted in enhanced virulence by P. infestans. In contrast, in planta expression of the dominant-negative CRN8R469A;D470A resulted in reduced P. infestans infection, further implicating CRN8 in virulence. Overall, our results indicate that similar to animal parasites, plant pathogens also translocate biochemically active kinase effectors inside host cells. PMID:22927814

  3. Phytophthora infestans effector AVRblb2 prevents secretion of a plant immune protease at the haustorial interface

    Science.gov (United States)

    Bozkurt, Tolga O.; Schornack, Sebastian; Win, Joe; Shindo, Takayuki; Ilyas, Muhammad; Oliva, Ricardo; Cano, Liliana M.; Jones, Alexandra M. E.; Huitema, Edgar; van der Hoorn, Renier A. L.; Kamoun, Sophien

    2011-01-01

    In response to pathogen attack, plant cells secrete antimicrobial molecules at the site of infection. However, how plant pathogens interfere with defense-related focal secretion remains poorly known. Here we show that the host-translocated RXLR-type effector protein AVRblb2 of the Irish potato famine pathogen Phytophthora infestans focally accumulates around haustoria, specialized infection structures that form inside plant cells, and promotes virulence by interfering with the execution of host defenses. AVRblb2 significantly enhances susceptibility of host plants to P. infestans by targeting the host papain-like cysteine protease C14 and specifically preventing its secretion into the apoplast. Plants altered in C14 expression were significantly affected in susceptibility to P. infestans in a manner consistent with a positive role of C14 in plant immunity. Our findings point to a unique counterdefense strategy that plant pathogens use to neutralize secreted host defense proteases. Effectors, such as AVRblb2, can be used as molecular probes to dissect focal immune responses at pathogen penetration sites. PMID:22143776

  4. Multiple recognition of RXLR effectors is associated with nonhost resistance of pepper against Phytophthora infestans

    Science.gov (United States)

    Lee, Hyun-Ah; Kim, Shin-Young; Oh, Sang-Keun; Yeom, Seon-In; Kim, Saet-Byul; Kim, Myung-Shin; Kamoun, Sophien; Choi, Doil

    2014-01-01

    Nonhost resistance (NHR) is a plant immune response to resist most pathogens. The molecular basis of NHR is poorly understood, but recognition of pathogen effectors by immune receptors, a response known as effector-triggered immunity, has been proposed as a component of NHR. We performed transient expression of 54 Phytophthora infestansRXLR effectors in pepper (Capsicum annuum) accessions. We used optimized heterologous expression methods and analyzed the inheritance of effector-induced cell death in an F2 population derived from a cross between two pepper accessions. Pepper showed a localized cell death response upon inoculation with P. infestans, suggesting that recognition of effectors may contribute to NHR in this system. Pepper accessions recognized as many as 36 effectors. Among the effectors, PexRD8 and Avrblb2 induced cell death in a broad range of pepper accessions. Segregation of effector-induced cell death in an F2 population derived from a cross between two pepper accessions fit 15 : 1, 9 : 7 or 3 : 1 ratios, depending on the effector. Our genetic data suggest that a single or two independent/complementary dominant genes are involved in the recognition of RXLR effectors. Multiple loci recognizing a series of effectors may underpin NHR of pepper to P. infestans and confer resistance durability. PMID:24889686

  5. The rise and fall of the Phytophthora infestans lineage that triggered the Irish potato famine

    Science.gov (United States)

    Yoshida, Kentaro; Schuenemann, Verena J; Cano, Liliana M; Pais, Marina; Mishra, Bagdevi; Sharma, Rahul; Lanz, Chirsta; Martin, Frank N; Kamoun, Sophien; Krause, Johannes; Thines, Marco; Weigel, Detlef; Burbano, Hernán A

    2013-01-01

    Phytophthora infestans, the cause of potato late blight, is infamous for having triggered the Irish Great Famine in the 1840s. Until the late 1970s, P. infestans diversity outside of its Mexican center of origin was low, and one scenario held that a single strain, US-1, had dominated the global population for 150 years; this was later challenged based on DNA analysis of historical herbarium specimens. We have compared the genomes of 11 herbarium and 15 modern strains. We conclude that the 19th century epidemic was caused by a unique genotype, HERB-1, that persisted for over 50 years. HERB-1 is distinct from all examined modern strains, but it is a close relative of US-1, which replaced it outside of Mexico in the 20th century. We propose that HERB-1 and US-1 emerged from a metapopulation that was established in the early 1800s outside of the species' center of diversity. DOI: http://dx.doi.org/10.7554/eLife.00731.001 PMID:23741619

