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Sample records for oomycete aphanomyces astaci

  1. Mitochondrial genomes and comparative genomics of Aphanomyces astaci and Aphanomyces invadans

    Science.gov (United States)

    The genus Aphanomyces (Saprolegniales, Oomycetes) includes species with variety of ecologies from saprotrophs to plant and animal parasites. Two important species in this genus are Aphanomyces astaci that causes the crayfish plague and its close relative, Aphanomyces invadans, which causes the epizo...

  2. Temporal variation in the prevalence of the crayfish plague pathogen, Aphanomyces astaci, in three Czech spiny-cheek crayfish populations

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    Matasová K.

    2011-06-01

    Full Text Available North American crayfish species are natural hosts of the crayfish plague pathogen Aphanomyces astaci. The spiny-cheek crayfish Orconectes limosus, widespread in Central Europe, is the main reservoir of A. astaci in Czech Republic. We tested if there are temporal changes in the prevalence of infected individuals (i.e., the proportion of individuals in which the pathogen is detected in spiny-cheek crayfish populations. Crayfish from three populations shown previously to be infected to different extents (high, intermediate and low, were repeatedly sampled in different years (2004–2010 and seasons. The presence of A. astaci in the soft abdominal crayfish cuticle was tested by specific amplification of the pathogen DNA. There was no substantial temporal variation in pathogen prevalence in the highly and very lowly infected populations. However, a significant long-term as well as seasonal decrease was found in the intermediately infected population. This decline could be related to a decrease in population density over the studied years, and to crayfish seasonal moulting, respectively. A reliable estimate of pathogen prevalence in American crayfish populations thus requires repeated monitoring over years, preferably during the same season before the main period of crayfish moulting.

  3. Prevalence of the crayfish plague pathogen Aphanomyces astaci in populations of the signal crayfish Pacifastacus leniusculus in France: evaluating the threat to native crayfish.

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    Lenka Filipová

    Full Text Available Aphanomyces astaci, the crayfish plague pathogen, first appeared in Europe in the mid-19(th century and is still responsible for mass mortalities of native European crayfish. The spread of this parasite across the continent is especially facilitated by invasive North American crayfish species that serve as its reservoir. In France, multiple cases of native crayfish mortalities have been suggested to be connected with the presence of the signal crayfish Pacifastacus leniusculus, which is highly abundant in the country. It shares similar habitats as the native white-clawed crayfish Austropotamobius pallipes and, when infected, the signal crayfish might therefore easily transmit the pathogen to the native species. We investigated the prevalence of A. astaci in French signal crayfish populations to evaluate the danger they represent to local populations of native crayfish. Over 500 individuals of Pacifastacus leniusculus from 45 French populations were analysed, plus several additional individuals of other non-indigenous crayfish species Orconectes limosus, O. immunis and Procambarus clarkii. Altogether, 20% of analysed signal crayfish tested positive for Aphanomyces astaci, and the pathogen was detected in more than half of the studied populations. Local prevalence varied significantly, ranging from 0% up to 80%, but wide confidence intervals suggest that the number of populations infected by A. astaci may be even higher than our results show. Analysis of several individuals of other introduced species revealed infections among two of these, O. immunis and P. clarkii. Our results confirm that the widespread signal crayfish serves as a key reservoir of Aphanomyces astaci in France and therefore represents a serious danger to native crayfish species, especially the white-clawed crayfish. The prevalence in other non-indigenous crayfish should also be investigated as they likely contribute to pathogen transmission in the country.

  4. Transcriptome of Aphanomyces euteiches: new oomycete putative pathogenicity factors and metabolic pathways.

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    Elodie Gaulin

    Full Text Available Aphanomyces euteiches is an oomycete pathogen that causes seedling blight and root rot of legumes, such as alfalfa and pea. The genus Aphanomyces is phylogenically distinct from well-studied oomycetes such as Phytophthora sp., and contains species pathogenic on plants and aquatic animals. To provide the first foray into gene diversity of A. euteiches, two cDNA libraries were constructed using mRNA extracted from mycelium grown in an artificial liquid medium or in contact to plant roots. A unigene set of 7,977 sequences was obtained from 18,864 high-quality expressed sequenced tags (ESTs and characterized for potential functions. Comparisons with oomycete proteomes revealed major differences between the gene content of A. euteiches and those of Phytophthora species, leading to the identification of biosynthetic pathways absent in Phytophthora, of new putative pathogenicity genes and of expansion of gene families encoding extracellular proteins, notably different classes of proteases. Among the genes specific of A. euteiches are members of a new family of extracellular proteins putatively involved in adhesion, containing up to four protein domains similar to fungal cellulose binding domains. Comparison of A. euteiches sequences with proteomes of fully sequenced eukaryotic pathogens, including fungi, apicomplexa and trypanosomatids, allowed the identification of A. euteiches genes with close orthologs in these microorganisms but absent in other oomycetes sequenced so far, notably transporters and non-ribosomal peptide synthetases, and suggests the presence of a defense mechanism against oxidative stress which was initially characterized in the pathogenic trypanosomatids.

  5. Emerging oomycete threats to plants and animals.

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    Derevnina, Lida; Petre, Benjamin; Kellner, Ronny; Dagdas, Yasin F; Sarowar, Mohammad Nasif; Giannakopoulou, Artemis; De la Concepcion, Juan Carlos; Chaparro-Garcia, Angela; Pennington, Helen G; van West, Pieter; Kamoun, Sophien

    2016-12-05

    Oomycetes, or water moulds, are fungal-like organisms phylogenetically related to algae. They cause devastating diseases in both plants and animals. Here, we describe seven oomycete species that are emerging or re-emerging threats to agriculture, horticulture, aquaculture and natural ecosystems. They include the plant pathogens Phytophthora infestans, Phytophthora palmivora, Phytophthora ramorum, Plasmopara obducens, and the animal pathogens Aphanomyces invadans, Saprolegnia parasitica and Halioticida noduliformans For each species, we describe its pathology, importance and impact, discuss why it is an emerging threat and briefly review current research activities.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'.

  6. AphanoDB: a genomic resource for Aphanomyces pathogens

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    Wincker Patrick

    2007-12-01

    Full Text Available Abstract Background The Oomycete genus Aphanomyces comprises devastating plant and animal pathogens. However, little is known about the molecular mechanisms underlying pathogenicity of Aphanomyces species. In this study, we report on the development of a public database called AphanoDB which is dedicated to Aphanomyces genomic data. As a first step, a large collection of Expressed Sequence Tags was obtained from the legume pathogen A. euteiches, which was then processed and collected into AphanoDB. Description Two cDNA libraries of A. euteiches were created: one from mycelium growing on synthetic medium and one from mycelium grown in contact to root tissues of the model legume Medicago truncatula. From these libraries, 18,684 expressed sequence tags were obtained and assembled into 7,977 unigenes which were compared to public databases for annotation. Queries on AphanoDB allow the users to retrieve information for each unigene including similarity to known protein sequences, protein domains and Gene Ontology classification. Statistical analysis of EST frequency from the two different growth conditions was also added to the database. Conclusion AphanoDB is a public database with a user-friendly web interface. The sequence report pages are the main web interface which provides all annotation details for each unigene. These interactive sequence report pages are easily available through text, BLAST, Gene Ontology and expression profile search utilities. AphanoDB is available from URL: http://www.polebio.scsv.ups-tlse.fr/aphano/.

  7. Aphanomyces astaci w Europie wyeliminował populację raków z ...

    African Journals Online (AJOL)

    user

    2013-10-30

    Oct 30, 2013 ... RNA gene, and internal transcribed spacer 2, complete sequence and 28S ribosomal ... Agar; ITS, internal transcribed spacer; PCR, polymerase chain reaction; NCBI, National ... Morphological characters of asexual structures and measurements .... have been described only on the basic morphological.

  8. Experimental infection and detection of Aphanomyces invadans in European catfish, rainbow trout and European eel.

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    Oidtmann, Birgit; Steinbauer, Peter; Geiger, Sheila; Hoffmann, Rudolf W

    2008-12-22

    European catfish Silurus glanis, European eel Anguilla anguilla and rainbow trout Oncorhynchus mykiss were challenged by intramuscular injection of zoospores of Aphanomyces invadans, the oomycete associated with epizootic ulcerative syndrome (EUS). The tropical three-spot gourami Trichogaster trichopterus is known to be highly susceptible and was used as a positive control. European catfish were highly susceptible and rainbow trout had moderate to low susceptibility, whereas eels appeared largely unaffected. Inflammatory host response in European catfish deviated from the effects seen in most other susceptible fish species and was characterised by a more loosely arranged accumulation of macrophages, small numbers of lymphocytes and multinucleated giant cells without occurrence of EUS-characteristic mycotic granulomas. Semi-nested and single round PCR assays were developed for this study to detect A. invadans DNA in clinical samples of experimentally infected fish. The detection limit of the assays equals 1 genomic unit. Specificity was examined by testing the DNA of various oomycetes, other relevant pathogens and commensals as well as host DNA. The single round assay used was fully specific, whereas cross-reaction with the closely related Aphanomyces frigidophilus was observed using the semi-nested assay. Analysis of samples by PCR allowed detection prior to detectable histopathological lesions. Two other published PCR protocols were compared to the PCR protocols presented here.

  9. Experimental infection of Aphanomyces invadans and susceptibility in seven species of tropical fish

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    Afzali, Seyedeh F.; Mohd Daud, Hassan Hj.; Sharifpour, Issa; Afsharnasab, Mohammad; Shankar, Shiv

    2015-01-01

    Aim: Epizootic ulcerative syndrome (EUS) causes by aquatic oomycete fungus, Aphanomyces invadans is a dangerous fish disease of a wide range of fresh and brackish water, wild and farmed fish throughout the world. The objective of the present study was to determine the susceptibility of a number of tropical fish species to the EUS and compare the severity of infection between experimental groups. Materials and Methods: Snakehead, Channa striata (Bloch, 1793); snakeskin gourami, Trichopodus pectoralis (Regan, 1910); koi carp, Cyprinus carpio (Linnaeus, 1758); broadhead catfish, Clarias macrocephalus (Günther, 1864); goldfish, Carassius auratus (Linnaeus, 1758); climbing perch, Anabas testudineus (Bloch, 1792); and Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) were challenged by intramuscular injection using zoospores of Aphanomyces invadans (NJM9701). The infected fish skins and muscles were examined for EUS histopathological characteristics, and the results on the severity of lesions and mortality were analyzed using SPSS program. Results: All zoospore-injected fish were shown to be susceptible to the EUS infection except Nile tilapia. Although, the general histopathological pattern was similar in the zoospore-injected group, but there were some variation in granulomatous reaction, that is the presence or absence of giant cells, and time of mortality were detected. The result of statistical analysis showed that there was a significant difference between species, (c2=145.11 and p<0.01). Conclusion: Gourami, koi carp, and catfish were demonstrated to be highly susceptible while goldfish and climbing perch were found to be moderately susceptible to the EUS infection. These findings suggested that the cellular response of fish to mycotic infection and granulomatous reaction varied in different fish species, which could not be an indicator of susceptibility or resistant to the EUS itself, although it was shown that the granulation rate and the level of maturity

  10. Experimental infection of Aphanomyces invadans and susceptibility in seven species of tropical fish

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    Seyedeh F. Afzali

    2015-09-01

    Full Text Available Aim: Epizootic ulcerative syndrome (EUS causes by aquatic oomycete fungus, Aphanomyces invadans is a dangerous fish disease of a wide range of fresh and brackish water, wild and farmed fish throughout the world. The objective of the present study was to determine the susceptibility of a number of tropical fish species to the EUS and compare the severity of infection between experimental groups. Materials and Methods: Snakehead, Channa striata (Bloch, 1793; snakeskin gourami, Trichopodus pectoralis (Regan, 1910; koi carp, Cyprinus carpio (Linnaeus, 1758; broadhead catfish, Clarias macrocephalus (Günther, 1864; goldfish, Carassius auratus (Linnaeus, 1758; climbing perch, Anabas testudineus (Bloch, 1792; and Nile tilapia, Oreochromis niloticus (Linnaeus, 1758 were challenged by intramuscular injection using zoospores of Aphanomyces invadans (NJM9701. The infected fish skins and muscles were examined for EUS histopathological characteristics, and the results on the severity of lesions and mortality were analyzed using SPSS program. Results: All zoospore-injected fish were shown to be susceptible to the EUS infection except Nile tilapia. Although, the general histopathological pattern was similar in the zoospore-injected group, but there were some variation in granulomatous reaction, that is the presence or absence of giant cells, and time of mortality were detected. The result of statistical analysis showed that there was a significant difference between species, (c2=145.11 and p<0.01. Conclusion: Gourami, koi carp, and catfish were demonstrated to be highly susceptible while goldfish and climbing perch were found to be moderately susceptible to the EUS infection. These findings suggested that the cellular response of fish to mycotic infection and granulomatous reaction varied in different fish species, which could not be an indicator of susceptibility or resistant to the EUS itself, although it was shown that the granulation rate and the level of

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

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    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.

  12. Plant Pathogenic Fungi and Oomycetes

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    Wit, de P.J.G.M.

    2015-01-01

    Fungi and Oomycetes are notorious plant pathogens and use similar strategies to infect plants. The majority of plants, however, is not infected by pathogens as they recognize pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors that mediate PAMP-triggered immunity (PTI) ,

  13. Plant Pathogenic Fungi and Oomycetes

    NARCIS (Netherlands)

    Wit, de P.J.G.M.

    2015-01-01

    Fungi and Oomycetes are notorious plant pathogens and use similar strategies to infect plants. The majority of plants, however, is not infected by pathogens as they recognize pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors that mediate PAMP-triggered immunity (PTI) ,

  14. Identification of markers associated with race-specific resistance to Aphanomyces root rot in alfalfa

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    Aphanomyces root rot, caused by Aphanomyces euteiches, is one of the most important diseases of alfalfa in the United States. Two races of the pathogen are recognized and although most cultivars are resistant to race 1, fewer have resistance to race 2, the predominant race in North America. Molecula...

  15. Mechanisms of qualitative and quantitative resistance to Aphanomyces root rot in alfalfa

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    Aphanomyces root rot (ARR), caused by Aphanomyces euteiches, is one of the most important diseases of alfalfa (Medicago sativa) in the United States. Two races of the pathogen are currently recognized. Most modern alfalfa cultivars have high levels of resistance to race 1 but few cultivars have resi...

  16. Oomycetes, effectors, and all that jazz.

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    Bozkurt, Tolga O; Schornack, Sebastian; Banfield, Mark J; Kamoun, Sophien

    2012-08-01

    Plant pathogenic oomycetes secrete a diverse repertoire of effector proteins that modulate host innate immunity and enable parasitic infection. Understanding how effectors evolve, translocate and traffic inside host cells, and perturb host processes are major themes in the study of oomycete-plant interactions. The last year has seen important progress in the study of oomycete effectors with, notably, the elucidation of the 3D structures of five RXLR effectors, and novel insights into how cytoplasmic effectors subvert host cells. In this review, we discuss these and other recent advances and highlight the most important open questions in oomycete effector biology. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Epizootic ulcerative syndrome caused by Aphanomyces invadans in captive bullseye snakehead Channa marulius collected from south Florida, USA

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    Saylor, Ryan [University of West Florida; Miller, Debra [University of Georgia; Vandersea, Mark [National Oceanic and Atmospheric Admin; Bevelhimer, Mark S [ORNL; Schofield, Pamela [U.S. Geological Survey; Bennett, Wayne [University of West Florida

    2010-02-01

    Epizootic ulcerative syndrome (EUS) caused by the oomycete Aphanomyces invadans is an invasive, opportunistic disease of both freshwater and estuarine fishes. Originally documented as the cause of mycotic granulomatosis of ornamental fishes in Japan and as the cause of EUS of fishes in southeast Asia and Australia, this pathogen is also present in estuaries and freshwater bodies of the Atlantic and gulf coasts of the USA. We describe a mass mortality event of 343 captive juvenile bullseye snakehead Channa marulius collected from freshwater canals in Miami-Dade County, Florida. Clinical signs appeared within the first 2 d of captivity and included petechiae, ulceration, erratic swimming, and inappetence. Histological examination revealed hyphae invading from the skin lesions deep into the musculature and internal organs. Species identification was confirmed using a species-specific PCR assay. Despite therapeutic attempts, 100% mortality occurred. This represents the first documented case of EUS in bullseye snakehead fish collected from waters in the USA. Future investigation of the distribution and prevalence of A. invadans within the bullseye snakehead range in south Florida may give insight into this pathogen-host system.

  18. Epizootic ulcerative syndrome caused by Aphanomyces invadans in captive bullseye snakehead Channa marulius collected from south Florida, USA.

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    Saylor, Ryan K; Miller, Debra L; Vandersea, Mark W; Bevelhimer, Mark S; Schofield, Pamela J; Bennett, Wayne A

    2010-01-25

    Epizootic ulcerative syndrome (EUS) caused by the oomycete Aphanomyces invadans is an invasive, opportunistic disease of both freshwater and estuarine fishes. Originally documented as the cause of mycotic granulomatosis of ornamental fishes in Japan and as the cause of EUS of fishes in southeast Asia and Australia, this pathogen is also present in estuaries and freshwater bodies of the Atlantic and gulf coasts of the USA. We describe a mass mortality event of 343 captive juvenile bullseye snakehead Channa marulius collected from freshwater canals in Miami-Dade County, Florida. Clinical signs appeared within the first 2 d of captivity and included petechiae, ulceration, erratic swimming, and inappetence. Histological examination revealed hyphae invading from the skin lesions deep into the musculature and internal organs. Species identification was confirmed using a species-specific PCR assay. Despite therapeutic attempts, 100% mortality occurred. This represents the first documented case of EUS in bullseye snakehead fish collected from waters in the USA. Future investigation of the distribution and prevalence of A. invadans within the bullseye snakehead range in south Florida may give insight into this pathogen-host system.

  19. Effect of arabinogalactan proteins from the root caps of pea and Brassica napus on Aphanomyces euteiches zoospore chemotaxis and germination.

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    Cannesan, Marc Antoine; Durand, Caroline; Burel, Carole; Gangneux, Christophe; Lerouge, Patrice; Ishii, Tadashi; Laval, Karine; Follet-Gueye, Marie-Laure; Driouich, Azeddine; Vicré-Gibouin, Maïté

    2012-08-01

    Root tips of many plant species release a number of border, or border-like, cells that are thought to play a major role in the protection of root meristem. However, little is currently known on the structure and function of the cell wall components of such root cells. Here, we investigate the sugar composition of the cell wall of the root cap in two species: pea (Pisum sativum), which makes border cells, and Brassica napus, which makes border-like cells. We find that the cell walls are highly enriched in arabinose and galactose, two major residues of arabinogalactan proteins. We confirm the presence of arabinogalactan protein epitopes on root cap cell walls using immunofluorescence microscopy. We then focused on these proteoglycans by analyzing their carbohydrate moieties, linkages, and electrophoretic characteristics. The data reveal (1) significant structural differences between B. napus and pea root cap arabinogalactan proteins and (2) a cross-link between these proteoglycans and pectic polysaccharides. Finally, we assessed the impact of root cap arabinogalactan proteins on the behavior of zoospores of Aphanomyces euteiches, an oomycetous pathogen of pea roots. We find that although the arabinogalactan proteins of both species induce encystment and prevent germination, the effects of both species are similar. However, the arabinogalactan protein fraction from pea attracts zoospores far more effectively than that from B. napus. This suggests that root arabinogalactan proteins are involved in the control of early infection of roots and highlights a novel role for these proteoglycans in root-microbe interactions.

  20. Factors influencing the sporulation and cyst formation of Aphanomyces invadans, etiological agent of ulcerative mycosis in Atlantic menhaden, Brevoortia tyrannus

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    Kiryu, Y.; Blazer, V.S.; Vogelbein, W.K.; Kator, H.; Shields, J.D.

    2005-01-01

    Oomycete infections caused by Aphanomyces invadans occur in freshwater and estuarine fishes around the world. Along the east coast of the USA, skin ulcers caused by A. invadans are prevalent in Atlantic menhaden, Brevoortia tyrannus. From laboratory observations low salinities appear crucial to transmission of the pathogen. To better understand aspects of transmission, we characterized sporulation and cyst formation of secondary zoospores of two isolates of A. invadans at different salinities and temperatures. Sporulation occurred only at low salinities. At room temperature (ca. 20-22 C), using "pond water" augmented with artificial sea salts, the endemic strain WIC and the Thailand strain PA7 of A. invadans produced free-swimming secondary zoospores at salinities of 0, 1 and 2 psu (practical salinity unit = ???), but not at 4 psu or higher. Secondary zoospores of another species, ATCC-62427 (Aphanomyces sp.), were observed at 1, 2, 4 and 8 psu but not at 0 and 12 psu. Secondary zoospores of all three isolates, especially WIC, were abundant and motile 1-2 d post-sporulation. Sporulation was temperature dependent and occurred over a relatively narrow range. No sporulation occurred at 4, 30 or 35 C for either WIC or PA7. For both strains zoospore production within 1-3 d after the initiation of sporulation was more prolific at 25 C than at 20 and 15 C. At 15 C production of zoospores was sustained over 11 d for WIC and 5 d for PA7. At room temperature single WIC secondary zoospores remained motile 12-18 h. Salinities exceeding 4 psu or vigorous shaking caused immediate cyst formation of WIC secondary zoospores. Exposure to menhaden tissue, but not tissues of other fishes to secondary zoospores (WIC), caused rapid (2 h) cyst formation. Cysts were capable of excysting when transferred to 1 psu water within 2-3 h of cyst formation. Cysts that had remained encysted in 6.5 psu for 24 h did not excyst when transferred to 1 psu water. Salinity and temperature requirements

  1. Effect of the copepod parasite Nicothoë astaci on haemolymph chemistry of the European lobster Homarus gammarus.

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    Davies, Charlotte E; Vogan, Claire L; Rowley, Andrew F

    2015-03-09

    The gills of the European lobster Homarus gammarus (L.) are susceptible to parasitization by the copepod Nicothoë astaci, the lobster louse. This copepod feeds on haemolymph of the host and can damage the gills, potentially affecting gaseous exchange capabilities. To investigate the host response to the parasite, haemolymph levels of total protein, haemocyanin, glucose and ammonia were quantified in adult lobsters carrying varying parasite loads. Parasite loads correlated positively with total haemolymph protein and haemocyanin concentrations but not with glucose or ammonia concentrations. The data suggest that lobsters with gills damaged by the feeding activities of N. astaci respond by producing higher levels of haemocyanin, which is both a key defence response and may compensate for their decreased respiratory functioning.

  2. Aphanomyces euteiches cell wall fractions containing novel glucan-chitosaccharides induce defense genes and nuclear calcium oscillations in the plant host Medicago truncatula.

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    Amaury Nars

    Full Text Available N-acetylglucosamine-based saccharides (chitosaccharides are components of microbial cell walls and act as molecular signals during host-microbe interactions. In the legume plant Medicago truncatula, the perception of lipochitooligosaccharide signals produced by symbiotic rhizobia and arbuscular mycorrhizal fungi involves the Nod Factor Perception (NFP lysin motif receptor-like protein and leads to the activation of the so-called common symbiotic pathway. In rice and Arabidopsis, lysin motif receptors are involved in the perception of chitooligosaccharides released by pathogenic fungi, resulting in the activation of plant immunity. Here we report the structural characterization of atypical chitosaccharides from the oomycete pathogen Aphanomyces euteiches, and their biological activity on the host Medicago truncatula. Using a combination of biochemical and biophysical approaches, we show that these chitosaccharides are linked to β-1,6-glucans, and contain a β-(1,3;1,4-glucan backbone whose β-1,3-linked glucose units are substituted on their C-6 carbon by either glucose or N-acetylglucosamine residues. This is the first description of this type of structural motif in eukaryotic cell walls. Glucan-chitosaccharide fractions of A. euteiches induced the expression of defense marker genes in Medicago truncatula seedlings independently from the presence of a functional Nod Factor Perception protein. Furthermore, one of the glucan-chitosaccharide fractions elicited calcium oscillations in the nucleus of root cells. In contrast to the asymmetric oscillatory calcium spiking induced by symbiotic lipochitooligosaccharides, this response depends neither on the Nod Factor Perception protein nor on the common symbiotic pathway. These findings open new perspectives in oomycete cell wall biology and elicitor recognition and signaling in legumes.

  3. Morphology and pathology of the ectoparasitic copepod, Nicothoë astaci ('lobster louse') in the European lobster, Homarus gammarus.

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    Wootton, Emma C; Pope, Edward C; Vogan, Claire L; Roberts, Emily C; Davies, Charlotte E; Rowley, Andrew F

    2011-09-01

    Ectoparasitic copepods have been reported in a wide range of aquatic animals, including crustacean shellfish. However, with the exception of the salmon louse, Lepeophtheirus salmonis, our knowledge of such parasites in commercial species is rudimentary. The current study examines the morphology and pathology of the parasitic copepod, Nicothoë astaci (the 'lobster louse') in its host, the European lobster, Homarus gammarus. Lobsters were sampled from waters surrounding Lundy Island (Bristol Channel, UK) and all individuals collected were found to harbour female adult N. astaci in their gills, with a mean of 47·3 parasites/lobster. The majority of N. astaci were found in the basal region of pleurobranch gills. The parasite was found to attach to gill filaments via its oral sucker, maxillae and maxillipeds, and to feed on host haemolymph (blood) through a funnel-like feeding channel. It caused varying degrees of damage to the host gill, including occlusion of gill filaments and disruption to the vascular system in the central axis. Although there was evidence of extensive host response (haemocytic infiltration) to the parasite, it was displaced from the parasite attachment site and thus was observed in the central gill axis below. The region of gill filament immediately underlying the parasite feeding channel was devoid of such activity suggesting that the parasite interferes with the cellular defence and haemostatic mechanisms of the lobster in order to maintain invasion of the host.

  4. Transformation of the oomycete pathogen, Phytophthora infestans.

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    Judelson, H S; Tyler, B M; Michelmore, R W

    1991-01-01

    A stable transformation procedure has been developed for Phytophthora infestans, an oomycete fungus that causes the late blight diseases of potato and tomato. This is the first description of reliable methods for transformation in an oomycete pathogen. Drug-resistant transformants were obtained by using vectors that contained bacterial genes for resistance to hygromycin B or G418 fused to promoters and terminators from the Hsp70 and Ham34 genes of the oomycete, Bremia lactucae. Using polyethylene glycol and CaCl2, vector DNA was introduced into protoplasts as a complex with cationic liposomes or with carrier DNA only. Transformants were obtained at similar frequencies with each combination of promoter and selectable marker and were confirmed by DNA and RNA hybridization and phosphotransferase assays. Transformation occurred through the integration of single or tandemly repeated copies of the plasmids into genomic DNA, conferring mitotically stable drug-resistant phenotypes. The sizes of the marker gene mRNAs in each transformant and the results of transcript mapping studies were consistent with the function of the B. lactucae regulatory sequences in P. infestans. A hygromycin-resistant transformant was tested and found to maintain pathogenicity, indicating that the gene transfer procedure will be useful for the molecular analysis of genes relevant to disease.

  5. The top 10 oomycete pathogens in molecular plant pathology

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    Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens that threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant pathogenic oomycete taxa based on scientific and economic importance. In total, ...

  6. Oomycetes and fungi: similar weaponry to attack plants

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    Latijnhouwers, M.; Wit, de P.J.G.M.; Govers, F.

    2003-01-01

    Fungi and Oomycetes are the two most important groups of eukaryotic plant pathogens. Fungi form a separate kingdom and are evolutionarily related to animals. Oomycetes are classified in the kingdom Protoctista and are related to heterokont, biflagellate, golden-brown algae. Fundamental differences

  7. Oomycetes and fungi: similar weaponry to attack plants

    NARCIS (Netherlands)

    Latijnhouwers, M.; Wit, de P.J.G.M.; Govers, F.

    2003-01-01

    Fungi and Oomycetes are the two most important groups of eukaryotic plant pathogens. Fungi form a separate kingdom and are evolutionarily related to animals. Oomycetes are classified in the kingdom Protoctista and are related to heterokont, biflagellate, golden-brown algae. Fundamental differences i

  8. The Top 10 oomycete pathogens in molecular plant pathology

    NARCIS (Netherlands)

    Kamoun, Sophien; Furzer, Oliver; Jones, Jonathan D G; Judelson, Howard S; Ali, Gul Shad; Dalio, Ronaldo J D; Roy, Sanjoy Guha; Schena, Leonardo; Zambounis, Antonios; Panabières, Franck; Cahill, David; Ruocco, Michelina; Figueiredo, Andreia; Chen, Xiao-Ren; Hulvey, Jon; Stam, Remco; Lamour, Kurt; Gijzen, Mark; Tyler, Brett M; Grünwald, Niklaus J; Mukhtar, M Shahid; Tomé, Daniel F A; Tör, Mahmut; Van Den Ackerveken, Guido; McDowell, John; Daayf, Fouad; Fry, William E; Lindqvist-Kreuze, Hannele; Meijer, Harold J G; Petre, Benjamin; Ristaino, Jean; Yoshida, Kentaro; Birch, Paul R J; Govers, Francine

    2015-01-01

    Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens which threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant-pathogenic oomycete species based on scientific and economic importance. In tot

  9. Speciation in fungal and oomycete plant pathogens.

    Science.gov (United States)

    Restrepo, Silvia; Tabima, Javier F; Mideros, Maria F; Grünwald, Niklaus J; Matute, Daniel R

    2014-01-01

    The process of speciation, by definition, involves evolution of one or more reproductive isolating mechanisms that split a single species into two that can no longer interbreed. Determination of which processes are responsible for speciation is important yet challenging. Several studies have proposed that speciation in pathogens is heavily influenced by host-pathogen dynamics and that traits that mediate such interactions (e.g., host mobility, reproductive mode of the pathogen, complexity of the life cycle, and host specificity) must lead to reproductive isolation and ultimately affect speciation rates. In this review, we summarize the main evolutionary processes that lead to speciation of fungal and oomycete plant pathogens and provide an outline of how speciation can be studied rigorously, including novel genetic/genomic developments.

  10. Population Structure, Races, and Host Range of Aphanomyces euteiches from Alfalfa Production Fields in the Central U.S.A.

    Science.gov (United States)

    Aphanomyces euteiches (races 1 and 2) cause root rot of alfalfa; however, its population biology and distribution were poorly understood in areas of the United States such as Illinois where alfalfa is a major crop. Objectives of this study were to (i) characterize the distribution and frequency of ...

  11. RNAseq and Proteomics for Analysing Complex Oomycete Plant Interactions.

    Science.gov (United States)

    Burra, Dharani D; Vetukuri, Ramesh R; Resjö, Svante; Grenville-Briggs, Laura J; Andreasson, Erik

    2016-01-01

    The oomycetes include some of the most devastating plant pathogens. In this review we discuss the latest results from oomycete and plant studies with emphasis on interaction studies. We focus on the outcomes of RNAseq and proteomics studies and some pitfalls of these approaches. Both pathogenic interactions and biological control are discussed. We underline the usefulness of studies at several levels of complexity from studies of one organism, up to two or more and within agricultural fields (managed settings) up to wild ecosystems. Finally we identify areas of future interest such as detailed interactome studies, dual RNAseq studies, peptide modification studies and population/meta omics with or without biological control agents.

  12. An improved high throughput sequencing method for studying oomycete communities

    DEFF Research Database (Denmark)

    Sapkota, Rumakanta; Nicolaisen, Mogens

    2015-01-01

    Culture-independent studies using next generation sequencing have revolutionizedmicrobial ecology, however, oomycete ecology in soils is severely lagging behind. The aimof this study was to improve and validate standard techniques for using high throughput sequencing as a tool for studying oomyce...

  13. Next generation sequencing of oomycete communities in nursery irrigation water

    Science.gov (United States)

    Joyce Eberhart; Fumiaki Funahashi; Zachary S.L. Foster; Jennifer Parke

    2017-01-01

    Horticultural nurseries are under increasing pressure to reduce, remediate, and recycle irrigation water. A major constraint for reusing irrigation water is contamination by waterborne plant pathogenic Phytophthora and Pythium species. Current research is focused on helping plant nurseries monitor oomycete pathogens in...

  14. Sodium, potassium-atpases in algae and oomycetes.

    Science.gov (United States)

    Barrero-Gil, Javier; Garciadeblás, Blanca; Benito, Begoña

    2005-08-01

    We have investigated the presence of K(+)-transporting ATPases that belong to the phylogenetic group of animal Na(+),K(+)-ATPases in the Pythium aphanidermatum Stramenopile oomycete, the Porphyra yezoensis red alga, and the Udotea petiolata green alga, by molecular cloning and expression in heterologous systems. PCR amplification and search in EST databases allowed one gene to be identified in each species that could encode ATPases of this type. Phylogenetic analysis of the sequences of these ATPases revealed that they cluster with ATPases of animal origin, and that the algal ATPases are closer to animal ATPases than the oomycete ATPase is. The P. yezoensis and P. aphanidermatum ATPases were functionally expressed in Saccharomyces cerevisiae and Escherichia coli alkali cation transport mutants. The aforementioned cloning and complementary searches in silicio for H(+)- and Na(+),K(+)-ATPases revealed a great diversity of strategies for plasma membrane energization in eukaryotic cells different from typical animal, plant, and fungal cells.

  15. Silencing of the Rac1 GTPase MtROP9 in Medicago truncatula stimulates early mycorrhizal and oomycete root colonizations but negatively affects rhizobial infection.

    Science.gov (United States)

    Kiirika, Leonard Muriithi; Bergmann, Hannah Friederike; Schikowsky, Christine; Wimmer, Diana; Korte, Joschka; Schmitz, Udo; Niehaus, Karsten; Colditz, Frank

    2012-05-01

    RAC/ROP proteins (ρ-related GTPases of plants) are plant-specific small G proteins that function as molecular switches within elementary signal transduction pathways, including the regulation of reactive oxygen species (ROS) generation during early microbial infection via the activation of NADPH oxidase homologs of plants termed RBOH (for respiratory burst oxidase homolog). We investigated the role of Medicago truncatula Jemalong A17 small GTPase MtROP9, orthologous to Medicago sativa Rac1, via an RNA interference silencing approach. Composite M. truncatula plants (MtROP9i) whose roots have been transformed by Agrobacterium rhizogenes carrying the RNA interference vector were generated and infected with the symbiotic arbuscular mycorrhiza fungus Glomus intraradices and the rhizobial bacterium Sinorhizobium meliloti as well as with the pathogenic oomycete Aphanomyces euteiches. MtROP9i transgenic lines showed a clear growth-reduced phenotype and revealed neither ROS generation nor MtROP9 and MtRBOH gene expression after microbial infection. Coincidently, antioxidative compounds were not induced in infected MtROP9i roots, as documented by differential proteomics (two-dimensional differential gel electrophoresis). Furthermore, MtROP9 knockdown clearly promoted mycorrhizal and A. euteiches early hyphal root colonization, while rhizobial infection was clearly impaired. Infected MtROP9i roots showed, in part, extremely swollen noninfected root hairs and reduced numbers of deformed nodules. S. meliloti nodulation factor treatments of MtROP9i led to deformed root hairs showing progressed swelling of its upper regions or even of the entire root hair and spontaneous constrictions but reduced branching effects occurring only at swollen root hairs. These results suggest a key role of Rac1 GTPase MtROP9 in ROS-mediated early infection signaling.

  16. In planta expression of oomycete and fungal genes.

    Science.gov (United States)

    Kanneganti, Thirumala-Devi; Huitema, Edgar; Kamoun, Sophien

    2007-01-01

    Large-scale genome sequencing projects have generated a wealth of sequence information for plant pathogenic microbes such as oomycetes and fungi. Functional genomic approaches are essential to exploit the sequence information to identify pathogen effector genes that trigger cellular and molecular responses in plant cells. This chapter describes two functional assays, agroinfiltration and agroinfection. These assays allow rapid functional expression of pathogen genes in plants and can be used in high-throughput screens.

  17. A domain-centric analysis of oomycete plant pathogen genomes reveals unique protein organization

    NARCIS (Netherlands)

    Seidl, M.F.; Ackerveken, van den G.; Govers, F.; Snel, B.

    2011-01-01

    Oomycetes comprise a diverse group of organisms that morphologically resemble fungi but belong to the stramenopile lineage within the supergroup of chromalveolates. Recent studies have shown that plant pathogenic oomycetes have expanded gene families that are possibly linked to their pathogenic life

  18. Saprolegnia brachydanis, a new oomycete isolated from zebra fish.

    Science.gov (United States)

    Ke, Xiaoli; Wang, Jianguo; Gu, Zemao; Li, Ming; Gong, Xiaoning

    2009-02-01

    Saprolegnia brachydanis is described from zebra fish (Brachydanio rerio) in Wuhan, Hubei Province, China. The species is illustrated and compared with other species of the genus. The distinctive characteristics of S. brachydanis are the production of glomerulate oogonia wrapped around by predominantly monoclinous antheridia which can be up to eight in one oogonium. The oogonial stalks are short, straight, or curved and the antheridia, twisted, can enwind one or more oogonia. The oospores cannot mature or easily abort. Morphological features of the oomycete and the ITS sequence of its rDNA as well as the comparison with related species are discussed in this article.

  19. 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.

  20. 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

  1. Enzymatic Activity of the Mycelium Compared with Oospore Development During Infection of Pea Roots by Aphanomyces euteiches

    DEFF Research Database (Denmark)

    Kjøller, Rasmus; Rosendahl, Søren

    1998-01-01

    To describe the disease cycle of the root pathogen Aphanomyces euteiches, enzymatic activity in the mycelium was compared with the development of oospores in pea roots. Plants were inoculated with two zoospore concentrations to achieve different disease levels. Hyphae were stained for fungal alka....... In these plants, oospores were found in 90% of the root length, while the enzymatic activity of the mycelium was low. This suggests that the pathogen mycelium is only active on living plants and does not grow saprophytically on dead plant material.......To describe the disease cycle of the root pathogen Aphanomyces euteiches, enzymatic activity in the mycelium was compared with the development of oospores in pea roots. Plants were inoculated with two zoospore concentrations to achieve different disease levels. Hyphae were stained for fungal...... concentration, the enzymatic activity of the pathogen mycelium peaked 10 to 14 days after inoculation, when oospore formation was initiated. Oospore formation was associated with a gradual increase in disease symptoms. At the last harvest, plants inoculated with the higher zoospore concentration had died...

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

    Directory of Open Access Journals (Sweden)

    Stephanie eBollmann

    2016-03-01

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

  3. Surviving freezing in plant tissues by oomycetous snow molds.

    Science.gov (United States)

    Murakami, Ryo; Yajima, Yuka; Kida, Ken-ichi; Tokura, Katsuyuki; Tojo, Motoaki; Hoshino, Tamotsu

    2015-04-01

    Oomyceteous snow molds, Pythium species, were reported to be less tolerant to chilling and freezing temperatures than other snow mold taxa. However, Pythium species are often found to be pathogenic on mosses in Polar Regions. We investigated the frost resistance of Pythium species from Temperate (Hokkaido, Japan) and Subantarctic Regions. Free mycelia and hyphal swellings, structures for survival, of Pythium iwayamai and Pythium paddicum lost viability within freeze-thaw 3 cycles; however, mycelia in host plants survived the treatment. It was reported that fungi in permafrost are characterized both by the presence of natural cryoprotectants in these ecotopes and by the ability to utilize their inherent mechanisms of protection. It is conceivable that plant substrates or derivatives thereof are natural cryoprotectants, enabling them to provide advantageous conditions to microorganisms under freezing conditions. Our results are the first to experimentally support this hypothesis.

  4. Detailed surface morphology of the 'lobster louse' copepod, Nicothoë astaci, a haematophagous gill parasite of the European lobster, Homarus gammarus.