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

    Directory of Open Access Journals (Sweden)

    Mireille van Damme

    Full Text Available Phytopathogenic oomycetes, such as Phytophthora infestans, secrete an arsenal of effector proteins that modulate plant innate immunity to enable infection. We describe CRN8, a host-translocated effector of P. infestans that has kinase activity in planta. CRN8 is a modular protein of the CRN effector family. The C-terminus of CRN8 localizes to the host nucleus and triggers cell death when the protein is expressed in planta. Cell death induction by CRN8 is dependent on its localization to the plant nucleus, which requires a functional nuclear localization signal (NLS. The C-terminal sequence of CRN8 has similarity to a serine/threonine RD kinase domain. We demonstrated that CRN8 is a functional RD kinase and that its auto-phosphorylation is dependent on an intact catalytic site. Co-immunoprecipitation experiments revealed that CRN8 forms a dimer or multimer. Heterologous expression of CRN8 in planta resulted in enhanced virulence by P. infestans. In contrast, in planta expression of the dominant-negative CRN8(R469A;D470A resulted in reduced P. infestans infection, further implicating CRN8 in virulence. Overall, our results indicate that similar to animal parasites, plant pathogens also translocate biochemically active kinase effectors inside host cells.

  7. Genotypic diversity and migration patterns of Phytophthora infestans in the Nordic countries.

    Science.gov (United States)

    Sjöholm, Lina; Andersson, Björn; Högberg, Nils; Widmark, Anna-Karin; Yuen, Jonathan

    2013-10-01

    In this study we investigated the genotypic diversity and the migration patterns of Phytophthora infestans in the Nordic countries. Isolates of P. infestans from outbreaks in 43 fields sampled in 2008 were collected using stratified sampling with country, field, and disease foci as the different strata. Microsatellites were used as markers to determine the genotypic variation in the sampled material. The results show a high genotypic variation of P. infestans in the Nordic countries with most of the genotypes found only once among the collected isolates. The major part of the genotypic variation was observed within the fields, with low differentiation between the fields. The observed low association of alleles among loci is consistent with frequent sexual reproduction of P. infestans in the Nordic countries. Coalescence analyses did not support a single common population for the four countries, thus indicating some degree of geographic differentiation. The analyses of migration patterns showed differing levels of gene flow among the Nordic countries. No correlation between migration rates and geographical distance could be seen. This could be explained by different degrees of genetic similarity between the pathogen populations in the different countries.

  8. Methanol extract of mycelia from Phytophthora infestans-induced resistance in potato.

    Science.gov (United States)

    Monjil, Mohammad Shahjahan; Nozawa, Takeshi; Shibata, Yusuke; Takemoto, Daigo; Ojika, Makoto; Kawakita, Kazuhito

    2015-03-01

    Plants recognize certain microbial compounds as elicitors in their active defence mechanisms. It has been shown that a series of defence reactions are induced in potato plant cells after treatment with water-soluble hyphal wall components prepared from Phytophthora infestans. In this study, a methanol extract from mycelia of P. infestans (MEM), which contains lipophilic compounds, was used as another elicitor for the induction of the defence reactions in potato. MEM elicitor induced reactive oxygen species (ROS), especially O2(-) and H2O2 production, and nitric oxide (NO) generation in potato leaves and suspension-cultured cells. Hypersensitive cell death was detected in potato leaves within 6-8 h after MEM elicitor treatment. The accumulation of phytoalexins was detected by MEM elicitor treatment in potato tubers. In potato suspension-cultured cells, several defence-related genes were induced by MEM elicitors, namely Strboh, Sthsr203J, StPVS3, StPR1, and StNR5, which regulate various defence-related functions. Enhanced resistance against P. infestans was found in MEM-treated potato plants. These results suggested that MEM elicitor is recognized by host and enhances defence activities to produce substances inhibitory to pathogens.