    Science.gov (United States)

    Davies, Charlotte E; Thomas, Gethin R; Maffeis, Thierry G G; Wootton, Emma C; Penny, Mark W; Rowley, Andrew F

    2014-10-01

    The ectoparasitic copepod, Nicothoë astaci (the 'lobster louse'), infests the gills of the European lobster, Homarus gammarus. There have been limited studies on this haematophagous species; therefore knowledge of this parasite is rudimentary. The current study examines the surface morphology of this parasitic copepod, detached from the host, concentrating on adaptations of the suctorial mouthpart, the oral disc. Cryo-scanning electron microscopy revealed structural adaptations that facilitate attachment of these parasites to the gill filaments of their lobster host. The aperture of the feeding channel, through which host haemolymph is drawn, is only ca. 5μm in diameter. The edge of the oral disc is lined with numerous setae, whilst the surface of the disc is covered with large numbers of small (<1μm in diameter) teeth-like structures, which presumably pierce through, and grip, the cuticle lining of the host's gill. Overall, these structures are thought to provide a 'vacuum seal' to assist in pumping of blood, via peristalsis, into the alimentary canal of the copepod host.

  5. PsAAT3, an oomycete-specific aspartate aminotransferase, is required for full pathogenicity of the oomycete pathogen Phytophthora sojae.

    Science.gov (United States)

    Wang, Rongbo; Zhang, Meixiang; Liu, Hong; Xu, Jing; Yu, Jia; He, Feng; Zhang, Xiong; Dong, Suomeng; Dou, Daolong

    2016-04-01

    Pathogen nutrient acquisition and metabolism are critical for successful infection and colonization. However, the nutrient requirements and metabolic pathways related to pathogenesis in oomycete pathogens are unknown. In this study, we bioinformatically identified Phytophthora sojae aspartate aminotransferases (AATs), which are key enzymes that coordinate carbon and nitrogen metabolism. We demonstrated that P. sojae encodes more AATs than the analysed fungi. Some of the AATs contained additional prephenate dehydratase and/or prephenate dehydrogenase domains in their N-termini, which are unique to oomycetes. Silencing of PsAAT3, an infection-inducible expression gene, reduced P. sojae pathogenicity on soybean plants and affected the growth under N-starving condition, suggesting that PsAAT3 is involved in pathogen pathogenicity and nitrogen utilisation during infection. Our results suggest that P. sojae and other oomycete pathogens may have distinct amino acid metabolism pathways and that PsAAT3 is important for its full pathogenicity.

  6. Draft Genome Sequence of the Mycoparasitic Oomycete Pythium periplocum Strain CBS 532.74.

    Science.gov (United States)

    Kushwaha, Sandeep K; Vetukuri, Ramesh R; Grenville-Briggs, Laura J

    2017-03-23

    The oomycete Pythium periplocum is an aggressive mycoparasite of a number of plant pathogenic fungi and oomycetes and therefore has potential as a biological control agent. Here, we report the first draft genome sequence of P. periplocum, which comprises 35.89 Mb. It contains 1,043 scaffolds and 14,399 predicted protein-coding genes. Copyright © 2017 Kushwaha et al.

  7. Entry of oomycete and fungal effectors into plant and animal host cells.

    Science.gov (United States)

    Kale, Shiv D; Tyler, Brett M

    2011-12-01

    Fungal and oomycete pathogens cause many destructive diseases of plants and important diseases of humans and other animals. Fungal and oomycete plant pathogens secrete numerous effector proteins that can enter inside host cells to condition susceptibility. Until recently it has been unknown if these effectors enter via pathogen-encoded translocons or via pathogen-independent mechanisms. Here we review recent evidence that many fungal and oomycete effectors enter via receptor-mediated endocytosis, and can do so in the absence of the pathogen. Surprisingly, a large number of these effectors utilize cell surface phosphatidyinositol-3-phosphate (PI-3-P) as a receptor, a molecule previously known only inside cells. Binding of effectors to PI-3-P appears to be mediated by the cell entry motif RXLR in oomycetes, and by diverse RXLR-like variants in fungi. PI-3-P appears to be present on the surface of animal cells also, suggesting that it may mediate entry of effectors of fungal and oomycete animal pathogens, for example, RXLR effectors found in the oomycete fish pathogen, Saprolegnia parasitica. Reagents that can block PI-3-P-mediated entry have been identified, suggesting new therapeutic strategies.

  8. Evaluation of secretion prediction highlights differing approaches needed for oomycete and fungal effectors

    Directory of Open Access Journals (Sweden)

    Jana eSperschneider

    2015-12-01

    Full Text Available The steadily increasing number of sequenced fungal and oomycete genomes has enabled detailed studies of how these eukaryotic microbes infect plants and cause devastating losses in food crops. During infection, fungal and oomycete pathogens secrete effector molecules which manipulate host plant cell processes to the pathogen’s advantage. Proteinaceous effectors are synthesised intracellularly and must be externalised to interact with host cells. Computational prediction of secreted proteins from genomic sequences is an important technique to narrow down the candidate effector repertoire for subsequent experimental validation. In this study, we benchmark secretion prediction tools on experimentally validated fungal and oomycete effectors. We observe that for a set of fungal SwissProt protein sequences, SignalP 4 and the neural network predictors of SignalP 3 (D-score and SignalP 2 perform best. For effector prediction in particular, the use of a sensitive method can be desirable to obtain the most complete candidate effector set. We show that the neural network predictors of SignalP 2 and 3, as well as TargetP were the most sensitive tools for fungal effector secretion prediction, whereas the hidden Markov model predictors of SignalP 2 and 3 were the most sensitive tools for oomycete effectors. Thus, previous versions of SignalP retain value for oomycete effector prediction, as the current version, SignalP 4, was unable to reliably predict the signal peptide of the oomycete Crinkler effectors in the test set. Our assessment of subcellular localisation predictors shows that cytoplasmic effectors are often predicted as not extracellular. This limits the reliability of secretion predictions that depend on these tools. We present our assessment with a view to informing future pathogenomics studies and suggest revised pipelines for secretion prediction to obtain optimal effector predictions in fungi and oomycetes.

  9. Fungal and Oomycete Diseases of Tropical Tree Fruit Crops.

    Science.gov (United States)

    Drenth, André; Guest, David I

    2016-08-04

    The tropics produce a range of fruit from tree crops that cannot be grown in colder climates. Bananas, mangos, several nuts, spices, coffee, and cacao are widely traded and much sought after around the world. However, the sustainable production of these tropical tree fruit crops faces significant challenges. Among these, losses due to pests and diseases play a large part in reducing yields, quality, and profitability. Using bananas and cacao as key examples, we outline some of the reasons fungal and oomycete diseases cause such significant losses to tropical tree crops. Cultivation of monocultures derived from limited genetic diversity, environmental conditions conducive for disease development, high levels of disease incidence and severity, a lack of disease resistance in planting materials, shortages of labor, and inadequate infrastructure and investment pose significant challenges, especially for smallholder producers. The expansion of travel and trade has given rise to emerging infectious plant diseases that add further insecurity and pressure. We conclude that holistic actions are needed on multiple fronts to address the growing problem of disease in tropical fruit tree crops.

  10. Codon-based phylogenetics introduces novel flagellar gene markers to oomycete systematics.

    Science.gov (United States)

    Robideau, Gregg P; Rodrigue, Nicolas; André Lévesque, C

    2014-10-01

    Oomycete systematics has traditionally been reliant on ribosomal RNA and mitochondrial cytochrome oxidase sequences. Here we report the use of two single-copy protein-coding flagellar genes, PF16 and OCM1, in oomycete systematics, showing their utility in phylogenetic reconstruction and species identification. Applying a recently proposed mutation-selection model of codon substitution, the phylogenetic relationships inferred by flagellar genes are largely in agreement with the current views of oomycete evolution, whereas nucleotide- and amino acid-level models produce biologically implausible reconstructions. Interesting parallels exist between the phylogeny inferred from the flagellar genes and zoospore ontology, providing external support for the tree obtained using the codon model. The resolution achieved for species identification is ample using PF16, and quite robust using OCM1, and the described PCR primers are able to amplify both genes for a range of oomycete genera. Altogether, when analyzed with a rich codon substitution model, these flagellar genes provide useful markers for the oomycete molecular toolbox.

  11. Reconstruction of Oomycete Genome Evolution Identifies Differences in Evolutionary Trajectories Leading to Present-Day Large Gene Families

    NARCIS (Netherlands)

    Seidl, M.F.; Ackerveken, van den G.; Govers, F.; Snel, B.

    2012-01-01

    The taxonomic class of oomycetes contains numerous pathogens of plants and animals but is related to nonpathogenic diatoms and brown algae. Oomycetes have flexible genomes comprising large gene families that play roles in pathogenicity. The evolutionary processes that shaped the gene content have no

  12. Reconstruction of Oomycete Genome Evolution Identifies Differences in Evolutionary Trajectories Leading to Present-Day Large Gene Families

    NARCIS (Netherlands)

    Seidl, M.F.; Ackerveken, van den G.; Govers, F.; Snel, B.

    2012-01-01

    The taxonomic class of oomycetes contains numerous pathogens of plants and animals but is related to nonpathogenic diatoms and brown algae. Oomycetes have flexible genomes comprising large gene families that play roles in pathogenicity. The evolutionary processes that shaped the gene content have

  13. Filamentous brown algae infected by the marine, holocarpic oomycete Eurychasma dicksonii

    Science.gov (United States)

    Tsirigoti, Amerssa; Kuepper, Frithjof C; Gachon, Claire MM; Katsaros, Christos

    2013-01-01

    The important role of the cytoskeletal scaffold is increasingly recognized in host-pathogen interactions. The cytoskeleton potentially functions as a weapon for both the plants defending themselves against fungal or oomycete parasites, and for the pathogens trying to overcome the resisting barrier of the plants. This concept, however, had not been investigated in marine algae so far. We are opening this scientific chapter with our study on the functional implications of the cytoskeleton in 3 filamentous brown algal species infected by the marine oomycete Eurychasma dicksonii. Our observations suggest that the cytoskeleton is involved in host defense responses and in fundamental developmental stages of E. dicksonii in its algal host. PMID:24025487

  14. Enzymatic Activity of the Mycelium Compared with Oospore Development During Infection of Pea Roots by Aphanomyces euteiches.

    Science.gov (United States)

    Kjøller, R; Rosendahl, S

    1998-09-01

    ABSTRACT To describe the disease cycle of the root pathogen Aphanomyces euteiches, enzymatic activity in the mycelium was compared with the development of oospores in pea roots. Plants were inoculated with two zoospore concentrations to achieve different disease levels. Hyphae were stained for fungal alkaline phosphatase activity in the roots. Additionally, enzyme activity was measured after electrophoresis of an A. euteiches-specific glucose-6-phosphate isozyme. Development of oospores in the roots was measured after staining the oospores with trypan blue. In plants inoculated with the higher zoospore concentration, the enzymatic activity of the pathogen mycelium peaked 10 to 14 days after inoculation, when oospore formation was initiated. Oospore formation was associated with a gradual increase in disease symptoms. At the last harvest, plants inoculated with the higher zoospore concentration had died. In these plants, oospores were found in 90% of the root length, while the enzymatic activity of the mycelium was low. This suggests that the pathogen mycelium is only active on living plants and does not grow saprophytically on dead plant material.

  15. 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, ...

  16. Distinctive expansion of potential virulence genes in the genome of the oomycete fish pathogen Saprolegnia parasitica

    NARCIS (Netherlands)

    Jiang, R.H.Y.; Bruijn, de I.; Haas, B.J.; Belmonte, R.; Löbach, L.; Christie, J.; Ackerveken, van den G.; Bottin, A.; Bulone, V.; Díaz-Moreno, S.M.; Dumas, B.; Fan, L.; Gaulin, E.; Govers, F.; Grenville-Briggs, L.J.; Horner, N.R.; Levin, J.Z.; Mammella, M.; Meijer, H.J.G.; Morris, P.; Nusbaum, C.; Oome, S.; Phillips, A.J.; Rooyen, van D.; Rzeszutek, E.; Saraiva, M.; Secombes, C.J.; Seidl, M.F.; Snel, B.; Stassen, J.H.M.; Sykes, S.; Tripathy, S.; Berg, H.; Vega-Arreguin, J.C.; Wawra, S.; Young, S.K.; Zeng, Q.; Dieguez-Uribeondo, J.; Russ, C.; Tyler, B.M.; West, van P.

    2013-01-01

    Oomycetes in the class Saprolegniomycetidae of the Eukaryotic kingdom Stramenopila have evolved as severe pathogens of amphibians, crustaceans, fish and insects, resulting in major losses in aquaculture and damage to aquatic ecosystems. We have sequenced the 63 Mb genome of the fresh water fish path

  17. Horizontal gene transfer facilitated the evolution of plant parasitic mechanisms in the oomycetes.

    Science.gov (United States)

    Richards, Thomas A; Soanes, Darren M; Jones, Meredith D M; Vasieva, Olga; Leonard, Guy; Paszkiewicz, Konrad; Foster, Peter G; Hall, Neil; Talbot, Nicholas J

    2011-09-13

    Horizontal gene transfer (HGT) can radically alter the genomes of microorganisms, providing the capacity to adapt to new lifestyles, environments, and hosts. However, the extent of HGT between eukaryotes is unclear. Using whole-genome, gene-by-gene phylogenetic analysis we demonstrate an extensive pattern of cross-kingdom HGT between fungi and oomycetes. Comparative genomics, including the de novo genome sequence of Hyphochytrium catenoides, a free-living sister of the oomycetes, shows that these transfers largely converge within the radiation of oomycetes that colonize plant tissues. The repertoire of HGTs includes a large number of putatively secreted proteins; for example, 7.6% of the secreted proteome of the sudden oak death parasite Phytophthora ramorum has been acquired from fungi by HGT. Transfers include gene products with the capacity to break down plant cell walls and acquire sugars, nucleic acids, nitrogen, and phosphate sources from the environment. Predicted HGTs also include proteins implicated in resisting plant defense mechanisms and effector proteins for attacking plant cells. These data are consistent with the hypothesis that some oomycetes became successful plant parasites by multiple acquisitions of genes from fungi.

  18. 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

  19. Effect of phosphorus and the arbuscular mycorrhizal fungus Glomus intraradices on disease severity of root rot of peas (Pisum sativum) caused by Aphanomyces euteiches

    DEFF Research Database (Denmark)

    Bødker, Lars; Kjøller, Rasmus; Rosendahl, Søren

    1998-01-01

    The effects of inorganic phosphate levels and the presence of arbuscular mycorrhiza on disease severity of Aphanomyces euteiches in pea roots were studied. Disease severity on roots and epicotyl as well as the oospore number within infected root tissue were correlated with the phosphorus (P) level...... in the growth medium. The arbuscular mycorrhizal fungus Glomus intraradices increased P uptake and the P concentration in the plant but reduced disease development in peas. Polyacrylamide gel electrophoresis followed by densitometry of glucose-6-phosphate dehydrogenase specific to A.euteiches was used...

  20. Expressed sequence tags from the oomycete fish pathogen Saprolegnia parasitica reveal putative virulence factors

    Directory of Open Access Journals (Sweden)

    van West Pieter

    2005-08-01

    Full Text Available Abstract Background The oomycete Saprolegnia parasitica is one of the most economically important fish pathogens. There is a dramatic recrudescence of Saprolegnia infections in aquaculture since the use of the toxic organic dye malachite green was banned in 2002. Little is known about the molecular mechanisms underlying pathogenicity in S. parasitica and other animal pathogenic oomycetes. In this study we used a genomics approach to gain a first insight into the transcriptome of S. parasitica. Results We generated 1510 expressed sequence tags (ESTs from a mycelial cDNA library of S. parasitica. A total of 1279 consensus sequences corresponding to 525944 base pairs were assembled. About half of the unigenes showed similarities to known protein sequences or motifs. The S. parasitica sequences tended to be relatively divergent from Phytophthora sequences. Based on the sequence alignments of 18 conserved proteins, the average amino acid identity between S. parasitica and three Phytophthora species was 77% compared to 93% within Phytophthora. Several S. parasitica cDNAs, such as those with similarity to fungal type I cellulose binding domain proteins, PAN/Apple module proteins, glycosyl hydrolases, proteases, as well as serine and cysteine protease inhibitors, were predicted to encode secreted proteins that could function in virulence. Some of these cDNAs were more similar to fungal proteins than to other eukaryotic proteins confirming that oomycetes and fungi share some virulence components despite their evolutionary distance Conclusion We provide a first glimpse into the gene content of S. parasitica, a reemerging oomycete fish pathogen. These resources will greatly accelerate research on this important pathogen. The data is available online through the Oomycete Genomics Database 1.

  1. Systemic Induction of the Defensin and Phytoalexin Pisatin Pathways in Pea (Pisum sativum against Aphanomyces euteiches by Acetylated and Nonacetylated Oligogalacturonides

    Directory of Open Access Journals (Sweden)

    Sameh Selim

    2017-06-01

    Full Text Available Oligogalacturonides (OGs are known for their powerful ability to stimulate the plant immune system but little is known about their mode of action in pea (Pisum sativum. In the present study, we investigated the elicitor activity of two fractions of OGs, with polymerization degrees (DPs of 2–25, in pea against Aphanomyces euteiches. One fraction was nonacetylated (OGs − Ac whereas the second one was 30% acetylated (OGs + Ac. OGs were applied by injecting the upper two rachises of the plants at three- and/or four-weeks-old. Five-week-old roots were inoculated with 105 zoospores of A. euteiches. The root infection level was determined at 7, 10 and 14 days after inoculation using the quantitative real-time polymerase chain reaction (qPCR. Results showed significant root infection reductions namely 58, 45 and 48% in the plants treated with 80 µg OGs + Ac and 59, 56 and 65% with 200 µg of OGs − Ac. Gene expression results showed the upregulation of genes involved in the antifungal defensins, lignans and the phytoalexin pisatin pathways and a priming effect in the basal defense, SA and ROS gene markers as a response to OGs. The reduction of the efficient dose in OGs + Ac is suggesting that acetylation is necessary for some specific responses. Our work provides the first evidence for the potential of OGs in the defense induction in pea against Aphanomyces root rot.

  2. 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

  3. The unique architecture and function of cellulose-interacting proteins in oomycetes revealed by genomic and structural analyses

    Directory of Open Access Journals (Sweden)

    Larroque Mathieu

    2012-11-01

    Full Text Available Abstract Background Oomycetes are fungal-like microorganisms evolutionary distinct from true fungi, belonging to the Stramenopile lineage and comprising major plant pathogens. Both oomycetes and fungi express proteins able to interact with cellulose, a major component of plant and oomycete cell walls, through the presence of carbohydrate-binding module belonging to the family 1 (CBM1. Fungal CBM1-containing proteins were implicated in cellulose degradation whereas in oomycetes, the Cellulose Binding Elicitor Lectin (CBEL, a well-characterized CBM1-protein from Phytophthora parasitica, was implicated in cell wall integrity, adhesion to cellulosic substrates and induction of plant immunity. Results To extend our knowledge on CBM1-containing proteins in oomycetes, we have conducted a comprehensive analysis on 60 fungi and 7 oomycetes genomes leading to the identification of 518 CBM1-containing proteins. In plant-interacting microorganisms, the larger number of CBM1-protein coding genes is expressed by necrotroph and hemibiotrophic pathogens, whereas a strong reduction of these genes is observed in symbionts and biotrophs. In fungi, more than 70% of CBM1-containing proteins correspond to enzymatic proteins in which CBM1 is associated with a catalytic unit involved in cellulose degradation. In oomycetes more than 90% of proteins are similar to CBEL in which CBM1 is associated with a non-catalytic PAN/Apple domain, known to interact with specific carbohydrates or proteins. Distinct Stramenopile genomes like diatoms and brown algae are devoid of CBM1 coding genes. A CBM1-PAN/Apple association 3D structural modeling was built allowing the identification of amino acid residues interacting with cellulose and suggesting the putative interaction of the PAN/Apple domain with another type of glucan. By Surface Plasmon Resonance experiments, we showed that CBEL binds to glycoproteins through galactose or N-acetyl-galactosamine motifs. Conclusions This study

  4. Draft Genome Sequence of the Mycoparasitic Oomycete Pythium oligandrum Strain CBS 530.74.

    Science.gov (United States)

    Kushwaha, Sandeep K; Vetukuri, Ramesh R; Grenville-Briggs, Laura J

    2017-05-25

    The oomycete Pythium oligandrum is a mycoparasite and licenced biological control agent. Here, we report the draft genome sequence of P. oligandrum strain CBS 530.74, which is 36.80 Mb. It contains 341 scaffolds and 11,647 predicted protein-coding genes. As reported for plant-pathogenic Pythium species, RXLR-type effector sequences are absent. Copyright © 2017 Kushwaha et al.

  5. Imbalanced Lignin Biosynthesis Promotes the Sexual Reproduction of Homothallic Oomycete Pathogens

    Science.gov (United States)

    Quentin, Michaël; Allasia, Valérie; Pegard, Anthony; Allais, Florent; Ducrot, Paul-Henri; Favery, Bruno; Levis, Caroline; Martinet, Sophie; Masur, Clarissa; Ponchet, Michel; Roby, Dominique; Schlaich, Nikolaus L.; Jouanin, Lise; Keller, Harald

    2009-01-01

    Lignin is incorporated into plant cell walls to maintain plant architecture and to ensure long-distance water transport. Lignin composition affects the industrial value of plant material for forage, wood and paper production, and biofuel technologies. Industrial demands have resulted in an increase in the use of genetic engineering to modify lignified plant cell wall composition. However, the interaction of the resulting plants with the environment must be analyzed carefully to ensure that there are no undesirable side effects of lignin modification. We show here that Arabidopsis thaliana mutants with impaired 5-hydroxyguaiacyl O-methyltransferase (known as caffeate O-methyltransferase; COMT) function were more susceptible to various bacterial and fungal pathogens. Unexpectedly, asexual sporulation of the downy mildew pathogen, Hyaloperonospora arabidopsidis, was impaired on these mutants. Enhanced resistance to downy mildew was not correlated with increased plant defense responses in comt1 mutants but coincided with a higher frequency of oomycete sexual reproduction within mutant tissues. Comt1 mutants but not wild-type Arabidopsis accumulated soluble 2-O-5-hydroxyferuloyl-l-malate. The compound weakened mycelium vigor and promoted sexual oomycete reproduction when applied to a homothallic oomycete in vitro. These findings suggested that the accumulation of 2-O-5-hydroxyferuloyl-l-malate accounted for the observed comt1 mutant phenotypes during the interaction with H. arabidopsidis. Taken together, our study shows that an artificial downregulation of COMT can drastically alter the interaction of a plant with the biotic environment. PMID:19148278

  6. Imbalanced lignin biosynthesis promotes the sexual reproduction of homothallic oomycete pathogens.

    Directory of Open Access Journals (Sweden)

    Michaël Quentin

    2009-01-01

    Full Text Available Lignin is incorporated into plant cell walls to maintain plant architecture and to ensure long-distance water transport. Lignin composition affects the industrial value of plant material for forage, wood and paper production, and biofuel technologies. Industrial demands have resulted in an increase in the use of genetic engineering to modify lignified plant cell wall composition. However, the interaction of the resulting plants with the environment must be analyzed carefully to ensure that there are no undesirable side effects of lignin modification. We show here that Arabidopsis thaliana mutants with impaired 5-hydroxyguaiacyl O-methyltransferase (known as caffeate O-methyltransferase; COMT function were more susceptible to various bacterial and fungal pathogens. Unexpectedly, asexual sporulation of the downy mildew pathogen, Hyaloperonospora arabidopsidis, was impaired on these mutants. Enhanced resistance to downy mildew was not correlated with increased plant defense responses in comt1 mutants but coincided with a higher frequency of oomycete sexual reproduction within mutant tissues. Comt1 mutants but not wild-type Arabidopsis accumulated soluble 2-O-5-hydroxyferuloyl-L-malate. The compound weakened mycelium vigor and promoted sexual oomycete reproduction when applied to a homothallic oomycete in vitro. These findings suggested that the accumulation of 2-O-5-hydroxyferuloyl-L-malate accounted for the observed comt1 mutant phenotypes during the interaction with H. arabidopsidis. Taken together, our study shows that an artificial downregulation of COMT can drastically alter the interaction of a plant with the biotic environment.

  7. Plants versus fungi and oomycetes: pathogenesis, defense and counter-defense in the proteomics era.

    Science.gov (United States)

    El Hadrami, Abdelbasset; El-Bebany, Ahmed F; Yao, Zhen; Adam, Lorne R; El Hadrami, Ismailx; Daayf, Fouad

    2012-01-01

    Plant-fungi and plant-oomycete interactions have been studied at the proteomic level for many decades. However, it is only in the last few years, with the development of new approaches, combined with bioinformatics data mining tools, gel staining, and analytical instruments, such as 2D-PAGE/nanoflow-LC-MS/MS, that proteomic approaches thrived. They allow screening and analysis, at the sub-cellular level, of peptides and proteins resulting from plants, pathogens, and their interactions. They also highlight post-translational modifications to proteins, e.g., glycosylation, phosphorylation or cleavage. However, many challenges are encountered during in planta studies aimed at stressing details of host defenses and fungal and oomycete pathogenicity determinants during interactions. Dissecting the mechanisms of such host-pathogen systems, including pathogen counter-defenses, will ensure a step ahead towards understanding current outcomes of interactions from a co-evolutionary point of view, and eventually move a step forward in building more durable strategies for management of diseases caused by fungi and oomycetes. Unraveling intricacies of more complex proteomic interactions that involve additional microbes, i.e., PGPRs and symbiotic fungi, which strengthen plant defenses will generate valuable information on how pathosystems actually function in nature, and thereby provide clues to solving disease problems that engender major losses in crops every year.

  8. Diversity of Aquatic Pseudomonas Species and Their Activity against the Fish Pathogenic Oomycete Saprolegnia.

    Science.gov (United States)

    Liu, Yiying; Rzeszutek, Elzbieta; van der Voort, Menno; Wu, Cheng-Hsuan; Thoen, Even; Skaar, Ida; Bulone, Vincent; Dorrestein, Pieter C; Raaijmakers, Jos M; de Bruijn, Irene

    2015-01-01

    Emerging fungal and oomycete pathogens are increasingly threatening animals and plants globally. Amongst oomycetes, Saprolegnia species adversely affect wild and cultivated populations of amphibians and fish, leading to substantial reductions in biodiversity and food productivity. With the ban of several chemical control measures, new sustainable methods are needed to mitigate Saprolegnia infections in aquaculture. Here, PhyloChip-based community analyses showed that the Pseudomonadales, particularly Pseudomonas species, represent one of the largest bacterial orders associated with salmon eggs from a commercial hatchery. Among the Pseudomonas species isolated from salmon eggs, significantly more biosurfactant producers were retrieved from healthy salmon eggs than from Saprolegnia-infected eggs. Subsequent in vivo activity bioassays showed that Pseudomonas isolate H6 significantly reduced salmon egg mortality caused by Saprolegnia diclina. Live colony mass spectrometry showed that strain H6 produces a viscosin-like lipopeptide surfactant. This biosurfactant inhibited growth of Saprolegnia in vitro, but no significant protection of salmon eggs against Saprolegniosis was observed. These results indicate that live inocula of aquatic Pseudomonas strains, instead of their bioactive compound, can provide new (micro)biological and sustainable means to mitigate oomycete diseases in aquaculture.

  9. Diversity of Aquatic Pseudomonas Species and Their Activity against the Fish Pathogenic Oomycete Saprolegnia.

    Directory of Open Access Journals (Sweden)

    Yiying Liu

    Full Text Available Emerging fungal and oomycete pathogens are increasingly threatening animals and plants globally. Amongst oomycetes, Saprolegnia species adversely affect wild and cultivated populations of amphibians and fish, leading to substantial reductions in biodiversity and food productivity. With the ban of several chemical control measures, new sustainable methods are needed to mitigate Saprolegnia infections in aquaculture. Here, PhyloChip-based community analyses showed that the Pseudomonadales, particularly Pseudomonas species, represent one of the largest bacterial orders associated with salmon eggs from a commercial hatchery. Among the Pseudomonas species isolated from salmon eggs, significantly more biosurfactant producers were retrieved from healthy salmon eggs than from Saprolegnia-infected eggs. Subsequent in vivo activity bioassays showed that Pseudomonas isolate H6 significantly reduced salmon egg mortality caused by Saprolegnia diclina. Live colony mass spectrometry showed that strain H6 produces a viscosin-like lipopeptide surfactant. This biosurfactant inhibited growth of Saprolegnia in vitro, but no significant protection of salmon eggs against Saprolegniosis was observed. These results indicate that live inocula of aquatic Pseudomonas strains, instead of their bioactive compound, can provide new (microbiological and sustainable means to mitigate oomycete diseases in aquaculture.

  10. Dietary supplementation of Zeolite on growth performance, immunological role, and disease resistance in Channa striatus against Aphanomyces invadans.

    Science.gov (United States)

    Jawahar, Suntharam; Nafar, Adil; Vasanth, Krishnan; Musthafa, Mohamed Saiyad; Arockiaraj, Jesu; Balasundaram, Chellam; Harikrishnan, Ramasamy

    2016-04-01

    Epizootic Ulcerative Syndrome (EUS) caused by Aphanomyces invadans which is a primary fungal parasitic pathogen, inflicts serious economic loss in tropical freshwater fish including snakehead murrel, Channa striatus. In the present study with an aim to circumvent the adverse effects of the traditional measures in graded levels (2%, 4%, and 6%) of Zeolite enriched diet on growth performance, hematology, immunological response, and disease resistance in C. striatus against A. invadans is reported. The final weight (FW), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), and average daily gain (ADG) were significantly high in infected fish fed with 4% or 6% Zeolite incorporated diets on 4th week. The maximum survival rates (SR) of 96% and 98% were observed when fed with 2% or 4% diets on 4th week. Similarly, the white blood cell (WBC), red blood cell (RBC), hematocrit (Hct), mean corpuscular volume (MCV), and mean corpuscular haemoglobin concentration (MCHC) were significantly high when fed with any Zeolite enriched diet. However, the haemoglobin (Hb) and mean corpuscular haemoglobin (MCH) were significantly high with 4% and 6% Zeolite diets. The total protein and globulin were significantly high with 4% and 6% diets; the albumin, glucose, cholesterol, and triglyceride were significantly elevated with any enriched diet. The 4% and 6% Zeolite diets significantly enhanced the phagocytic activity on 2nd week but the 2% diet could increase it on 4th week. The respiratory burst (RB) activity, complement activity, and lymphocyte proliferation level were significantly enhanced with 4% and 6% Zeolite diets on weeks 1 and 2 while with 2% diet on 4th week. All enriched diets significantly increased the lysozyme activity during the experimental period. Superoxide anion (SOA) production significantly enhanced with 6% diet on weeks 1 and 2 whereas with 2% diet on week 4. Lower cumulative mortality of 10% and 15% was found with 4% and 6

  11. Endoproteolytic activities in pea roots inoculated with the arbuscular mycorrhizal fungus Glomus mosseae and/orAphanomyces euteiches in relation to bioprotection

    DEFF Research Database (Denmark)

    Slezack, S; DUMAS-GAUDOT, E; Rosendahl, Søren;

    1999-01-01

    was observed which was correlated with the amount of pathogen occurring in roots. Qualitative differences were seen among the endoproteolytic activities detected in roots inoculated with zoospores or mycelium. The constitutive as well as mycorrhizal and pathogen-induced activities were further characterized......Arbuscular mycorrhizal (AM) symbioses are known to play a role in increased resistance of plants against soilborne pathogens. Mechanisms involved in this phenomenon are not yet well understood. This work investigates possible roles of endoproteolytic activities in bioprotection of Pisum sativum...... roots by Glomus mosseae against Aphanomyces euteiches. First, it is demonstrated that bioprotection occurs only in pre-mycorrhizal plants. Second, endoproteolytic activities were analysed qualitatively and quantitatively during AM symbiosis, in plants infected with either zoospores or mycelium of A...

  12. EumicrobeDBLite: a lightweight genomic resource and analytic platform for draft oomycete genomes.

    Science.gov (United States)

    Panda, Arijit; Sen, Diya; Ghosh, Arup; Gupta, Akash; C, Mathu Malar; Prakash Mishra, Gyan; Singh, Deeksha; Ye, Wenwu; Tyler, Brett M; Tripathy, Sucheta

    2016-10-27

    We have developed EumicrobeDBLite-a lightweight comprehensive genome resource and sequence analysis platform for oomycete organisms. EumicrobeDBLite is a successor of the VBI Microbial Database (VMD) that was built using the Genome Unified Schema (GUS). In this version, GUS has been greatly simplified with the removal of many obsolete modules and the redesign of others to incorporate contemporary data. Several dependences, such as perl object layers used for data loading in VMD, have been replaced with independent lightweight scripts. EumicrobeDBLite now runs on a powerful annotation engine developed at our laboratory, called 'Genome Annotator Lite'. Currently, this database has 26 publicly available genomes and 10 expressed sequence tag (EST) datasets of oomycete organisms. The browser page has dynamic tracks presenting comparative genomics analyses, coding and non-coding data, tRNA genes, repeats and EST alignments. In addition, we have defined 44 777 core conserved proteins from 12 oomycete organisms which form 2974 clusters. Synteny viewing is enabled by the incorporation of the Genome Synteny Viewer (GSV) tool. The user interface has undergone major changes for ease of browsing. Queryable comparative genomics information, conserved orthologous genes and pathways are among the new key features updated in this database. The browser has been upgraded to enable user upload of GFF files for quick view of genome annotation comparisons. The toolkit page integrates the EMBOSS package and has a gene prediction tool. Annotations for the organisms are updated once every 6 months to ensure quality. The database resource is available at www.eumicrobedb.org.

  13. Use of high throughput sequencing to study oomycete communities in soil and roots

    DEFF Research Database (Denmark)

    Sapkota, Rumakanta; Nicolaisen, Mogens

    2015-01-01

    communities, DNA extracted from carrot tissue samples with symptoms of Pythium infection and soil samples collected from agricultural fields. Sequence data from Pythium and Phytophthora mock communities showed that our strategy successfully detected all included species. Taxonomic assignments of operational...... earlier in similar studies but with limited success, were used in this study with an improved protocol. Our result shows that the proportion of retrieved oomycete sequences dramatically increased, mainly by increasing the annealing temperature during PCR. The optimized protocol was validated using mock...

  14. Multiple horizontal gene transfer events and domain fusions have created novel regulatory and metabolic networks in the oomycete genome.

    Directory of Open Access Journals (Sweden)

    Paul Francis Morris

    Full Text Available Complex enzymes with multiple catalytic activities are hypothesized to have evolved from more primitive precursors. Global analysis of the Phytophthora sojae genome using conservative criteria for evaluation of complex proteins identified 273 novel multifunctional proteins that were also conserved in P. ramorum. Each of these proteins contains combinations of protein motifs that are not present in bacterial, plant, animal, or fungal genomes. A subset of these proteins were also identified in the two diatom genomes, but the majority of these proteins have formed after the split between diatoms and oomycetes. Documentation of multiple cases of domain fusions that are common to both oomycetes and diatom genomes lends additional support for the hypothesis that oomycetes and diatoms are monophyletic. Bifunctional proteins that catalyze two steps in a metabolic pathway can be used to infer the interaction of orthologous proteins that exist as separate entities in other genomes. We postulated that the novel multifunctional proteins of oomycetes could function as potential Rosetta Stones to identify interacting proteins of conserved metabolic and regulatory networks in other eukaryotic genomes. However ortholog analysis of each domain within our set of 273 multifunctional proteins against 39 sequenced bacterial and eukaryotic genomes, identified only 18 candidate Rosetta Stone proteins. Thus the majority of multifunctional proteins are not Rosetta Stones, but they may nonetheless be useful in identifying novel metabolic and regulatory networks in oomycetes. Phylogenetic analysis of all the enzymes in three pathways with one or more novel multifunctional proteins was conducted to determine the probable origins of individual enzymes. These analyses revealed multiple examples of horizontal transfer from both bacterial genomes and the photosynthetic endosymbiont in the ancestral genome of Stramenopiles. The complexity of the phylogenetic origins of these

  15. Aquatic fungi of twelve Augustów Lakes with reference to the chemistry of the environment

    Directory of Open Access Journals (Sweden)

    Bazyli Czeczuga

    2014-08-01

    Full Text Available Seventy five species of fungi were found in tbe Augustów Lakes. The following fungi unknown from Poland were rocorded: Rhizophydium pollinis-pini, Chytriomyces cosmarii, C. poculatus, Lageaidium humanum, Aphanomyces astaci, Leptolegeniella piligena, Achlya klebsiana, Cladolegnia unispora, Zoophagus pectosporus, Rhodosporidium toruloides and Vargamyces aguaticus.

  16. 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

  17. Parental transfer of the antimicrobial protein LBP/BPI protects Biomphalaria glabrata eggs against oomycete infections.

    Directory of Open Access Journals (Sweden)

    Olga Lucia Baron

    Full Text Available Vertebrate females transfer antibodies via the placenta, colostrum and milk or via the egg yolk to protect their immunologically immature offspring against pathogens. This evolutionarily important transfer of immunity is poorly documented in invertebrates and basic questions remain regarding the nature and extent of parental protection of offspring. In this study, we show that a lipopolysaccharide binding protein/bactericidal permeability increasing protein family member from the invertebrate Biomphalaria glabrata (BgLBP/BPI1 is massively loaded into the eggs of this freshwater snail. Native and recombinant proteins displayed conserved LPS-binding, antibacterial and membrane permeabilizing activities. A broad screening of various pathogens revealed a previously unknown biocidal activity of the protein against pathogenic water molds (oomycetes, which is conserved in human BPI. RNAi-dependent silencing of LBP/BPI in the parent snails resulted in a significant reduction of reproductive success and extensive death of eggs through oomycete infections. This work provides the first functional evidence that a LBP/BPI is involved in the parental immune protection of invertebrate offspring and reveals a novel and conserved biocidal activity for LBP/BPI family members.

  18. 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...

  19. Monitoring streams and stormwater ponds for early detection of oomycete plant pathogens in western Washington, a citizen science project

    Science.gov (United States)

    Marianne Elliott; Lucy Rollins; Gary Chastagner

    2017-01-01

    Sudden Oak Death (SOD) is the common name for a disease caused by Phytophthora ramorum (oomycetes), an invasive plant pathogen of regulatory concern. The nursery, timber, forest specialty product, and Christmas tree industries in Washington are at risk because of the spread of P. ramorum within nurseries and from nurseries into...

  20. Transcriptional and Antagonistic Responses of Biocontrol Strain Lysobacter enzymogenes OH11 to the Plant Pathogenic Oomycete Pythium aphanidermatum

    Directory of Open Access Journals (Sweden)

    Yangyang Zhao

    2017-06-01

    Full Text Available Lysobacter enzymogenes is a ubiquitous, beneficial, plant-associated bacterium emerging as a novel biological control agent. It has the potential to become a new source of antimicrobial secondary metabolites such as the Heat-Stable Antifungal Factor (HSAF, which is a broad-spectrum antimycotic with a novel mode of action. However, very little information about how L. enzymogenes detects and responds to fungi or oomycetes has been reported. An in vitro confrontation bioassay between the pathogenic oomycete Pythium aphanidermatum and the biocontrol bacterial strain L. enzymogenes OH11 was used to analyze the transcriptional changes in the bacteria that were induced by the oomycetes. Analysis was performed at three time points of the interaction, starting before inhibition zone formation until inhibition zone formation. A L. enzymogenes OH11 DNA microarray was constructed for the analysis. Microarray analysis indicated that a wide range of genes belonging to 14 diverse functions in L. enzymogenes were affected by P. aphanidermatum as critical antagonistic effects occurred. L. enzymogenes detected and responded to the presence of P. aphanidermatum early, but alteration of gene expression typically occurred after inhibition zone formation. The presence of P. aphanidermatum increased the twitching motility and HSAF production in L. enzymogenes. We also performed a contact interaction between L. enzymogenes and P. aphanidermatum, and found that HSAF played a critical role in the interaction. Our experiments demonstrated that L. enzymogenes displayed transcriptional and antagonistic responses to P. aphanidermatum in order to gain advantages in the competition with this oomycete. This study revealed new insights into the interactions between bacteria and oomycete.