  9. Prediction and validation of potential pathogenic microRNAs involved in Phytophthora infestans infection.

    Science.gov (United States)

    Cui, Juanjuan; Luan, Yushi; Wang, Weichen; Zhai, Junmiao

    2014-03-01

    Being one kind of approximately 22nt long small RNA, miRNA has shown its roles in host-pathogen interaction, providing one possible way for pathogen infection. Though Phytophthora infestans is a major pathogen that causes devastating late blight of potato, tomato and so on, so far there have not been any systematic researches on miRNAs and even pathogenic miRNAs in P. infestans. Here, for the first time we comprehensively predicted and identified pathogenic miRNAs that may exist in P. infestans. First, a total of 128 putative miRNAs belonging to 66 miRNA family were identified by bioinformatic approaches. Then, 33 vital pathogenic miRNAs were screened by constructing miRNA-miRNA relationship networks. Finally, four potential pathogenic miRNAs were chosen for detection, two of which are chosen for validation. The expression quantity of pi-miR466 and pi-miR1918 changed dramatically during incubation of tomato leaves, implying that they are potential pathogenic miRNAs.

  10. Comparative analysis of sterol acquisition in the oomycetes Saprolegnia parasitica and Phytophthora infestans

    Science.gov (United States)

    Dahlin, Paul; Srivastava, Vaibhav; Ekengren, Sophia; McKee, Lauren S.; Bulone, Vincent

    2017-01-01

    The oomycete class includes pathogens of animals and plants which are responsible for some of the most significant global losses in agriculture and aquaculture. There is a need to replace traditional chemical means of controlling oomycete growth with more targeted approaches, and the inhibition of sterol synthesis is one promising area. To better direct these efforts, we have studied sterol acquisition in two model organisms: the sterol-autotrophic Saprolegnia parasitica, and the sterol-heterotrophic Phytophthora infestans. We first present a comprehensive reconstruction of a likely sterol synthesis pathway for S. parasitica, causative agent of the disease saprolegniasis in fish. This pathway shows multiple potential routes of sterol synthesis, and draws on several avenues of new evidence: bioinformatic mining for genes with sterol-related functions, expression analysis of these genes, and analysis of the sterol profiles in mycelium grown in different media. Additionally, we explore the extent to which P. infestans, which causes the late blight in potato, can modify exogenously provided sterols. We consider whether the two very different approaches to sterol acquisition taken by these pathogens represent any specific survival advantages or potential drug targets. PMID:28152045

  11. Multiple recognition of RXLR effectors is associated with nonhost resistance of pepper against Phytophthora infestans.

    Science.gov (United States)

    Lee, Hyun-Ah; Kim, Shin-Young; Oh, Sang-Keun; Yeom, Seon-In; Kim, Saet-Byul; Kim, Myung-Shin; Kamoun, Sophien; Choi, Doil

    2014-08-01

    Nonhost resistance (NHR) is a plant immune response to resist most pathogens. The molecular basis of NHR is poorly understood, but recognition of pathogen effectors by immune receptors, a response known as effector-triggered immunity, has been proposed as a component of NHR. We performed transient expression of 54 Phytophthora infestansRXLR effectors in pepper (Capsicum annuum) accessions. We used optimized heterologous expression methods and analyzed the inheritance of effector-induced cell death in an F2 population derived from a cross between two pepper accessions. Pepper showed a localized cell death response upon inoculation with P. infestans, suggesting that recognition of effectors may contribute to NHR in this system. Pepper accessions recognized as many as 36 effectors. Among the effectors, PexRD8 and Avrblb2 induced cell death in a broad range of pepper accessions. Segregation of effector-induced cell death in an F2 population derived from a cross between two pepper accessions fit 15:1, 9:7 or 3:1 ratios, depending on the effector. Our genetic data suggest that a single or two independent/complementary dominant genes are involved in the recognition of RXLR effectors. Multiple loci recognizing a series of effectors may underpin NHR of pepper to P. infestans and confer resistance durability.

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

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    Liangliang Gao

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

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

    Science.gov (United States)

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

    2012-03-01

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

  14. 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.

  15. The rise and fall of the Phytophthora infestans lineage that triggered the Irish potato famine.

    Science.gov (United States)

    Yoshida, Kentaro; Schuenemann, Verena J; Cano, Liliana M; Pais, Marina; Mishra, Bagdevi; Sharma, Rahul; Lanz, Chirsta; Martin, Frank N; Kamoun, Sophien; Krause, Johannes; Thines, Marco; Weigel, Detlef; Burbano, Hernán A

    2013-05-28

    Phytophthora infestans, the cause of potato late blight, is infamous for having triggered the Irish Great Famine in the 1840s. Until the late 1970s, P. infestans diversity outside of its Mexican center of origin was low, and one scenario held that a single strain, US-1, had dominated the global population for 150 years; this was later challenged based on DNA analysis of historical herbarium specimens. We have compared the genomes of 11 herbarium and 15 modern strains. We conclude that the 19th century epidemic was caused by a unique genotype, HERB-1, that persisted for over 50 years. HERB-1 is distinct from all examined modern strains, but it is a close relative of US-1, which replaced it outside of Mexico in the 20th century. We propose that HERB-1 and US-1 emerged from a metapopulation that was established in the early 1800s outside of the species' center of diversity. DOI:http://dx.doi.org/10.7554/eLife.00731.001.

  16. Late blight (Phytophthora infestans occurring on stems - a new problem in potato crops

    Directory of Open Access Journals (Sweden)

    Józef Kapsa

    2013-12-01

    Full Text Available In recent years changes in the occurrence of the first potato late blight (Phytophthora infestans symptoms have been noted. Observations of potato crops have showed that occurrence of the blight symptoms is sometimes on the stem instead on the leaves. The aim of the study carried out in 1995-2001 was to determine occurrence and harmfulness of the stem late blight infections. Survey of many potato crops (490 potato fields made in 1997-2001, around Poland enabled assessment of the incidence of stem blight. Average 69,1% of observed crops were affected with stem blight. The stem blight incidence was not connected with the rate of the leaf form of late blight developing on the foliage. Stem form of the disease has appeared more often in the years with less rainfall during June and July. Its occurrence was influenced by micro climate inside potato canopy. Glasshouse experiments confirmed the importance of stem lesions in decreasing tuber yield (11,2-42,9% and increasing tuber infections. Results have shown that tubers contaminated with spores were the least probable source of the stem form of late blight.

  17. Screening of novel microorganisms for biosurfactant and biocontrol activity against Phytophthora infestans.

    Science.gov (United States)

    Tomar, Sonica; Singh, B P; Lal, Mehi; Ma, Khan; Hussain, Touseef; Sharma, Sanjeev; Kaushik, S K; Kumar, Satish

    2014-09-01

    In the present study, 95 isolates of bacteria were tested for their biosurfactant as well as biocontrol activity against Phytophthora infestans. The results revealed that only 15.8% isolates showed biosurfactant activity. The emulsification index ranged from 0-68% and 24.2% isolates showed positive reaction for biosurfactant properties. In emulsification assay and oil spreading test, 18.95% and 5.26% isolates, respectively scored positive for biosurfactant production. Among all, only five isolates were found effective against P. infestans, for biocontrol properties. Pseudomonas aeruginosa-1 showed 62.22% inhibition zone after 72 hrs while P. aeruginosa-3 showed 46.42%. Forty-eight hrs old culture supernatants were highly effective in food-poisoning test, tuber slice test and detached leaf method against P. infestans. In whole potato plant test, bacterial cell based formulation, culture supernatant and bacterial cell suspension of P. aeruginosa-1 showed 10.42%, 9.94% and 17.96% diseases severity respectively, as against 53.96% in control. This isolate holds promise as biological control agent against P. infestans in field.

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

    Science.gov (United States)

    van Damme, Mireille; Bozkurt, Tolga O; Cakir, Cahid; Schornack, Sebastian; Sklenar, Jan; Jones, Alexandra M E; Kamoun, Sophien

    2012-01-01

    Phytopathogenic oomycetes, such as Phytophthora infestans, secrete an arsenal of effector proteins that modulate plant innate immunity to enable infection. We describe CRN8, a host-translocated effector of P. infestans that has kinase activity in planta. CRN8 is a modular protein of the CRN effector family. The C-terminus of CRN8 localizes to the host nucleus and triggers cell death when the protein is expressed in planta. Cell death induction by CRN8 is dependent on its localization to the plant nucleus, which requires a functional nuclear localization signal (NLS). The C-terminal sequence of CRN8 has similarity to a serine/threonine RD kinase domain. We demonstrated that CRN8 is a functional RD kinase and that its auto-phosphorylation is dependent on an intact catalytic site. Co-immunoprecipitation experiments revealed that CRN8 forms a dimer or multimer. Heterologous expression of CRN8 in planta resulted in enhanced virulence by P. infestans. In contrast, in planta expression of the dominant-negative CRN8(R469A;D470A) resulted in reduced P. infestans infection, further implicating CRN8 in virulence. Overall, our results indicate that similar to animal parasites, plant pathogens also translocate biochemically active kinase effectors inside host cells.