  1. Patterns of plant subcellular responses to successful oomycete infections reveal differences in host cell reprogramming and endocytic trafficking

    Science.gov (United States)

    Lu, Yi-Ju; Schornack, Sebastian; Spallek, Thomas; Geldner, Niko; Chory, Joanne; Schellmann, Swen; Schumacher, Karin; Kamoun, Sophien; Robatzek, Silke

    2016-01-01

    Summary Adapted filamentous pathogens such as the oomycetes Hyaloperonospora arabidopsidis (Hpa) and Phytophthora infestans (Pi) project specialized hyphae, the haustoria, inside living host cells for the suppression of host defence and acquisition of nutrients. Accommodation of haustoria requires reorganization of the host cell and the biogenesis of a novel host cell membrane, the extrahaustorial membrane (EHM), which envelops the haustorium separating the host cell from the pathogen. Here, we applied live-cell imaging of fluorescent-tagged proteins labelling a variety of membrane compartments and investigated the subcellular changes associated with accommodating oomycete haustoria in Arabidopsis and N. benthamiana. Plasma membrane-resident proteins differentially localized to the EHM. Likewise, secretory vesicles and endosomal compartments surrounded Hpa and Pi haustoria revealing differences between these two oomycetes, and suggesting a role for vesicle trafficking pathways for the pathogen-controlled biogenesis of the EHM. The latter is supported by enhanced susceptibility of mutants in endosome-mediated trafficking regulators. These observations point at host subcellular defences and specialization of the EHM in a pathogen-specific manner. Defence-associated haustorial encasements, a double-layered membrane that grows around mature haustoria, were frequently observed in Hpa interactions. Intriguingly, all tested plant proteins accumulated at Hpa haustorial encasements suggesting the general recruitment of default vesicle trafficking pathways to defend pathogen access. Altogether, our results show common requirements of subcellular changes associated with oomycete biotrophy, and highlight differences between two oomycete pathogens in reprogramming host cell vesicle trafficking for haustoria accommodation. This provides a framework for further dissection of the pathogen-triggered reprogramming of host subcellular changes. PMID:22233428

  2. Proteinase inhibitory activities of two two-domain Kazal proteinase inhibitors from the freshwater crayfish Pacifastacus leniusculus and the importance of the P(2) position in proteinase inhibitory activity.

    Science.gov (United States)

    Donpudsa, Suchao; Söderhäll, Irene; Rimphanitchayakit, Vichien; Cerenius, Lage; Tassanakajon, Anchalee; Söderhäll, Kenneth

    2010-11-01

    Serine proteinase inhibitors are found ubiquitously in living organisms and involved in homeostasis of processes using proteinases as well as innate immune defense. Two two-domain Kazal-type serine proteinase inhibitors (KPIs), KPI2 and KPI8, have been identified from the hemocyte cDNA library of the crayfish Pacifastacus leniusculus. Unlike other KPIs from P. leniusculus, they are found specific to the hemocytes and contain an uncommon P(2) amino acid residue, Gly. To unveil their inhibitory activities, the two KPIs and their domains were over-expressed. By testing against subtilisin, trypsin, chymotrypsin and elastase, the KPI2 was found to inhibit strongly against subtilisin and weakly against trypsin, while the KPI8 was strongly active against only trypsin. With their P(1) Ser and Lys residues, the KPI2_domain2 and KPI8_domain2 were responsible for strong inhibition against subtilisin and trypsin, respectively. Mutagenesis of KPI8_domain1 at P(2) amino acid residue from Gly to Pro, mimicking the P(2) residue of KPI8_domain2, rendered the KPI8_domain1 strongly active against trypsin, indicating the important role of P(2) residue in inhibitory activities of the Kazal-type serine proteinase inhibitors. Only the KPI2 was found to inhibit against the extracellular serine proteinases from the pathogenic oomycete of the freshwater crayfish, Aphanomyces astaci.

  3. A Survey of Phytopathogenic Fungi and Oomycetes in Riyadh, Saudi Arabia

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    Arya Widyawan

    2015-06-01

    Full Text Available A survey of phytopathogenic fungi and Oomyceteswas conducted in Riyadh, Kingdom of Saudi Arabia duringOctober 2008 – May 2009. Total of 223 samples were collectedfrom four regions; Al-Kharj, Oyaynah, Old Diriyah, and Al Amariyah. Isolation was done using Potato Dextrose Agar(PDA. Infected parts were cut then sterilized in chlorox(10%, then were put in petridish that contain PDA andincubated at 25-27 °C. A total twelve genera of fungi andsingle genera of Oomycetes were isolated from the infectedplants and identifi ed as Fusarium spp., Alternaria spp.,Helmintosphorium (Bipolaris spp., Sclerotium spp., Rhizoctoniaspp., Cladosporium spp., Mauginiella scattae, Erysiphe spp.,Leveillula spp., Macrophomina phaseolina, Ustilago spp.,Ulocladium spp., and Phytium spp.

  4. Expressed Sequence Tags from the oomycete Plasmopara halstedii, an obligate parasite of the sunflower

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    Mouzeyar Said

    2007-12-01

    Full Text Available Abstract Background Sunflower downy mildew is a major disease caused by the obligatory biotrophic oomycete Plasmopara halstedii. Little is known about the molecular mechanisms underlying its pathogenicity. In this study we used a genomics approach to gain a first insight into the transcriptome of P. halstedii. Results To identify genes from the obligatory biotrophic oomycete Plasmopara halstedii that are expressed during infection in sunflower (Helianthus annuus L. we employed the suppression subtraction hybridization (SSH method from sunflower seedlings infected by P. halstedii. Using this method and random sequencing of clones, a total of 602 expressed sequence tags (ESTs corresponding to 230 unique sequence sets were identified. To determine the origin of the unisequences, PCR primers were designed to amplify these gene fragments from genomic DNA isolated either from P. halstedii sporangia or from Helianthus annuus. Only 145 nonredundant ESTs which correspond to a total of 373 ESTs (67.7% proved to be derived from P. halstedii genes and that are expressed during infection in sunflower. A set of 87 nonredundant sequences were identified as showing matches to sequences deposited in public databases. Nevertheless, about 7% of the ESTs seem to be unique to P. halstedii without any homolog in any public database. Conclusion A summary of the assignment of nonredundant ESTs to functional categories as well as their relative abundance is listed and discussed. Annotation of the ESTs revealed a number of genes that could function in virulence. We provide a first glimpse into the gene content of P. halstedii. These resources should accelerate research on this important 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. Do jasmonates play a role in arbuscular mycorrhiza-induced local bioprotection of Medicago truncatula against root rot disease caused by Aphanomyces euteiches?

    Science.gov (United States)

    Hilou, Adama; Zhang, Haoqiang; Franken, Philipp; Hause, Bettina

    2014-01-01

    Bioprotective effects of mycorrhization with two different arbuscular mycorrhizal (AM) fungi, Funneliformis mosseae and Rhizophagus irregularis, against Aphanomyces euteiches, the causal agent of root rot in legumes, were studied in Medicago truncatula using phenotypic and molecular markers. Previous inoculation with an AM-fungus reduced disease symptoms as well as the amount of pathogen within roots, as determined by the levels of A. euteiches rRNA or transcripts of the gene sterol C24 reductase. Inoculation with R. irregularis was as efficient as that with F. mosseae. To study whether jasmonates play a regulatory role in bioprotection of M. truncatula by the AM fungi, composite plants harboring transgenic roots were used to modulate the expression level of the gene encoding M. truncatula allene oxide cyclase 1, a key enzyme in jasmonic acid biosynthesis. Neither an increase nor a reduction in allene oxide cyclase levels resulted in altered bioprotection by the AM fungi against root infection by A. euteiches. These data suggest that jasmonates do not play a major role in the local bioprotective effect of AM fungi against the pathogen A. euteiches in M. truncatula roots.

  7. Comparative Genomics Including the Early-Diverging Smut Fungus Ceraceosorus bombacis Reveals Signatures of Parallel Evolution within Plant and Animal Pathogens of Fungi and Oomycetes.

    Science.gov (United States)

    Sharma, Rahul; Xia, Xiaojuan; Riess, Kai; Bauer, Robert; Thines, Marco

    2015-08-27

    Ceraceosorus bombacis is an early-diverging lineage of smut fungi and a pathogen of cotton trees (Bombax ceiba). To study the evolutionary genomics of smut fungi in comparison with other fungal and oomycete pathogens, the genome of C. bombacis was sequenced and comparative genomic analyses were performed. The genome of 26.09 Mb encodes for 8,024 proteins, of which 576 are putative-secreted effector proteins (PSEPs). Orthology analysis revealed 30 ortholog PSEPs among six Ustilaginomycotina genomes, the largest groups of which are lytic enzymes, such as aspartic peptidase and glycoside hydrolase. Positive selection analyses revealed the highest percentage of positively selected PSEPs in C. bombacis compared with other Ustilaginomycotina genomes. Metabolic pathway analyses revealed the absence of genes encoding for nitrite and nitrate reductase in the genome of the human skin pathogen Malassezia globosa, but these enzymes are present in the sequenced plant pathogens in smut fungi. Interestingly, these genes are also absent in cultivable oomycete animal pathogens, while nitrate reductase has been lost in cultivable oomycete plant pathogens. Similar patterns were also observed for obligate biotrophic and hemi-biotrophic fungal and oomycete pathogens. Furthermore, it was found that both fungal and oomycete animal pathogen genomes are lacking cutinases and pectinesterases. Overall, these findings highlight the parallel evolution of certain genomic traits, revealing potential common evolutionary trajectories among fungal and oomycete pathogens, shaping the pathogen genomes according to their lifestyle.

  8. Immunodetection of fungal and oomycete pathogens: established and emerging threats to human health, animal welfare and global food security.

    Science.gov (United States)

    Thornton, Christopher R; Wills, Odette E

    2015-02-01

    Filamentous fungi (moulds), yeast-like fungi, and oomycetes cause life-threatening infections of humans and animals and are a major constraint to global food security, constituting a significant economic burden to both agriculture and medicine. As well as causing localized or systemic infections, certain species are potent producers of allergens and toxins that exacerbate respiratory diseases or cause cancer and organ damage. We review the pathogenic and toxigenic organisms that are etiologic agents of both animal and plant diseases or that have recently emerged as serious pathogens of immunocompromised individuals. The use of hybridoma and phage display technologies and their success in generating monoclonal antibodies for the detection and control of fungal and oomycete pathogens are explored. Monoclonal antibodies hold enormous potential for the development of rapid and specific tests for the diagnosis of human mycoses, however, unlike plant pathology, their use in medical mycology remains to be fully exploited.

  9. Multiple candidate effectors from the oomycete pathogen Hyaloperonospora arabidopsidis suppress host plant immunity.

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    Georgina Fabro

    2011-11-01

    Full Text Available Oomycete pathogens cause diverse plant diseases. To successfully colonize their hosts, they deliver a suite of effector proteins that can attenuate plant defenses. In the oomycete downy mildews, effectors carry a signal peptide and an RxLR motif. Hyaloperonospora arabidopsidis (Hpa causes downy mildew on the model plant Arabidopsis thaliana (Arabidopsis. We investigated if candidate effectors predicted in the genome sequence of Hpa isolate Emoy2 (HaRxLs were able to manipulate host defenses in different Arabidopsis accessions. We developed a rapid and sensitive screening method to test HaRxLs by delivering them via the bacterial type-three secretion system (TTSS of Pseudomonas syringae pv tomato DC3000-LUX (Pst-LUX and assessing changes in Pst-LUX growth in planta on 12 Arabidopsis accessions. The majority (~70% of the 64 candidates tested positively contributed to Pst-LUX growth on more than one accession indicating that Hpa virulence likely involves multiple effectors with weak accession-specific effects. Further screening with a Pst mutant (ΔCEL showed that HaRxLs that allow enhanced Pst-LUX growth usually suppress callose deposition, a hallmark of pathogen-associated molecular pattern (PAMP-triggered immunity (PTI. We found that HaRxLs are rarely strong avirulence determinants. Although some decreased Pst-LUX growth in particular accessions, none activated macroscopic cell death. Fewer HaRxLs conferred enhanced Pst growth on turnip, a non-host for Hpa, while several reduced it, consistent with the idea that turnip's non-host resistance against Hpa could involve a combination of recognized HaRxLs and ineffective HaRxLs. We verified our results by constitutively expressing in Arabidopsis a sub-set of HaRxLs. Several transgenic lines showed increased susceptibility to Hpa and attenuation of Arabidopsis PTI responses, confirming the HaRxLs' role in Hpa virulence. This study shows TTSS screening system provides a useful tool to test whether

  10. Decay of genes encoding the oomycete flagellar proteome in the downy mildew Hyaloperonospora arabidopsidis.

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    Howard S Judelson

    Full Text Available Zoospores are central to the life cycles of most of the eukaryotic microbes known as oomycetes, but some genera have lost the ability to form these flagellated cells. In the plant pathogen Phytophthora infestans, genes encoding 257 proteins associated with flagella were identified by comparative genomics. These included the main structural components of the axoneme and basal body, proteins involved in intraflagellar transport, regulatory proteins, enzymes for maintaining ATP levels, and others. Transcripts for over three-quarters of the genes were up-regulated during sporulation, and persisted to varying degrees in the pre-zoospore stage (sporangia and motile zoospores. Nearly all of these genes had orthologs in other eukaryotes that form flagella or cilia, but not species that lack the organelle. Orthologs of 211 of the genes were also absent from a sister taxon to P. infestans that lost the ability to form flagella, the downy mildew Hyaloperonospora arabidopsidis. Many of the genes retained in H. arabidopsidis were also present in other non-flagellates, suggesting that they play roles both in flagella and other cellular processes. Remnants of the missing genes were often detected in the H. arabidopsidis genome. Degradation of the genes was associated with local compaction of the chromosome and a heightened propensity towards genome rearrangements, as such regions were less likely to share synteny with P. infestans.

  11. Molecular phylogeny and taxonomy of Lagenidium-like oomycetes pathogenic to mammals.

    Science.gov (United States)

    Spies, Christoffel F J; Grooters, Amy M; Lévesque, C André; Rintoul, Tara L; Redhead, Scott A; Glockling, Sally L; Chen, Chi-Yu; de Cock, Arthur W A M

    2016-08-01

    Over the past twenty years, infections caused by previously unrecognised oomycete pathogens with morphological and molecular similarities to known Lagenidium species have been observed with increasing frequency, primarily in dogs but also in cats and humans. Three of these pathogens were formally described as Lagenidium giganteum forma caninum, Lagenidium deciduum, and Paralagenidium karlingii in advance of published phylogenetic verification. Due to the complex nature of Lagenidium taxonomy alongside recent reports of mammalian pathogenic species, these taxa needed to be verified with due consideration of the available data for Lagenidium and its allied genera. This study does so through morphologic characterisation of the mammalian pathogenic species, and phylogenetic analyses. The six-gene phylogeny generally supports the most recent comprehensive classification of Lagenidium with a well-supported Lagenidium clade that includes the mammalian pathogens L. giganteum f. caninum and L. deciduum, and well-supported clades for which the names Myzocytiopsis and Salilagenidium can be applied. The genus Paralagenidium is phylogenetically unrelated to any of the main clades within the class Peronosporomycetes. Close relationships between pathogens of mammals and those of insects or nematodes were revealed. Further characterisation of Lagenidium-like taxa is needed to establish the risk of mammalian infection by pathogens of insects and nematodes. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  12. Do colonization by dark septate endophytes and elevated temperature affect pathogenicity of oomycetes?

    Science.gov (United States)

    Tellenbach, Christoph; Sieber, Thomas N

    2012-10-01

    Phialocephala subalpina is one of the most frequent dark septate root endophytes in tree roots but its function in forest ecosystems is largely unknown. A full-factorial infection experiment was performed, using six P. subalpina isolates, two pathogenic oomycetes (Phytophthora plurivora [syn. Phytophthora citricola s.l.] and Elongisporangium undulatum [syn. Pythium undulatum]) and two temperature regimes (17.9 and 21.6 °C) to examine the ability of P. subalpina to protect Norway spruce seedlings against root pathogens. Seedling survival, disease intensity and seedling growth were affected by P. subalpina genotype, temperature and pathogen species. Some P. subalpina isolates effectively reduced mortality and disease intensity caused by the two pathogens. Elevated temperature adversely affected seedling growth but did not aggravate the effect of the pathogens. Elongisporangium undulatum but not P. plurivora significantly reduced plant growth. Colonization density of P. subalpina measured by quantitative PCR was not affected by temperature or the presence of the pathogens. In conclusion, P. subalpina confers an indirect benefit to its host and might therefore be tolerated in natural ecosystems, despite negative effects on plant health and plant growth.

  13. An Oomycete CRN Effector Reprograms Expression of Plant HSP Genes by Targeting their Promoters.

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    Tianqiao Song

    2015-12-01

    Full Text Available Oomycete pathogens produce a large number of CRN effectors to manipulate plant immune responses and promote infection. However, their functional mechanisms are largely unknown. Here, we identified a Phytophthora sojae CRN effector PsCRN108 which contains a putative DNA-binding helix-hairpin-helix (HhH motif and acts in the plant cell nucleus. Silencing of the PsCRN108 gene reduced P. sojae virulence to soybean, while expression of the gene in Nicotiana benthamiana and Arabidopsis thaliana enhanced plant susceptibility to P. capsici. Moreover, PsCRN108 could inhibit expression of HSP genes in A. thaliana, N. benthamiana and soybean. Both the HhH motif and nuclear localization signal of this effector were required for its contribution to virulence and its suppression of HSP gene expression. Furthermore, we found that PsCRN108 targeted HSP promoters in an HSE- and HhH motif-dependent manner. PsCRN108 could inhibit the association of the HSE with the plant heat shock transcription factor AtHsfA1a, which initializes HSP gene expression in response to stress. Therefore, our data support a role for PsCRN108 as a nucleomodulin in down-regulating the expression of plant defense-related genes by directly targeting specific plant promoters.

  14. Activity profiling of vacuolar processing enzymes reveals a role for VPE during oomycete infection.

    Science.gov (United States)

    Misas-Villamil, Johana C; Toenges, Gerrit; Kolodziejek, Izabella; Sadaghiani, Amir M; Kaschani, Farnusch; Colby, Thomas; Bogyo, Matthew; van der Hoorn, Renier A L

    2013-02-01

    Vacuolar processing enzymes (VPEs) are important cysteine proteases that are implicated in the maturation of seed storage proteins, and programmed cell death during plant-microbe interactions and development. Here, we introduce a specific, cell-permeable, activity-based probe for VPEs. This probe is highly specific for all four Arabidopsis VPEs, and labeling is activity-dependent, as illustrated by sensitivity for inhibitors, pH and reducing agents. We show that the probe can be used for in vivo imaging and displays multiple active isoforms of VPEs in various tissues and in both monocot and dicot plant species. Thus, VPE activity profiling is a robust, simple and powerful tool for plant research for a wide range of applications. Using VPE activity profiling, we discovered that VPE activity is increased during infection with the oomycete pathogen Hyaloperonospora arabidopsidis (Hpa). The enhanced VPE activity is host-derived and EDS1-independent. Sporulation of Hpa is reduced on vpe mutant plants, demonstrating a role for VPE during compatible interactions that is presumably independent of programmed cell death. Our data indicate that, as an obligate biotroph, Hpa takes advantage of increased VPE activity in the host, e.g. to mediate protein turnover and nutrient release.

  15. An Oomycete CRN Effector Reprograms Expression of Plant HSP Genes by Targeting their Promoters.

    Science.gov (United States)

    Song, Tianqiao; Ma, Zhenchuan; Shen, Danyu; Li, Qi; Li, Wanlin; Su, Liming; Ye, Tingyue; Zhang, Meixiang; Wang, Yuanchao; Dou, Daolong

    2015-12-01

    Oomycete pathogens produce a large number of CRN effectors to manipulate plant immune responses and promote infection. However, their functional mechanisms are largely unknown. Here, we identified a Phytophthora sojae CRN effector PsCRN108 which contains a putative DNA-binding helix-hairpin-helix (HhH) motif and acts in the plant cell nucleus. Silencing of the PsCRN108 gene reduced P. sojae virulence to soybean, while expression of the gene in Nicotiana benthamiana and Arabidopsis thaliana enhanced plant susceptibility to P. capsici. Moreover, PsCRN108 could inhibit expression of HSP genes in A. thaliana, N. benthamiana and soybean. Both the HhH motif and nuclear localization signal of this effector were required for its contribution to virulence and its suppression of HSP gene expression. Furthermore, we found that PsCRN108 targeted HSP promoters in an HSE- and HhH motif-dependent manner. PsCRN108 could inhibit the association of the HSE with the plant heat shock transcription factor AtHsfA1a, which initializes HSP gene expression in response to stress. Therefore, our data support a role for PsCRN108 as a nucleomodulin in down-regulating the expression of plant defense-related genes by directly targeting specific plant promoters.

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

    Science.gov (United States)

    Xiang, Qijun; Judelson, Howard S

    2014-01-01

    Life cycle progression in eukaryotic microbes is often influenced by environment. In the oomycete Phytophthora infestans, which causes late blight on potato and tomato, sporangia have been reported to form mostly at night. By growing P. infestans under different light regimes at constant temperature and humidity, we show that light contributes to the natural pattern of sporulation by delaying sporulation until the following dark period. However, illumination does not permanently block sporulation or strongly affect the total number of sporangia that ultimately form. Based on measurements of sporulation-induced genes such as those encoding protein kinase Pks1 and Myb transcription factors Myb2R1 and Myb2R3, it appears that most spore-associated transcripts start to rise four to eight hours before sporangia appear. Their mRNA levels oscillate with the light/dark cycle and increase with the amount of sporangia. An exception to this pattern of expression is Myb2R4, which is induced several hours before the other genes and declines after cultures start to sporulate. Transformants over-expressing Myb2R4 produce twice the number of sporangia and ten-fold higher levels of Myb2R1 mRNA than wild-type, and chromatin immunoprecipitation showed that Myb2R4 binds the Myb2R1 promoter in vivo. Myb2R4 thus appears to be an early regulator of sporulation. We attempted to silence eight Myb genes by DNA-directed RNAi, but succeeded only with Myb2R3, which resulted in suppressed sporulation. Ectopic expression studies of seven Myb genes revealed that over-expression frequently impaired vegetative growth, and in the case of Myb3R6 interfered with sporangia dormancy. We observed that the degree of silencing induced by a hairpin construct was correlated with its copy number, and ectopic expression was often unstable due to epigenetic silencing and transgene excision.

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

    Directory of Open Access Journals (Sweden)

    Qijun Xiang

    Full Text Available Life cycle progression in eukaryotic microbes is often influenced by environment. In the oomycete Phytophthora infestans, which causes late blight on potato and tomato, sporangia have been reported to form mostly at night. By growing P. infestans under different light regimes at constant temperature and humidity, we show that light contributes to the natural pattern of sporulation by delaying sporulation until the following dark period. However, illumination does not permanently block sporulation or strongly affect the total number of sporangia that ultimately form. Based on measurements of sporulation-induced genes such as those encoding protein kinase Pks1 and Myb transcription factors Myb2R1 and Myb2R3, it appears that most spore-associated transcripts start to rise four to eight hours before sporangia appear. Their mRNA levels oscillate with the light/dark cycle and increase with the amount of sporangia. An exception to this pattern of expression is Myb2R4, which is induced several hours before the other genes and declines after cultures start to sporulate. Transformants over-expressing Myb2R4 produce twice the number of sporangia and ten-fold higher levels of Myb2R1 mRNA than wild-type, and chromatin immunoprecipitation showed that Myb2R4 binds the Myb2R1 promoter in vivo. Myb2R4 thus appears to be an early regulator of sporulation. We attempted to silence eight Myb genes by DNA-directed RNAi, but succeeded only with Myb2R3, which resulted in suppressed sporulation. Ectopic expression studies of seven Myb genes revealed that over-expression frequently impaired vegetative growth, and in the case of Myb3R6 interfered with sporangia dormancy. We observed that the degree of silencing induced by a hairpin construct was correlated with its copy number, and ectopic expression was often unstable due to epigenetic silencing and transgene excision.

  18. Population genetics of fungal and oomycete effectors involved in gene-for-gene interactions.

    Science.gov (United States)

    Stukenbrock, Eva H; McDonald, Bruce A

    2009-04-01

    Antagonistic coevolution between plants and pathogens has generated a broad array of attack and defense mechanisms. In the classical avirulence (Avr) gene-for-gene model, the pathogen gene evolves to escape host recognition while the host resistance (R) gene evolves to track the evolving pathogen elicitor. In the case of host-specific toxins (HST), the evolutionary arms race may be inverted, with the gene encoding the pathogen toxin evolving to maintain recognition of the host sensitivity target while the host sensitivity gene evolves to escape binding with the toxin. Pathogen effector genes, including those encoding Avr elicitors and HST, often show elevated levels of polymorphism reflecting the coevolutionary arms race between host and pathogen. However, selection can also eliminate variation in the coevolved gene and its neighboring regions when advantageous alleles are swept to fixation. The distribution and diversity of corresponding host genes will have a major impact on the distribution and diversity of effectors in the pathogen population. Population genetic analyses including both hosts and their pathogens provide an essential tool to understand the diversity and dynamics of effector genes. Here, we summarize current knowledge about the population genetics of fungal and oomycete effector genes, focusing on recent studies that have used both spatial and temporal collections to assess the diversity and distribution of alleles and to monitor changes in allele frequencies over time. These studies illustrate that effector genes exhibit a significant degree of diversity at both small and large sampling scales, suggesting that local selection plays an important role in their evolution. They also illustrate that Avr elicitors and HST may be recognizing the same R genes in plants, leading to evolutionary outcomes that differ for necrotrophs and biotrophs while affecting the evolution of the corresponding R genes. Under this scenario, the optimal number of R genes

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

    Science.gov (United States)

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

    2015-09-01

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

  20. 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.

  1. Chitin synthases from Saprolegnia are involved in tip growth and represent a potential target for anti-oomycete drugs.

    Directory of Open Access Journals (Sweden)

    Gea Guerriero

    Full Text Available Oomycetes represent some of the most devastating plant and animal pathogens. Typical examples are Phytophthora infestans, which causes potato and tomato late blight, and Saprolegnia parasitica, responsible for fish diseases. Despite the economical and environmental importance of oomycete diseases, their control is difficult, particularly in the aquaculture industry. Carbohydrate synthases are vital for hyphal growth and represent interesting targets for tackling the pathogens. The existence of 2 different chitin synthase genes (SmChs1 and SmChs2 in Saprolegnia monoica was demonstrated using bioinformatics and molecular biology approaches. The function of SmCHS2 was unequivocally demonstrated by showing its catalytic activity in vitro after expression in Pichia pastoris. The recombinant SmCHS1 protein did not exhibit any activity in vitro, suggesting that it requires other partners or effectors to be active, or that it is involved in a different process than chitin biosynthesis. Both proteins contained N-terminal Microtubule Interacting and Trafficking domains, which have never been reported in any other known carbohydrate synthases. These domains are involved in protein recycling by endocytosis. Enzyme kinetics revealed that Saprolegnia chitin synthases are competitively inhibited by nikkomycin Z and quantitative PCR showed that their expression is higher in presence of the inhibitor. The use of nikkomycin Z combined with microscopy showed that chitin synthases are active essentially at the hyphal tips, which burst in the presence of the inhibitor, leading to cell death. S. parasitica was more sensitive to nikkomycin Z than S. monoica. In conclusion, chitin synthases with species-specific characteristics are involved in tip growth in Saprolegnia species and chitin is vital for the micro-organisms despite its very low abundance in the cell walls. Chitin is most likely synthesized transiently at the apex of the cells before cellulose, the major

  2. Oomycete Species Associated with Soybean Seedlings in North America-Part II: Diversity and Ecology in Relation to Environmental and Edaphic Factors.

    Science.gov (United States)

    Rojas, J Alejandro; Jacobs, Janette L; Napieralski, Stephanie; Karaj, Behirda; Bradley, Carl A; Chase, Thomas; Esker, Paul D; Giesler, Loren J; Jardine, Doug J; Malvick, Dean K; Markell, Samuel G; Nelson, Berlin D; Robertson, Alison E; Rupe, John C; Smith, Damon L; Sweets, Laura E; Tenuta, Albert U; Wise, Kiersten A; Chilvers, Martin I

    2017-03-01

    Soybean (Glycine max (L.) Merr.) is produced across a vast swath of North America, with the greatest concentration in the Midwest. Root rot diseases and damping-off are a major concern for production, and the primary causal agents include oomycetes and fungi. In this study, we focused on examination of oomycete species distribution in this soybean production system and how environmental and soil (edaphic) factors correlate with oomycete community composition at early plant growth stages. Using a culture-based approach, 3,418 oomycete isolates were collected from 11 major soybean-producing states and most were identified to genus and species using the internal transcribed spacer region of the ribosomal DNA. Pythium was the predominant genus isolated and investigated in this study. An ecology approach was taken to understand the diversity and distribution of oomycete species across geographical locations of soybean production. Metadata associated with field sample locations were collected using geographical information systems. Operational taxonomic units (OTU) were used in this study to investigate diversity by location, with OTU being defined as isolate sequences with 97% identity to one another. The mean number of OTU ranged from 2.5 to 14 per field at the state level. Most OTU in this study, classified as Pythium clades, were present in each field in every state; however, major differences were observed in the relative abundance of each clade, which resulted in clustering of states in close proximity. Because there was similar community composition (presence or absence) but differences in OTU abundance by state, the ordination analysis did not show strong patterns of aggregation. Incorporation of 37 environmental and edaphic factors using vector-fitting and Mantel tests identified 15 factors that correlate with the community composition in this survey. Further investigation using redundancy analysis identified latitude, longitude, precipitation, and temperature

  3. Filamentous brown algae infected by the marine, holocarpic oomycete Eurychasma dicksonii: first results on the organization and the role of cytoskeleton in both host and parasite.

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    Tsirigoti, Amerssa; Kuepper, Frithjof C; Gachon, Claire Mm; Katsaros, Christos

    2013-11-01

    The important role of the cytoskeletal scaffold is increasingly recognized in host-pathogen interactions. The cytoskeleton potentially functions as a weapon for both the plants defending themselves against fungal or oomycete parasites, and for the pathogens trying to overcome the resisting barrier of the plants. This concept, however, had not been investigated in marine algae so far. We are opening this scientific chapter with our study on the functional implications of the cytoskeleton in 3 filamentous brown algal species infected by the marine oomycete Eurychasma dicksonii. Our observations suggest that the cytoskeleton is involved in host defense responses and in fundamental developmental stages of E. dicksonii in its algal host.

  4. CFGP 2.0: a versatile web-based platform for supporting comparative and evolutionary genomics of fungi and Oomycetes.

    Science.gov (United States)

    Choi, Jaeyoung; Cheong, Kyeongchae; Jung, Kyongyong; Jeon, Jongbum; Lee, Gir-Won; Kang, Seogchan; Kim, Sangsoo; Lee, Yin-Won; Lee, Yong-Hwan

    2013-01-01

    In 2007, Comparative Fungal Genomics Platform (CFGP; http://cfgp.snu.ac.kr/) was publicly open with 65 genomes corresponding to 58 fungal and Oomycete species. The CFGP provided six bioinformatics tools, including a novel tool entitled BLASTMatrix that enables search homologous genes to queries in multiple species simultaneously. CFGP also introduced Favorite, a personalized virtual space for data storage and analysis with these six tools. Since 2007, CFGP has grown to archive 283 genomes corresponding to 152 fungal and Oomycete species as well as 201 genomes that correspond to seven bacteria, 39 plants and 105 animals. In addition, the number of tools in Favorite increased to 27. The Taxonomy Browser of CFGP 2.0 allows users to interactively navigate through a large number of genomes according to their taxonomic positions. The user interface of BLASTMatrix was also improved to facilitate subsequent analyses of retrieved data. A newly developed genome browser, Seoul National University Genome Browser (SNUGB), was integrated into CFGP 2.0 to support graphical presentation of diverse genomic contexts. Based on the standardized genome warehouse of CFGP 2.0, several systematic platforms designed to support studies on selected gene families have been developed. Most of them are connected through Favorite to allow of sharing data across the platforms.

  5. Virulence of oomycete pathogens from Phragmites australis-invaded and noninvaded soils to seedlings of wetland plant species.

    Science.gov (United States)

    Crocker, Ellen V; Karp, Mary Ann; Nelson, Eric B

    2015-06-01

    Soil pathogens affect plant community structure and function through negative plant-soil feedbacks that may contribute to the invasiveness of non-native plant species. Our understanding of these pathogen-induced soil feedbacks has relied largely on observations of the collective impact of the soil biota on plant populations, with few observations of accompanying changes in populations of specific soil pathogens and their impacts on invasive and noninvasive species. As a result, the roles of specific soil pathogens in plant invasions remain unknown. In this study, we examine the diversity and virulence of soil oomycete pathogens in freshwater wetland soils invaded by non-native Phragmites australis (European common reed) to better understand the potential for soil pathogen communities to impact a range of native and non-native species and influence invasiveness. We isolated oomycetes from four sites over a 2-year period, collecting nearly 500 isolates belonging to 36 different species. These sites were dominated by species of Pythium, many of which decreased seedling survival of a range of native and invasive plants. Despite any clear host specialization, many of the Pythium species were differentially virulent to the native and non-native plant species tested. Isolates from invaded and noninvaded soils were equally virulent to given individual plant species, and no apparent differences in susceptibility were observed between the collective groups of native and non-native plant species.

  6. Enhanced resistance in Theobroma cacao against oomycete and fungal pathogens by secretion of phosphatidylinositol-3-phosphate-binding proteins.

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    Helliwell, Emily E; Vega-Arreguín, Julio; Shi, Zi; Bailey, Bryan; Xiao, Shunyuan; Maximova, Siela N; Tyler, Brett M; Guiltinan, Mark J

    2016-03-01

    The internalization of some oomycete and fungal pathogen effectors into host plant cells has been reported to be blocked by proteins that bind to the effectors' cell entry receptor, phosphatidylinositol-3-phosphate (PI3P). This finding suggested a novel strategy for disease control by engineering plants to secrete PI3P-binding proteins. In this study, we tested this strategy using the chocolate tree Theobroma cacao. Transient expression and secretion of four different PI3P-binding proteins in detached leaves of T. cacao greatly reduced infection by two oomycete pathogens, Phytophthora tropicalis and Phytophthora palmivora, which cause black pod disease. Lesion size and pathogen growth were reduced by up to 85%. Resistance was not conferred by proteins lacking a secretory leader, by proteins with mutations in their PI3P-binding site, or by a secreted PI4P-binding protein. Stably transformed, transgenic T. cacao plants expressing two different PI3P-binding proteins showed substantially enhanced resistance to both P. tropicalis and P. palmivora, as well as to the fungal pathogen Colletotrichum theobromicola. These results demonstrate that secretion of PI3P-binding proteins is an effective way to increase disease resistance in T. cacao, and potentially in other plants, against a broad spectrum of pathogens. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  7. 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.

  8. Microbe-independent entry of oomycete RxLR effectors and fungal RxLR-like effectors into plant and animal cells is specific and reproducible.

    Science.gov (United States)

    Tyler, Brett M; Kale, Shiv D; Wang, Qunqing; Tao, Kai; Clark, Helen R; Drews, Kelly; Antignani, Vincenzo; Rumore, Amanda; Hayes, Tristan; Plett, Jonathan M; Fudal, Isabelle; Gu, Biao; Chen, Qinghe; Affeldt, Katharyn J; Berthier, Erwin; Fischer, Gregory J; Dou, Daolong; Shan, Weixing; Keller, Nancy P; Martin, Francis; Rouxel, Thierry; Lawrence, Christopher B

    2013-06-01

    A wide diversity of pathogens and mutualists of plant and animal hosts, including oomycetes and fungi, produce effector proteins that enter the cytoplasm of host cells. A major question has been whether or not entry by these effectors can occur independently of the microbe or requires machinery provided by the microbe. Numerous publications have documented that oomycete RxLR effectors and fungal RxLR-like effectors can enter plant and animal cells independent of the microbe. A recent reexamination of whether the RxLR domain of oomycete RxLR effectors is sufficient for microbe-independent entry into host cells concluded that the RxLR domains of Phytophthora infestans Avr3a and of P. sojae Avr1b alone are NOT sufficient to enable microbe-independent entry of proteins into host and nonhost plant and animal cells. Here, we present new, more detailed data that unambiguously demonstrate that the RxLR domain of Avr1b does show efficient and specific entry into soybean root cells and also into wheat leaf cells, at levels well above background nonspecific entry. We also summarize host cell entry experiments with a wide diversity of oomycete and fungal effectors with RxLR or RxLR-like motifs that have been independently carried out by the seven different labs that coauthored this letter. Finally we discuss possible technical reasons why specific cell entry may have been not detected by Wawra et al. (2013).

  9. Role of pathogen-derived cell wall carbohydrates and prostaglandin E2 in immune response and suppression of fish immunity by the oomycete Saprolegnia parasitica.

    Science.gov (United States)

    Belmonte, Rodrigo; Wang, Tiehui; Duncan, Gary J; Skaar, Ida; Mélida, Hugo; Bulone, Vincent; van West, Pieter; Secombes, Christopher J

    2014-11-01

    Saprolegnia parasitica is a freshwater oomycete that is capable of infecting several species of fin fish. Saprolegniosis, the disease caused by this microbe, has a substantial impact on Atlantic salmon aquaculture. No sustainable treatment against saprolegniosis is available, and little is known regarding the host response. In this study, we examined the immune response of Atlantic salmon to S. parasitica infection and to its cell wall carbohydrates. Saprolegnia triggers a strong inflammatory response in its host (i.e., induction of interleukin-1β1 [IL-1β1], IL-6, and tumor necrosis factor alpha), while severely suppressing the expression of genes associated with adaptive immunity in fish, through downregulation of T-helper cell cytokines, antigen presentation machinery, and immunoglobulins. Oomycete cell wall carbohydrates were recognized by fish leukocytes, triggering upregulation of genes involved in the inflammatory response, similar to what is observed during infection. Our data suggest that S. parasitica is capable of producing prostaglandin [corrected] E2 (PGE2) in vitro, a metabolite not previously shown to be produced by oomycetes, and two proteins with homology to vertebrate enzymes known to play a role in prostaglandin biosynthesis have been identified in the oomycete genome. Exogenous PGE2 was shown to increase the inflammatory response in fish leukocytes incubated with cell wall carbohydrates while suppressing genes involved in cellular immunity (gamma interferon [IFN-γ] and the IFN-γ-inducible protein [γ-IP]). Inhibition of S. parasitica zoospore germination and mycelial growth by two cyclooxygenase inhibitors (aspirin and indomethacin) also suggests that prostaglandins may be involved in oomycete development.

  10. Evaluation of fungicides enestroburin and SYP1620 on their inhibitory activities to fungi and oomycetes and systemic translocation in plants.

    Science.gov (United States)

    Liu, Pengfei; Wang, Haiqiang; Zhou, Yuxin; Meng, Qingxiao; Si, Naiguo; Hao, Jianjun J; Liu, Xili

    2014-06-01

    Enestroburin and SYP1620 are newly developed strobilurin chemicals carrying fungicidal activity and need to be fully characterized in activities of anti-oomycete or anti-fungi, disease prevention and systemic translocation in planta. Their inhibitory activities were examined by amending the chemical in agar media, on which selected plant pathogens were grown and mycelial growth were measured. Effective concentrations for 50% inhibition (EC50) of mycelial growth were calculated to determine the level of fungicide sensitivity of the pathogen. Azoxystrobin was used as control. To examine the prevention and systemic translocation in plants, the fungicides were either sprayed on wheat leaves or dipped on wheat roots, which then were detected using high performance liquid chromatography. All the three fungicides inhibited mycelial growth of Sphacelotheca reiliana, Phytophthora infestans, Peronophythora litchi, and Magnaporthe oryzae, with EC50 values ranging from 0.02 to 2.84μg/ml; EC50 of SYP1620 was significantly lower than that of azoxystrobin and enestroburin on Valsa mali, Gaeumannomyces graminis, Alternaria solani, and Colletotrichun orbiculare. The three QoI fungicides showed strong inhibitory activities on spore germination against the 13 pathogens tested and were highly effective on biotrophic pathogens tested. Enestroburin and SYP1620 penetrated and spread in wheat leaves, but the penetration and translocation levels were lower compared to azoxystrobin. The three fungicides were all rapidly taken up by wheat roots and transported upwards, with greater fungicide concentrations in roots than in stems and leaves. The results indicate that enestroburin and SYP1620 are systemic fungicides that inhibit a broad spectrum of fungi and oomycetes.