  19. Testing Taxonomic Predictivity of Foliar and Tuber Resistance to Phytophthora infestans in Wild Relatives of Potato.

    Science.gov (United States)

    Khiutti, A; Spooner, D M; Jansky, S H; Halterman, D A

    2015-09-01

    Potato late blight, caused by the oomycete phytopathogen Phytophthora infestans, is a devastating disease found in potato-growing regions worldwide. Long-term management strategies to control late blight include the incorporation of host resistance to predominant strains. However, due to rapid genetic changes within pathogen populations, rapid and recurring identification and integration of novel host resistance traits is necessary. Wild relatives of potato offer a rich source of desirable traits, including late blight resistance, but screening methods can be time intensive. We tested the ability of taxonomy, ploidy, crossing group, breeding system, and geography to predict the presence of foliar and tuber late blight resistance in wild Solanum spp. Significant variation for resistance to both tuber and foliar late blight was found within and among species but there was no discernable predictive power based on taxonomic series, clade, ploidy, breeding system, elevation, or geographic location. We observed a moderate but significant correlation between tuber and foliar resistance within species. Although previously uncharacterized sources of both foliar and tuber resistance were identified, our study does not support an assumption that taxonomic or geographic data can be used to predict sources of late blight resistance in wild Solanum spp.

  20. A Phytophthora infestans RXLR effector targets plant PP1c isoforms that promote late blight disease.

    Science.gov (United States)

    Boevink, Petra C; Wang, Xiaodan; McLellan, Hazel; He, Qin; Naqvi, Shaista; Armstrong, Miles R; Zhang, Wei; Hein, Ingo; Gilroy, Eleanor M; Tian, Zhendong; Birch, Paul R J

    2016-01-29

    Plant pathogens deliver effectors to alter host processes. Knowledge of how effectors target and manipulate host proteins is critical to understand crop disease. Here, we show that in planta expression of the RXLR effector Pi04314 enhances leaf colonization by Phytophthora infestans via activity in the host nucleus and attenuates induction of jasmonic and salicylic acid-responsive genes. Pi04314 interacts with three host protein phosphatase 1 catalytic (PP1c) isoforms, causing their re-localization from the nucleolus to the nucleoplasm. Re-localization of PP1c-1 also occurs during infection and is dependent on an R/KVxF motif in the effector. Silencing the PP1c isoforms or overexpression of a phosphatase-dead PP1c-1 mutant attenuates infection, demonstrating that host PP1c activity is required for disease. Moreover, expression of PP1c-1mut abolishes enhanced leaf colonization mediated by in planta Pi04314 expression. We argue that PP1c isoforms are susceptibility factors forming holoenzymes with Pi04314 to promote late blight disease.

  1. Transcriptional dynamics of Phytophthora infestans during sequential stages of hemibiotrophic infection of tomato.

    Science.gov (United States)

    Zuluaga, Andrea P; Vega-Arreguín, Julio C; Fei, Zhangjun; Ponnala, Lalit; Lee, Sang Jik; Matas, Antonio J; Patev, Sean; Fry, William E; Rose, Jocelyn K C

    2016-01-01

    Hemibiotrophic plant pathogens, such as the oomycete Phytophthora infestans, employ a biphasic infection strategy, initially behaving as biotrophs, where minimal symptoms are exhibited by the plant, and subsequently as necrotrophs, feeding on dead plant tissue. The regulation of this transition and the breadth of molecular mechanisms that modulate plant defences are not well understood, although effector proteins secreted by the pathogen are thought to play a key role. We examined the transcriptional dynamics of P. infestans in a compatible interaction with its host tomato (Solanum lycopersicum) at three infection stages: biotrophy; the transition from biotrophy to necrotrophy; and necrotrophy. The expression data suggest a tight temporal regulation of many pathways associated with the suppression of plant defence mechanisms and pathogenicity, including the induction of putative cytoplasmic and apoplastic effectors. Twelve of these were experimentally evaluated to determine their ability to suppress necrosis caused by the P. infestans necrosis-inducing protein PiNPP1.1 in Nicotiana benthamiana. Four effectors suppressed necrosis, suggesting that they might prolong the biotrophic phase. This study suggests that a complex regulation of effector expression modulates the outcome of the interaction.

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

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    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.

  3. IDENTIFICATION OF KEY MOLECULAR COMPONENTS OF THE RESISTANCE OF CHERRY TOMATO AGAINST Phytophthora infestans

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    LILIANA LÓPEZ KLEINE

    2012-01-01

    Full Text Available 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 interacción incompatible a las 36 horas posinoculación, 15 genes se detectaron como activados globalmente tomando en conjunto los 3 tiempos analizados y 12 genes tanto globalmente como a las 36 horas. Análisis de Northern blot permitieron confirmar la expresión diferencial detectada con los análisis de microarreglos y estudiar la expresión diferencial de otros genes de resistencia en plantas (PR en interacciones compatible e incompatible en esta interacción.

  4. 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.

  5. Population Structure of Phytophthora infestans in the Toluca Valley Region of Central Mexico.

    Science.gov (United States)

    Grünwald, N J; Flier, W G; Sturbaum, A K; Garay-Serrano, E; van den Bosch, T B; Smart, C D; Matuszak, J M; Lozoya-Saldaña, H; Turkensteen, L J; Fry, W E

    2001-09-01

    ABSTRACT We tested the hypothesis that the population of Phytophthora infestans in the Toluca valley region is genetically differentiated according to habitat. Isolates were sampled in three habitats from (i) wild Solanum spp. (WILD), (ii) land-race varieties in low-input production systems (RURAL), and (iii) modern cultivars in high-input agriculture (VALLEY). Isolates were sampled in 1988-89 (n= 179) and in 1997-98 (n= 389). In both sampling periods, the greatest genetic diversity was observed in RURAL and VALLEY habitats. Based on the Glucose-6-phosphate isomerase and Peptidase allozymes, the subpopulations from the three habitats were significantly differentiated in both sampling periods. In contrast to allozyme data for 1997-98, no differences were found among the three subpopulations for sensitivity to metalaxyl. Two groups of isolates identical for allozyme and mating type were further investigated by restriction fragment length polymorphism fingerprinting; 65% of one group and 85% of another group were demonstrated to be unique. The genetic diversity data and the chronology of disease occurrence during the season are consistent with the hypothesis that populations of P. infestans on wild Solanum populations are derived from populations on cultivated potatoes in the central highlands of Mexico near Toluca.

  6. 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.

  7. Phytophthora sojae TatD nuclease positively regulates sporulation and negatively regulates pathogenesis.

    Science.gov (United States)

    Chen, Linlin; Shen, Danyu; Sun, Nannan; Xu, Jing; Wang, Wen; Dou, Daolong

    2014-10-01

    During pathogenic interactions, both the host and pathogen are exposed to conditions that induce programmed cell death (PCD). Certain aspects of PCD have been recently examined in eukaryotic microbes but not in oomycetes. Here, we identified conserved TatD proteins in Phytophthora sojae; the proteins are key components of DNA degradation in apoptosis. We selected PsTatD4 for further investigation because the enzyme is unique to the oomycete branch of the phylogenetic tree. The purified protein exhibited DNase activity in vitro. Its expression was upregulated in sporangia and later infective stages but downregulated in cysts and during early infection. Functional analysis revealed that the gene was required for sporulation and zoospore production, and the expression levels were associated with the numbers of hydrogen-peroxide-induced terminal dUTP nick end-labeling-positive cells. Furthermore, overexpression of PsTatD4 gene reduced the virulence in a susceptible soybean cultivar. Together, these data suggest that apoptosis may play different roles in the early and late infective stages of P. sojae, and that PsTatD4 is a key regulator of infection. The association of PsTatD4 and apoptosis will lay a foundation to understanding the basic biology of apoptosis and its roles in P. sojae disease cycle.

  8. A combined mitochondrial and nuclear multilocus phylogeny of the genus Phytophthora.

    Science.gov (United States)

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

    2014-05-01

    The most recent phylogenetic analysis of the genus Phytophthora was completed in 2008 (Blair et al., 2008) and utilized 8.1 kb of sequence data from seven nuclear loci. Given the large number of species that have recently been described, this study was undertaken to broaden the available information on the phylogeny of the genus. A total of 166 isolates representing 92 recognized species and 17 provisional species were analyzed, including many of the same isolates used in the nuclear multilocus study of Blair et al. (2008). Four mitochondrial genes (cox2, nad9, rps10 and secY) were sequenced with a total of 2373 bp used in the analysis; the species relationships recovered with mitochondrial data were largely consistent with those observed previously in the nuclear analysis. Combining the new mitochondrial data with the nuclear data from Blair et al. (2008) generated a dataset of 10,828 bp representing 11 loci, however resolution of basal clade relationships was still low. We therefore implemented a modified multispecies coalescent approach with a subset of the data, and recovered increased resolution and moderate to high support for clade relationships. A more detailed analysis of species from clades 2 and 8 identified an additional seven phylogenetic lineages that warrant further investigation to determine if they represent distinct species. As has been reported in other phylogenetic studies of the genus, there was no consistent correlation between phylogenetic relatedness and morphological features or ecology.