  11. Rapid and dynamic subcellular reorganization following mechanical stimulation of Arabidopsis epidermal cells mimics responses to fungal and oomycete attack

    Directory of Open Access Journals (Sweden)

    Takemoto Daigo

    2008-06-01

    Full Text Available Abstract Background Plant cells respond to the presence of potential fungal or oomycete pathogens by mounting a basal defence response that involves aggregation of cytoplasm, reorganization of cytoskeletal, endomembrane and other cell components and development of cell wall appositions beneath the infection site. This response is induced by non-adapted, avirulent and virulent pathogens alike, and in the majority of cases achieves penetration resistance against the microorganism on the plant surface. To explore the nature of signals that trigger this subcellular response and to determine the timing of its induction, we have monitored the reorganization of GFP-tagged actin, microtubules, endoplasmic reticulum (ER and peroxisomes in Arabidopsis plants – after touching the epidermal surface with a microneedle. Results Within 3 to 5 minutes of touching the surface of Arabidopsis cotyledon epidermal cells with fine glass or tungsten needles, actin microfilaments, ER and peroxisomes began to accumulate beneath the point of contact with the needle. Formation of a dense patch of actin was followed by focusing of actin cables on the site of contact. Touching the cell surface induced localized depolymerization of microtubules to form a microtubule-depleted zone surrounding a dense patch of GFP-tubulin beneath the needle tip. The concentration of actin, GFP-tubulin, ER and peroxisomes remained focused on the contact site as the needle moved across the cell surface and quickly dispersed when the needle was removed. Conclusion Our results show that plant cells can detect the gentle pressure of a microneedle on the epidermal cell surface and respond by reorganizing subcellular components in a manner similar to that induced during attack by potential fungal or oomycete pathogens. The results of our study indicate that during plant-pathogen interactions, the basal defence response may be induced by the plant's perception of the physical force exerted by the

  12. A gene for plant protection: expression of a bean polygalacturonase inhibitor in tobacco confers a strong resistance against Rhizoctonia solani and two oomycetes.

    Directory of Open Access Journals (Sweden)

    Orlando eBorras-Hidalgo

    2012-12-01

    Full Text Available We have tested whether a gene encoding a polygalacturonase-inhibiting protein (PGIP protects tobacco against a fungal pathogen (Rhizoctonia solani and two oomycetes (Phytophthora parasitica var. nicotianae and Peronospora hyoscyami f. sp. tabacina. The trials were performed in greenhouse conditions for R. solani and P. parasitica and in the field for P. hyoscyami. Our results show that expression of PGIP is a powerful way of engineering a broad-spectrum disease resistance.

  13. Plant-pathogenic oomycetes, Escherichia coli strains, and Salmonella spp. Frequently found in surface water used for irrigation of fruit and vegetable crops in New York State.

    Science.gov (United States)

    Jones, Lisa A; Worobo, Randy W; Smart, Christine D

    2014-08-01

    In the United States, surface water is commonly used to irrigate a variety of produce crops and can harbor pathogens responsible for food-borne illnesses and plant diseases. Understanding when pathogens infest water sources is valuable information for produce growers to improve the food safety and production of these crops. In this study, prevalence data along with regression tree analyses were used to correlate water quality parameters (pH, temperature, turbidity), irrigation site properties (source, the presence of livestock or fowl nearby), and precipitation data to the presence and concentrations of Escherichia coli, Salmonella spp., and hymexazol-insensitive (HIS) oomycetes (Phytophthora and Pythium spp.) in New York State surface waters. A total of 123 samples from 18 sites across New York State were tested for E. coli and Salmonella spp., of which 33% and 43% were positive, respectively. Additionally, 210 samples from 38 sites were tested for HIS oomycetes, and 88% were found to be positive, with 10 species of Phytophthora and 11 species of Pythium being identified from the samples. Regression analysis found no strong correlations between water quality parameters, site factors, or precipitation to the presence or concentration of E. coli in irrigation sources. For Salmonella, precipitation (≤ 0.64 cm) 3 days before sampling was correlated to both presence and the highest counts. Analyses for oomycetes found creeks to have higher average counts than ponds, and higher turbidity levels were associated with higher oomycete counts. Overall, information gathered from this study can be used to better understand the food safety and plant pathogen risks of using surface water for irrigation.

  14. A simple method for normalization of DNA extraction to improve the quantitative detection of soil-borne plant pathogenic oomycetes by real-time PCR.

    Science.gov (United States)

    Li, M; Ishiguro, Y; Kageyama, K; Zhu, Z

    2015-08-01

    Most of the current research into the quantification of soil-borne pathogenic oomycetes lacks determination of DNA extraction efficiency, probably leading to an incorrect estimation of DNA quantity. In this study, we developed a convenient method by using a 100 bp artificially synthesized DNA sequence derived from the mitochondrion NADH dehydrogenase subunit 2 gene of Thunnus thynnus as a control to determine the DNA extraction efficiency. The control DNA was added to soils and then co-extracted along with soil genomic DNA. DNA extraction efficiency was determined by the control DNA. Two different DNA extraction methods were compared and evaluated using different types of soils, and the commercial kit was proved to give more consistent results. We used the control DNA combined with real-time PCR to quantify the oomycete DNAs from 12 naturally infested soils. Detectable target DNA concentrations were three to five times higher after normalization. Our tests also showed that the extraction efficiencies varied on a sample-to-sample basis and were DNA control for the normalization of DNA extraction by real-time PCR. By combining two different efficient soil DNA extraction methods, the developed quantification method dramatically improved the results. This study also proves that the developed normalization method is necessary and useful for the accurate quantification of soil-borne plant pathogenic oomycetes. © 2015 The Society for Applied Microbiology.

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

    Science.gov (United States)

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

    2012-01-01

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

  16. 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.

  17. Chemical Characterization and Anti-Oomycete Activity of Laureliopsis philippianna Essential Oils against Saprolegnia parasitica and S. australis

    Directory of Open Access Journals (Sweden)

    Alejandro Madrid

    2015-05-01

    Full Text Available Laureliopsis philippiana (Looser R. Schodde (Monimiaceae is a native tree widespread in the forest areas in the south of Chile and Argentina, known for its medicinal properties and excellent wood. The aim of this study was to evaluate the chemical composition of L. philippiana leaf and bark essential oils (EOs using gas chromatography-mass spectrometry (GC-MS, and to quantify its anti-oomycete activity, specifically against Saprolegnia parasitica and S. australis. Only six components were identified in leaf EO, 96.92% of which are phenylpropanoids and 3.08% are terpenes. As for bark EO, 29 components were identified, representing 67.61% for phenylpropanoids and 32.39% for terpenes. Leaf EO was characterized mainly by safrole (96.92% and β-phellandrene (1.80%. Bark EO was characterized mainly by isosafrole (30.07%, safrole (24.41%, eucalyptol (13.89%, methyleugenol (7.12%, and eugenol (6.01%. Bark EO has the most promising anti-Saprolegnia activity, with a minimum inhibition concentration (MIC value of 30.0 µg/mL against mycelia growth and a minimum fungicidal concentration (MFC value of 50.0 μg/mL against spores; for leaf EO, the MIC and MFC values are 100 and 125 µg/mL, respectively. These findings demonstrate that bark EO has potential to be developed as a remedy for the control of Saprolegnia spp. in aquaculture.

  18. Eelgrass slabs, a soilless culture substrate that inhibits adhesion of fungi and oomycetes and enhances antioxidant activity in tomato.

    Science.gov (United States)

    Meot-Duros, Laetitia; Le Floch, Gaëtan; Meot, Benoit; Letousey, Patricia; Jacob, Bruno; Barbier, Georges

    2011-10-26

    Composed of a marine plant, Zostera sp., eelgrass slabs are a novel organic substrate for soilless cultures used in tomato production. The benefit of using eelgrass slabs for growing tomatoes was assessed by comparing it with coconut fiber slabs in regard to contamination by Pythium spp. and to the antioxidant properties of tomato fruits. First, tomato root contamination by Pythium spp. was studied by direct plate counting, and a molecular comparison of fungal and oomycete communities was conducted using PCR-DHPLC. Second, the antioxidant properties of tomato fruits were analyzed by measuring total phenol and carotenoid contents and by evaluating radical scavenging activity. Compared to plants grown on coconut fiber slabs, those on eelgrass slabs presented a lower rate of Pythium spp. root contamination. Moreover, culture on eelgrass slabs produced fruits with better radical scavenging activity and higher total phenol content compared to controls. Carotenoid content was not affected by the type of substrate. This study highlights the value of detrital leaves of Zostera sp. as a substrate for soilless culture that reduces root contamination and also promotes the production of tomato fruits with better nutritional value.

  19. In vitro susceptibility of the oomycete Pythium insidiosum to metallic compounds containing cadmium, lead, copper, manganese or zinc.

    Science.gov (United States)

    Ribeiro, Tatiana Corrêa; Weiblen, Carla; Botton, Sônia de Avila; Pereira, Daniela Isabel Brayer; de Jesus, Francielli Pantella Kunz; Verdi, Camila Marina; Gressler, Leticia Trevisan; Sangioni, Luís Antonio; Santurio, Janio Morais

    2017-08-01

    Pythium insidiosum is an aquatic oomycete that causes pythiosis, an important and severe disease of difficult treatment that affects humans, domestic and wild animals. This infection is often described in horses in Brazil and humans in Thailand. In clinical practice, we have observed many cases that do not respond to available therapies, indicating the need to explore alternative therapeutic approaches. In this sense, studies using metal compounds in conjunction with available antimicrobial agents have been demonstrated greater antimicrobial activity. Thus, in this research, we tested in vitro activities of metallic compounds containing cadmium, lead, copper, manganese, or zinc against 23 isolates of P. insidiosum. The assays were performed by broth microdilution based on CLSI M38-A2 document. The minimum inhibitory and fungicidal concentrations were established for all isolates. Copper acetate and cadmium acetate showed the highest inhibitory effects, with minimal inhibitory concentration ranging from 4-64 μg/ml and 16-256 μg/ml, respectively. The mean geometric for minimal fungicidal concentrations were, respectively, 26 μg/ml and 111.43 μg/ml for copper acetate and cadmium acetate. These results suggest that copper and cadmium can inhibit P. insidiosum growth, highlighting the greater inhibitory activity of copper acetate. In addition, our results propose that copper and/or cadmium compounds can be used in upcoming researches to formulate effective new complexed drugs against P. insidiosum in in vitro and in vivo experimental models. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Mandipropamid targets the cellulose synthase-like PiCesA3 to inhibit cell wall biosynthesis in the oomycete plant pathogen, Phytophthora infestans.

    Science.gov (United States)

    Blum, Mathias; Boehler, Martine; Randall, Eva; Young, Vanessa; Csukai, Michael; Kraus, Sabrina; Moulin, Florence; Scalliet, Gabriel; Avrova, Anna O; Whisson, Stephen C; Fonne-Pfister, Raymonde

    2010-03-01

    Oomycete plant pathogens cause a wide variety of economically and environmentally important plant diseases. Mandipropamid (MPD) is a carboxylic acid amide (CAA) effective against downy mildews, such as Plasmopara viticola on grapes and potato late blight caused by Phytophthora infestans. Historically, the identification of the mode of action of oomycete-specific control agents has been problematic. Here, we describe how a combination of biochemical and genetic techniques has been utilized to identify the molecular target of MPD in P. infestans. Phytophthora infestans germinating cysts treated with MPD produced swelling symptoms typical of cell wall synthesis inhibitors, and these effects were reversible after washing with H(2)O. Uptake studies with (14)C-labelled MPD showed that this oomycete control agent acts on the cell wall and does not enter the cell. Furthermore, (14)C glucose incorporation into cellulose was perturbed in the presence of MPD which, taken together, suggests that the inhibition of cellulose synthesis is the primary effect of MPD. Laboratory mutants, insensitive to MPD, were raised by ethyl methane sulphonate (EMS) mutagenesis, and gene sequence analysis of cellulose synthase genes in these mutants revealed two point mutations in the PiCesA3 gene, known to be involved in cellulose synthesis. Both mutations in the PiCesA3 gene result in a change to the same amino acid (glycine-1105) in the protein. The transformation and expression of a mutated PiCesA3 allele was carried out in a sensitive wild-type isolate to demonstrate that the mutations in PiCesA3 were responsible for the MPD insensitivity phenotype.

  1. bZIP transcription factors in the oomycete phytophthora infestans with novel DNA-binding domains are involved in defense against oxidative stress.

    Science.gov (United States)

    Gamboa-Meléndez, Heber; Huerta, Apolonio I; Judelson, Howard S

    2013-10-01

    Transcription factors of the basic leucine zipper (bZIP) family control development and stress responses in eukaryotes. To date, only one bZIP has been described in any oomycete; oomycetes are members of the stramenopile kingdom. In this study, we describe the identification of 38 bZIPs from the Phytophthora infestans genome. Half contain novel substitutions in the DNA-binding domain at a site that in other eukaryotes is reported to always be Asn. Interspecific comparisons indicated that the novel substitutions (usually Cys, but also Val and Tyr) arose after oomycetes diverged from other stramenopiles. About two-thirds of P. infestans bZIPs show dynamic changes in mRNA levels during the life cycle, with many of the genes being upregulated in sporangia, zoospores, or germinated zoospore cysts. One bZIP with the novel Cys substitution was shown to reside in the nucleus throughout growth and development. Using stable gene silencing, the functions of eight bZIPs with the Cys substitution were tested. All but one were found to play roles in protecting P. infestans from hydrogen peroxide-induced injury, and it is proposed that the novel Cys substitution serves as a redox sensor. A ninth bZIP lacking the novel Asn-to-Cys substitution, but having Cys nearby, was also shown through silencing to contribute to defense against peroxide. Little effect on asexual development, plant pathogenesis, or resistance to osmotic stress was observed in transformants silenced for any of the nine bZIPs.

  2. Back to basics: an evaluation of NaOH and alternative rapid DNA extraction protocols for DNA barcoding, genotyping, and disease diagnostics from fungal and oomycete samples.

    Science.gov (United States)

    Osmundson, Todd W; Eyre, Catherine A; Hayden, Katherine M; Dhillon, Jaskirn; Garbelotto, Matteo M

    2013-01-01

    The ubiquity, high diversity and often-cryptic manifestations of fungi and oomycetes frequently necessitate molecular tools for detecting and identifying them in the environment. In applications including DNA barcoding, pathogen detection from plant samples, and genotyping for population genetics and epidemiology, rapid and dependable DNA extraction methods scalable from one to hundreds of samples are desirable. We evaluated several rapid extraction methods (NaOH, Rapid one-step extraction (ROSE), Chelex 100, proteinase K) for their ability to obtain DNA of quantity and quality suitable for the following applications: PCR amplification of the multicopy barcoding locus ITS1/5.8S/ITS2 from various fungal cultures and sporocarps; single-copy microsatellite amplification from cultures of the phytopathogenic oomycete Phytophthora ramorum; probe-based P. ramorum detection from leaves. Several methods were effective for most of the applications, with NaOH extraction favored in terms of success rate, cost, speed and simplicity. Frozen dilutions of ROSE and NaOH extracts maintained PCR viability for over 32 months. DNA from rapid extractions performed poorly compared to CTAB/phenol-chloroform extracts for TaqMan diagnostics from tanoak leaves, suggesting that incomplete removal of PCR inhibitors is an issue for sensitive diagnostic procedures, especially from plants with recalcitrant leaf chemistry. NaOH extracts exhibited lower yield and size than CTAB/phenol-chloroform extracts; however, NaOH extraction facilitated obtaining clean sequence data from sporocarps contaminated by other fungi, perhaps due to dilution resulting from low DNA yield. We conclude that conventional extractions are often unnecessary for routine DNA sequencing or genotyping of fungi and oomycetes, and recommend simpler strategies where source materials and intended applications warrant such use.

  3. Development of a bipartite ecdysone-responsive gene switch for the oomycete Phytophthora infestans and its use to manipulate transcription during axenic culture and plant infection.

    Science.gov (United States)

    Gamboa-Meléndez, Heber; Judelson, Howard S

    2015-01-01

    Conditional expression systems have been proven to be useful tools for the elucidation of gene function in many taxa. Here, we report the development of the first useful inducible promoter system for an oomycete, based on an ecdysone receptor (EcR) and the ecdysone analogue methoxyfenozide. In Phytophthora infestans, the potato late blight pathogen, a monopartite transactivator containing the VP16 activation domain from herpes simplex virus, the GAL4 DNA-binding domain from yeast and the EcR receptor domain from the spruce budworm enabled high levels of expression of a β-glucuronidase (GUS) reporter gene, but unacceptable basal activity in the absence of the methoxyfenozide inducer. Greatly improved performance was obtained using a bipartite system in which transcription is activated by a heterodimer between a chimera of VP16 and the migratory locust retinoid X receptor, and a separate EcR-DNA-binding domain chimera. Transformants were obtained that exhibited >100-fold activation of the reporter by methoxyfenozide, with low basal levels of expression and induced activity approaching that of the strong ham34 promoter. Performance varied between transformants, probably as a result of position effects. The addition of methoxyfenozide enabled strong induction during hyphal growth, zoosporogenesis and colonization of tomato. No significant effects of the inducer or transactivators on growth, development or pathogenicity were observed. The technology should therefore be a useful addition to the arsenal of methods for the study of oomycete plant pathogens.

  4. Screening of oomycete fungi for their potential role in reducing the biting midge (Diptera: Ceratopogonidae) larval populations in Hervey Bay, Queensland, Australia.

    Science.gov (United States)

    Stephen, Kirsty; Kurtböke, D Ipek

    2011-05-01

    Biting midges are globally distributed pests causing significant economic losses and transmitting arbovirus diseases to both animals and humans. Current biological and chemical control strategies for biting midge target destruction of adult forms, but strategies directed at immature stages of the insect have yet to be explored in Australia. In the present study, coastal waters of Hervey Bay region in Queensland, Australia were screened to detect the habitats of biting midge at immature stages. These results were then correlated to local environmental conditions and naturally occurring entomopathogenic fungal flora, in particular the Oomycete fungi, to determine their reducing effect on insect immature stages in the search for biological control agents in the region. The dominant species of biting midge found within this study was Culicoides subimmaculatus occuring between mean high water neaps and mean high water spring tide levels. Within this intertidal zone, the presence of C. subimmaculatus larvae was found to be influenced by both sediment size and distance from shore. Halophytophthora isolates colonized both dead and alive pupae. However, the association was found to be surface colonization rather than invasion causing the death of the host. Lack of aggressive oomycete fungal antagonists towards midge larvae might correlate with increased incidences of biting midge infestations in the region.

  5. Screening of Oomycete Fungi for Their Potential Role in Reducing the Biting Midge (Diptera: Ceratopogonidae Larval Populations in Hervey Bay, Queensland, Australia

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    D. Ipek Kurtböke

    2011-05-01

    Full Text Available Biting midges are globally distributed pests causing significant economic losses and transmitting arbovirus diseases to both animals and humans. Current biological and chemical control strategies for biting midge target destruction of adult forms, but strategies directed at immature stages of the insect have yet to be explored in Australia. In the present study, coastal waters of Hervey Bay region in Queensland, Australia were screened to detect the habitats of biting midge at immature stages. These results were then correlated to local environmental conditions and naturally occurring entomopathogenic fungal flora, in particular the Oomycete fungi, to determine their reducing effect on insect immature stages in the search for biological control agents in the region. The dominant species of biting midge found within this study was Culicoides subimmaculatus occuring between mean high water neaps and mean high water spring tide levels. Within this intertidal zone, the presence of C. subimmaculatus larvae was found to be influenced by both sediment size and distance from shore. Halophytophthora isolates colonized both dead and alive pupae. However, the association was found to be surface colonization rather than invasion causing the death of the host. Lack of aggressive oomycete fungal antagonists towards midge larvae might correlate with increased incidences of biting midge infestations in the region.

  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. 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

  8. Arabidopsis nonhost resistance gene PSS1 confers immunity against an oomycete and a fungal pathogen but not a bacterial pathogen that cause diseases in soybean

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    Sumit Rishi

    2012-06-01

    Full Text Available Abstract Background Nonhost resistance (NHR provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Three Arabidopsis thaliana PEN (penetration deficient genes, PEN1, 2 and 3 have been shown to provide NHR against the barley pathogen Blumeria graminis f. sp. hordei at the prehaustorial level. Arabidopsis pen1-1 mutant lacking the PEN1 gene is penetrated by the hemibiotrophic oomycete pathogen Phytophthora sojae, the causal organism of the root and stem rot disease in soybean. We investigated if there is any novel nonhost resistance mechanism in Arabidopsis against the soybean pathogen, P. sojae. Results The P.sojaesusceptible (pss 1 mutant was identified by screening a mutant population created in the Arabidopsis pen1-1 mutant that lacks penetration resistance against the non adapted barley biotrophic fungal pathogen, Blumeria graminis f. sp. hordei. Segregation data suggested that PEN1 is not epistatic to PSS1. Responses of pss1 and pen1-1 to P. sojae invasion were distinct and suggest that PSS1 may act at both pre- and post-haustorial levels, while PEN1 acts at the pre-haustorial level against this soybean pathogen. Therefore, PSS1 encodes a new form of nonhost resistance. The pss1 mutant is also infected by the necrotrophic fungal pathogen, Fusarium virguliforme, which causes sudden death syndrome in soybean. Thus, a common NHR mechanism is operative in Arabidopsis against both hemibiotrophic oomycetes and necrotrophic fungal pathogens that are pathogenic to soybean. However, PSS1 does not play any role in immunity against the bacterial pathogen, Pseudomonas syringae pv. glycinea, that causes bacterial blight in soybean. We mapped PSS1 to a region very close to the southern telomere of chromosome 3 that carries no known disease resistance genes. Conclusions The study revealed that Arabidopsis PSS1 is a novel nonhost resistance gene that confers a new form of

  9. Zoosporogênese in vitro entre isolados do oomiceto Pythium insidiosum In vitro zoosporogenesis among oomycetes Pythium insidiosum isolates

    Directory of Open Access Journals (Sweden)

    Daniela Isabel Brayer Pereira

    2008-02-01

    Full Text Available Pythium insidiosum é um oomiceto aquático, responsável pela etiologia da pitiose, uma enfermidade crônica, observada freqüentemente em eqüinos. A produção de zoósporos móveis por este microrganismo se constitui no fator determinante da ocorrência da enfermidade. Este estudo avaliou a zoosporogênese e quantificou a produção de zoósporos de 32 amostras de Pythium insidiosum isoladas de eqüinos naturalmente infectados. Pythium insidiosum foi cultivado em meio Corn Meal Agar acrescido de fragmentos de grama, durante 5 dias, a 37°C. Posteriormente, os fragmentos de grama parasitados foram incubados em Meio de Indução a 37°C, por 24 horas. Observou-se que 16 amostras (50% produziram 20.000 zoósporos mL-1, 12 isolados (37,5% produziram acima de 20.000 zoósporos mL-1, enquanto quatro amostras (12,5% produziram menos de 20.000 zoósporos mL-1. O período de maior produção de zoósporos foi entre 6 e 8 horas de incubação. O protocolo utilizado na indução da zoosporogênese mostrou-se eficiente e representa uma importante ferramenta, tanto para a identificação do Pythium insidiosum, como para a obtenção de zoósporos em quantidades suficientes para a inoculação em animais experimentais e aplicação no desenvolvimento de testes de suscetibilidade.Pythium insidiosum is an aquatic oomycete and the etiology of a chronic disease called pythiosis, commonly found in the skin of horses. The production of mobile zoospores by this microorganism is the determinant factor of this disease. This study evaluated the zoosporogenesis and quantification of zoospores in 32 samples of Pythium insidiosum isolated from horses with pythiosis. The assay used culture of the Pythium insidiosum in Corn Meal Agar plus grass blades for 5 days at 37°C. The grass blades were incubated in Induction Medium at 37°C for 24 hours. The findings showed 16 samples (50% yielded 20,000 zoospores mL-1, 12 (37.5% samples yielded over 20,000 zoospores mL-1 and 4

  10. 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.

  11. Antifungal, anti-oomycete and phytotoxic effects of volatile organic compounds from the endophytic fungus Xylaria sp. strain PB3f3 isolated from Haematoxylon brasiletto.

    Science.gov (United States)

    Sánchez-Ortiz, B L; Sánchez-Fernández, R E; Duarte, G; Lappe-Oliveras, P; Macías-Rubalcava, M L

    2016-05-01

    To determine the antifungal, anti-oomycete and phytotoxic activity; and chemical composition of the volatile organic compounds (VOCs) produced by endophytic fungus Xylaria sp. PB3f3 isolated from Haematoxylon brasiletto Karst. Bioactivity and chemical composition of the VOCs from Xylaria sp. PB3f3 were established by using simple and multiple antagonism bioassays, and gas chromatography/mass spectrometry, respectively. The results showed that Xylaria sp. PB3f3 inhibited the growth of the oomycetes Pythium aphanidermatum (78·3%), Phytophthora capsici (48·3%), and the fungi Alternaria solani (24·5%) and Fusarium oxysporum (24·2%), in multiple antagonism bioassays. Volatile organic compounds, produced at 20 and 30 days of fungal growth, inhibited root elongation on Amaranthus hypochondriacus (27·6%) and on Solanum lycopersicum (53·2%). Forty VOCs were identified at 10, 20 and 30 days in Xylaria sp. PB3f3 cultures. The compounds with the highest fibre affinity were: 3-methyl-1-butanol and thujopsene, at 10 days of fungal growth; an unidentified amine and 2-methyl-1-butanol at 20 days; and 2-methyl-1-propanol at 30 days. In the gas phase assay method 2-methyl-1-propanol and 2-methyl-1-butanol showed significant inhibitory effects on root elongation and germination of Am. hypochondriacus and S. lycopersicum. Xylaria sp. PB3f3 and its VOCs showed significant phytotoxic effects on root elongation and germination of Am. hypochondriacus and S. lycopersicum. The genus Xylaria produces a great variety of secondary metabolites, but, up date, there are no reports of the identification of bioactive volatile compounds. Thus, Xylaria sp. PB3f3 and its VOCs are a possible candidate for the biological control of weeds. © 2016 The Society for Applied Microbiology.

  12. Root rot of peas in the Netherlands: fungal pathogens, inoculum potential and soil receptivity.

    NARCIS (Netherlands)

    Oyarzun, P.J.

    1994-01-01

    Fungi associated to pea (Pisum sativum L.) root rot were studied. Fusarium and Oomycetes were most common. Fusarium solani f. sp. pisi, Fsp, was widely distributed and the most frequent fungus in roots of diseased crops. The pathogens Thielaviopsis basicola , Tb, and Aphanomyces euteiches, Ae, wer

  13. Tomato I2 Immune Receptor Can Be Engineered to Confer Partial Resistance to the Oomycete Phytophthora infestans in Addition to the Fungus Fusarium oxysporum.

    Science.gov (United States)

    Giannakopoulou, Artemis; Steele, John F C; Segretin, Maria Eugenia; Bozkurt, Tolga O; Zhou, Ji; Robatzek, Silke; Banfield, Mark J; Pais, Marina; Kamoun, Sophien

    2015-12-01

    Plants and animals rely on immune receptors, known as nucleotide-binding domain and leucine-rich repeat (NLR)-containing proteins, to defend against invading pathogens and activate immune responses. How NLR receptors respond to pathogens is inadequately understood. We previously reported single-residue mutations that expand the response of the potato immune receptor R3a to AVR3a(EM), a stealthy effector from the late blight oomycete pathogen Phytophthora infestans. I2, another NLR that mediates resistance to the will-causing fungus Fusarium oxysporum f. sp. lycopersici, is the tomato ortholog of R3a. We transferred previously identified R3a mutations to I2 to assess the degree to which the resulting I2 mutants have an altered response. We discovered that wild-type I2 protein responds weakly to AVR3a. One mutant in the N-terminal coiled-coil domain, I2(I141N), appeared sensitized and displayed markedly increased response to AVR3a. Remarkably, I2(I141N) conferred partial resistance to P. infestans. Further, I2(I141N) has an expanded response spectrum to F. oxysporum f. sp. lycopersici effectors compared with the wild-type I2 protein. Our results suggest that synthetic immune receptors can be engineered to confer resistance to phylogenetically divergent pathogens and indicate that knowledge gathered for one NLR could be exploited to improve NLR from other plant species.

  14. Detection of Differential Host Susceptibility to the Marine Oomycete Pathogen Eurychasma dicksonii by Real-Time PCR: Not All Algae Are Equal▿ †

    Science.gov (United States)

    Gachon, Claire M. M.; Strittmatter, Martina; Müller, Dieter G.; Kleinteich, Julia; Küpper, Frithjof C.

    2009-01-01

    In the marine environment, a growing body of evidence points to parasites as key players in the control of population dynamics and overall ecosystem structure. However, their prevalence and impact on marine macroalgal communities remain virtually unknown. Indeed, infectious diseases of seaweeds are largely underdocumented, partly because of the expertise required to diagnose them with a microscope. Over the last few years, however, real-time quantitative PCR (qPCR) has emerged as a rapid and reliable alternative to visual symptom scoring for monitoring pathogens. Thus, we present here a qPCR assay suitable for the detection and quantification of the intracellular oomycete pathogen Eurychasma dicksonii in its ectocarpalean and laminarialean brown algal hosts. qPCR and microscopic observations made of laboratory-controlled cultures revealed that clonal brown algal strains exhibit different levels of resistance against Eurychasma, ranging from high susceptibility to complete absence of symptoms. This observation strongly argues for the existence of a genetic determinism for disease resistance in brown algae, which would have broad implications for the dynamics and genetic structure of natural populations. We also used qPCR for the rapid detection of Eurychasma in filamentous brown algae collected in Northern Europe and South America and found that the assay is specific, robust, and widely applicable to field samples. Hence, this study opens the perspective of combining large-scale disease monitoring in the field with laboratory-controlled experiments on the genome model seaweed Ectocarpus siliculosus to improve our understanding of brown algal diseases. PMID:19011072

  15. Extraction, characterization and biological activity of a (1,3)(1,6)-β-d-glucan from the pathogenic oomycete Pythium insidiosum.

    Science.gov (United States)

    Tondolo, Juliana S M; Ledur, Pauline C; Loreto, Érico S; Verdi, Camila M; Bitencourt, Paula E R; de Jesus, Francielli P K; Rocha, Jean P; Alves, Sydney H; Sassaki, Guilherme L; Santurio, Janio M

    2017-02-10

    Pythiosis is a life-threatening infectious disease caused by the pathogenic oomycete Pythium insidiosum. This study is the first to evaluate the P. insidiosum glucan content and its biological activities. The enzymatic quantification of the glucans in P. insidiosum mycelia showed that the β-glucan content was 18.99%±3.59. The cell wall polysaccharide extract consisted of ∼81.7% carbohydrates (exclusively glucose) and ∼18.3% residual amino acids and peptides. The results from monosaccharide composition, methylation and 1D/2D NMR spectroscopy analyses indicated the presence of a highly branched (1,3)(1,6)-β-d-glucan, with (1,6)-β-d-glucopyranosil side-branching unit on average every 1-2 repeat units. In vitro, the β-d-glucan extract could significantly promote spleen lymphocyte proliferation in human, equine and mouse cell cultures. BALB/c mice that were subcutaneously pre-immunized with three doses of 0.5, 2.5 and 5.0mg of β-glucan/mouse, showed a significant increase in IL-2, IL-6, IL-10, TNF-α and IL-17A production compared to non-immunized mice. These results suggested that β-d-glucan extract induces significant and specific Th17 cellular immune response and provided the theoretical basis for further experiments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Practical disinfection chemicals for fishing and crayfishing gear against crayfish plague transfer

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    Jussila J.

    2014-01-01

    Full Text Available We tested four commercial disinfectants against crayfish plague (Aphanomyces astaci spores in both aquatic solutions and with material mimicking fishing and crayfishing gear, e.g. traps, ropes, mesh, etc. The tested disinfectants were Proxitane®5:14, Proxitane®12:20, Wofasteril®E400, Virkon®S and hydrogen peroxide. The effects of the chemicals were initially tested in liquid zoospore cultures and the effective concentrations were then further tested using clean and dirty model materials (PP sheet, nylon rope, cotton fabric contaminated with A. astaci spore solutions. The disinfectants effective against infective crayfish plague spores with both clean and dirty model materials were Proxinate®5:14 (effective concentration was 30 mg·L-1 of PAA and Virkon®S (3 g·L-1, while Proxinate®12:20 (10 mg·L-1 of PAA and Wofasteril®E400 (30 mg·L-1 of PAA worked only with clean model materials. Hydrogen peroxide was not effective in the tested concentrations and conditions. Based on the results, the disinfectants most suitable for the fishing and crayfishing gear disinfection would be Proxitane®5:14 and Virkon®S, with the condition that all the gear should be thoroughly cleaned of organic matter to ensure inactivation of A. astaci spores.

  17. RECENT SUSPECT CASES AND A PILOT DETECTION STUDY

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    KOZUBÍKOVÁ E.

    2006-01-01

    Full Text Available There are only very limited reports about the occurrence of the crayfish plague in Czechia. In recent years, mass mortalities of Astacus spp. with symptoms of possible crayfish plague were noticed in three streams in the country – two in Central Bohemia (1998-9 and one in Silesia (2004. Three dead individuals from the last outbreak were examined for the presence of the crayfish plague pathogen, Aphanomyces astaci, by observation of the presence of hyphae in their cuticle and by a PCR-based diagnostic method. In all three cases the detection was positive. Although causes of mass mortalities from two other localities lack such a direct confirmation, the indirect evidence supports the same conclusion. The main potential vector of A. astaci in Czechia is the American spiny-cheeck crayfish Orconectes limosus, widespread in large rivers of the western part of the country and in various isolated standing waters. Using the same molecular method, we investigated the presence of A. astaci in living O. limosus individuals from six localities (three running and three standing waters. The analysis indicated the presence of the pathogen in animals from five out of six investigated Orconectes populations. One of them is present in the stream where two European Astacus species had gone extinct in 1998-9. Our results suggest that the crayfish plague is still present in Czechia, and that populations of O. limosus represent a reservoir for the crayfish plague pathogen, which directly endangers populations of the native crayfish.

  18. First evidence of crayfish plague agent in populations of the marbled crayfish (Procambarus fallax forma virginalis

    Directory of Open Access Journals (Sweden)

    Keller N.S.

    2014-01-01

    Full Text Available The introduction of non-indigenous species and associated diseases can cause declines in indigenous flora and fauna and threaten local biodiversity. The crayfish plague pathogen (Aphanomyces astaci, carried and transmitted by latent infected North American crayfish, can lead to high mortalities in indigenous European crayfish populations. Although the parthenogenetic marbled crayfish (Procambarus fallax (Hagen, 1870  forma virginalis is common in the aquarium trade and has established wild populations in Europe, its carrier status is still unknown. This study investigated one captive and three established wild-living marbled crayfish populations for an infection with the crayfish plague pathogen applying real-time PCR. We demonstrate that captive, as well as two wild marbled crayfish populations were infected by A. astaci. Although infection status in laboratory kept specimens reached high levels, marbled crayfish showed no obviously plague-related mortality. Furthermore, sequence analysis revealed that captive crayfish carried the A. astaci genotype Pc, which has earlier been isolated from the North American red swamp crayfish (Procambarus clarkii. The results indicate that due to its positive carrier status marbled crayfish poses a greater threat to local biodiversity in Europe than considered until now.

  19. 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.

  20. Genetic dissection of a TIR-NB-LRR locus from the wild North American grapevine species Muscadinia rotundifolia identifies paralogous genes conferring resistance to major fungal and oomycete pathogens in cultivated grapevine.

    Science.gov (United States)

    Feechan, Angela; Anderson, Claire; Torregrosa, Laurent; Jermakow, Angelica; Mestre, Pere; Wiedemann-Merdinoglu, Sabine; Merdinoglu, Didier; Walker, Amanda R; Cadle-Davidson, Lance; Reisch, Bruce; Aubourg, Sebastien; Bentahar, Nadia; Shrestha, Bipna; Bouquet, Alain; Adam-Blondon, Anne-Françoise; Thomas, Mark R; Dry, Ian B

    2013-11-01

    The most economically important diseases of grapevine cultivation worldwide are caused by the fungal pathogen powdery mildew (Erysiphe necator syn. Uncinula necator) and the oomycete pathogen downy mildew (Plasmopara viticola). Currently, grapegrowers rely heavily on the use of agrochemicals to minimize the potentially devastating impact of these pathogens on grape yield and quality. The wild North American grapevine species Muscadinia rotundifolia was recognized as early as 1889 to be resistant to both powdery and downy mildew. We have now mapped resistance to these two mildew pathogens in M. rotundifolia to a single locus on chromosome 12 that contains a family of seven TIR-NB-LRR genes. We further demonstrate that two highly homologous (86% amino acid identity) members of this gene family confer strong resistance to these unrelated pathogens following genetic transformation into susceptible Vitis vinifera winegrape cultivars. These two genes, designated resistance to Uncinula necator (MrRUN1) and resistance to Plasmopara viticola (MrRPV1) are the first resistance genes to be cloned from a grapevine species. Both MrRUN1 and MrRPV1 were found to confer resistance to multiple powdery and downy mildew isolates from France, North America and Australia; however, a single powdery mildew isolate collected from the south-eastern region of North America, to which M. rotundifolia is native, was capable of breaking MrRUN1-mediated resistance. Comparisons of gene organization and coding sequences between M. rotundifolia and the cultivated grapevine V. vinifera at the MrRUN1/MrRPV1 locus revealed a high level of synteny, suggesting that the TIR-NB-LRR genes at this locus share a common ancestor. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

  1. KEYNOTE PRESENTATION AND ROUNDTABLE SESSION 4. CRAYFISH PATHOLOGY IN EUROPE:PAST, PRESENT AND A PROGRAMME FOR THE FUTURE

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    EDGERTON B. F.

    2004-01-01

    Full Text Available The devastating affects of disease on European freshwater crayfish are well known as epizootics in wild populations have occurred throughout much of Europe since the mid XVIIIe s. After protracted and rigorous debate, the cause of the disease named crayfish plague was proved to be the fungus Aphanomyces astaci in 1934. In the last 70 years, much of the research conducted in the field of crayfish pathology has concentrated on fungi, especially improving diagnostic techniques for A. astaci. Similarly, diagnostic responses to epizootics in European crayfish have concentrated almost entirely on fungal isolation and/or identification. On the other hand, viruses have proved to be the most important pathogens in the growing global crustacean aquaculture and fishery industries. Rickettsia-like organisms (RLO are also important. Critically, diagnostic techniques necessary to detect the full range of potential pathogens of crayfish are rarely utilized in the field of crayfish pathology in Europe. Histopathological analysis, required for the diagnosis of infections by viruses and RLOs, is absent from most European studies. Epizootics unrelated to A. astaci in European crayfish and epizootics in introduced American crayfish species highlight the inadequate current state of knowledge in the field. Presently, the field is ill-equipped to determine the cause(s of these epizootics. Moreover, crayfish conservation strategies may be undermined and even detrimental to the longterm goals; eg., stocking programs may spread undetected pathogens. Therefore, critical limitations in the field of crayfish pathology have major repercussions in management of freshwater crayfish. Guiding principles and a concept for a trans-European Community research and education program were developed to address this serious issue and are presented herein.

  2. Extracellular recognition of oomycetes during biotrophic infection of plants

    NARCIS (Netherlands)

    Raaymakers, Tom M.; Van Den Ackerveken, Guido

    2016-01-01

    Extracellular recognition of pathogens by plants constitutes an important early detection system in plant immunity. Microbe-derived molecules, also named patterns, can be recognized by pattern recognition receptors (PRRs) on the host cell membrane that trigger plant immune responses. Most knowledge

  3. 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...

  4. Molecular detection of oomycetes species in water courses

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    Oszako Tomasz

    2016-12-01

    Full Text Available In Poland, about 20% of forest nurseries use irrigation water coming from natural superficial reservoirs, presumed to be the first source of infection caused by harmful pathogens belonging to the Oomycota class, especially Phytophthora genus and Pythium genus. The forest nursery is the only place where forest managers can react before pathogens leave it with asymptomatic plants or soil attached to their roots. The aim of this research was detection and identification phytopathogens in water samples. In order to recognise genus Phytophthora or Pythium in water collected from 33 places in five different forest districts in Poland, two DNA-based approaches of identification were applied: (i the TaqMan probes, and (ii sequencing of the ITS6/4 region.