  9. Expression of resistance gene analogs in woodland strawberry (Fragaria vesca) during infection with Phytophthora cactorum.

    Science.gov (United States)

    Chen, Xiao-Ren; Brurberg, May Bente; Elameen, Abdelhameed; Klemsdal, Sonja Sletner; Martinussen, Inger

    2016-10-01

    Important losses in strawberry production are often caused by the oomycete Phytophthora cactorum, the causal agent of crown rot. However, very limited studies at molecular levels exist of the mechanisms related to strawberry resistance against this pathogen. To begin to rectify this situation, a PCR-based approach (NBS profiling) was used to isolate strawberry resistance gene analogs (RGAs) with altered expression in response to P. cactorum during a time course (2, 4, 6, 24, 48, 96 and 192 h post-infection). Twenty-three distinct RGA fragments of the NB-LRR type were identified from a resistance genotype (Bukammen) of the wild species Fragaria vesca. The gene transcriptional profiles after infection showed that the response of most RGAs was quicker and stronger in the resistance genotype (Bukammen) than in the susceptible one (FDP821) during the early infection stage. The transcriptional patterns of one RGA (RGA109) were further monitored and compared during the P. cactorum infection of two pairs of resistant and susceptible genotype combinations (Bukammen/FDP821 and FDR1218/1603). The 5' end sequence was cloned, and its putative protein was characteristic of NBS-LRR R protein. Our results yielded a first insight into the strawberry RGAs responding to P. cactorum infection at molecular level.

  10. Phylogenetic history of Phytophthora cryptogea and P. drechsleri isolates from floriculture crops in North Carolina greenhouses.

    Science.gov (United States)

    Olson, H A; Carbone, I; Benson, D M

    2011-11-01

    The evolutionary history of Phytophthora cryptogea and P. drechsleri isolates previously collected from floriculture crops in North Carolina commercial greenhouses was explored with coalescent- and parsimony-based analyses. Initially, 68 isolates representing 13 location-host groups were sequenced at multiple loci. Sequences of all isolates within a group were identical. A subset of isolates were selected, cloned to resolve heterozygous sites, and analyzed with SNAP Workbench. The internal transcribed spacer (ITS) region of the ribosomal DNA and cytochrome oxidase II gene genealogies were congruent and indicated that P. cryptogea and P. drechsleri are sister species diverged from a common ancestor with no evidence of gene flow. In contrast, genealogies inferred from β-tubulin (β-tub) and translation elongation factor 1α (EF-1α) genes were in conflict with these loci. Coalescent analysis based on a nonrecombining partition in β-tub and EF-1α showed an initial (older) split between P. cryptogea and P. drechsleri, with a later (recent) event separating the remaining P. cryptogea haplotypes from P. drechsleri. A parsimony-based minimal ancestral recombination graph inferred recombination between P. cryptogea and P. drechsleri isolates in the ITS region and β-tub, suggesting genetic exchange between species. Also, putative recombination between A1 and A2 mating types of P. cryptogea suggests that sexual reproduction has occurred in the history of these P. cryptogea isolates.

  11. 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.

  12. 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.

  13. 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.

  14. 31P NMR studies on the effect of phosphite on Phytophthora palmivora.

    Science.gov (United States)

    Niere, J O; Griffith, J M; Grant, B R

    1990-01-01

    31P NMR spectra were obtained from perchloric acid (PCA) and KOH extracts of Phytophthora palmivora mycelium. Signals indicating the presence of large amounts of short-chain polyphosphate were observed in the spectra of PCA extracts of mycelia grown under both low (0.1 mM) and high (10 mM) phosphate conditions. The mean chain length of polyphosphate was calculated from the relative areas of signals arising from terminal and internal P nuclei in the polyphosphate chain. The small amount of polyphosphate evident in the KOH extract had an average chain length similar to PCA-soluble polyphosphate. 32P tracer studies indicated that phosphorus in the PCA fraction accounted for between 50 and 60% of total phosphorus, the bulk of the remainder being divided between the lipid and KOH extracts. The presence of the fungicide phosphorous acid markedly reduced the average chain length of acid-soluble polyphosphate. This reduction occurred both under low-phosphate conditions, in which treatment with phosphorous acid retards growth, and under high-phosphate conditions, in which no significant growth retardation is observed. Treatment with phosphorous acid perturbed phosphorus distribution and lipid composition under low-phosphate conditions.