  5. Histological changes and antioxidant enzyme activity in signal crayfish (Pacifastacus leniusculus) associated with sub-acute peracetic acid exposure.

    Science.gov (United States)

    Chupani, Latifeh; Zuskova, Eliska; Stara, Alzbeta; Velisek, Josef; Kouba, Antonin

    2016-01-01

    Peracetic acid (PAA) is a powerful disinfectant recently adopted as a therapeutic agent in aquaculture. A concentration of 10 mg L(-1) PAA effectively suppresses zoospores of Aphanomyces astaci, the agent of crayfish plague. To aid in establishing safe therapeutic guideline, the effects of PAA on treated crayfish were investigated through assessment of histological changes and oxidative damage. Adult female signal crayfish Pacifastacus leniusculus (n = 135) were exposed to 2 mg L(-1) and 10 mg L(-1) of PAA for 7 days followed by a 7 day recovery period in clean water. Superoxide dismutase activity was significantly lower in gill and hepatopancreas after three days exposure to 10 mg L(1) PAA than in the group treated with 2 mg L(-1) PAA and a control in only clean water. Catalase activity in gill and hepatopancreas remained unaffected by both exposures. Glutathione reductase was significantly decreased in gill of 10 mg L(-1) PAA treated crayfish and increased in group exposed to 2 mg L(-1) compared to control after 7 days exposure. Antioxidant enzyme activity in exposed groups returned to control values after recovery period. Gill, hepatopancreas, and antennal gland showed slight damage in crayfish treated with 2 mg L(-1) of PAA compared to the control group. The extent and frequency of histological alterations were more pronounced in animals exposed to 10 mg L(-1). The gill was the most affected organ, infiltrated by granular hemocytes and displaying malformations of lamella tips and disorganization of epithelial cells. After a 7 day recovery period, the infiltrating cells in affected tissues of the exposed crayfish began to return to normal levels. Results suggested that the given concentrations could be applied to signal crayfish against crayfish plague agent in aquaculture; however, further studies are required for safe use.

  6. Monitoring of white-clawed crayfish (Austropotamobius pallipes population during a crayfish plague outbreak followed by rescue

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    Collas M.

    2016-01-01

    Full Text Available A mass mortality was detected in the downstream section of one of the most extensive French populations of the endangered white-clawed crayfish, Austropotamobius pallipes, on June 26, 2013. This population occupied a 12 km stretch of the La Lucelle brook, with an estimated size of around 150 000 individuals. The presence of the crayfish plague pathogen was quickly diagnosed as the cause of the mortality, and monitoring was carried out to follow the spread of the disease from 15 July 2013 for one year. Results showed that after a fast spread between 15 and 25 July 2013 (upstream progression of mortality for about 4 km, the mortality front was limited to a stretch of a few hundred meters from August until December 2013. During winter, mortality was always observed, confirming that disease remained active. In April 2014, the mortality front was halted by a large dam in the brook (2 m high, 0.56 km from brook source. Two months later, 30 live crayfish were observed above the dam. On the 30 August 2014, no crayfish were found above the dam. Infected individuals analysed for microsatellite markers confirmed the Pacifastacus leniusculus strain of Aphanomyces astaci at the origin of this outbreak. Before the crayfish plague spread upstream of the large dam, a sample of 576 individuals was collected from upstream of the dam and translocated to another stream in the same French department. In July 2014, observations by night confirmed the presence of translocated white-clawed crayfish in the receiving brook.

  7. GENETIC DIFFERENCES AMONG NOBLE CRAYFISH (ASTACUS ASTACUS STOCKS IN FINLAND, SWEDEN AND ESTONIA BASED ON THE ITS1 REGION

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    ALARANTA A.

    2006-01-01

    Full Text Available Noble crayfish (Astacus astacus is indigenous to Finland. The distribution of A. astacus has diminished dramatically during the past century, due to environmental changes, crayfish plague (Aphanomyces astaci outbreaks and stocking of alien signal crayfish (Pacifastacus leniusculus. Due to an active reintroduction policy and partly due to illegal introductions, the origins of noble crayfish populations are somewhat unknown. For conservation purposes it is essential to know if the populations are autochthonous or if they are a mixture of several different populations. Genetic variation of seven Finnish noble crayfish populations was studied comparing the variation in a short tandem repeat in the rDNA internal transcribed spacer 1 region (ITS1 region. Five Swedish and five Estonian populations were used as reference populations. Based on the ITS1 fragment variation, some of the analysed Finnish noble crayfish populations were most likely original populations or originated from one source population. They differed from the other populations according to the Population Divergence Test. However, there were no differences between some of the Finnish populations and this may be a consequence of multiple stockings. Differences among noble crayfish populations from the three countries were also studied. Five of the Finnish populations differed from the Swedish and the Estonian populations. One population, Lake Saimaa, did not differ from one Estonian and two Swedish populations. Furthermore, a population from northern Finland was not different from a population in northern Sweden. The Estonian populations had a larger number of fragments present in their genotypes compared to the Finnish and the Swedish populations. Private fragments, which were typical to only one country, were found in two Finnish, in four Estonian and in three Swedish populations.

  8. CRN13 candidate effectors from plant and animal eukaryotic pathogens are DNA-binding proteins which trigger host DNA damage response.

    Science.gov (United States)

    Ramirez-Garcés, Diana; Camborde, Laurent; Pel, Michiel J C; Jauneau, Alain; Martinez, Yves; Néant, Isabelle; Leclerc, Catherine; Moreau, Marc; Dumas, Bernard; Gaulin, Elodie

    2016-04-01

    To successfully colonize their host, pathogens produce effectors that can interfere with host cellular processes. Here we investigated the function of CRN13 candidate effectors produced by plant pathogenic oomycetes and detected in the genome of the amphibian pathogenic chytrid fungus Batrachochytrium dendrobatidis (BdCRN13). When expressed in Nicotiana, AeCRN13, from the legume root pathogen Aphanomyces euteiches, increases the susceptibility of the leaves to the oomycete Phytophthora capsici. When transiently expressed in amphibians or plant cells, AeCRN13 and BdCRN13 localize to the cell nuclei, triggering aberrant cell development and eventually causing cell death. Using Förster resonance energy transfer experiments in plant cells, we showed that both CRN13s interact with nuclear DNA and trigger plant DNA damage response (DDR). Mutating key amino acid residues in a predicted HNH-like endonuclease motif abolished the interaction of AeCRN13 with DNA, the induction of DDR and the enhancement of Nicotiana susceptibility to P. capsici. Finally, H2AX phosphorylation, a marker of DNA damage, and enhanced expression of genes involved in the DDR were observed in A. euteiches-infected Medicago truncatula roots. These results show that CRN13 from plant and animal eukaryotic pathogens promotes host susceptibility by targeting nuclear DNA and inducing DDR.

  9. Mapping Fusarium solani and Aphanomyces euteiches root rot resistance and root architecture quantitative trait loci in common bean (Phaseolus vulgaris)

    Science.gov (United States)

    Root rot diseases of bean (Phaseolus vulgaris L.) are a constraint to dry and snap bean production. We developed the RR138 RIL mapping population from the cross of OSU5446, a susceptible line that meets current snap bean processing industry standards, and RR6950, a root rot resistant dry bean in th...

  10. Epizootic ulcerative syndrome: Exotic fish disease threatens Africa’s aquatic ecosystems

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    Karl D.A. Huchzermeyer

    2012-09-01

    Full Text Available In late 2006 an unusual ulcerative condition in wild fish was reported for the first time in Africa from the Chobe and upper Zambezi Rivers in Botswana and Namibia. Concern increased with subsistence fishermen reporting large numbers of ulcerated fish in their catches. In April 2007 the condition was confirmed as an outbreak of epizootic ulcerative syndrome (EUS. The causative agent, Aphanomyces invadans, is a pathogenic water mould of fish that shows little host specificity. Ulcers follow infection of tissues by oomycete zoospores, resulting in a granulomatous inflammation associated with invading oomycete hyphae. Granulomatous tracts surrounding oomycete hyphae within the necrotic tissues characterise the diagnostic histological picture. The upper Zambezi floodplain at the confluence with the Chobe River spans the four countries of Botswana, Namibia, Zambia and Zimbabwe, making disease control a challenge. The floodplain ecosystem supports a high fish diversity of around 80 species, and is an important breeding and nursery ground. The annual cycle of flooding brings about changes in water quality that are thought to favour the infectivity of A. invadans, with diseased fish appearing soon after the plains become flooded. Since 2006 the disease has spread rapidly upstream along the upper Zambezi and its tributaries. By 2010 the disease was reported from the Okavango Delta in Botswana and in 2011 from the Western Cape Province of South Africa. EUS has the potential to disrupt floodplain ecosystems elsewhere in Africa where high fish diversity forms the basis of subsistence fisheries and local economies, and is a direct threat to freshwater fish culture.

  11. Occurrence of fungi and fungus-like organisms in the Horodnianka River in the vicinity of Białystok, Poland.

    Science.gov (United States)

    Kiziewicz, Bozena; Zdrojkowska, Ewa; Gajo, Bernadetta; Godlewska, Anna; Muszyńska, Elzbieta; Mazalska, Bozenna

    2011-01-01

    Studies of fungi and fungus- like organisms in the northeastern Poland have mainly concentrated on running waters in the vicinity of Białystok, including the Horodnianka River. The main objective was to investigate biodiversity of fungi and fungus-like organisms which take part in decomposition of organic matter commonly found in inland waters. To obtain a complete picture of species composition of fungi and fungus-like organisms in running waters we decided to explore representative sites of the Horodnianka River such as Olmonty, Hryniewicze and Horodniany with close localization of landfill. Fungal species were isolated using baiting technique. Baits of onion skin (Alium cepa), hemp-seeds (Cannabis sativa), impregnated cellophane and snake skin (Natrix natrix) were applied to isolate fungi from water of the Horodnianka River. The fungal community consists of 26 species, 10 species of fungi belonging to class Chytridiomycetes (3), anamorphic fungi (6), and Zygomycetes (1). 16 species belong to fungus-like organisms from class Oomycetes. Most of the recognized species have already been found in other running waters. From all the examined habitats the fungi belonging to 26 species of 18 genera Achlya, Alternaria, Aphanomyces, Aspergillus, Catenophlyctis, Dictyuchus, Fusarium, Karlingia, Lagenidium, Leptomitus, Olpidiopsis, Penicillium, Phlyctochytrium, Pythium, Saprolegnia, Scoliognia, Thraustotheca and Zoophagus were obtained. Certain fungal species like Aphanomyces laevis, Fusarium aqueductum, F. moniliforme, F. oxysporum, Leptomitus lacteus, Saprolegnia feax and S. parasitica were found at all the study sites. Among fungi potentially pathogenic and allergogenic for humans the genera Alternaria, Aspergillus, Fusarium, Lagenidium and Penicillium have already been described. However, the species Lagenidium giganteum and Achlya androgyna are new in the fungal biota of Poland. The greatest number of fungal species occurred in Olmonty (24), the smallest in Horodniany

  12. Response of soybean fungal and oomycete pathogens to apigenin and genistein

    Science.gov (United States)

    Plants recognize invading pathogens and respond biochemically to prevent invasion or inhibit the colonization of plant cells. Many plant defense compounds are flavonoids and some of these are known to have a broad spectrum of biological activity. In this study, we tested two flavonoids, apigenin and...

  13. Occurrence, aggressiveness, somatic growth and reproduction of phenylamide-resistant and -sensitive oomycete pathogens

    Science.gov (United States)

    Pink rot of potato, caused by Phytophthora erythroseptica, is a major field and post-harvest problem in Idaho, particularly since 1998 when isolates resistant to the phenylamide fungicide metalaxyl-M were detected. Isolates of P. erythroseptica were collected from infected tubers in 2001 and 2002 f...

  14. Efficiency comparison of three methods for extracting genomic DNA of the pathogenic oomycete Pythium insidiosum.

    Science.gov (United States)

    Lohnoo, Tassanee; Jongruja, Nujarin; Rujirawat, Thidarat; Yingyon, Wanta; Lerksuthirat, Tassanee; Nampoon, Umporn; Kumsang, Yothin; Onpaew, Pornpit; Chongtrakool, Piriyaporn; Keeratijarut, Angsana; Brandhorst, Tristan T; Krajaejun, Theerapong

    2014-03-01

    The fungus-like organism Pythium insidiosum is the causative agent of a life-threatening tropical infectious disease, pythiosis, which has high rates of morbidity and mortality. A lack of reliable diagnostic tools and effective treatments for pythiosis presents a major challenge to healthcare professionals. Unfortunately, surgical removal of infected organs remains the default treatment for pythiosis. P. insidiosum is an understudied organism. In-depth study of the pathogen at the molecular level could lead to better means of infection control High quality genomic DNA (gDNA) is needed for molecular biology-based research and application development, such as: PCR-assisted diagnosis, population studies, phylogenetic analysis, and molecular genetics assays. To evaluate quality and quantity of the P. insidiosum gDNA extracted by three separate protocols intended for fungal gDNA preparation. Seven P. insidiosum isolates were subjected to gDNA extraction by using conventional-extraction, rapid-extraction, and salt-extraction protocols. The conventional protocol offered the best gDNA in terms of quality and quantity, and could be scaled up. The rapid-extraction protocol had a short turnaround time, but the quality and quantity of the gDNA obtained were limited. The salt-extraction protocol was simple, rapid, and efficient, making it appealing for high throughput preparation of small-scale gDNA samples. Compared to rapid-extraction protocol, both conventional-extraction and salt-extraction protocols provided a better quality and quantity of gDNA, suitable for molecular studies of P. insidiosum. In contrast to the other two methods, the salt-extraction protocol does not require the use of hazardous and expensive materials such as phenol, chloroform, or liquid nitrogen.

  15. Monthly variations of Oomycetes (zoosporic fungi and aquatic Hypomycetes at Sohag (Upper Egypt

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    A. M. Khallil

    2014-01-01

    Full Text Available Fifty-eight fungal species related to twenty-six genera of Perenosporales and Saprolegniales (32 species, 7 genera, 671 colonies and aquatic Hyphomycetes (26 species; 19 genera; 1038 colonies were recovered from the surface water (zoosporic fungi and submerged decaying leaves (aquatic Hyphomycetes samples collected monthly (10 samples each month during the period of experiment (18 months. The richest samples in either zoosporic fungi or aquatic Hyphomycetes were those of comparatively low or moderate temperature, high contents of organic matter and dissolved oxygen. The pH volue and the total soluble salts did not show any regular monthly variations and did not exhibit any considerable influence on fungal population. Achlya racemosa, Dictyuchus sterile (Saprolegniales and Alatospora acuminata, Trisclophorus monosporus (aquatic Hyphomycetes were the most prevalent species. Some fungal species showed their highest population in winter months whereas others in summer months. Moreover, some species were recovered throughout the year. One species of Saprolegniales (Isoachlya toruloides and three species of aquatic Hyphomycetes (Exophiala jeanselmei, Flabellospora Sp. and Varicosporium delicatum are new records to Egypt.

  16. Caught in the act: discovering secreted proteins from fungi and oomycetes in action

    DEFF Research Database (Denmark)

    Roth, Doris; Grell, Morten Nedergaard; Jensen, Annette Bruun;

    -infected host systems. By methods such as TAST (transposon-assisted signal trapping) and PCR with degenerated primers, the libraries are screened for secreted proteins, especially enzymes, which are then further characterized. We investigate a fourth system, the mycorrhizal fungus Paxillus convolutus...

  17. Efficient multiplex simple sequence repeat genotyping of the oomycete plant pathogen Phytophthora infestans

    NARCIS (Netherlands)

    Li, Y.; Cooke, D.E.L.; Jacobsen, E.; Lee, van der T.A.J.

    2013-01-01

    Genotyping is fundamental to population analysis. To accommodate fast, accurate and cost-effective genotyping, a one-step multiplex PCR method employing twelve simple sequence repeat (SSR) markers was developed for high-throughput screening of Phytophthora infestans populations worldwide. The SSR

  18. Volatile organic compounds from native potato-associated Pseudomonas as potential anti-oomycete agents.

    Directory of Open Access Journals (Sweden)

    Mout eDeVrieze

    2015-11-01

    Full Text Available The plant kingdom represents a prominent biodiversity island for microbes that associate with the below- or aboveground organs of vegetal species. Both the root and the leaf represent interfaces where dynamic biological interactions influence plant life. Beside well-studied communication strategies based on soluble compounds and protein effectors, bacteria were recently shown to interact both with host plants and other microbial species through the emissions of volatile organic compounds (VOCs. Focusing on the potato late blight-causing agent Phytophthora infestans, this work addresses the potential role of the bacterial volatilome in suppressing plant diseases. In a previous study, we isolated and identified a large collection of strains with anti-Phytophthora potential from both the phyllosphere and the rhizosphere of potato. Here we report the characterization and quantification of their emissions of biogenic volatiles, comparing 16 Pseudomonas strains differing in i origin of isolation (phyllosphere vs. rhizosphere, ii in vitro inhibition of P. infestans growth and sporulation behavior, and iii protective effects against late blight on potato leaf discs. We systematically tested the pharmacological inhibitory activity of core and strain-specific single compounds against P. infestans mycelial growth and sporangial behavior in order to identify key effective candidate molecules present in the complex natural VOCs blends. We envisage the plant bacterial microbiome as a reservoir for functional VOCs and establish the basis for finding the primary enzymatic toolset that enables the production of active components of the volatile bouquet in plant-associated bacteria. Comprehension of these functional interspecies interactions will open perspectives for the sustainable control of plant diseases in forthcoming agriculture.

  19. ÉVOLUTION DE LA RÉPARTITION DES ÉCREVISSES EN FRANCE MÉTROPOLITAINE SELON LES ENQUÊTES NATIONALES MENÉES PAR LE CONSEIL SUPÉRIEUR DE LA PÊCHE DE 1977 À 2001

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    CHANGEUX T.

    2003-04-01

    Full Text Available Selon les enquêtes nationales menées par le Conseil supérieur de la pêche depuis 1977 en France métropolitaine, la répartition des espèces d’écrevisses montre que les espèces autochtones (Austropotamobius pallipes, Astacus astacus, Austropotamobius torrentium sont soit rares, soit en forte régression, alors que les espèces introduites (Orconectes limosus, Pacifastacus leniusculus, Procambarus clarkii, Astacus leptodactylus progressent. L’interdiction de transport vivant des espèces introduites, à l’exception d’A. leptodactylus, n’a pas enrayé le phénomène avec une accélération particulière de la progression de P. leniusculus ces cinq dernières années, certainement responsable de la recrudescence des cas de peste (Aphanomyces astaci. Les autres mesures favorisant les espèces autochtones, comme la limitation des prélèvements par pêche et les programmes de réintroduction, n’inversent pas la tendance. Il semble donc nécessaire de développer une politique de conservation centrée sur la préservation de l’habitat et le respect de certaines règles de prophylaxie à déterminer. Cela ne peut s’envisager que sur des bassins versants de petite surface facilement contrôlables s’il existe un fort engagement des autorités locales. Les 55 arrêtés de biotope, et surtout les 154 sites Natura 2000 avec leurs plans de gestion associés, apparaissent comme des voies prometteuses pour mettre en œuvre ce type d’actions en France. Le cas de l’île Corse, récemment colonisée par O. limosus, mériterait des mesures réglementaires particulières pour éviter que P. leniusculus et P. clarkii, ne la suivent dans l’avenir.

  20. NFP, a LysM protein controlling Nod factor perception, also intervenes in Medicago truncatula resistance to pathogens.

    Science.gov (United States)

    Rey, Thomas; Nars, Amaury; Bonhomme, Maxime; Bottin, Arnaud; Huguet, Stéphanie; Balzergue, Sandrine; Jardinaud, Marie-Françoise; Bono, Jean-Jacques; Cullimore, Julie; Dumas, Bernard; Gough, Clare; Jacquet, Christophe

    2013-05-01

    Plant LysM proteins control the perception of microbial-derived N-acetylglucosamine compounds for the establishment of symbiosis or activation of plant immunity. This raises questions about how plants, and notably legumes, can differentiate friends and foes using similar molecular actors and whether any receptors can intervene in both symbiosis and resistance. To study this question, nfp and lyk3 LysM-receptor like kinase mutants of Medicago truncatula that are affected in the early steps of nodulation, were analysed following inoculation with Aphanomyces euteiches, a root oomycete. The role of NFP in this interaction was further analysed by overexpression of NFP and by transcriptome analyses. nfp, but not lyk3, mutants were significantly more susceptible than wildtype plants to A. euteiches, whereas NFP overexpression increased resistance. Transcriptome analyses on A. euteiches inoculation showed that mutation in the NFP gene led to significant changes in the expression of c. 500 genes, notably involved in cell dynamic processes previously associated with resistance to pathogen penetration. nfp mutants also showed an increased susceptibility to the fungus Colletotrichum trifolii. These results demonstrate that NFP intervenes in M. truncatula immunity, suggesting an unsuspected role for NFP in the perception of pathogenic signals. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  1. Emergence of epizootic ulcerative syndrome in native fish of the Murray-Darling River System, Australia: hosts, distribution and possible vectors.

    Science.gov (United States)

    Boys, Craig A; Rowland, Stuart J; Gabor, Melinda; Gabor, Les; Marsh, Ian B; Hum, Steven; Callinan, Richard B

    2012-01-01

    Epizootic ulcerative syndrome (EUS) is a fish disease of international significance and reportable to the Office International des Epizootics. In June 2010, bony herring Nematalosa erebi, golden perch Macquaria ambigua, Murray cod Maccullochella peelii and spangled perch Leiopotherapon unicolor with severe ulcers were sampled from the Murray-Darling River System (MDRS) between Bourke and Brewarrina, New South Wales Australia. Histopathology and polymerase chain reaction identified the fungus-like oomycete Aphanomyces invadans, the causative agent of EUS. Apart from one previous record in N. erebi, EUS has been recorded in the wild only from coastal drainages in Australia. This study is the first published account of A. invadans in the wild fish populations of the MDRS, and is the first confirmed record of EUS in M. ambigua, M. peelii and L. unicolor. Ulcerated carp Cyprinus carpio collected at the time of the same epizootic were not found to be infected by EUS, supporting previous accounts of resistance against the disease by this species. The lack of previous clinical evidence, the large number of new hosts (n = 3), the geographic extent (200 km) of this epizootic, the severity of ulceration and apparent high pathogenicity suggest a relatively recent invasion by A. invadans. The epizootic and associated environmental factors are documented and discussed within the context of possible vectors for its entry into the MDRS and recommendations regarding continued surveillance, research and biosecurity are made.

  2. Emergence of epizootic ulcerative syndrome in native fish of the Murray-Darling River System, Australia: hosts, distribution and possible vectors.

    Directory of Open Access Journals (Sweden)

    Craig A Boys

    Full Text Available Epizootic ulcerative syndrome (EUS is a fish disease of international significance and reportable to the Office International des Epizootics. In June 2010, bony herring Nematalosa erebi, golden perch Macquaria ambigua, Murray cod Maccullochella peelii and spangled perch Leiopotherapon unicolor with severe ulcers were sampled from the Murray-Darling River System (MDRS between Bourke and Brewarrina, New South Wales Australia. Histopathology and polymerase chain reaction identified the fungus-like oomycete Aphanomyces invadans, the causative agent of EUS. Apart from one previous record in N. erebi, EUS has been recorded in the wild only from coastal drainages in Australia. This study is the first published account of A. invadans in the wild fish populations of the MDRS, and is the first confirmed record of EUS in M. ambigua, M. peelii and L. unicolor. Ulcerated carp Cyprinus carpio collected at the time of the same epizootic were not found to be infected by EUS, supporting previous accounts of resistance against the disease by this species. The lack of previous clinical evidence, the large number of new hosts (n = 3, the geographic extent (200 km of this epizootic, the severity of ulceration and apparent high pathogenicity suggest a relatively recent invasion by A. invadans. The epizootic and associated environmental factors are documented and discussed within the context of possible vectors for its entry into the MDRS and recommendations regarding continued surveillance, research and biosecurity are made.

  3. Fractionation of Saprolegnia diclina (Oomycetes) satelite DNAs by AgNO3/Cs2SO4 density gradient centrifugation.

    Science.gov (United States)

    Neish, G A; Green, B R

    1977-12-14

    Saprolegnia diclina DNA has been fractionated using preparative AgNO3/Cs2SO4 and CsCl density gradients. In addition to the previously identified major satellite DNA, there are two minor DNA components banding at 1.682 and 1.701 g - cm(-3) in CsCl. Purified major satellite DNA bands at 1.707 g - cm(-3) giving a base composition of 48% G + C in good agreement with 47% G + C calculated from its Tm value. The nuclear DNA base composition is 58% G + C by both methods. The base composition of the major satellite DNA suggests that it may represent ribosomal DNA cistrons.

  4. Real-time PCR for detection and quantification of fungal and oomycete tomato pathogens in plant and soil samples

    NARCIS (Netherlands)

    Lievens, B.; Brouwer, M.; Vanachter, A.C.R.C.; Cammue, B.P.A.; Thomma, B.P.H.J.

    2006-01-01

    Although new, rapid detection and identification technologies are becoming available more and more for various plant pathogens, pathogen quantification remains one of the main challenges in the disease management of many crops. Currently, real-time polymerase chain reaction (PCR) is the most straigh

  5. Real-time PCR for detection and quantification of fungal and oomycete tomato pathogens in plant and soil samples

    NARCIS (Netherlands)

    Lievens, B.; Brouwer, M.; Vanachter, A.C.R.C.; Cammue, B.P.A.; Thomma, B.P.H.J.

    2006-01-01

    Although new, rapid detection and identification technologies are becoming available more and more for various plant pathogens, pathogen quantification remains one of the main challenges in the disease management of many crops. Currently, real-time polymerase chain reaction (PCR) is the most straigh

  6. Purification, crystallization and preliminary X-ray diffraction analysis of an oomycete-derived Nep1-­like protein

    Science.gov (United States)

    Luberacki, Borries; Weyand, Michael; Seitz, Ulrich; Koch, Wolfgang; Oecking, Claudia; Ottmann, Christian

    2008-01-01

    The elicitor protein Nep1-like protein from the plant pathogen Pythium aphanidermatum was purified and crystallized using the hanging-drop vapour-diffusion method. A native data set was collected to 1.35 Å resolution at 100 K using synchrotron radiation. Since selenomethionine-labelled protein did not crystallize under the original conditions, a second crystal form was identified that yielded crystals that diffracted to 2.1 Å resolution. A multiple-wavelength anomalous dispersion (MAD) experiment was performed at 100 K and all four selenium sites were identified, which allowed solution of the structure. PMID:19052381

  7. Purification, crystallization and preliminary X-ray diffraction analysis of an oomycete-derived Nep1-like protein.

    Science.gov (United States)

    Luberacki, Borries; Weyand, Michael; Seitz, Ulrich; Koch, Wolfgang; Oecking, Claudia; Ottmann, Christian

    2008-12-01

    The elicitor protein Nep1-like protein from the plant pathogen Pythium aphanidermatum was purified and crystallized using the hanging-drop vapour-diffusion method. A native data set was collected to 1.35 A resolution at 100 K using synchrotron radiation. Since selenomethionine-labelled protein did not crystallize under the original conditions, a second crystal form was identified that yielded crystals that diffracted to 2.1 A resolution. A multiple-wavelength anomalous dispersion (MAD) experiment was performed at 100 K and all four selenium sites were identified, which allowed solution of the structure.

  8. 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

  9. Morphological and molecular phylogenetic analysis of two Saprolegnia sp. (Oomycetes) isolated from silver crucian carp and zebra fish.

    Science.gov (United States)

    Ke, Xiao L; Wang, Jian G; Gu, Ze M; Li, Ming; Gong, Xiao N

    2009-05-01

    Two Saprolegnia isolates, JY isolated from silver crucian carp (Carassius auratus gibelio Bloch) and BMY isolated from zebra fish (Brachydanio rerio Hamilton) came from infections occurring concurrently in different locations in China. To confirm whether the two isolates were from the same Saprolegnia clone, comparative studies have been carried out based on their morphological, physiological and molecular characteristics. Observations showed that morphologically (both asexual and sexual organs) the two isolates were broadly similar and both isolates underwent repeated zoospore emergence. Comparing 704 base pairs of internal transcribed spacer (ITS) region and the 5.8S rDNA, we found isolates JY and BMY shared an identical ITS sequence with a minor variation (99.6% similarity). Forty available sequences for representatives Saprolegnia spp. belonged to four phylogenetically separate clades. The two studied isolates fell within clade I that comprised a group of isolates which showed almost an identical ITS sequence but had been identified as a number of different morphological species. Our findings suggest that isolates JY and BMY appear to belong to the S. ferax clade and this clade (I) contains a number of closely related phylogenetic species. This is distinct from the more common fish pathogenic isolates, which belong to the S. parasitica clade (III) and are characterized by having cysts decorated by bundles of long hooked hairs and two further clades (II and IV) containing largely saprotrophic or soil born species.

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

    Directory of Open Access Journals (Sweden)

    Yang Bi

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

  11. A mineral seed coating for control of seedling diseases of alfalfa suitable for organic production systems

    Science.gov (United States)

    Most alfalfa seed is treated with the systemic fungicide mefenoxam (Apron XL) for control of soilborne seedling diseases. However, Apron XL does not have activity against Aphanomyces euteiches, the causal agent of Aphanomyces root rot (ARR), which is an important component of the alfalfa root rot co...

  12. 卵菌纲病害用杀菌剂的开发进展%Recent Advances on the Development of Fungicides Used for Control of Oomycete Diseases

    Institute of Scientific and Technical Information of China (English)

    刘长令; 李继德

    2000-01-01

    本文对近期开发的防治卵茴纲病害用杀菌剂作了简要的介绍.之中涉及涉(咪)唑(啉酮)类、酰胺类、氨基酸衍生拘和甲氧基丙烯酸酯类化合物的结构、合成方法、生物活性、作用机理以及应用等.

  13. Nicotiana benthamiana calreticulin 3a is required for the ethylene-mediated production of phytoalexins and disease resistance against oomycete pathogen Phytophthora infestans.

    Science.gov (United States)

    Matsukawa, Mizuki; Shibata, Yusuke; Ohtsu, Mina; Mizutani, Aki; Mori, Hitoshi; Wang, Ping; Ojika, Makoto; Kawakita, Kazuhito; Takemoto, Daigo

    2013-08-01

    Mature Nicotiana benthamiana shows strong resistance to the potato late blight pathogen Phytophthora infestans. By screening using virus-induced random gene silencing, we isolated a gene for plant-specific calreticulin NbCRT3a as a required gene for resistance of N. benthamiana against P. infestans. NbCRT3a encodes an endoplasmic reticulum quality-control (ERQC) chaperone for the maturation of glycoproteins, including glycosylated cell-surface receptors. NbCRT3a-silenced plants showed no detectable growth defects but resistance to P. infestans was significantly compromised. Defense responses induced by the treatment with INF1 (a secretory protein of P. infestans), such as production of reactive oxygen species and accumulation of phytoalexins, were suppressed in NbCRT3a-silenced N. benthamiana. Expression of an ethylene-regulated gene for phytoalexin biosynthesis, NbEAS, was reduced in NbCRT3a-silenced plants, whereas the expression of salicylic acid-regulated NbPR-1a was not affected. Consistently, induction of ethylene production by INF1 was suppressed in NbCRT3a-silenced plants. Resistance reactions induced by a hyphal wall components elicitor prepared from P. infestans were also impaired in NbCRT3a-silenced plants. However, cell death induced by active mitogen-activated protein kinase kinase (NbMEK2(DD)) was not affected by the silencing of NbCRT3a. Thus, NbCRT3a is required for the initiation of resistance reactions of N. benthamiana in response to elicitor molecules derived from P. infestans.

  14. Synthesis and Evaluation of Novel Oxyalkylated Derivatives of 2′,4′-Dihydroxychalcone as Anti-Oomycete Agents against Bronopol Resistant Strains of Saprolegnia sp.

    Science.gov (United States)

    Flores, Susana; Montenegro, Iván; Villena, Joan; Cuellar, Mauricio; Werner, Enrique; Godoy, Patricio; Madrid, Alejandro

    2016-01-01

    A series of novel oxyalkylchalcones substituted with alkyl groups were designed and synthesized, and the antioomycete activity of the series was evaluated in vitro against Saprolegnia strains. All tested O-alkylchalcones were synthesized by means of nucleophilic substitution from the natural compound 2′,4′-dihydroxychalcone (1) and the respective alkyl bromide. The natural chalcone (1) and 10 synthetic oxyalkylchalcones (2–11) were tested against Saprolegnia parasitica and Saprolegnia australis. Among synthetic analogs, 2-hydroxy,4-farnesyloxychalcone (11) showed the most potent activity against Saprolegnia sp., with MIC and MOC values of 125 µg/mL (similar to bronopol at 150 µg/mL) and 175 µg/mL, respectively; however, 2′,4′-dihydroxychalcone (1) was the strongest and most active molecule, with MIC and MOC values of 6.25 µg/mL and 12.5 µg/mL. PMID:27556457

  15. New role for Cdc14 phosphatase: localization to basal bodies in the oomycete phytophthora and its evolutionary coinheritance with eukaryotic flagella.

    Directory of Open Access Journals (Sweden)

    Audrey M V Ah-Fong

    Full Text Available Cdc14 protein phosphatases are well known for regulating the eukaryotic cell cycle, particularly during mitosis. Here we reveal a distinctly new role for Cdc14 based on studies of the microbial eukaryote Phytophthora infestans, the Irish potato famine agent. While Cdc14 is transcribed constitutively in yeast and animal cells, the P. infestans ortholog is expressed exclusively in spore stages of the life cycle and not in vegetative hyphae where the bulk of mitosis takes place. PiCdc14 expression is first detected in nuclei at sporulation, and during zoospore formation the protein accumulates at the basal body, which is the site from which flagella develop. The association of PiCdc14 with basal bodies was supported by co-localization studies with the DIP13 basal body protein and flagellar β-tubulin, and by demonstrating the enrichment of PiCdc14 in purified flagella-basal body complexes. Overexpressing PiCdc14 did not cause defects in growth or mitosis in hyphae, but interfered with cytoplasmic partitioning during zoosporogenesis. This cytokinetic defect might relate to its ability to bind microtubules, which was shown using an in vitro cosedimentation assay. The use of gene silencing to reveal the precise function of PiCdc14 in flagella is not possible since we showed previously that silencing prevents the formation of the precursor stage, sporangia. Nevertheless, the association of Cdc14 with flagella and basal bodies is consistent with their phylogenetic distribution in eukaryotes, as species that lack the ability to produce flagella generally also lack Cdc14. An ancestral role of Cdc14 in the flagellar stage of eukaryotes is thereby proposed.

  16. Whole genome sequence of the emerging oomycete pathogen Pythium insidiosum strain CDC-B5653 isolated from an infected human in the USA

    Directory of Open Access Journals (Sweden)

    Marina S. Ascunce

    2016-03-01

    Full Text Available Pythium insidiosum ATCC 200269 strain CDC-B5653, an isolate from necrotizing lesions on the mouth and eye of a 2-year-old boy in Memphis, Tennessee, USA, was sequenced using a combination of Illumina MiSeq (300 bp paired-end, 14 millions reads and PacBio (10  Kb fragment library, 356,001 reads. The sequencing data were assembled using SPAdes version 3.1.0, yielding a total genome size of 45.6 Mb contained in 8992 contigs, N50 of 13 Kb, 57% G + C content, and 17,867 putative protein-coding genes. This Whole Genome Shotgun project has been deposited at DDBJ/EMBL/GenBank under the accession JRHR00000000.

  17. Synthesis and Evaluation of Novel Oxyalkylated Derivatives of 2',4'-Dihydroxychalcone as Anti-Oomycete Agents against Bronopol Resistant Strains of Saprolegnia sp.

    Science.gov (United States)

    Flores, Susana; Montenegro, Iván; Villena, Joan; Cuellar, Mauricio; Werner, Enrique; Godoy, Patricio; Madrid, Alejandro

    2016-01-01

    A series of novel oxyalkylchalcones substituted with alkyl groups were designed and synthesized, and the antioomycete activity of the series was evaluated in vitro against Saprolegnia strains. All tested O-alkylchalcones were synthesized by means of nucleophilic substitution from the natural compound 2',4'-dihydroxychalcone (1) and the respective alkyl bromide. The natural chalcone (1) and 10 synthetic oxyalkylchalcones (2-11) were tested against Saprolegnia parasitica and Saprolegnia australis. Among synthetic analogs, 2-hydroxy,4-farnesyloxychalcone (11) showed the most potent activity against Saprolegnia sp., with MIC and MOC values of 125 µg/mL (similar to bronopol at 150 µg/mL) and 175 µg/mL, respectively; however, 2',4'-dihydroxychalcone (1) was the strongest and most active molecule, with MIC and MOC values of 6.25 µg/mL and 12.5 µg/mL.

  18. Temperature and water quality effects in simulated woodland pools on the infection of Culex mosquito larvae by Lagenidium giganteum (Oomycetes: Lagenidiales) in North Carolina

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D.R.; Axtell, R.C.

    1987-06-01

    Asexual stages of the California (CA) isolate of Lagenidium giganteum cultured on sunflower seed extract (SFE)-agar, were applied to outdoor pools containing Culex larvae near Raleigh, NC in August and September 1984. Infection rates among the larvae ranged from 19 to 74% at 2-4 days posttreatment and subsequent epizootics eliminated most of the newly hatched larvae for at least 10 days posttreatment. Substantial reductions in numbers of larvae and adult emergence were achieved from a single application of the fungus. Water quality and temperature data are presented. From laboratory assays of organically polluted water, the percent infection of Culex quinquefasciatus by the fungus was correlated with water quality and temperature. A logistic model of water quality (COD and NH/sub 3/-N) effects on infectivity rates by the CA isolate is described.

  19. The transcription factor VvWRKY33 is involved in the regulation of grapevine (Vitis vinifera) defense against the oomycete pathogen Plasmopara viticola.

    Science.gov (United States)

    Merz, Patrick R; Moser, Tina; Höll, Janine; Kortekamp, Andreas; Buchholz, Günther; Zyprian, Eva; Bogs, Jochen

    2015-03-01

    Grapevine (Vitis vinifera ssp. vinifera) is one of the most important fruit species; however, it is highly susceptible to various pathogens, which can cause severe crop losses in viticulture. It has been shown that several WRKY class transcription factors (TFs) are part of the signal transduction cascade, which leads to the activation of plant defense reactions against various pathogens. In the present investigation, a full-length cDNA was isolated from V. vinifera leaf tissue encoding a predicted protein, designated VvWRKY33, which shows the characteristics of group I WRKY protein family. VvWRKY33 induction correlates with the expression of VvPR10.1 (pathogenesis-related 10.1) gene in the leaves of the resistant cultivar 'Regent' after infection with Plasmopara viticola, whereas in the susceptible cultivar 'Lemberger' VvWRKY33 and VvPR10.1 are not induced. Corresponding expression of the TF and VvPR10.1 was even obtained in uninfected ripening berries. In planta, analysis of VvWRKY33 has been performed by ectopic expression of VvWRKY33 in grapevine leaves of greenhouse plants mediated via Agrobacterium tumefaciens transformation. In consequence, VvWRKY33 strongly increases resistance to P. viticola in the susceptible cultivar 'Shiraz' and reduces pathogen sporulation of about 50-70%, indicating a functional role for resistance in grapevine. Complementation of the resistance-deficient Arabidopsis thaliana Columbia-0 (Col-0) mutant line wrky33-1 by constitutive expression of VvWRKY33 restores resistance against Botrytis cinerea to wild-type level and in some complemented mutant lines even exceeds the resistance level of the parental line Col-0. Our results support the involvement of VvWRKY33 in the defense reaction of grapevine against different pathogens. © 2014 Scandinavian Plant Physiology Society.

  20. Arabidopsis thaliana and the Robin Hood parasite: a chivalrous oomycete that steals fitness from fecund hosts and benefits the poorest one?

    Science.gov (United States)

    Salvaudon, Lucie; Héraudet, Virginie; Shykoff, Jacqui A

    2008-10-23

    Are parasites always harmful to their hosts? By definition, indeed, but in a few cases and particular environments, hosts experience higher fitness in the presence than in the absence of their parasites. Symbiotic associations form a continuum of interactions, from deleterious to beneficial effects on hosts. In this paper, we investigate the outcome of parasite infection of Arabidopsis thaliana by its natural pathogen Hyaloperonospora arabidopsis. This system exhibits a wide range of parasite impact on host fitness with, surprisingly, deleterious effects on high fecundity hosts and, at the opposite extreme, seemingly beneficial effects on the least fecund one. This phenomenon might result from varying levels of tolerance among host lines and even overcompensation for parasite damage analogous to what can be observed in plant-herbivore systems.

  1. Elucidating the diversity of aquatic microdochium and trichoderma species and their activity against the fish pathogen Saprolegnia diclina

    NARCIS (Netherlands)

    Liu, Yiying; Zachow, Christin; Raaijmakers, J.M.; Bruijn, De Irene

    2016-01-01

    Animals and plants are increasingly threatened by emerging fungal and oomycete diseases. Amongst oomycetes, Saprolegnia species cause population declines in aquatic animals, especially fish and amphibians, resulting in significant perturbation in biodiversity, ecological balance and food security

  2. Elucidating the diversity of aquatic microdochium and trichoderma species and their activity against the fish pathogen Saprolegnia diclina

    NARCIS (Netherlands)

    Liu, Yiying; Zachow, Christin; Raaijmakers, J.M.; Bruijn, De Irene

    2016-01-01

    Animals and plants are increasingly threatened by emerging fungal and oomycete diseases. Amongst oomycetes, Saprolegnia species cause population declines in aquatic animals, especially fish and amphibians, resulting in significant perturbation in biodiversity, ecological balance and food

  3. Elucidating the diversity of aquatic Microdochium and Trichoderma species and their activity against the fish pathogen Saprolegnia diclina

    NARCIS (Netherlands)

    Liu, Yiying; Zachow, Christin; Raaijmakers, J.M.; De Bruijn, I.

    2016-01-01

    Animals and plants are increasingly threatened by emerging fungal and oomycete diseases. Amongst oomycetes, Saprolegnia species cause population declines in aquatic animals, especially fish and amphibians, resulting in significant perturbation in biodiversity, ecological balance and food security.

  4. The Phytophthora infestans avirulence gene PiaAvr4 and its potato counterpart R4

    NARCIS (Netherlands)

    Poppel, van P.M.J.A.

    2009-01-01

    The potato late blight disease that is caused by the oomycete pathogen Phytophthora infestans is a major threat for potato crops worldwide. In recent years research on oomycete plant pathogens was boosted by the availability of novel genomic tools and resources for several oomycete genera, such as

  5. The Phytophthora infestans avirulence gene PiaAvr4 and its potato counterpart R4

    NARCIS (Netherlands)

    Poppel, van P.M.J.A.

    2009-01-01

    The potato late blight disease that is caused by the oomycete pathogen Phytophthora infestans is a major threat for potato crops worldwide. In recent years research on oomycete plant pathogens was boosted by the availability of novel genomic tools and resources for several oomycete genera, such as P

  6. Deciphering microbial landscapes of fish eggs to mitigate emerging diseases

    NARCIS (Netherlands)

    Liu, Y.; Bruijn, de I.; Jack, A.L.H.; Drynan, K.; Berg, van den A.H.; Thoen, E.; Sandoval-Sierra, V.; Skaar, I.; West, van P.; Diéguez-Uribeondo, J.; Voort, van der M.; Mendez, R.; Mazzola, M.; Raaijmakers, J.M.

    2014-01-01

    Animals and plants are increasingly suffering from diseases caused by fungi and oomycetes. These emerging pathogens are now recognized as a global threat to biodiversity and food security. Among oomycetes, Saprolegnia species cause significant declines in fish and amphibian populations. Fish eggs ha

  7. The fish egg microbiome

    NARCIS (Netherlands)

    Liu, Y.

    2016-01-01

    Y. Liu Prof. dr. F. Govers (promotor); Prof. dr. J.M. Raaijmakers (promotor); Dr. I. de Bruijn (co-promotor); Wageningen University, 13 June 2016, 170 pp. The fish egg microbiome: diversity and activity against the oomycete pathogen Saprolegnia Emerging oomycete pat

  8. Infection of Arabidopsis thaliana by Phytophthora parasitica and identification of variation in host specificity

    NARCIS (Netherlands)

    Wang, Y.; Meng, Y.; Zhang, M.; Tong, X.; Wang, Q.; Sun, Y.; Quan, J.; Govers, F.; Shan, W.

    2011-01-01

    Oomycete pathogens cause severe damage to a wide range of agriculturally important crops and natural ecosystems. They represent a unique group of plant pathogens that are evolutionarily distant from true fungi. In this study, we established a new plant–oomycete pathosystem in which the broad host ra

  9. The fish egg microbiome

    NARCIS (Netherlands)

    Liu, Y.

    2016-01-01

    Y. Liu Prof. dr. F. Govers (promotor); Prof. dr. J.M. Raaijmakers (promotor); Dr. I. de Bruijn (co-promotor); Wageningen University, 13 June 2016, 170 pp. The fish egg microbiome: diversity and activity against the oomycete pathogen Saprolegnia Emerging oomycete

  10. Effector identification in the lettuce downy mildew Bremia lactucae by massively parallel transcriptome sequencing

    NARCIS (Netherlands)

    Stassen, J.H.; Seidl, M.F.; Vergeer, P.W.; Nijman, I.J.; Snel, B.; Cuppen, E.; van den Ackerveken, G.

    2012-01-01

    Lettuce downy mildew (Bremia lactucae) is a rapidly adapting oomycete pathogen affecting commercial lettuce cultivation. Oomycetes are known to use a diverse arsenal of secreted proteins (effectors) to manipulate their hosts. Two classes of effector are known to be translocated by the host: the

  11. Identification and functional analysis of downy mildew effectors in lettuce and Arabidopsis

    NARCIS (Netherlands)

    Stassen, J.H.M.|info:eu-repo/dai/nl/314004416

    2012-01-01

    Oomycete pathogens cause large losses in many crop plants. Chemical control measures are undesirable and are becoming less effective. Resistance breeding has traditionally made use of dominant resistance genes to which oomycete pathogens have often been quick to adapt. Novel approaches towards

  12. 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

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

    NARCIS (Netherlands)

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

    2015-01-01

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

  14. Effector identification in the lettuce downy mildew Bremia lactucae by massively parallel transcriptome sequencing

    NARCIS (Netherlands)

    Stassen, J.H.; Seidl, M.F.; Vergeer, P.W.; Nijman, I.J.; Snel, B.; Cuppen, E.; van den Ackerveken, G.

    2012-01-01

    Lettuce downy mildew (Bremia lactucae) is a rapidly adapting oomycete pathogen affecting commercial lettuce cultivation. Oomycetes are known to use a diverse arsenal of secreted proteins (effectors) to manipulate their hosts. Two classes of effector are known to be translocated by the host: the RXLR

  15. Use of low-cost chemotherapeutic and medicinal plants against Thai silver barb (Barbonymus gonionotus)

    OpenAIRE

    Chowdhury, M.B.R.; Rahman, T.

    2012-01-01

    Studies were conducted to select and apply the effective low-cost chemotherapeutic and medicinal plants against diseased fish under laboratory and field condition. Thai silver barbs (Barbonymus gonionotus) weighing 20-25 gm were experimentally infected with a virulent bacterial pathogen (Aeromonas hydrophila) and a fungal pathogen (Aphanomyces invadans). Based on the previous studies, four chemotherapeutics, viz., salt + lime, alum, doxycycline and oxytetracycline were selected and applied to...

  16. Mycorrhizal symbiosis: ancient signalling mechanisms co-opted

    NARCIS (Netherlands)

    Geurts, R.; Vleeshouwers, V.G.A.A.

    2012-01-01

    Mycorrhizal root endosymbiosis is an ancient property of land plants. Two parallel studies now provide novel insight into the mechanism driving this interaction and how it is used by other filamentous microbes like pathogenic oomycetes.

  17. Mining Genomes of Biological Control Strains of Pseudomonas spp.: Unexpected Gems and Tailings

    Science.gov (United States)

    The biocontrol bacterium Pseudomonas fluorescens Pf-5 suppresses numerous soilborne plant diseases and produces an array of structurally-characterized secondary metabolites that are toxic to plant pathogenic bacteria, fungi and Oomycetes. Biosynthetic gene clusters for these metabolites compose nea...

  18. Foreword: Special issue on fungal grapevine diseases

    Science.gov (United States)

    An impressively large proportion of fungicides applied in European, North American and Australian agriculture has been used to manage grapevine powdery mildew (Erysiphe necator), grapevine downy mildew (Plasmopara viticola), and botrytis bunch rot (Botrytis cinerea). These fungal and oomycetous plan...

  19. Host‐induced gene silencing inhibits the biotrophic pathogen causing downy mildew of lettuce

    National Research Council Canada - National Science Library

    Govindarajulu, Manjula; Epstein, Lynn; Wroblewski, Tadeusz; Michelmore, Richard W

    2015-01-01

    .... As a proof‐of‐concept, we generated stable transgenic lettuce plants expressing si RNA s targeting potentially vital genes of Bremia lactucae , a biotrophic oomycete that causes downy mildew, the most important...

  20. Silencing of the major family of NBS-LRR-encoding genes in lettuce results in the loss of multiple resistance specificities

    National Research Council Canada - National Science Library

    Wroblewski, T; Piskurewicz, U; Finkers-Tomczak, A.M; Ochoa, O; Michelmore, R

    2007-01-01

    ...¿leucine-rich repeat (NBS¿LRR) proteins. One of its members, RGC2B, encodes Dm3 which determines resistance to downy mildew caused by the oomycete Bremia lactucae carrying the cognate avirulence gene, Avr3...

  1. Tomato root microbiota and Phytophthora parasitica-associated disease

    National Research Council Canada - National Science Library

    Marie Larousse; Corinne Rancurel; Camille Syska; Ferran Palero; Catherine Etienne; Benoit Industri; Xavier Nesme; Marc Bardin; Eric Galiana

    2017-01-01

    .... Colonization of the host root surface by the oomycete was associated with a shift in microbial community involving a Bacteroidetes/Proteobacteria transition and Flavobacteriaceae as the most abundant family...

  2. Exposition of cork oak roots to cryptogein reduced the Infection by Phytophtora cinnamomi

    OpenAIRE

    Maia, I.; Medeira, C.; Candeias, I.; A.C. Moreira; Melo, Eduardo P.; Cravador, A.

    2009-01-01

    The oomycete P. cinnamomi has been described as strong contributing factor to the decline of cork oak and holm oak stands occurring in the Iberian Peninsula. There are no eradication methods available against this pathogen.

  3. Muddied waters: suspended sediment impacts on gill structure and aerobic scope in an endangered native and an invasive freshwater crayfish

    DEFF Research Database (Denmark)

    Rosewarne, P.J.; Svendsen, Jon Christian; Mortimer, R.J.G.

    2014-01-01

    Suspended sediment (SS) loadings in freshwater habitats have increased over the past century and SS is now a significant environmental stressor. Greater tolerance to environmental stressors has been proposed as a factor in the success of aquatic invasive species. Further, parasites may interact...... with environmental stressors to increase host susceptibility to loss of fitness and mortality. We compared the effects of SS exposure on the gill structure and aerobic scope of the endangered white-clawed crayfish (Austropotamobius pallipes), and the invasive signal crayfish (Pacifastacus leniusculus), and assessed...... impacts in relation to parasite burden. SS caused gill fouling and reduction in aerobic scope in both species, though A. pallipes was more susceptible than invasive P. leniusculus. The parasite Branchiobdella astaci, a crayfish worm that infests the gills, interacted with the sediment to affect gill...

  4. Keratinophilic fungi in various types of water bodies

    Directory of Open Access Journals (Sweden)

    Bazyli Czeczuga

    2014-08-01

    Full Text Available The keratinophilic fungi in various types of water bodies (slough. pond. beach pool. two lakes and two rivers were studied. Samples of water were collected every other month for bydrochemical analysis and once a month (1989-1990 in order to determine the fungus content. Human hair, snippings of finger-nails, chips of hoofs, feathers and snake exuviae were used as bait. Twenty-five species of keratinophilic fungi were found in various types of water bodies. Hyphochytrium catenoides, Aphanomyces stellatus, Leptolegniella caudala and Achlya oligacantha represent new records as koratinophilic fungi.

  5. Evolution of filamentous plant pathogens: gene exchange across eukaryotic kingdoms.

    Science.gov (United States)

    Richards, Thomas A; Dacks, Joel B; Jenkinson, Joanna M; Thornton, Christopher R; Talbot, Nicholas J

    2006-09-19

    Filamentous fungi and oomycetes are eukaryotic microorganisms that grow by producing networks of thread-like hyphae, which secrete enzymes to break down complex nutrients, such as wood and plant material, and recover the resulting simple sugars and amino acids by osmotrophy. These organisms are extremely similar in both appearance and lifestyle and include some of the most economically important plant pathogens . However, the morphological similarity of fungi and oomycetes is misleading because they represent some of the most distantly related eukaryote evolutionary groupings, and their shared osmotrophic growth habit is interpreted as being the result of convergent evolution . The fungi branch with the animals, whereas the oomycetes branch with photosynthetic algae as part of the Chromalveolata . In this report, we provide strong phylogenetic evidence that multiple horizontal gene transfers (HGT) have occurred from filamentous ascomycete fungi to the distantly related oomycetes. We also present evidence that a subset of the associated gene families was initially the product of prokaryote-to-fungi HGT. The predicted functions of the gene products associated with fungi-to-oomycete HGT suggest that this process has played a significant role in the evolution of the osmotrophic, filamentous lifestyle on two separate branches of the eukaryote tree.

  6. Cytochromes of Aquatic Fungi

    Science.gov (United States)

    Gleason, Frank H.; Unestam, Torgny

    1968-01-01

    The cytochrome systems of two classes of aquatic fungi, the Oomycetes and Chytridiomycetes, were studied by means of reduced-minus-oxidized difference spectra at room and at low temperature. At room temperature, all of these fungi have a c-type cytochrome with an absorption maximum at 551 mμ and a b-type cytochrome at 564 mμ. The Oomycetes have a-type cytochromes at 605 mμ, and the Chytridiomycetes have a-type cytochromes at 606 mμ (Blastocladiales) or at 609 mμ (Monoblepharidales). Additional b-type cytochromes are found at 557 mμ in the Oomycetes and at approximately 560 mμ in the Chytridiomycetes. The data obtained from spectra at low temperature are consistent with these conclusions. Thus, the difference spectra reveal variation between the cytochrome systems of these two classes of aquatic fungi. PMID:5650068

  7. 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.

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

    Science.gov (United States)

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

  9. 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...

  10. 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...

  11. 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...

  12. Significance of inducible defense-related proteins in infected plants

    NARCIS (Netherlands)

    Loon, L.C. van; Rep, M.; Pieterse, C.M.J.

    2006-01-01

    Inducible defense-related proteins have been described in many plant species upon infection with oomycetes, fungi, bacteria, or viruses, or insect attack. Several types of proteins are common and have been classified into 17 families of pathogenesis-related proteins (PRs). Others have so far been fo

  13. 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.

  14. Implementation of systematic reviews in EFSA scientific outputs workflow (CFT/EFSA/AMU/2010/01)

    DEFF Research Database (Denmark)

    O'Connor, A. M.; Lövei, G.; Eales, J.

    2012-01-01

    The Panel on Plant Health was asked to deliver a scientific opinion on the Pest Risk Analysis on Phytophthora ramorum prepared by the FP6 project RAPRA, taking into account comments by Member States and additional information since RAPRA. P. ramorum is the oomycete causing sudden oak death in the...

  15. 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...

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

    NARCIS (Netherlands)

    Zhu, S.

    2014-01-01

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

  17. Whole Genome Sequences of the Raspberry and Strawberry Pathogens Phytophthora rubi and P. fragariae.

    Science.gov (United States)

    Tabima, Javier F; Kronmiller, Brent A; Press, Caroline M; Tyler, Brett M; Zasada, Inga A; Grünwald, Niklaus J

    2017-10-01

    Phytophthora rubi and P. fragariae are two closely related oomycete plant pathogens that exhibit strong morphological and physiological similarities but are specialized to infect different hosts of economic importance, namely, raspberry and strawberry. Here, we report the draft genome sequences of these two Phytophthora species as a first step toward understanding the genomic processes underlying plant host adaptation in these pathogens.

  18. Host-induced aneuploidy and phenotypic diversification in the Sudden Oak Death pathogen Phytophthora ramorum

    Science.gov (United States)

    Aneuploidy can result in significant phenotypic changes, which can sometimes be selectively advantageous. For example, aneuploidy confers resistance to antifungal drugs in human pathogenic fungi. Aneuploidy has also been observed in invasive fungal and oomycete plant pathogens in the field. Environm...

  19. Phenotypic diversification is associated with host-induced transposon derepression in the sudden oak death pathogen Phytophthora ramorum

    Science.gov (United States)

    T. Kasuga; M. Kozanitas; M. Bui; D. Huberli; D. M. Rizzo; M. Garbelotto

    2012-01-01

    The oomycete pathogen Phytophthora ramorum is responsible for sudden oak death (SOD) in California coastal forests. P. ramorum is a generalist pathogen with over 100 known host species. Three or four closely related genotypes of P. ramorum (from a single lineage) were...

  20. The effects of Phytophthora ramorum infection on hydraulic conductivity and tylosis formation in tanoak sapwood

    Science.gov (United States)

    Bradley R. Collins; Jennifer L. Parke; Barb Lachenbruch; Everett M. Hansen

    2009-01-01

    Tanoak (Lithocarpus densiflorus (Hook. and Arn.) Rehder) is highly susceptible to sudden oak death, a disease caused by the oomycete Phytophthora ramorum Werres, De Cock & Man in’t Veld. Symptoms include a dying crown, bleeding cankers, and, eventually, death of infected trees. The cause of mortality is not well understood, but recent research indicates that...

  1. Phytophthora-ID.org: A sequence-based Phytophthora identification tool

    Science.gov (United States)

    N.J. Grünwald; F.N. Martin; M.M. Larsen; C.M. Sullivan; C.M. Press; M.D. Coffey; E.M. Hansen; J.L. Parke

    2010-01-01

    Contemporary species identification relies strongly on sequence-based identification, yet resources for identification of many fungal and oomycete pathogens are rare. We developed two web-based, searchable databases for rapid identification of Phytophthora spp. based on sequencing of the internal transcribed spacer (ITS) or the cytochrome oxidase...

  2. Comparative and functional analysis of the widely occurring family of Nep1-like proteins

    NARCIS (Netherlands)

    Oome, Stan; van den Ackerveken, Guido

    2014-01-01

    Nep1-like proteins (NLP) are best known for their cytotoxic activity in dicot plants. NLP are taxonomically widespread among microbes with very different lifestyles. To learn more about this enigmatic protein family, we analyzed more than 500 available NLP protein sequences from fungi, oomycetes, an

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  4. Silencing of the major family of NBS-LRR-encoding genes in lettuce results in the loss of multiple resistance specificities

    NARCIS (Netherlands)

    Wroblewski, T.; Piskurewicz, U.; Finkers-Tomczak, A.M.; Ochoa, O.; Michelmore, R.

    2007-01-01

    The RGC2 gene cluster in lettuce (Lactuca sativa) is one of the largest known families of genes encoding nucleotide binding site¿leucine-rich repeat (NBS¿LRR) proteins. One of its members, RGC2B, encodes Dm3 which determines resistance to downy mildew caused by the oomycete Bremia lactucae carrying

  5. 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

  6. Vectors for fluorescent protein tagging in Phytophthora: tools for functional genomics and cell biology.

    Science.gov (United States)

    Ah-Fong, Audrey M V; Judelson, Howard S

    2011-09-01

    Fluorescent tagging has become the strategy of choice for examining the subcellular localisation of proteins. To develop a versatile community resource for this method in oomycetes, plasmids were constructed that allow the expression of either of four spectrally distinct proteins [cyan fluorescent protein (CFP), green fluorescent protein (GFP), yellow fluorescent protein (YFP), and mCherry], alone or fused at their N- or C-termini, to sequences of interest. Equivalent sets of plasmids were made using neomycin or hygromycin phosphotransferases (nptII, hpt) as selectable markers, to facilitate double-labelling and aid work in diverse species. The fluorescent proteins and drug-resistance markers were fused to transcriptional regulatory sequences from the oomycete Bremia lactucae, which are known to function in diverse oomycetes, although the promoter in the fluorescence cassette (ham34) can be replaced easily by a promoter of interest. The function of each plasmid was confirmed in Phytophthora infestans. Moreover, fusion proteins were generated using targeting sequences for the endoplasmic reticulum, Golgi, mitochondria, nuclei, and peroxisomes. Studies of the distribution of the fusions in mycelia and sporangia provided insight into cellular organisation at different stages of development. This toolbox of vectors should advance studies of gene function and cell biology in Phytophthora and other oomycetes. Copyright © 2011 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  7. Quantitative trait loci for resistance to two fungal pathogens in Quercus robur

    Science.gov (United States)

    Cécile Robin; Amira Mougou-Hamdane; Jean-Marc Gion; Antoine Kremer; Marie-Laure. Desprez-Loustau

    2012-01-01

    Powdery mildew, caused by Erysiphe alphitoides (Ascomycete), is the most frequent disease of oaks, which are also known to be host plants for Phytophthora cinnamomi (Oomycete), the causal agent of ink disease. Components of genetic resistance to these two pathogens, infecting either leaves or root and collar, were...

  8. The xylem as battleground for plant hosts and vascular wilt pathogens

    NARCIS (Netherlands)

    Yadeta, K.A.; Thomma, B.P.H.J.

    2013-01-01

    Vascular wilts are among the most destructive plant diseases that occur in annual crops as well as in woody perennials. These diseases are generally caused by soil-borne bacteria, fungi, and oomycetes that infect through the roots and enter the water-conducting xylem vessels where they proliferate a

  9. Carbohydrate-related enzymes of important Phytophthora plant pathogens

    NARCIS (Netherlands)

    Brouwer, Henk; Coutinho, Pedro M; Henrissat, Bernard; de Vries, Ronald P; van den Brink, J.

    2014-01-01

    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 CAZy

  10. Genomewide analysis of phospholipid signaling genes in Phytophthora spp.: novelties and a missing link

    NARCIS (Netherlands)

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

    2006-01-01

    Phospholipids are cellular membrane components in eukaryotic cells that execute many important roles in signaling. Genes encoding enzymes required for phosphollipid signaling and metabolism have been characterized in several organisms, but only a few have been described for oomycetes. In this study,

  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. 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...

  13. Protists are an integral part of the Arabidopsis thaliana microbiome.

    Science.gov (United States)

    Sapp, Melanie; Ploch, Sebastian; Fiore-Donno, Anna Maria; Bonkowski, Michael; Rose, Laura E

    2017-10-02

    Although protists occupy a vast range of habitats and are known to interact with plants among other things via disease suppression, competition or growth stimulation, their contributions to the "phytobiome" are not well described. To contribute to a more comprehensive picture of the plant holobiont, we examined cercozoan and oomycete taxa living in association with the model plant Arabidopsis thaliana grown in two different soils. Soil, roots, leaves and wooden toothpicks were analyzed before and after surface sterilization. Cercozoa were identified using 18S rRNA gene metabarcoding, whereas the Internal Transcribed Spacer (ITS1) was used to determine oomycetes. Subsequent analyses revealed strong spatial structuring of protist communities between compartments, although oomycetes appeared more specialized than Cercozoa. With regards to oomycetes, only members of the Peronosporales and taxa belonging to the genus Globisporangium were identified as shared members of the A. thaliana microbiome. This also applied to cercozoan taxa belonging to the Glissomonadida and Cercomonadida. We identified a strong influence by edaphic factors on the rhizosphere, but not for the phyllosphere. Distinct differences of Cercozoa found preferably in wood or fresh plant material imply specific niche adaptations. Our results highlight the importance of micro-eukaryotes for the plant holobiont. This article is protected by copyright. All rights reserved. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  14. 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

  15. First report of Leptolegnia chapmanii (Peronosporomycetes: Saprolegniales) affecting mosquitoes in Central Brazil

    Science.gov (United States)

    Numerous isolates of an oomycete ‘fungus’, Leptolegnia chapmanii, are reported from Brazil for the first time. This aquatic pathogen was baited with Aedes aegypti sentinel larvae from stagnant, temporary bodies of water in selected locations under secondary tropical forests in and near the central B...

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  17. The nature of biotrophy in Phytophtora infestans

    NARCIS (Netherlands)

    Scheepens, P.C.

    1978-01-01

    Phytophthora infestans, being an intermediate type between the facultative and obligate parasites among the Peronosporales (class Oomycetes ), was used to study the factors which are responsible for the inability of obligate parasites to grow axenically. In a comparative study on mitochondrial elec

  18. Homologous RXLR effectors from Hyaloperonospora arabidopsidis and Phytophthora sojae suppress immunity in distantly related plants

    Science.gov (United States)

    Diverse pathogens secrete effector proteins into plant cells to manipulate host cellular processes. Oomycete pathogens contain very large complements of predicted effector genes defined by an RXLR host cell entry motif. The genome of Hyaloperonospora arabidopsidis (Hpa, downy mildew of Arabidopsis) ...

  19. 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...

  20. 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...

  1. 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...

  2. Identification of Candidate Signaling Genes Including Regulators of Chromosome Condensation 1 Protein Family Differentially Expressed in the Soybean - Phytophthora Sojae Interaction

    Science.gov (United States)

    Stem and root rot caused by the oomycete pathogen, Phytopthora sojae, is a serious soybean disease. Use of Phytophthora resistance genes (Rps) in soybean cultivars has been very effective in controlling this pathogen. Resistance encoded by Rps genes is manifested through activation of defense resp...

  3. 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

  4. 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

  5. Focus issue articles on emerging and re-emerging plant diseases

    Science.gov (United States)

    This review sums up the key findings of seventeen articles on emerging and re-emerging plant diseases that are designated for the July focus issue in Phytopathology. The emerging and re-emerging diseases discussed include those caused by three viral, six fungal, five oomycete, and four bacterial pa...

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

    NARCIS (Netherlands)

    Huang, S.

    2005-01-01

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

  7. 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

  8. Development and application of loop-mediated isothermal amplification (LAMP) for detection of Plasmopara viticola

    NARCIS (Netherlands)

    Kong, X.; Qin, W.; Xiaoqing, X.; Kong, F.; Schoen, C.D.; Feng, J.; Wang, Z.; Zhang, H.

    2016-01-01

    A rapid LAMP (loop-mediated isothermal amplification) detection method was developed on the basis of the ITS sequence of P. viticola, the major causal agent of grape downy mildew. Among the 38 fungal and oomycete species tested, DNA isolated exclusively from P. viticola resulted in a specific

  9. Unveiling and deploying durability of late blight resistance in potato : from natural stacking to cisgenic stacking

    NARCIS (Netherlands)

    Kwang-Ryong Jo,

    2013-01-01

    The potato, which receives an increased attention as a food crop, has long been in threats from the oomycete Phytophthora infestans, the causal agent of late blight. This disease still remains the most important constraint in potato producing regions of the world. It might cause the complete destruc

  10. Significance of inducible defense-related proteins in infected plants

    NARCIS (Netherlands)

    Loon, L.C. van; Rep, M.; Pieterse, C.M.J.

    2006-01-01

    Inducible defense-related proteins have been described in many plant species upon infection with oomycetes, fungi, bacteria, or viruses, or insect attack. Several types of proteins are common and have been classified into 17 families of pathogenesis-related proteins (PRs). Others have so far been

  11. Next-generation communication

    NARCIS (Netherlands)

    Bisseling, T.; Dangl, J.L.; Schulze-Lefert, P.

    2009-01-01

    In the past decade, there have been major advances in our understanding of the molecular interplay between plants and various classes of microbial pathogens (bacteria, fungi, oomycetes, viruses, and nematodes) and microbial symbionts (rhizobia or mycorrhizal fungi). These fundamental insights, revie

  12. An ancient R gene from Solanum bulbocastanum confers broad-spectrum resistance to late Phytophthora infestans in cultivated potato and tomato

    NARCIS (Netherlands)

    Vossen, van der E.A.G.; Sikkema, A.; Lintel Hekkert, te B.; Gross, J.; Stevens, P.; Muskens, M.; Wouters, T.C.A.E.; Pereira, A.B.; Stiekema, W.J.; Allefs, S.

    2003-01-01

    Late blight, caused by the oomycete pathogen Phytophthora infestans, is the most devastating disease for potato cultivation. Here, we describe the positional cloning of the Rpi-blb1 gene from the wild potato species Solanum bulbocastanum known for its high levels of resistance to late blight. The Rp

  13. Spatial and temporal aspects of tylosis formation in tanoak inoculated with Phytophthora ramorum

    Science.gov (United States)

    Brad Collins; Jennifer Parke

    2008-01-01

    Phytophthora ramorum is an oomycete pathogen that causes sudden oak death in several species of Fagaceae including tanoak (Lithocarpus densiflorus). Symptoms on tanoak include stem cankers and crown death. Stem infection was thought to be restricted to bark and cambium, but has recently been shown to include sapwood....

  14. Spatial and temporal analysis of populations of the Sudden Oak Death pathogen in Oregon forests

    Science.gov (United States)

    Sudden oak death caused by the oomycete Phytophthora ramorum was first discovered in California towards the end of the 20th century and subsequently emerged on tanoak forests in Oregon before its first detection in 2001 by aerial surveys. The Oregon Department of Forestry has since monitored the epi...

  15. 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

  16. Identification of cell wall-associated proteins from Phytophthora ramorum

    NARCIS (Netherlands)

    Meijer, H.J.G.; Vondervoort, van de P.J.I.; Yin, Q.Y.; Koster, de C.G.; Klis, F.M.; Govers, F.; Groot, de P.W.J.

    2006-01-01

    The oomycete genus Phytophthora comprises a large group of fungal-like plant pathogens. Two Phytophthora genomes recently have been sequenced; one of them is the genome of Phytophthora ramorum, the causal agent of sudden oak death. During plant infection, extracellular proteins, either soluble secre

  17. Distribution, diversity, and activity of antibiotic-producing Pseudomonas spp.

    NARCIS (Netherlands)

    Souza, de J.T.

    2002-01-01

    Bacteria of the genus Pseudomonas are potential biocontrol agents of plant diseases caused by various fungi and oomycetes. Antibiotic production is an important trait responsible for the activity of several Pseudomonas strains against plant pathogens. Despite the amount of informati

  18. Genome Assembly of Bell Pepper Endornavirus from Small RNA

    Science.gov (United States)

    Luria, Neta; Dombrovsky, Aviv

    2012-01-01

    The family Endornaviridae infects diverse hosts, including plants, fungi, and oomycetes. Here we report for the first time the assembly of bell pepper endornavirus by next-generation sequencing of viral small RNA. Such a population of small RNA indicates the activation of the viral immunity silencing machinery by this cryptic virus, which probably encodes a novel silencing suppressor. PMID:22733884

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  20. Plant integrity: an important factor in plant-pathogen interactions

    DEFF Research Database (Denmark)

    Orlowska, Elzbieta Zofia; Llorente, Briardo; Cvitanich, Cristina

    2013-01-01

    the hemibiotrophic oomycete pathogen Phytophthora infestans. Furthermore, in the Sarpo Mira–P. infestans interactions, the plant’s meristems, the stalks or both, seem to be associated with the development of the hypersensitive response and both the plant’s roots and shoots contain antimicrobial compounds when...

  1. 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.

  2. Field evaluation of seed treatment fungicides for control of damping-off of chickpea caused by metalaxyl-resistant Pythium spp, 2015

    Science.gov (United States)

    Pythium spp. are ubiquitous and often cause seed rot and damping-off in cool and wet conditions. However, Pythium seed rot and damping-off have been effectively managed through seed treatment with the fungicde metalaxyl. Through continual use of metalaxyl over the past three decades, many Oomycete p...

  3. Significance of inducible defense-related proteins in infected plants

    NARCIS (Netherlands)

    Loon, L.C. van; Rep, M.; Pieterse, C.M.J.

    2006-01-01

    Inducible defense-related proteins have been described in many plant species upon infection with oomycetes, fungi, bacteria, or viruses, or insect attack. Several types of proteins are common and have been classified into 17 families of pathogenesis-related proteins (PRs). Others have so far been fo

  4. Differences in intensity and specificity of hypersensitive response induction in Nicotiana spp. by INF1, INF2A, and INF2B of Phytophthora infestans

    NARCIS (Netherlands)

    Huitema, E.; Vleeshouwers, V.G.A.A.; Cakir, C.; Kamoun, S.; Govers, F.

    2005-01-01

    Elicitins form a family of structurally related proteins that induce the hypersensitive response (HR) in plants, particularly Nicotiana spp. The elicitin family is composed of several classes. Most species of the plant-pathogenic oomycete genus Phytophthora produce the well-characterized 10-kDa

  5. Assessing the effectiveness of peracetic acid to remediate post-vaccination Saprolegnia spp.-associated mortality in Atlantic salmon Salmo salar parr in recirculation aquaculture systems

    Science.gov (United States)

    Disease is a major barrier to aquaculture production worldwide, and within the salmon industry it is responsible for the majority of market supply fluctuation. Ubiquitous oomycetes of the Saprolegnia genus are particularly problematic disease agents, associated with an estimated 10% mortality among ...

  6. 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

  7. Evaluating systemic semi-selective chemicals for the management of apple replant disease in fumigated and non-fumigated orchards systems

    Science.gov (United States)

    Apple Replant Disease (ARD) is a phenomenon where apple trees are stunted when replanted onto old apple soil, as the result of apple monoculture resulting in soil microbial changes where pathogenic and parasitic organism s predominate. The main soilborne organisms that cause ARD include oomycetes, f...

  8. GK4, a G-protein-coupled receptor with a phosphatidylinositol phosphate kinase domain in Phytophthora infestans, is involved in sporangia development and virulence

    NARCIS (Netherlands)

    Hua, C.; Meijer, H.J.G.; Keijzer, de J.; Zhao, W.; Wang, Y.; Govers, F.

    2013-01-01

    For dispersal and host infection plant pathogens largely depend on asexual spores. Pathogenesis and sporulation are complex processes that are governed by cellular signalling networks including G-protein and phospholipid signalling. Oomycetes possess a family of novel proteins called GPCR-PIPKs (GKs

  9. The potential of effector-target genes in breeding for plant innate immunity

    NARCIS (Netherlands)

    Gawehns, F.; Cornelissen, B.J.C.; Takken, F.L.W.

    2013-01-01

    Increasing numbers of infectious crop diseases that are caused by fungi and oomycetes urge the need to develop alternative strategies for resistance breeding. As an alternative for the use of resistance (R) genes, the application of mutant susceptibility (S) genes has been proposed as a potentially

  10. Urban activities influence on Phytophthora species diversity in British Columbia, Canada

    Science.gov (United States)

    Angela Dale; Nicolas Feau; Julien Ponchart; Guillaume Bilodeau; Jean Berube; R.C. Hamelin

    2017-01-01

    Phytophthora de Bary, a genus of Oomycetes, is known as a plant pathogenic genus. The best-known species infect a wide range of hosts, including economically valuable angiosperm and gymnosperm tree species and important agricultural crops. Many Phytophthora are invasive and have been disseminated through nursery and...

  11. Resistance to Phytophthora cinnamomi in the Genus Abies

    Science.gov (United States)

    John Frampton; Fikret Isik; Mike Benson; Jaroslav Kobliha; Jan Stjskal

    2012-01-01

    A major limiting factor for the culture of true firs as Christmas trees is their susceptibility to Oomycete species belonging to the genus Phytophthora. In North Carolina alone, the Fraser fir (Abies fraseri [Pursh] Poir.) Christmas tree industry loses 6 to 7 million dollars annually to root rot primarily caused by ...

  12. Identification of cell wall-associated proteins from Phytophthora ramorum

    NARCIS (Netherlands)

    Meijer, H.J.G.; Vondervoort, van de P.J.I.; Yin, Q.Y.; Koster, de C.G.; Klis, F.M.; Govers, F.; Groot, de P.W.J.

    2006-01-01

    The oomycete genus Phytophthora comprises a large group of fungal-like plant pathogens. Two Phytophthora genomes recently have been sequenced; one of them is the genome of Phytophthora ramorum, the causal agent of sudden oak death. During plant infection, extracellular proteins, either soluble

  13. Effect of fungus gnat Bradysia impatiens (Diptera: Sciaridae) feeding on subsequent Pythium aphanidermatum infection of geranium seedlings (Pelargonium x hortorum)

    Science.gov (United States)

    Dark-winged fungus gnats in the genus Bradysia (Diptera: Sciaridae) and root rot pathogens in the genus Pythium (Oomycetes) are important pests of greenhouse floriculture. Observations have pointed to a possible correlation between Pythium root rot disease and fungus gnat infestations; however, inte...

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Draft Genome Sequence of the Rhizobacterium Pseudomonas chlororaphis PCL1601, Displaying Biocontrol against Soilborne Phytopathogens.

    Science.gov (United States)

    Vida, Carmen; de Vicente, Antonio; Cazorla, Francisco M

    2017-04-06

    In this study, we present the draft genome sequence of the bacterial strain Pseudomonas chlororaphis PCL1601. This bacterium was isolated from the rhizosphere of healthy avocado trees and displayed antagonistic and biological control activities against different soilborne phytopathogenic fungi and oomycetes. Copyright © 2017 Vida et al.

  16. Targeted gene mutation in Phytophthora spp.

    NARCIS (Netherlands)

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

    2006-01-01

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

  17. The nature of biotrophy in Phytophthora infestans

    NARCIS (Netherlands)

    Scheepens, P.C.

    1978-01-01

    Phytophthora infestans, being an intermediate type between the facultative and obligate parasites among the Peronosporales (class Oomycetes ), was used to study the factors which are responsible for the inability of

  18. 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

  19. Distribution, diversity, and activity of antibiotic-producing Pseudomonas spp.

    NARCIS (Netherlands)

    Souza, de J.T.

    2002-01-01

    Bacteria of the genus Pseudomonas are potential biocontrol agents of plant diseases caused by various fungi and oomycetes. Antibiotic production is an important trait responsible for the activity of several Pseudomonas

  20. 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

  1. 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

  2. Soil feedback and pathogen activity in Prunus serotina throughout its native range

    NARCIS (Netherlands)

    Reinhart, K.O.; Royo, A.A.; Putten, van der W.H.; Clay, K.

    2005-01-01

    1 Oomycete soil pathogens are known to have a negative effect on Prunus serotina seedling establishment and to promote tree diversity in a deciduous forest in Indiana, USA. Here, we investigate whether negative feedbacks operate widely in its native range in eastern USA. 2 In laboratory experiments,

  3. Phytophthora infestans avirulence genes: mapping, cloning and diversity in field isolates

    NARCIS (Netherlands)

    Guo, J.

    2008-01-01

    Potato late blight, caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary, is the most disastrous disease on potato worldwide and also the greatest threat to potato production in China. Loss of yield and quality, and the costs of chemical control of potato late blight account for

  4. The Rpi-blb2 gene from Solanum bulbocastanum is a Mi-1 gene homolog conferring broadspectrum late blight resistance in potato

    NARCIS (Netherlands)

    Vossen, van der E.A.G.; Gross, J.; Sikkema, A.; Muskens, M.; Wouters, T.C.A.E.; Wolters, P.; Pereira, A.B.; Allefs, S.

    2005-01-01

    The necessity to develop potato and tomato crops that possess durable resistance against the oomycete pathogen Phytophthora infestans is increasing as more virulent, crop-specialized and pesticide resistant strains of the pathogen are rapidly emerging. Here, we describe the positional cloning of the

  5. 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...

  6. 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

  7. Molecular evolution of an Avirulence Homolog (Avh) gene subfamily in Phytophthora ramorum

    Science.gov (United States)

    GossErica M.; Caroline M. Press; Niklaus J. Grünwald

    2008-01-01

    Pathogen effectors can serve a virulence function on behalf of the pathogen or trigger a rapid defense response in resistant hosts. Sequencing of the Phytophthora ramorum genome and subsequent analysis identified a diverse superfamily of approximately 350 genes that are homologous to the four known avirulence genes in plant pathogenic oomycetes and...