  15. Stromata, sporangiomata and chlamydosori of Phytophthora ramorum on inoculated Mediterranean woody plants.

    Science.gov (United States)

    Moralejo, Eduardo; Puig, Miquel; García, José A; Descals, Enrique

    2006-11-01

    Three types of multihyphal structures, stromata, sporangiomata and chlamydosori, are described for the plant pathogen Phytophthora ramorum. Their morphology, morphogenesis and position on the host organ were observed by dissecting, compound and scanning electron microscopy. Stromata were consistently formed one to two weeks after zoospore inoculation of detached leaves and fruits of an assortment of Mediterranean sclerophyll shrubs. Stroma initials appeared subcuticularly or subepidermally and developed as small hyphal aggregates by repeated branching, budding, swelling and interweaving, eventually forming a prosenchyma. They always emerged through the adaxial side of the leaf by rupture of the overlying host tissue. Occasionally sporangia and chlamydosori (packed clusters of chlamydospores) were formed on the stromata. Sporangiomata bore short sporangiophores and clusters of 20-100 sporangia and resembled sporodochia of the mitosporic fungi. The biological significance of these multihyphal structures is discussed. Some epidemiological aspects were also studied: several understorey species of the holm oak (Quercus ilex) woodland were susceptible to in vitro infection with three isolates of P. ramorum originally collected from different ornamental hosts. The risk of spread to this ecosystem is evaluated.

  16. 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.

  17. High affinity recognition of a Phytophthora protein by Arabidopsis via an RGD motif.

    Science.gov (United States)

    Senchou, V; Weide, R; Carrasco, A; Bouyssou, H; Pont-Lezica, R; Govers, F; Canut, H

    2004-02-01

    The RGD tripeptide sequence, a cell adhesion motif present in several extracellular matrix proteins of mammalians, is involved in numerous plant processes. In plant-pathogen interactions, the RGD motif is believed to reduce plant defence responses by disrupting adhesions between the cell wall and plasma membrane. Photoaffinity cross-linking of [125I]-azido-RGD heptapeptide in the presence of purified plasma membrane vesicles of Arabidopsis thaliana led to label incorporation into a single protein with an apparent molecular mass of 80 kDa. Incorporation could be prevented by excess RGD peptides, but also by the IPI-O protein, an RGD-containing protein secreted by the oomycete plant pathogen Phytophthora infestans. Hydrophobic cluster analysis revealed that the RGD motif of IPI-O (positions 53-56) is readily accessible for interactions. Single amino acid mutations in the RGD motif in IPI-O (of Asp56 into Glu or Ala) resulted in the loss of protection of the 80-kDa protein from labelling. Thus, the interaction between the two proteins is mediated through RGD recognition and the 80-kDa RGD-binding protein has the characteristics of a receptor for IPI-O. The IPI-O protein also disrupted cell wall-plasma membrane adhesions in plasmolysed A. thaliana cells, whereas IPI-O proteins mutated in the RGD motif (D56A and D56E) did not.

  18. 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.

  19. AFLP analysis reveals a clonal population of Phytophthora pinifolia in Chile.

    Science.gov (United States)

    Durán, Alvaro; Gryzenhout, Marieka; Drenth, André; Slippers, Bernard; Ahumada, Rodrigo; Wingfield, Brenda D; Wingfield, Michael J

    2010-09-01

    Phytophthora pinifolia is the causal agent of the recently discovered needle disease of Pinus radiata in Chile, referred to as "Daño Foliar del Pino" (DFP). The genetic structure of the pathogen population is unknown, which hinders our understanding of its appearance and spread in Chile since 2004. In this study, a population of 88 cultures of P. pinifolia isolated from P. radiata at several localities in Chile was evaluated for genotypic diversity using amplified fragment length polymorphisms (AFLPs). Results of the AFLP analyses showed that the P. pinifolia population in Chile consists of two near identical genotypes but with no genetic differentiation based on geography, year of isolation or the part of the tree from which the isolates were obtained. Mating experiments did not lead to the production of gametangia suggesting that the organism is sterile. The fact that a single clonal genotype dominates the population of P. pinifolia in Chile supports the hypothesis that P. pinifolia was recently introduced into this country and that its impact is due to a new and susceptible host encounter.

  20. 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.