  8. Genomics-guided discovery of secondary metabolites and their regulation in Pseudomonas protegens Pf-5

    Science.gov (United States)

    Pseudomonas protegens strain Pf-5 is a well-characterized rhizosphere bacterium known for its production of a diverse spectrum of secondary metabolites and its capacity to suppress plant diseases caused by soilborne fungal, bacterial and oomycete pathogens. Metabolites produced by Pf-5 include 2,4-...

  9. The rare codon AGA is involved in regulation of pyoluteorin biosynthesis in Pseudomonas protegens Pf-5

    Science.gov (United States)

    The soil bacterium Pseudomonas protegens Pf-5 can colonize root and seed surfaces of many plants, protecting them from infection by plant pathogenic fungi and oomycetes. This capacity to suppress disease is attributed in part to Pf-5’s production of a large spectrum of antibiotics, which is controll...

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

    NARCIS (Netherlands)

    Huang, S.

    2005-01-01

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

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

    NARCIS (Netherlands)

    Huang, S.

    2005-01-01

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

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

    NARCIS (Netherlands)

    Enckevort, van L.J.G.

    2000-01-01

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

  13. Genome analyses of the sunflower pathogen Plasmopara halstedii provide insights into effector evolution in downy mildews and Phytophthora

    NARCIS (Netherlands)

    Sharma, Rahul; Xia, Xiaojuan; Cano, Liliana M; Evangelisti, Edouard; Kemen, Eric; Judelson, Howard; Oome, Stan; Sambles, Christine; van den Hoogen, D Johan; Kitner, Miloslav; Klein, Joël; Meijer, Harold J G; Spring, Otmar; Win, Joe; Zipper, Reinhard; Bode, Helge B; Govers, Francine; Kamoun, Sophien; Schornack, Sebastian; Studholme, David J; Van den Ackerveken, Guido; Thines, Marco

    2015-01-01

    BACKGROUND: Downy mildews are the most speciose group of oomycetes and affect crops of great economic importance. So far, there is only a single deeply-sequenced downy mildew genome available, from Hyaloperonospora arabidopsidis. Further genomic resources for downy mildews are required to study thei

  14. Nine things to know about elicitins

    NARCIS (Netherlands)

    Derevnina, Lida; Dagdas, Yasin F.; Concepcion, De la Juan Carlos; Bialas, Aleksandra; Kellner, Ronny; Petre, Benjamin; Domazakis, Emmanouil; Du, Juan; Wu, Chih Hang; Lin, Xiao; Aguilera-Galvez, Carolina; Cruz-Mireles, Neftaly; Vleeshouwers, Vivianne G.A.A.; Kamoun, Sophien

    2016-01-01

    Elicitins are structurally conserved extracellular proteins in Phytophthora and Pythium oomycete pathogen species. They were first described in the late 1980s as abundant proteins in Phytophthora culture filtrates that have the capacity to elicit hypersensitive (HR) cell death and disease resistance

  15. Root rot diseases of sugar beet

    Directory of Open Access Journals (Sweden)

    Jacobsen Barry J.

    2006-01-01

    Full Text Available Root rot diseases of sugar beet caused by Rhizoctonia solani (AG 2-2 IIIB and AG 2-2 IV, R. crocorum, Aphanomyces cochlioides, Phoma betae, Macrophomina phaeseolina, Fusarium oxysporum f.sp. radicis-betae, Pythium aphanidermatum Phytophthora drechsleri, Rhizopus stolonifer, R. arrhizus and Sclerotium rolfsii cause significant losses wherever sugar beets are grown. However, not all these soil-borne pathogens have been reported in all sugar beet production areas. Losses include reduced harvestable tonnage and reduced white sugar recovery. Many of these pathogens also cause post harvest losses in storage piles. Control for diseases caused by these pathogens include disease resistant cultivars, avoidance of stresses, cultural practices such as water management and the use of fungicides.

  16. Microparasites of worldwide mullets.

    Science.gov (United States)

    Ovcharenko, Mykola

    2015-01-01

    The present review is focus on parasitic organisms, previously considered as protozoans. Viral, prokaryotic and fungal parasites caused diseases and disorders of worldwide mullets were also observed. Most of the known viruses associated with a high mortality of mullets were detected in Mugil cephalus. Prokaryotic microparasites were registered in M. cephalus, Moolgarda cunnesiu, Liza ramada and Mugil liza. Fungal pathogens were associated with representatives of the genera Aphanomyces, Achlya, Phialemonium, Ichthyophonus. Ichthyophonus sp. can be considered as a potential threat for marine fish aquaculture, especially in culture conditions. A new hyperparasitic microsporidium like organism was recorded in myxozoan Myxobolus parvus infecting grey mullet Liza haematocheilus in the Russian coastal zone of the Sea of Japan. The protozoan representatives of the phyla Dinoflagellata, Euglenozoa, Ciliophora and Apicomplexa were reviewed and analyzed. The review of myxosporean parasites from grey mullets includes 64 species belonging to 13 genera and 9 families infecting 16 fish species

  17. [Water fungi occurence in the River Supraśl-bath Jurowce near Białystok].

    Science.gov (United States)

    Kiziewicz, Bozena; Kozłowska, Mariola; Godlewska, Anna; Muszyńvska, Elzbieta; Mazalska, Bozenna

    2004-01-01

    Studies on the occurrence of aquatic fungi in the bathing sites of the Supraśl River in Jurowce village were collected in years 2000-2003. Hydrochemical analysis was performed using standard methods. Bait method was used to isolate the fungi. In the Supraśl River at Jurowce village 36 fungi species were identified, among them fish pathogens Achlya orion, Aphanomyces laevis, Dictyuchus monosporus, Saprolegnia ferax, Saprolegnia monoica, S. parasitica, human pathogens Aspergillus flavus, Candida albicans, Lagenidium humanum, Penicillium mycetomagenum, Rhizophydium keratinophilum and Trichosporon cutaneum, phytopathogens Achlya racemosa, Phytophthora gonapodoides, Pythium butleri, P. myriotylum and P. debaryanum. Physicochemical parameters of waters in Supraśl River-bathing sites had no important effect on the occurrence of fungi.

  18. Impact of climate and diseases on pea yields: what perspectives with climate change?

    Directory of Open Access Journals (Sweden)

    Bénézit Maud

    2017-01-01

    Full Text Available For farmers, pea crop is characterized by a large yield variability between years, between areas, and even between fields in a same small area in a given year. In dry year, spring pea crops are mostly affected by water stress and high temperature but significant yield losses can also be caused by a root disease, Aphanomyces euteiches, particularly during wet years. Winter pea can escape partially from drought, high temperature, and root disease during the reproductive phase of the crop cycle. However, when winters are mild, without progressive negative temperatures, which provide frost acclimation, available cultivars are not resistant enough to frost and are susceptible to aerial diseases such as ascochyta blight and bacterial blight (Pseudomonas syringae pv. pisi, thus leading to yield losses. A better adaptation of sowing dates, an improvement of lodging resistance and a limitation of the sowing density can limit the development of ascochyta blight for winter pea crops. For spring pea, an increased use of Aphanomyces soil test could avoid to sow the crop in infested fields. Current spring pea varieties are the result of changes in plant architecture including the reduction of 1000-seed weight that have led to yield losses by increasing the fragility of variety facing these stresses. The development of a pea crop model, simulating the effect of various stress encountered on winter and spring pea crops, can help to better define the regions adapted for the production of these two types of cultivars, and also help the breeders to better define and choose which trait to improve in order to increase the pea productivity and yield stability. National and European projects are in course to breed new varieties more adapted to different stresses.

  19. Novas citações de Chytridiomycota e Oomycota para o Parque Estadual das Fontes do Ipiranga (PEFI, SP, Brasil New records of Chytridiomycota and Oomycota from the "Parque Estadual das Fontes do Ipiranga (PEFI", SP, Brazil

    Directory of Open Access Journals (Sweden)

    Carmen Lidia Amorim Pires-Zottarelli

    2007-03-01

    Full Text Available Levantamento de fungos zoospóricos realizado em lagos artificiais do Parque Estadual das Fontes do Ipiranga (PEFI, situado na cidade de São Paulo, Estado de São Paulo, Brasil, resultou no isolamento de 41 táxons, sendo 36 identificados em nível específico. Vinte e três táxons pertencem ao Reino Fungi, filo Chytridiomycota, ordens Chytridiales, Monoblepharidales e Spizellomicetales e, 18 ao Reino Straminipila, filo Oomycota, ordens Saprolegniales e Peronosporales. Dentre os fungos isolados, 14 são mencionados pela primeira vez para o PEFI: Aphanomyces helicoides von Minden, Catenochytridium kevorkianii Sparrow, Catenochytridium sp., Chytriomyces appendiculatus Karling, C. aureus Karling, C. hyalinus Karling, C. spinosus Fay, Diplophlyctis asteroidea Dogma, D. complicata (Willoughby Dogma, Karlingia dubia Karling, Nowakowskiella hemisphaerospora Shanor, Saprolegnia australis Elliott, Septochytrium variabile Berdan e Truittella sp., os quais são descritos, comentados e ilustrados. O gênero Truitella é mencionado pela primeira vez para o Brasil.A survey of zoosporic fungi from artificial lakes of the Fontes do Ipiranga State Park, in the city of São Paulo, São Paulo State, Brazil, yielded the isolation of 41 taxa with 36 species. Twenty-three taxa belong to Chytridiales, Monoblepharidales and Spizellomycetales of the Phylum Chytridiomycota, Fungi Kingdom and 18 belong to Saprolegniales and Peronosporales, Phylum Oomycota, Straminipila Kingdom. Of these, 14 are first-time records for this State Park: Aphanomyces helicoides von Minden, Catenochytridium kevorkianii Sparrow, Catenochytridium sp., Chytriomyces appendiculatus Karling, C. aureus Karling, C. hyalinus Karling, C. spinosus Fay, Diplophlyctis asteroidea Dogma, D. complicata (Willoughby Dogma, Karlingia dubia Karling, Nowakowskiella hemisphaerospora Shanor, Saprolegnia australis Elliott, Septochytrium variabile Berdan and Truittella sp., which are described, commented and

  20. Biofumigation on Post-Harvest Diseases of Fruits Using a New Volatile-Producing Fungus of Ceratocystis fimbriata.

    Directory of Open Access Journals (Sweden)

    Qian Li

    Full Text Available A variety of volatile organic compounds (VOCs produced by Ceratocystis fimbriata have strong bioactivity against a wide range of fungi, bacteria and oomycetes. Mycelial growth, conidial production, and spore germination of fungi and oomycetes were significantly inhibited after exposure to cultures of C. fimbriata, and colony formation of bacteria was also inhibited. Two post-harvest diseases, peach brown rot caused by Monilinia fructicola and citrus green mold caused by Penicillium digitatum, were controlled during a 4-day storage by enclosing wound-inoculated fruits with 10 standard diameter Petri plate cultures of C. fimbriata in a 15 L box. The fruits were freshly inoculated at onset of storage and the cultures of C. fimbriata were 6 days old. Percentage of control was 92 and 97%, respectively. After exposure to C. fimbriata VOCs, severely misshapen hyphae and conidia of these two post-harvest pathogens were observed by scanning electron microscopy, and their pathogenicity was lost or greatly reduced.

  1. 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.

  2. External lipid PI3P mediates entry of eukaryotic pathogen effectors into plant and animal host cells.

    Science.gov (United States)

    Kale, Shiv D; Gu, Biao; Capelluto, Daniel G S; Dou, Daolong; Feldman, Emily; Rumore, Amanda; Arredondo, Felipe D; Hanlon, Regina; Fudal, Isabelle; Rouxel, Thierry; Lawrence, Christopher B; Shan, Weixing; Tyler, Brett M

    2010-07-23

    Pathogens of plants and animals produce effector proteins that are transferred into the cytoplasm of host cells to suppress host defenses. One type of plant pathogens, oomycetes, produces effector proteins with N-terminal RXLR and dEER motifs that enable entry into host cells. We show here that effectors of another pathogen type, fungi, contain functional variants of the RXLR motif, and that the oomycete and fungal RXLR motifs enable binding to the phospholipid, phosphatidylinositol-3-phosphate (PI3P). We find that PI3P is abundant on the outer surface of plant cell plasma membranes and, furthermore, on some animal cells. All effectors could also enter human cells, suggesting that PI3P-mediated effector entry may be very widespread in plant, animal and human pathogenesis. Entry into both plant and animal cells involves lipid raft-mediated endocytosis. Blocking PI3P binding inhibited effector entry, suggesting new therapeutic avenues.

  3. Pythium campanulatum sp. nov., isolated from the rhizosphere of maize, its taxonomy, ITS region of rDNA, and comparison with related species.

    Science.gov (United States)

    Mathew, Ritta; Singh, Kusum Kumari; Paul, Bernard

    2003-09-12

    Pythium campanulatum sp. nov. was isolated from some soil samples taken in the rhizosphere of maize (Zea mays) in north-eastern India. This species is characterized by the absence of zoospores and sporangia, antheridial branches wrapping around the oogonia leaving one to two campanulate antheridial cells after fertilization, and aplerotic oospores. The ITS region of its rDNA is comprised of 922 bases. This oomycete is closely related to Pythium orthogonon, Pythium nunn and Pythium toruloides. However, it has its own characteristic features and is completely devoid of zoospores. Taxonomic description of this new species and its comparison with related oomycetes, together with the sequence of the PCR-amplified internal transcribed region (spacers ITS1, ITS2, and the gene 5.8S) of its rDNA are given here.

  4. 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...

  5. Transcriptomic analysis of the interaction between Helianthus annuus and its obligate parasite Plasmopara halstedii shows single nucleotide polymorphisms in CRN sequences

    Directory of Open Access Journals (Sweden)

    Gouzy Jérôme

    2011-10-01

    Full Text Available Abstract Background Downy mildew in sunflowers (Helianthus annuus L. is caused by the oomycete Plasmopara halstedii (Farl. Berlese et de Toni. Despite efforts by the international community to breed mildew-resistant varieties, downy mildew remains a major threat to the sunflower crop. Very few genomic, genetic and molecular resources are currently available to study this pathogen. Using a 454 sequencing method, expressed sequence tags (EST during the interaction between H. annuus and P. halstedii have been generated and a search was performed for sites in putative effectors to show polymorphisms between the different races of P. halstedii. Results A 454 pyrosequencing run of two infected sunflower samples (inbred lines XRQ and PSC8 infected with race 710 of P. halstedii, which exhibit incompatible and compatible interactions, respectively generated 113,720 and 172,107 useable reads. From these reads, 44,948 contigs and singletons have been produced. A bioinformatic portal, HP, was specifically created for in-depth analysis of these clusters. Using in silico filtering, 405 clusters were defined as being specific to oomycetes, and 172 were defined as non-specific oomycete clusters. A subset of these two categories was checked using PCR amplification, and 86% of the tested clusters were validated. Twenty putative RXLR and CRN effectors were detected using PSI-BLAST. Using corresponding sequences from four races (100, 304, 703 and 710, 22 SNPs were detected, providing new information on pathogen polymorphisms. Conclusions This study identified a large number of genes that are expressed during H. annuus/P. halstedii compatible or incompatible interactions. It also reveals, for the first time, that an infection mechanism exists in P. halstedii similar to that in other oomycetes associated with the presence of putative RXLR and CRN effectors. SNPs discovered in CRN effector sequences were used to determine the genetic distances between the four races

  6. Plasmopara halstedii virus causes hypovirulence in Plasmopara halstedii, the downy mildew pathogen of the sunflower.

    Science.gov (United States)

    Grasse, Wolfgang; Zipper, Reinhard; Totska, Maria; Spring, Otmar

    2013-08-01

    Plasmopara halstedii virus (PhV) is an isometric virus recently found in the oomycete Plasmopara halstedii. The fully sequenced virus genome consists of two ss(+)RNA strands encoding for the virus polymerase and the coat protein, respectively. Most of previously screened field isolates of P. halstedii were found to harbor PhV, but effects of PhV on the pathogenicity and aggressiveness of the oomycete have not been investigated yet. To assess the influence of PhV on the infectivity of P. halstedii, virus-free isolates of the oomycete were searched for, cultivated on sunflower and used for single zoospore infection. Four genetically homogenous strains belonging to three different pathotypes (710, 730, 750) were established. Subcultures of each strain were successfully infected with PhV. This afforded pairs of isogenic strains with and without virus and allowed assessment of the pathogenicity (susceptibility to specific sunflower genotypes) and aggressiveness (intensity of infection, time scale and density of sporulation) in cultivation of sunflower. While no significant difference was found in the pathogenicity of P. halstedii strains with and without virus towards sunflower seedlings of different resistance (pathotype differentials), the aggressiveness of the oomycete was diminished by PhV. Compared to the virus-free strains, the time required for the first sporulation (latent period) increased by about 1 day post inoculation. Progression of the pathogen from the hypocotyl into the epicotyl of sunflower (systemic infection) was reduced by about one third in the presence of virus. In the virus containing strains, the average density of sporangia produced per cm² cotyledon reached only 75% of the virus-free controls. In summary, the presence of PhV leads to hypovirulence effects by weakening the aggressiveness of P. halstedii.

  7. NiaA, the structural nitrate reductase gene of Phytophthora infestans: isolation, characterization and expression analysis in Aspergillus nidulans.

    Science.gov (United States)

    Pieterse, C M; van't Klooster, J; van den Berg-Velthuis, G C; Govers, F

    1995-03-01

    The nitrate reductase (NR) gene niaA of the oomycete Phytophthora infestans was selected from a gene library by heterologous hybridization. NiaA occurs as a single-copy gene ant its expression is regulated by the nitrogen source. The nucleotide sequence of niaA was determined and comparison of the deduced amino-acid sequence of 902 residues with NRs of higher fungi and plants revealed a significant homology, particularly within the three cofactor-binding domains for molybdenum, heme and FAD. The P. infestans niaA gene was used as a model gene to test whether oomycete genes are functional in the ascomycete Aspergillus nidulans, a fungus which is highly accessible for molecular genetic studies. The complete niaA gene was stably integrated into the genome of a nia- deletion mutant of A. nidulans. However, transformants containing one or more copies of the niaA gene were not able to complement the nia- mutant. This suggests that there is no functional expression of the introduced niaA gene in A. nidulans. In addition, the activity of two other oomycete gene promoters was analyzed in a transient expression assay. Plasmids containing chimaeric genes with the promoter of the P. infestans ubiquitin gene ubi3R, or the Bremia lactucae ham34 gene, fused to the coding sequence of the Escherichia coli beta-glucuronidase (GUS) reporter gene, were transferred to A. nidulans protoplasts. No significant GUS activity was detectable indicating that the ubi3R and ham34 promoters are not active in A. nidulans. Apparently, the regulatory sequences which are sufficient for gene activation in oomycetes are not functional in the ascomycete A. nidulans.

  8. A common toxin fold mediates microbial attack and plant defense.

    Science.gov (United States)

    Ottmann, Christian; Luberacki, Borries; Küfner, Isabell; Koch, Wolfgang; Brunner, Frédéric; Weyand, Michael; Mattinen, Laura; Pirhonen, Minna; Anderluh, Gregor; Seitz, Hanns Ulrich; Nürnberger, Thorsten; Oecking, Claudia

    2009-06-23

    Many plant pathogens secrete toxins that enhance microbial virulence by killing host cells. Usually, these toxins are produced by particular microbial taxa, such as bacteria or fungi. In contrast, many bacterial, fungal and oomycete species produce necrosis and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs) that trigger leaf necrosis and immunity-associated responses in various plants. We have determined the crystal structure of an NLP from the phytopathogenic oomycete Pythium aphanidermatum to 1.35A resolution. The protein fold exhibits structural similarities to cytolytic toxins produced by marine organisms (actinoporins). Computational modeling of the 3-dimensional structure of NLPs from another oomycete, Phytophthora parasitica, and from the phytopathogenic bacterium, Pectobacterium carotovorum, revealed a high extent of fold conservation. Expression of the 2 oomycete NLPs in an nlp-deficient P. carotovorum strain restored bacterial virulence, suggesting that NLPs of prokaryotic and eukaryotic origins are orthologous proteins. NLP mutant protein analyses revealed that identical structural properties were required to cause plasma membrane permeabilization and cytolysis in plant cells, as well as to restore bacterial virulence. In sum, NLPs are conserved virulence factors whose taxonomic distribution is exceptional for microbial phytotoxins, and that contribute to host infection by plasma membrane destruction and cytolysis. We further show that NLP-mediated phytotoxicity and plant defense gene expression share identical fold requirements, suggesting that toxin-mediated interference with host integrity triggers plant immunity-associated responses. Phytotoxin-induced cellular damage-associated activation of plant defenses is reminiscent of microbial toxin-induced inflammasome activation in vertebrates and may thus constitute another conserved element in animal and plant innate immunity.

  9. Accurate and adequate spatiotemporal expression and localization of RPW8.2 is key to activation of resistance at the host-pathogen interface

    OpenAIRE

    Wang, Wenming; Berkey, Robert; Wen, Yingqiang; Xiao, Shunyuan

    2010-01-01

    Numerous fungal and oomycete pathogens penetrate the plant cell wall and extract nutrition from the host cells by a feeding structure called the haustorium. We recently revealed that the Arabidopsis resistance protein RPW8.2 is specifically targeted to the extrahaustorial membrane (EHM) for activation of haustorium-targeted resistance to powdery mildew pathogens. Consistent with its EHM-localization, RPW8.2 contains a putative transmembrane (TM) domain at its N-terminus. Here, we show that tr...

  10. Activation of Zoosporogenesis-Specific Genes in Phytophthora infestans Involves a 7-Nucleotide Promoter Motif and Cold-Induced Membrane Rigidity

    OpenAIRE

    Tani, Shuji; Judelson, Howard

    2006-01-01

    Infections of plants by the oomycete Phytophthora infestans typically result from zoospores, which develop from sporangia at cold temperatures. To help understand the relevant cold-induced signaling pathway, factors regulating the transcription of the zoosporogenesis-specific NIF (nuclear LIM-interactor-interacting factor) gene family were examined. Sequences required for inducing PinifC3 were identified by analyzing truncated and mutated promoters using the β-glucuronidase reporter in stable...

  11. Preliminary checklist of fungi of the Fernow Experimental Forest. Forest Service general technical report (Final)

    Energy Technology Data Exchange (ETDEWEB)

    Stephenson, S.L.; Kumar, A.; Bhatt, R.; Dubey, T.; Landolt, J.C.

    1994-01-01

    The report provides a checklist of fungi found on the Fernow Experimental Forest in West Virginia during 4 years of research and collecting by the authors. More than 500 fungi in seven major taxonomic groups (Acrasiomycetes, Myxomycetes, Chytridiomycetes, Oomycetes, Ascomycetes, Deuteromycetes, and Basidiomycetes) are listed alphabetically by genus and species. Also provided is a general description of the forest vegetation of the Fernow Experimental Forest.

  12. Mobile genetic elements in the genome of the beneficial rhizobacterium Pseudomonas fluorescens Pf-5

    OpenAIRE

    2009-01-01

    Abstract Background Pseudomonas fluorescens Pf-5 is a plant-associated bacterium that inhabits the rhizosphere of a wide variety of plant species and and produces secondary metabolites suppressive of fungal and oomycete plant pathogens. The Pf-5 genome is rich in features consistent with its commensal lifestyle, and its sequence has revealed attributes associated with the strain's ability to compete and survive in the dynamic and microbiologically complex rhizosphere habitat. In this study, w...

  13. Implementation of systematic reviews in EFSA scientific outputs workflow (CFT/EFSA/AMU/2010/01)

    DEFF Research Database (Denmark)

    O'Connor, A. M.; Lövei, G.; Eales, J.

    2012-01-01

    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....

  14. 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....

  15. 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...

  16. 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.

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

    Science.gov (United States)

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

    2014-04-04

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

  18. mRNA-Seq analysis of the Pseudoperonospora cubensis transcriptome during cucumber (Cucumis sativus L. infection.

    Directory of Open Access Journals (Sweden)

    Elizabeth A Savory

    Full Text Available Pseudoperonospora cubensis, an oomycete, is the causal agent of cucurbit downy mildew, and is responsible for significant losses on cucurbit crops worldwide. While other oomycete plant pathogens have been extensively studied at the molecular level, Ps. cubensis and the molecular basis of its interaction with cucurbit hosts has not been well examined. Here, we present the first large-scale global gene expression analysis of Ps. cubensis infection of a susceptible Cucumis sativus cultivar, 'Vlaspik', and identification of genes with putative roles in infection, growth, and pathogenicity. Using high throughput whole transcriptome sequencing, we captured differential expression of 2383 Ps. cubensis genes in sporangia and at 1, 2, 3, 4, 6, and 8 days post-inoculation (dpi. Additionally, comparison of Ps. cubensis expression profiles with expression profiles from an infection time course of the oomycete pathogen Phytophthora infestans on Solanum tuberosum revealed similarities in expression patterns of 1,576-6,806 orthologous genes suggesting a substantial degree of overlap in molecular events in virulence between the biotrophic Ps. cubensis and the hemi-biotrophic P. infestans. Co-expression analyses identified distinct modules of Ps. cubensis genes that were representative of early, intermediate, and late infection stages. Collectively, these expression data have advanced our understanding of key molecular and genetic events in the virulence of Ps. cubensis and thus, provides a foundation for identifying mechanism(s by which to engineer or effect resistance in the host.

  19. 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.

  20. Physcomitrella patens auxin conjugate synthetase (GH3) double knockout mutants are more resistant to Pythium infection than wild type.

    Science.gov (United States)

    Mittag, Jennifer; Šola, Ivana; Rusak, Gordana; Ludwig-Müller, Jutta

    2015-07-01

    Auxin homeostasis is involved in many different plant developmental and stress responses. The auxin amino acid conjugate synthetases belonging to the GH3 family play major roles in the regulation of free indole-3-acetic acid (IAA) levels and the moss Physcomitrella patens has two GH3 genes in its genome. A role for IAA in several angiosperm--pathogen interactions was reported, however, in a moss--oomycete pathosystem it had not been published so far. Using GH3 double knockout lines we have investigated the role of auxin homeostasis during the infection of P. patens with the two oomycete species, Pythium debaryanum and Pythium irregulare. We show that infection with P. debaryanum caused stronger disease symptoms than with P. irregulare. Also, P. patens lines harboring fusion constructs of an auxin-inducible promoter from soybean (GmGH3) with a reporter (ß-glucuronidase) showed higher promoter induction after P. debaryanum infection than after P. irregulare, indicating a differential induction of the auxin response. Free IAA was induced upon P. debaryanum infection in wild type by 1.6-fold and in two GH3 double knockout (GH3-doKO) mutants by 4- to 5-fold. All GH3-doKO lines showed a reduced disease symptom progression compared to wild type. Since P. debaryanum can be inhibited in growth on medium containing IAA, these data might indicate that endogenous high auxin levels in P. patens GH3-doKO mutants lead to higher resistance against the oomycete.

  1. Nanoparticles Composed of Zn and ZnO Inhibit Peronospora tabacina Spore Germination in vitro and P. tabacina Infectivity on Tobacco Leaves

    Directory of Open Access Journals (Sweden)

    George Wagner

    2016-03-01

    Full Text Available Manufactured nanoparticles (NPs are increasingly being used for commercial purposes and certain NP types have been shown to have broad spectrum antibacterial activity. In contrast, their activities against fungi and fungi-like oomycetes are less studied. Here, we examined the potential of two types of commercially available Zn NPs (Zn NPs and ZnO NPs to inhibit spore germination and infectivity on tobacco leaves resulting from exposure to the fungi-like oomycete pathogen Peronospora tabacina (P. tabacina. Both types of NPs, as well as ZnCl2 and bulk ZnO control treatments, inhibited spore germination compared to a blank control. ZnO ENMs were shown to be a much more powerful suppressor of spore germination and infectivity than bulk ZnO. ZnO and Zn NPs significantly inhibited leaf infection at 8 and 10 mg·L−1, respectively. Both types of NPs were found to provide substantially higher concentration dependent inhibition of spore germination and infectivity than could be readily explained by the presence of dissolved Zn. These results suggest that both NP types have potential for use as economic, low-dose, potentially non-persistent anti-microbial agents against the oomycete P. tabacina.

  2. Cross-kingdom host shifts of phytomyxid parasites.

    Science.gov (United States)

    Neuhauser, Sigrid; Kirchmair, Martin; Bulman, Simon; Bass, David

    2014-02-23

    Phytomyxids (plasmodiophorids and phagomyxids) are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. Plasmodiophorids are best known as pathogens or vectors for viruses of arable crops (e.g. clubroot in brassicas, powdery potato scab, and rhizomania in sugar beet). Some phytomyxid parasites are of considerable economic and ecologic importance globally, and their hosts include important species in marine and terrestrial environments. However most phytomyxid diversity remains uncharacterised and knowledge of their relationships with host taxa is very fragmentary. Our molecular and morphological analyses of phytomyxid isolates-including for the first time oomycete and sea-grass parasites-demonstrate two cross-kingdom host shifts between closely related parasite species: between angiosperms and oomycetes, and from diatoms/brown algae to angiosperms. Switching between such phylogenetically distant hosts is generally unknown in host-dependent eukaryote parasites. We reveal novel plasmodiophorid lineages in soils, suggesting a much higher diversity than previously known, and also present the most comprehensive phytomyxid phylogeny to date. Such large-scale host shifts between closely related obligate biotrophic eukaryote parasites is to our knowledge unique to phytomyxids. Phytomyxids may readily adapt to a wide diversity of new hosts because they have retained the ability to covertly infect alternative hosts. A high cryptic diversity and ubiquitous distribution in agricultural and natural habitats implies that in a changing environment phytomyxids could threaten the productivity of key species in marine and terrestrial environments alike via host shift speciation.

  3. 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.

  4. Taxonomic analysis of the microbial community in stored sugar beets using high-throughput sequencing of different marker genes.

    Science.gov (United States)

    Liebe, Sebastian; Wibberg, Daniel; Winkler, Anika; Pühler, Alfred; Schlüter, Andreas; Varrelmann, Mark

    2016-02-01

    Post-harvest colonization of sugar beets accompanied by rot development is a serious problem due to sugar losses and negative impact on processing quality. Studies on the microbial community associated with rot development and factors shaping their structure are missing. Therefore, high-throughput sequencing was applied to describe the influence of environment, plant genotype and storage temperature (8°C and 20°C) on three different communities in stored sugar beets, namely fungi (internal transcribed spacers 1 and 2), Fusarium spp. (elongation factor-1α gene fragment) and oomycetes (internal transcribed spacers 1). The composition of the fungal community changed during storage mostly influenced by the storage temperature followed by a weak environmental effect. Botrytis cinerea was the prevalent species at 8°C whereas members of the fungal genera Fusarium and Penicillium became dominant at 20°C. This shift was independent of the plant genotype. Species richness within the genus Fusarium also increased during storage at both temperatures whereas the oomycetes community did not change. Moreover, oomycetes species were absent after storage at 20°C. The results of the present study clearly show that rot development during sugar beet storage is associated with pathogens well known as causal agents of post-harvest diseases in many other crops.

  5. Ancient Origin of the U2 Small Nuclear RNA Gene-Targeting Non-LTR Retrotransposons Utopia.

    Directory of Open Access Journals (Sweden)

    Kenji K Kojima

    Full Text Available Most non-long terminal repeat (non-LTR retrotransposons encoding a restriction-like endonuclease show target-specific integration into repetitive sequences such as ribosomal RNA genes and microsatellites. However, only a few target-specific lineages of non-LTR retrotransposons are distributed widely and no lineage is found across the eukaryotic kingdoms. Here we report the most widely distributed lineage of target sequence-specific non-LTR retrotransposons, designated Utopia. Utopia is found in three supergroups of eukaryotes: Amoebozoa, SAR, and Opisthokonta. Utopia is inserted into a specific site of U2 small nuclear RNA genes with different strength of specificity for each family. Utopia families from oomycetes and wasps show strong target specificity while only a small number of Utopia copies from reptiles are flanked with U2 snRNA genes. Oomycete Utopia families contain an "archaeal" RNase H domain upstream of reverse transcriptase (RT, which likely originated from a plant RNase H gene. Analysis of Utopia from oomycetes indicates that multiple lineages of Utopia have been maintained inside of U2 genes with few copy numbers. Phylogenetic analysis of RT suggests the monophyly of Utopia, and it likely dates back to the early evolution of eukaryotes.

  6. Ancient Origin of the U2 Small Nuclear RNA Gene-Targeting Non-LTR Retrotransposons Utopia.

    Science.gov (United States)

    Kojima, Kenji K; Jurka, Jerzy

    2015-01-01

    Most non-long terminal repeat (non-LTR) retrotransposons encoding a restriction-like endonuclease show target-specific integration into repetitive sequences such as ribosomal RNA genes and microsatellites. However, only a few target-specific lineages of non-LTR retrotransposons are distributed widely and no lineage is found across the eukaryotic kingdoms. Here we report the most widely distributed lineage of target sequence-specific non-LTR retrotransposons, designated Utopia. Utopia is found in three supergroups of eukaryotes: Amoebozoa, SAR, and Opisthokonta. Utopia is inserted into a specific site of U2 small nuclear RNA genes with different strength of specificity for each family. Utopia families from oomycetes and wasps show strong target specificity while only a small number of Utopia copies from reptiles are flanked with U2 snRNA genes. Oomycete Utopia families contain an "archaeal" RNase H domain upstream of reverse transcriptase (RT), which likely originated from a plant RNase H gene. Analysis of Utopia from oomycetes indicates that multiple lineages of Utopia have been maintained inside of U2 genes with few copy numbers. Phylogenetic analysis of RT suggests the monophyly of Utopia, and it likely dates back to the early evolution of eukaryotes.

  7. Effects of latrunculin B on the actin cytoskeleton and hyphal growth in Phytophthora infestans.

    Science.gov (United States)

    Ketelaar, Tijs; Meijer, Harold J G; Spiekerman, Marjolein; Weide, Rob; Govers, Francine

    2012-12-01

    The actin cytoskeleton is conserved in all eukaryotes, but its functions vary among different organisms. In oomycetes, the function of the actin cytoskeleton has received relatively little attention. We have performed a bioinformatics study and show that oomycete actin genes fall within a distinct clade that is divergent from plant, fungal and vertebrate actin genes. To obtain a better understanding of the functions of the actin cytoskeleton in hyphal growth of oomycetes, we studied the actin organization in Phytophthora infestans hyphae and the consequences of treatment with the actin depolymerising drug latrunculin B (latB). This revealed that latB treatment causes a concentration dependent inhibition of colony expansion and aberrant hyphal growth. The most obvious aberrations observed upon treatment with 0.1 μM latB were increased hyphal branching and irregular tube diameters whereas at higher concentrations latB (0.5 and 1 μM) tips of expanding hyphae changed into balloon-like shapes. This aberrant growth correlated with changes in the organization of the actin cytoskeleton. In untreated hyphae, staining with fluorescently tagged phalloidin revealed two populations of actin filaments: long, axially oriented actin filament cables and cortical actin filament plaques. Two hyphal subtypes were recognized, one containing only plaques and the other containing both cables and plaques. In the latter, some hyphae had an apical zone without actin filament plaques. Upon latB treatment, the proportion of hyphae without actin filament cables increased and there were more hyphae with a short apical zone without actin filament plaques. In general, actin filament plaques were more resilient against actin depolymerisation than actin filament cables. Besides disturbing hyphal growth and actin organization, actin depolymerisation also affected the positioning of nuclei. In the presence of latB, the distance between nuclei and the hyphal tip decreased, suggesting that the actin

  8. 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.

  9. Carbohydrate-active enzymes in pythium and their role in plant cell wall and storage polysaccharide degradation.

    Directory of Open Access Journals (Sweden)

    Marcelo M Zerillo

    Full Text Available Carbohydrate-active enzymes (CAZymes are involved in the metabolism of glycoconjugates, oligosaccharides, and polysaccharides and, in the case of plant pathogens, in the degradation of the host cell wall and storage compounds. We performed an in silico analysis of CAZymes predicted from the genomes of seven Pythium species (Py. aphanidermatum, Py. arrhenomanes, Py. irregulare, Py. iwayamai, Py. ultimum var. ultimum, Py. ultimum var. sporangiiferum and Py. vexans using the "CAZymes Analysis Toolkit" and "Database for Automated Carbohydrate-active Enzyme Annotation" and compared them to previously published oomycete genomes. Growth of Pythium spp. was assessed in a minimal medium containing selected carbon sources that are usually present in plants. The in silico analyses, coupled with our in vitro growth assays, suggest that most of the predicted CAZymes are involved in the metabolism of the oomycete cell wall with starch and sucrose serving as the main carbohydrate sources for growth of these plant pathogens. The genomes of Pythium spp. also encode pectinases and cellulases that facilitate degradation of the plant cell wall and are important in hyphal penetration; however, the species examined in this study lack the requisite genes for the complete saccharification of these carbohydrates for use as a carbon source. Genes encoding for xylan, xyloglucan, (galacto(glucomannan and cutin degradation were absent or infrequent in Pythium spp.. Comparative analyses of predicted CAZymes in oomycetes indicated distinct evolutionary histories. Furthermore, CAZyme gene families among Pythium spp. were not uniformly distributed in the genomes, suggesting independent gene loss events, reflective of the polyphyletic relationships among some of the species.

  10. Transformation of Pythium aphanidermatum to geneticin resistance.

    Science.gov (United States)

    Weiland, John J

    2003-03-01

    Conditions for the production of protoplasts and gene transfer in Pythium aphanidermatum were investigated. Efficient protoplast generation was possible after culture of mycelium in potato dextrose broth followed by digestion with 0.5% (w/v) each of cellulase and beta- d-glucanase. Plasmid pHAMT35N/SK encoding the nptII gene under control of the Ham34 promoter from the oomycete Bremia lactucae was used to define electroporation parameters for gene transfer. A square-wave electroporation pulse of 2500 V/cm at 50 microF capacitance reproducibly produced transformants, albeit at low efficiency (0.1-0.4 transformants from approximately 10(5) regenerable protoplasts per microgram of DNA). Thirty-two independent transformants exhibited wild-type growth on potato dextrose agar amended with geneticin at 50 microg/ml, a concentration that near completely inhibited the growth of untransformed P. aphanidermatum. Southern blot analysis indicated that transforming DNA was integrated into the oomycete genome and that the DNA was stably inherited through sporogenesis. Growth on geneticin-free media, the ability to form zoospores or oospores, and the ability to cause disease in sugarbeet seedlings in the laboratory were indistinguishable between a subset of the transformed isolates and the progenitor isolate 898B. Co-electroporation of pHAMT35N/SK with plasmid pACT-GUS encoding the Escherichia coli gusA gene controlled by oomycete transcriptional promoter and terminator sequences or with pEGFP encoding enhanced green fluorescent protein under the control of the immediate early promoter from the mammalian cytomegalovirus produced, respectively, stable beta-glucuronidase and transient expression of blue-green fluorescence. Application of the technique to studies on the biochemical basis for pathogenesis in this agriculturally important group of fungi is discussed.

  11. Light suppresses sporulation and epidemics of Peronospora belbahrii.

    Science.gov (United States)

    Cohen, Yigal; Vaknin, Moshe; Ben-Naim, Yariv; Rubin, Avia E

    2013-01-01

    Peronospora belbahrii is a biotrophic oomycete attacking sweet basil. It propagates asexually by producing spores on dichotomously branched sporophores emerging from leaf stomata. Sporulation occurs when infected plants are incubated for at least 7.5h in the dark in moisture-saturated atmosphere at 10-27°C. Exposure to light suppresses spore formation but allows sporophores to emerge from stomata. Incandescent or CW fluorescent light of 3.5 or 6 µmoles.m(2).s(-1) respectively, caused 100% inhibition of spore formation on lower leaf surface even when only the upper leaf surface was exposed to light. The inhibitory effect of light failed to translocate from an illuminated part of a leaf to a shaded part of the same leaf. Inhibition of sporulation by light was temperature-dependent. Light was fully inhibitory at 15-27°C but not at 10°C, suggesting that enzyme(s) activity and/or photoreceptor protein re-arrangement induced by light occur at ≥15°C. DCMU or paraquat could not abolish light inhibition, indicating that photosystem I and photosystem II are not involved. Narrow band led illumination showed that red light (λmax 625 nm) was most inhibitory and blue light (λmax 440 nm) was least inhibitory, suggesting that inhibition in P. belbahrii, unlike other oomycetes, operates via a red light photoreceptor. Nocturnal illumination of basil in the field (4-10 µmoles.m(2).s(-1) from 7pm to 7am) suppressed sporulation of P. belbahrii and reduced epidemics of downy mildew, thus reducing the need for fungicide applications. This is the first report on red light inhibition of sporulation in oomycetes and on the practical application of light for disease control in the field.

  12. Modulation of Plant RAB GTPase-Mediated Membrane Trafficking Pathway at the Interface Between Plants and Obligate Biotrophic Pathogens.

    Science.gov (United States)

    Inada, Noriko; Betsuyaku, Shigeyuki; Shimada, Takashi L; Ebine, Kazuo; Ito, Emi; Kutsuna, Natsumaro; Hasezawa, Seiichiro; Takano, Yoshitaka; Fukuda, Hiroo; Nakano, Akihiko; Ueda, Takashi

    2016-09-01

    RAB5 is a small GTPase that acts in endosomal trafficking. In addition to canonical RAB5 members that are homologous to animal RAB5, land plants harbor a plant-specific RAB5, the ARA6 group, which regulates trafficking events distinct from canonical RAB5 GTPases. Here, we report that plant RAB5, both canonical and plant-specific members, accumulate at the interface between host plants and biotrophic fungal and oomycete pathogens. Biotrophic fungi and oomycetes colonize living plant tissues by establishing specialized infection hyphae, the haustorium, within host plant cells. We found that Arabidopsis thaliana ARA6/RABF1, a plant-specific RAB5, is localized to the specialized membrane that surrounds the haustorium, the extrahaustorial membrane (EHM), formed by the A. thaliana-adapted powdery mildew fungus Golovinomyces orontii Whereas the conventional RAB5 ARA7/RABF2b was also localized to the EHM, endosomal SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) and RAB5-activating proteins were not, which suggests that the EHM has modified endosomal characteristic. The recruitment of host RAB5 to the EHM was a property shared by the barley-adapted powdery mildew fungus Blumeria graminis f.sp. hordei and the oomycete Hyaloperonospora arabidopsidis, but the extrahyphal membrane surrounding the hypha of the hemibiotrophic fungus Colletotrichum higginsianum at the biotrophic stage was devoid of RAB5. The localization of RAB5 to the EHM appears to correlate with the functionality of the haustorium. Our discovery sheds light on a novel relationship between plant RAB5 and obligate biotrophic pathogens.

  13. Silencing of acidic pathogenesis-related PR-1 genes increases extracellular beta-(1 -> 3)-glucanase activity at the onset of tobacco defence reactions

    DEFF Research Database (Denmark)

    Riviere, M.P.; Marais, A.; Ponchet, M.

    2008-01-01

    silenced. Plants lacking extracellular PR-1s were more susceptible than wild-type plants to the oomycete Phytophthora parasitica but displayed unaffected systemic acquired resistance and developmental resistance to this pathogen. Treatment with salicylic acid up-regulates the PR-1g gene, encoding a basic...... protein of the PR-1 family, in PR-1-deficient tobacco, indicating that PR-1 expression may repress that of PR-1g. This shows that acidic PR-1s are dispensable for expression of salicylic acid-dependent acquired resistances against P. parasitica and may reveal a functional overlap in tobacco defence...

  14. EFSA BIOHAZ Panel (EFSA Panel on Biological Hazards), 2013. Scientific Opinion on the maintenance of the list of QPS biological agents intentionally added to food and feed (2013 update)

    DEFF Research Database (Denmark)

    Licht, Tine Rask; Baggesen, Dorte Lau

    a harmonised generic pre-assessment to support safety risk assessments performed by EFSA’s scientific Panels. The safety of unambiguously defined biological agents (at the highest taxonomic unit appropriate for the purpose for which an application is intended), and the completeness of the body of knowledge...... is the one in the most recently published scientific opinion. The 2013 update reviews previously assessed microorganisms including bacteria, yeasts, filamentous fungi, oomycetes and viruses used for plant protection purposes. All taxonomic units previously recommended for the QPS list had their status...

  15. The phylogenetic and taxonomic implications of flagellar rootlet morphology among zoosporic fungi.

    Science.gov (United States)

    Barr, D J

    1981-01-01

    Rootlet morphology shows that the Oomycetes excluding the Thraustochytriales, the Thraustochytriales independently, and the Hyphochytriomycetes probably evolved as three distinctive lines from chrysophycean ancestors. The Plasmodiophoromycetes rootlet system does not show any similarity to rootlet systems in other zoosporic fungi, and this class may have arisen from the Protozoa. The varied rootlet systems present in the Chytridiomycetes show that this class has a very primitive origin and long evolutionary history. The composition of the rootlet systems in different Chytridiomycete taxa indicate that the Monoblepharidiales evolved from the Chytridiales, and the Blastocladiales from the Spizellomycetales.

  16. Phylogeny of an Albugo sp. infecting Barbarea vulgaris in Denmark and its frequency of symptom development in natural populations of two evolutionary divergent plant types

    DEFF Research Database (Denmark)

    van Mölken, Tamara; Heimes, Christine; Hauser, Thure Pavlo

    2014-01-01

    The oomycete Albugo candida has long been considered a broad spectrum generalist pathogen, but recent studies suggest that it is diverged into several more specialised species in addition to the generalist Albugo candida s.s.. Whereas these species cause the disease white blister rust in many...... that the Albugo sp. infecting B. vulgaris may indeed be an independent specialised species. White blister rust and Albugo DNA was only detected in two populations of the plant type that frequently develops symptoms upon controlled inoculations. The lack of white rust and Albugo sp. DNA in the other plant type may...

  17. Nunamycin and Nunapeptin: Two novel cyclic peptides are key components of the antimicrobial activity of the Greenlandic isolate Pseudomonas fluorescens In5

    DEFF Research Database (Denmark)

    Hennessy, Rosanna Catherine; Phippen, Christopher; Nielsen, Kristian F.

    Pseudomonas spp. are a rich source of secondary metabolites including bioactive non-ribosomal peptides (NRPs) and polyketides. NRPs are synthesised in large assembly lines by multi-domain modular enzymes known as NRP-synthetases (NRPS). Nunamycin and nunapeptin are two cyclic NRPs synthesised...... by the Greenlandic isolate P. fluorescens In5. Nunamycin shows antifungal activity against the basidiomycete Rhizoctonia solani whereas the only partially structure elucidated nunapeptin appears most active against the ascomycete Fusarium graminearum and the oomycete Pythium aphanidermatum. Originally isolated from...

  18. Two novel cyclic peptides are key components of the antimicrobial activity of the Greenlandic isolate Pseudomonas sp. In5

    DEFF Research Database (Denmark)

    Hennessy, Rosanna Catherine; Phippen, Christopher; Nielsen, Kristian F.

    Pseudomonas sp. are a rich source of secondary metabolites including bioactive non-ribosomal peptides (NRPs) and polyketides. NRPs are synthesised in large assembly lines by multi-domain modular enzymes known as NRP-synthetases (NRPS). Nunamycin and nunapeptin are two cyclic NRPs synthesised...... by the Greenlandic isolate Pseudomonas sp. In5. Nunamycin shows antifungal activity against the basidiomycete Rhizoctonia solani whereas the only partially structure elucidated nunapeptin appears most active against the ascomycete Fusarium graminearum and the oomycete Pythium aphanidermatum. Originally isolated from...

  19. Update on Eus Diagnostics, Infection Trials and Online Slide Collection

    DEFF Research Database (Denmark)

    Boutrup, Torsten Snogdal; Fry, Christian

    2012-01-01

    reisolated from a rainbow trout, with clinically disease, resulted in no mortality in 10 three spotted guramis, with only one fish showing a slight reddening. We have performed intra muscular injection trials in rainbow trout at temperatures at 10, 15, 18 and 22 degrees Celsius respectively. Here we have...... that Oomycal growth in rainbow trout don’t support a normal pathogenic potential of the organism, but an attenuated strain with lower virulence. Following the above described trials we have collected material for histology, Oomycete reisolation and PCR. From this material, pictures will be uploaded to the EURL...

  20. 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...

  1. Horizontal gene transfer in osmotrophs: playing with public goods.

    Science.gov (United States)

    Richards, Thomas A; Talbot, Nicholas J

    2013-10-01

    Osmotrophic microorganisms, such as fungi and oomycetes, feed by secreting depolymerizing enzymes to process complex food sources in the extracellular environment, and taking up the resulting simple sugars, micronutrients and amino acids. As a consequence of this lifestyle, osmotrophs engage in the acquisition and protection of public goods. In this Opinion article, we propose that horizontal gene transfer (HGT) has played a key part in shaping both the repertoire of proteins required for osmotrophy and the nature of public goods interactions in which eukaryotic microorganisms engage.

  2. Differential recognition of highly divergent downy mildew avirulence gene alleles by RPP1 resistance genes from two Arabidopsis lines.

    Science.gov (United States)

    Rehmany, Anne P; Gordon, Anna; Rose, Laura E; Allen, Rebecca L; Armstrong, Miles R; Whisson, Stephen C; Kamoun, Sophien; Tyler, Brett M; Birch, Paul R J; Beynon, Jim L

    2005-06-01

    The perception of downy mildew avirulence (Arabidopsis thaliana Recognized [ATR]) gene products by matching Arabidopsis thaliana resistance (Recognition of Peronospora parasitica [RPP]) gene products triggers localized cell death (a hypersensitive response) in the host plant, and this inhibits pathogen development. The oomycete pathogen, therefore, is under selection pressure to alter the form of these gene products to prevent detection. That the pathogen maintains these genes indicates that they play a positive role in pathogen survival. Despite significant progress in cloning plant RPP genes and characterizing essential plant components of resistance signaling pathways, little progress has been made in identifying the oomycete molecules that trigger them. Concluding a map-based cloning effort, we have identified an avirulence gene, ATR1NdWsB, that is detected by RPP1 from the Arabidopsis accession Niederzenz in the cytoplasm of host plant cells. We report the cloning of six highly divergent alleles of ATR1NdWsB from eight downy mildew isolates and demonstrate that the ATR1NdWsB alleles are differentially recognized by RPP1 genes from two Arabidopsis accessions (Niederzenz and Wassilewskija). RPP1-Nd recognizes a single allele of ATR1NdWsB; RPP1-WsB also detects this allele plus three additional alleles with divergent sequences. The Emco5 isolate expresses an allele of ATR1NdWsB that is recognized by RPP1-WsB, but the isolate evades detection in planta. Although the Cala2 isolate is recognized by RPP1-WsA, the ATR1NdWsB allele from Cala2 is not, demonstrating that RPP1-WsA detects a novel ATR gene product. Cloning of ATR1NdWsB has highlighted the presence of a highly conserved novel amino acid motif in avirulence proteins from three different oomycetes. The presence of the motif in additional secreted proteins from plant pathogenic oomycetes and its similarity to a host-targeting signal from malaria parasites suggest a conserved role in pathogenicity.

  3. Reference: 457 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available n et al. 2006 Oct. Plant J. 48(2):238-48. The Arabidopsis BAP1 gene encodes a small protein with a C2-like domain. Here...er and is associated with membranes in vivo. We identify multiple roles of BAP1 in negatively re...gulating defense responses and cell death in Arabidopsis thaliana. The loss of BAP1 function ...confers an enhanced disease resistance to virulent bacterial and oomycete pathogens. The enhanced resistance... is mediated by salicylic acid, PAD4 and a disease resistance gene SNC1. BAP1 is

  4. 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...... is a risk of further entry (of known or new lineages and/or mating types), establishment and […] impact”. It is advisable to avoid introductions of different lineages because of inherent phenotypic differences and the potential for sexual recombination. The Panel supports the management options proposed...

  5. Cloning and characterization of a pectin lyase gene from Colletotrichum lindemuthianum and comparative phylogenetic/structural analyses with genes from phytopathogenic and saprophytic/opportunistic microorganisms.

    Science.gov (United States)

    Lara-Márquez, Alicia; Zavala-Páramo, María G; López-Romero, Everardo; Calderón-Cortés, Nancy; López-Gómez, Rodolfo; Conejo-Saucedo, Ulises; Cano-Camacho, Horacio

    2011-12-09

    Microorganisms produce cell-wall-degrading enzymes as part of their strategies for plant invasion/nutrition. Among these, pectin lyases (PNLs) catalyze the depolymerization of esterified pectin by a β-elimination mechanism. PNLs are grouped together with pectate lyases (PL) in Family 1 of the polysaccharide lyases, as they share a conserved structure in a parallel β-helix. The best-characterized fungal pectin lyases are obtained from saprophytic/opportunistic fungi in the genera Aspergillus and Penicillium and from some pathogens such as Colletotrichum gloeosporioides.The organism used in the present study, Colletotrichum lindemuthianum, is a phytopathogenic fungus that can be subdivided into different physiological races with different capacities to infect its host, Phaseolus vulgaris. These include the non-pathogenic and pathogenic strains known as races 0 and 1472, respectively. Here we report the isolation and sequence analysis of the Clpnl2 gene, which encodes the pectin lyase 2 of C. lindemuthianum, and its expression in pathogenic and non-pathogenic races of C. lindemuthianum grown on different carbon sources. In addition, we performed a phylogenetic analysis of the deduced amino acid sequence of Clpnl2 based on reported sequences of PNLs from other sources and compared the three-dimensional structure of Clpnl2, as predicted by homology modeling, with those of other organisms. Both analyses revealed an early separation of bacterial pectin lyases from those found in fungi and oomycetes. Furthermore, two groups could be distinguished among the enzymes from fungi and oomycetes: one comprising enzymes from mostly saprophytic/opportunistic fungi and the other formed mainly by enzymes from pathogenic fungi and oomycetes. Clpnl2 was found in the latter group and was grouped together with the pectin lyase from C. gloeosporioides. The Clpnl2 gene of C. lindemuthianum shares the characteristic elements of genes coding for pectin lyases. A time-course analysis

  6. Cloning and characterization of a pectin lyase gene from Colletotrichum lindemuthianum and comparative phylogenetic/structural analyses with genes from phytopathogenic and saprophytic/opportunistic microorganisms

    Directory of Open Access Journals (Sweden)

    Lara-Márquez Alicia

    2011-12-01

    Full Text Available Abstract Background Microorganisms produce cell-wall-degrading enzymes as part of their strategies for plant invasion/nutrition. Among these, pectin lyases (PNLs catalyze the depolymerization of esterified pectin by a β-elimination mechanism. PNLs are grouped together with pectate lyases (PL in Family 1 of the polysaccharide lyases, as they share a conserved structure in a parallel β-helix. The best-characterized fungal pectin lyases are obtained from saprophytic/opportunistic fungi in the genera Aspergillus and Penicillium and from some pathogens such as Colletotrichum gloeosporioides. The organism used in the present study, Colletotrichum lindemuthianum, is a phytopathogenic fungus that can be subdivided into different physiological races with different capacities to infect its host, Phaseolus vulgaris. These include the non-pathogenic and pathogenic strains known as races 0 and 1472, respectively. Results Here we report the isolation and sequence analysis of the Clpnl2 gene, which encodes the pectin lyase 2 of C. lindemuthianum, and its expression in pathogenic and non-pathogenic races of C. lindemuthianum grown on different carbon sources. In addition, we performed a phylogenetic analysis of the deduced amino acid sequence of Clpnl2 based on reported sequences of PNLs from other sources and compared the three-dimensional structure of Clpnl2, as predicted by homology modeling, with those of other organisms. Both analyses revealed an early separation of bacterial pectin lyases from those found in fungi and oomycetes. Furthermore, two groups could be distinguished among the enzymes from fungi and oomycetes: one comprising enzymes from mostly saprophytic/opportunistic fungi and the other formed mainly by enzymes from pathogenic fungi and oomycetes. Clpnl2 was found in the latter group and was grouped together with the pectin lyase from C. gloeosporioides. Conclusions The Clpnl2 gene of C. lindemuthianum shares the characteristic elements of

  7. High throughput recombinant protein production of fungal secreted proteins

    DEFF Research Database (Denmark)

    Vala, Andrea Lages Lino; Roth, Doris; Grell, Morten Nedergaard

    2011-01-01

    a high-throughput protein production system with a special focus on fungal secreted proteins. We use a ligation independent cloning to clone target genes into expression vectors for E. coli and P. pastoris and a small scale test expression to identify constructs producing soluble protein. Expressed...... interaction), between fungi of the order Entomophthorales and aphids (pathogenic interaction), and in the mycoparasitic interaction between the oomycetes Pythium oligandrum and P. ultimum. In general, the high-throughput protein production system can lead to a better understanding of fungal/host interactions...

  8. How do filamentous pathogens deliver effector proteins into plant cells?

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    Benjamin Petre

    2014-02-01

    Full Text Available Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens.

  9. How Do Filamentous Pathogens Deliver Effector Proteins into Plant Cells?

    Science.gov (United States)

    Petre, Benjamin; Kamoun, Sophien

    2014-01-01

    Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens. PMID:24586116

  10. Effets allélopathiques des Brassicacées via leurs actions sur les agents pathogènes telluriques et les mycorhizes : analyse bibliographique. Partie 1

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    Reau Raymond

    2005-05-01

    Full Text Available Brassicas contain glucosinolates (GSL which decomposition is able to reduce the growth of populations of soil-borne fungi, bacterias or nematodes. These biocid effects on soil-borne microorganisms make a form of allelopathy phenomenon. The allelopathic properties depends on the GLS composition of the Brassicas: Indian mustard and in a lower extend Oilseed rape could have the most powerfull action, White mustard would have a weaker action. These properties also depends on crop residues: green manure with quick decomposition would result with a higher action than crop residues after grain harvest. The main mechanisms are known. In vitro, isothiocyanates obtained from the GSL decomposition inhibit all the phases of the cycle of Aphanomyces eutiches, the fungus responsible for root rot of peas. The mycelian growth of Gaeumannomyces graminis tritici, the fungus responsible for the wheat take all is inhibited by some isothyocyanates at low concentration. Furthermore, several studies give the evidence that the incorporation of Brassicas residues into the soil does inhibit the growth of both soil-borne pathogens. At last, the presence of roots of Brassicas inhibits the germination of the mycorhizes known to improve the mineral nutrition of its host plant. This phenomenon could explain the depressive effect of oilseed rape on the nutrition of a subsequent maize. This knowledge of Brassicas effects into cropping systems offers issues for a better management of precedent effects of Brassicas; these effects being positive (integrated cop protection or negative (management of subsequent crop nutrition after Brassicas.

  11. Effets allélopathiques des Brassicacées via leurs actions sur les agents pathogènes telluriques et les mycorhizes : analyse bibliographique. Partie II

    Directory of Open Access Journals (Sweden)

    Reau Raymond

    2005-07-01

    Full Text Available Brassicas contain glucosinolates (GSL which decomposition is able to reduce the growth of populations of soil-borne fungi, bacterias or nematodes. These biocid effects on soil-borne microorganisms make a form of allelopathy phenomenon. The allelopathic properties depends on the GLS composition of the Brassicas: Indian mustard and in a lower extend Oilseed rape culd have the most powerfull action, White mustard would have a weaker action. These properties also depends on crop residues: green manure with quick decomposition would result with a higher action than crop residues after grain harvest.The main mechanisms are known. In vitro, isothiocyanates obtained from the GSL decomposition inhibit all the phases of the cycle of Aphanomyces eutiches, the fungus responsible for root rot of peas. The mycelian growth of Gaeumannomyces graminis tritici, the fungus responsible for the wheat take all is inhibited by some isothyocyanates at low concentration. Furthermore, several studies give the evidence that the incorporation of Brassicas residues into the soil does inhibit the growth of both soil-borne pathogens. At last, the presence of roots of Brassicas inhibits the germination of the mycorhizes known to improve the mineral nutrition of its host plant. This phenomenon could explain the depressive effect of oilseed rape on the nutrition of a subsequent maize.This knowledge of Brassicas effects into cropping systems offers issues for a better management of precedent effects of Brassicas; these effects being positive (integrated cop protection or negative (management of subsequent crop nutrition after Brassicas.

  12. PENGEMBANGAN TEKNIK DIAGNOSA PENYAKIT EPIZOOTIC ULCERATIVE SYNDROME (EUS PADA IKAN MELALUI PENDEKATAN GEJALA KLINIS, ISOLASI PATOGEN, HISTOPATOLOGIS

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    Ade Nurdin

    2012-08-01

    Full Text Available Epizootic Ulcerative Syndrome (EUS adalah penyakit pada ikan yang disebabkan oleh infeksi jamur parasitik Aphanomyces invadans. Penelitian ini bertujuan untuk mendiagnosa patogen penyebab penyakit EUS melalui perpaduan 3 (tiga basis pendekatan, yaitu: (1 gejala klinis, (2, isolasi patogen, dan (3 histopatologis. Sebanyak 30 ekor ikan uji diinfeksi spora jamur A. invadans secara buatan sebanyak 100 spora/ekor ikan melalui penyuntikan secara intra muskular (IM, dan 30 ekor lainnya diinjeksi dengan phosphate buffered saline (PBS sebagai kontrol. Hasil penelitian menunjukkan bahwa gejala klinis yang muncul adalah timbulnya bercak-bercak merah pada tubuh ikan, selanjutnya berkembang menjadi ulser (ulcer karena invasi hifa cendawan ke dalam otot/daging ikan. Hasil isolasi jamur dari ulser ditemukan adanya hifa aseptat dengan diameter 7,5-10,0 μm; memproduksi zoospora primer berbentuk cluster achloyd dan zoospora sekunder berbentuk biflagellata. Secara histopatologis ditemukan adanya invasi hifa dan sel granuloma (mycotic dermatitis granulomatosis.

  13. Etiology and pathogenesis of skin ulcers in menhaden, Brevoortia tyrannis: does Pfiesteria piscicida play a role?

    Science.gov (United States)

    Blazer, V.; Vogelbein, W.K.; Densmore, C.; Kator, H.; Zwerner, D.; Lilley, J.

    2000-01-01

    The toxic dinoflagellate, Pfiesteria piscicida, is widely blamed for adverse human health effects, acute fish kills and skin lesion events in fishes, particularly menhaden, Brevoortia tyrannis, inhabiting coastal waters from Delaware to North Carolina, USA. In response, we initiated studies to clarify the etiology and pathogenesis of presumed 'Pfiesteria-specific' menhaden skin lesions. Histopathologically, all lesions (>150 fish examined) were associated with a highly invasive and pathogenic fungus eliciting severe tissue necrosis and intense granulomatous inflammation. Severity and extent of the host response indicates that ulcers were at least 1 week old or older. Maryland and Virginia currently use menhaden ulcers as one of several indicators of local Pfiesteria activity. However, their chronic nature, advanced age, and consistent fungal involvement suggest that their use for this purpose may not be valid. We recently isolated an Aphanomyces sp. from the menhaden lesions which by appearance in culture, temperature growth curves, pathogenicity studies in snakehead and positive immunohistochemical staining with polyclonal antibodies suggest the infectious agent is A. invadans (cause of epizootic ulcerative syndrome in Asia, Japan and Australia) or a very closely related species. Ongoing research will address pathogenicity of the fungus in menhaden, genetic comparisons of isolates, and the role of environmental stressors, including P. piscicida, in initiation of the infection. Copyright (C) 2000.

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

    Science.gov (United States)

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

    2015-11-01

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

  15. 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.

  16. Arabidopsis late blight: infection of a nonhost plant by Albugo laibachii enables full colonization by Phytophthora infestans.

    Science.gov (United States)

    Belhaj, Khaoula; Cano, Liliana M; Prince, David C; Kemen, Ariane; Yoshida, Kentaro; Dagdas, Yasin F; Etherington, Graham J; Schoonbeek, Henk-Jan; van Esse, H Peter; Jones, Jonathan D G; Kamoun, Sophien; Schornack, Sebastian

    2017-01-01

    The oomycete pathogen Phytophthora infestans causes potato late blight, and as a potato and tomato specialist pathogen, is seemingly poorly adapted to infect plants outside the Solanaceae. Here, we report the unexpected finding that P. infestans can infect Arabidopsis thaliana when another oomycete pathogen, Albugo laibachii, has colonized the host plant. The behaviour and speed of P. infestans infection in Arabidopsis pre-infected with A. laibachii resemble P. infestans infection of susceptible potato plants. Transcriptional profiling of P. infestans genes during infection revealed a significant overlap in the sets of secreted-protein genes that are induced in P. infestans upon colonization of potato and susceptible Arabidopsis, suggesting major similarities in P. infestans gene expression dynamics on the two plant species. Furthermore, we found haustoria of A. laibachii and P. infestans within the same Arabidopsis cells. This Arabidopsis-A. laibachii-P. infestans tripartite interaction opens up various possibilities to dissect the molecular mechanisms of P. infestans infection and the processes occurring in co-infected Arabidopsis cells.

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

    Science.gov (United States)

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

    2015-02-01

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

  18. Comparative Analyses of Exoproteinases Produced by Three Phytopathogenic Microorganisms

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    Tatiana A. Valueva

    2011-01-01

    Full Text Available Proteinases secreted by the oomycete Phytophthora infestans (Mont. de Bary, Rhizoctonia solani, and Fusarium culmorum belonging to different families of fungi have been studied to determine if the exoenzyme secretion depends on the environmental conditions and the phylogenetic position of the pathogen. The substrate specificity of the extracellular proteinases of F. culmorum, R. solani, and P. infestans and their sensitivity to the action of synthetic and protein inhibitors suggest that they contain trypsin-like and subtilisin-like enzymes regardless of culture medium composition. The relation of trypsin-like and subtilisin-like enzymes is dependent on the culture medium composition, especially on the form of nitrogen nutrition, particularly in the case of the exoenzymes secreted by R. solani. Phylogenetic analyses have shown that the exoproteinase set of ascomycetes and oomycetes has more similarities than basidiomycetes although they are more distant relatives. Our data suggests that the multiple proteinases secreted by pathogenic fungi could play different roles in pathogenesis, increasing the adaptability and host range, or could have different functions in survival in various ecological habitats outside the host.

  19. Seed defensins of barnyard grass Echinochloa crusgalli (L.) Beauv.

    Science.gov (United States)

    Odintsova, Tatyana I; Rogozhin, Eugene A; Baranov, Yurij; Musolyamov, Alexander Kh; Yalpani, Nasser; Egorov, Tsezi A; Grishin, Eugene V

    2008-01-01

    From the annual weed barnyard grass Echinochloa crusgalli (L.) Beauv., two novel defensins Ec-AMP-D1 and Ec-AMP-D2 that differ by a single amino acid substitution were isolated by a combination of different chromatographic procedures. Both defensins were active against several phytopathogenic fungi and the oomycete Phytophthora infestans at micromolar concentrations. The Ec-AMP-D1 showed higher activity against the oomycete than Ec-AMP-D2. The comparison of the amino acid sequences of the antifungal E. crusgalli defensins with those of earlier characterized T. kiharae defensins [T.I. Odintsova, Ts.A. Egorov, A.Kh. Musolyamov, M.S. Odintsova, V.A. Pukhalsky, E.V. Grishin, Seed defensins from T. kiharae and related species: genome localization of defensin-encoding genes, Biochimie, 89 (2007) 605-612.] that were devoid of substantial antifungal activity point to the C-terminal region of the molecule as the main determinant of the antifungal activity of E. crusgalli defensins.

  20. Elucidating the Diversity of Aquatic Microdochium and Trichoderma Species and Their Activity against the Fish Pathogen Saprolegnia diclina.

    Science.gov (United States)

    Liu, Yiying; Zachow, Christin; Raaijmakers, Jos M; de Bruijn, Irene

    2016-01-21

    Animals and plants are increasingly threatened by emerging fungal and oomycete diseases. Amongst oomycetes, Saprolegnia species cause population declines in aquatic animals, especially fish and amphibians, resulting in significant perturbation in biodiversity, ecological balance and food security. Due to the prohibition of several chemical control agents, novel sustainable measures are required to control Saprolegnia infections in aquaculture. Previously, fungal community analysis by terminal restriction fragment length polymorphism (T-RFLP) revealed that the Ascomycota, specifically the genus Microdochium, was an abundant fungal phylum associated with salmon eggs from a commercial fish farm. Here, phylogenetic analyses showed that most fungal isolates obtained from salmon eggs were closely related to Microdochium lycopodinum/Microdochium phragmitis and Trichoderma viride species. Phylogenetic and quantitative PCR analyses showed both a quantitative and qualitative difference in Trichoderma population between diseased and healthy salmon eggs, which was not the case for the Microdochium population. In vitro antagonistic activity of the fungi against Saprolegnia diclina was isolate-dependent; for most Trichoderma isolates, the typical mycoparasitic coiling around and/or formation of papilla-like structures on S. diclina hyphae were observed. These results suggest that among the fungal community associated with salmon eggs, Trichoderma species may play a role in Saprolegnia suppression in aquaculture.

  1. An RLP23-SOBIR1-BAK1 complex mediates NLP-triggered immunity.

    Science.gov (United States)

    Albert, Isabell; Böhm, Hannah; Albert, Markus; Feiler, Christina E; Imkampe, Julia; Wallmeroth, Niklas; Brancato, Caterina; Raaymakers, Tom M; Oome, Stan; Zhang, Heqiao; Krol, Elzbieta; Grefen, Christopher; Gust, Andrea A; Chai, Jijie; Hedrich, Rainer; Van den Ackerveken, Guido; Nürnberger, Thorsten

    2015-10-05

    Plants and animals employ innate immune systems to cope with microbial infection. Pattern-triggered immunity relies on the recognition of microbe-derived patterns by pattern recognition receptors (PRRs). Necrosis and ethylene-inducing peptide 1-like proteins (NLPs) constitute plant immunogenic patterns that are unique, as these proteins are produced by multiple prokaryotic (bacterial) and eukaryotic (fungal, oomycete) species. Here we show that the leucine-rich repeat receptor protein (LRR-RP) RLP23 binds in vivo to a conserved 20-amino-acid fragment found in most NLPs (nlp20), thereby mediating immune activation in Arabidopsis thaliana. RLP23 forms a constitutive, ligand-independent complex with the LRR receptor kinase (LRR-RK) SOBIR1 (Suppressor of Brassinosteroid insensitive 1 (BRI1)-associated kinase (BAK1)-interacting receptor kinase 1), and recruits a second LRR-RK, BAK1, into a tripartite complex upon ligand binding. Stable, ectopic expression of RLP23 in potato (Solanum tuberosum) confers nlp20 pattern recognition and enhanced immunity to destructive oomycete and fungal plant pathogens, such as Phytophthora infestans and Sclerotinia sclerotiorum. PRRs that recognize widespread microbial patterns might be particularly suited for engineering immunity in crop plants.

  2. Changing Ploidy as a Strategy: The Irish Potato Famine Pathogen Shifts Ploidy in Relation to Its Sexuality.

    Science.gov (United States)

    Li, Ying; Shen, He; Zhou, Qian; Qian, Kun; van der Lee, Theo; Huang, Sanwen

    2017-01-01

    The oomycete Phytophthora infestans was the causal agent of the Irish Great Famine and is a recurring threat to global food security. The pathogen can reproduce both sexually and asexually, with high potential to adapt to various environments and great risk to break disease resistance genes in potato. As are other oomycetes, P. infestans is regarded to be diploid during the vegetative phase of its life cycle, although some studies reported trisomy and polyploidy. Using microsatellite fingerprinting, genome-wide assessment of single nucleotide polymorphisms, nuclear DNA quantification, and microscopic counting of chromosome numbers, we assessed the ploidy level of a comprehensive selection of isolates. All progenies from sexual populations of P. infestans in nature were found to be diploid, in contrast nearly all dominant asexual lineages, including the most important pandemic clonal lineages US-1 and 13_A2 were triploid. Such triploids possess significantly more allelic variation than diploids. We observed that triploid genotype can change to a diploid genome constitution when exposed to artificial stress conditions. This study reveals that fluctuations in the ploidy level may be a key factor in the adaptation process of this notorious plant destroyer and imposes an extra challenge to control this disease.

  3. Effector identification in the lettuce downy mildew Bremia lactucae by massively parallel transcriptome sequencing.

    Science.gov (United States)

    Stassen, Joost H M; Seidl, Michael F; Vergeer, Pim W J; Nijman, Isaäc J; Snel, Berend; Cuppen, Edwin; Van den Ackerveken, Guido

    2012-09-01

    Lettuce downy mildew (Bremia lactucae) is a rapidly adapting oomycete pathogen affecting commercial lettuce cultivation. Oomycetes are known to use a diverse arsenal of secreted proteins (effectors) to manipulate their hosts. Two classes of effector are known to be translocated by the host: the RXLRs and Crinklers. To gain insight into the repertoire of effectors used by B. lactucae to manipulate its host, we performed massively parallel sequencing of cDNA derived from B. lactucae spores and infected lettuce (Lactuca sativa) seedlings. From over 2.3 million 454 GS FLX reads, 59 618 contigs were assembled representing both plant and pathogen transcripts. Of these, 19 663 contigs were determined to be of B. lactucae origin as they matched pathogen genome sequences (SOLiD) that were obtained from >270 million reads of spore-derived genomic DNA. After correction of cDNA sequencing errors with SOLiD data, translation into protein models and filtering, 16 372 protein models remained, 1023 of which were predicted to be secreted. This secretome included elicitins, necrosis and ethylene-inducing peptide 1-like proteins, glucanase inhibitors and lectins, and was enriched in cysteine-rich proteins. Candidate host-translocated effectors included 78 protein models with RXLR effector features. In addition, we found indications for an unknown number of Crinkler-like sequences. Similarity clustering of secreted proteins revealed additional effector candidates. We provide a first look at the transcriptome of B. lactucae and its encoded effector arsenal.

  4. MAMP (Microbe-Associated Molecular Pattern triggered immunity in Plants

    Directory of Open Access Journals (Sweden)

    Mari-Anne eNewman

    2013-05-01

    Full Text Available Plants are sessile organisms that are under constant attack from microbes. They rely on both preformed defenses, and their innate immune system to ward of the microbial pathogens. Preformed defences include for example the cell wall and cuticle, which act as physical barriers to microbial colonization. The plant immune system is composed of surveillance systems that perceive several general microbe elicitors, which allow plants to switch from growth and development into a defense mode, rejecting most potentially harmful microbes. The elicitors are essential structures for pathogen survival and are conserved among pathogens. The conserved microbe-specific molecules, referred to as microbe- or pathogen-associated molecular patterns (MAMPs or PAMPs, are recognized by the plant innate immune systems pattern recognition receptors (PRRs. General elicitors like flagellin (Flg, elongation factor Tu (EF-Tu, peptidoglycan (PGN, lipopolysaccharides (LPS, Ax21 (Activator of XA21-mediated immunity in rice, fungal chitin and β-glucans from oomycetes are recognized by plant surface localized PRRs. Several of the MAMPs and their corresponding PRRs have, in recent years, been identified. This review focuses on the current knowledge regarding important MAMPs from bacteria, fungi and oomycetes, their structure, the plant PRRs that recognizes them, and how they induce MAMP-triggered immunity (MTI in plants.

  5. Expression in Escherichia coli, purification, refolding and antifungal activity of an osmotin from Solanum nigrum

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    Magalhães Cláudio P

    2008-03-01

    Full Text Available Abstract Background Heterologous protein expression in microorganisms may contribute to identify and demonstrate antifungal activity of novel proteins. The Solanum nigrum osmotin-like protein (SnOLP gene encodes a member of pathogenesis-related (PR proteins, from the PR-5 sub-group, the last comprising several proteins with different functions, including antifungal activity. Based on deduced amino acid sequence of SnOLP, computer modeling produced a tertiary structure which is indicative of antifungal activity. Results To validate the potential antifungal activity of SnOLP, a hexahistidine-tagged mature SnOLP form was overexpressed in Escherichia coli M15 strain carried out by a pQE30 vector construction. The urea solubilized His6-tagged mature SnOLP protein was affinity-purified by immobilized-metal (Ni2+ affinity column chromatography. As SnOLP requires the correct formation of eight disulfide bonds, not correctly formed in bacterial cells, we adapted an in vitro method to refold the E. coli expressed SnOLP by using reduced:oxidized gluthatione redox buffer. This method generated biologically active conformations of the recombinant mature SnOLP, which exerted antifungal action towards plant pathogenic fungi (Fusarium solani f. sp.glycines, Colletotrichum spp., Macrophomina phaseolina and oomycete (Phytophthora nicotiana var. parasitica under in vitro conditions. Conclusion Since SnOLP displays activity against economically important plant pathogenic fungi and oomycete, it represents a novel PR-5 protein with promising utility for biotechnological applications.

  6. Expression in Escherichia coli, purification, refolding and antifungal activity of an osmotin from Solanum nigrum

    Science.gov (United States)

    Campos, Magnólia de A; Silva, Marilia S; Magalhães, Cláudio P; Ribeiro, Simone G; Sarto, Rafael PD; Vieira, Eduardo A; Grossi de Sá, Maria F

    2008-01-01

    Background Heterologous protein expression in microorganisms may contribute to identify and demonstrate antifungal activity of novel proteins. The Solanum nigrum osmotin-like protein (SnOLP) gene encodes a member of pathogenesis-related (PR) proteins, from the PR-5 sub-group, the last comprising several proteins with different functions, including antifungal activity. Based on deduced amino acid sequence of SnOLP, computer modeling produced a tertiary structure which is indicative of antifungal activity. Results To validate the potential antifungal activity of SnOLP, a hexahistidine-tagged mature SnOLP form was overexpressed in Escherichia coli M15 strain carried out by a pQE30 vector construction. The urea solubilized His6-tagged mature SnOLP protein was affinity-purified by immobilized-metal (Ni2+) affinity column chromatography. As SnOLP requires the correct formation of eight disulfide bonds, not correctly formed in bacterial cells, we adapted an in vitro method to refold the E. coli expressed SnOLP by using reduced:oxidized gluthatione redox buffer. This method generated biologically active conformations of the recombinant mature SnOLP, which exerted antifungal action towards plant pathogenic fungi (Fusarium solani f. sp.glycines, Colletotrichum spp., Macrophomina phaseolina) and oomycete (Phytophthora nicotiana var. parasitica) under in vitro conditions. Conclusion Since SnOLP displays activity against economically important plant pathogenic fungi and oomycete, it represents a novel PR-5 protein with promising utility for biotechnological applications. PMID:18334031

  7. Horizontal transfer of a nitrate assimilation gene cluster and ecological transitions in fungi: a phylogenetic study.

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    Jason C Slot

    Full Text Available High affinity nitrate assimilation genes in fungi occur in a cluster (fHANT-AC that can be coordinately regulated. The clustered genes include nrt2, which codes for a high affinity nitrate transporter; euknr, which codes for nitrate reductase; and NAD(PH-nir, which codes for nitrite reductase. Homologs of genes in the fHANT-AC occur in other eukaryotes and prokaryotes, but they have only been found clustered in the oomycete Phytophthora (heterokonts. We performed independent and concatenated phylogenetic analyses of homologs of all three genes in the fHANT-AC. Phylogenetic analyses limited to fungal sequences suggest that the fHANT-AC has been transferred horizontally from a basidiomycete (mushrooms and smuts to an ancestor of the ascomycetous mold Trichoderma reesei. Phylogenetic analyses of sequences from diverse eukaryotes and eubacteria, and cluster structure, are consistent with a hypothesis that the fHANT-AC was assembled in a lineage leading to the oomycetes and was subsequently transferred to the Dikarya (Ascomycota+Basidiomycota, which is a derived fungal clade that includes the vast majority of terrestrial fungi. We propose that the acquisition of high affinity nitrate assimilation contributed to the success of Dikarya on land by allowing exploitation of nitrate in aerobic soils, and the subsequent transfer of a complete assimilation cluster improved the fitness of T. reesei in a new niche. Horizontal transmission of this cluster of functionally integrated genes supports the "selfish operon" hypothesis for maintenance of gene clusters.

  8. 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

  9. The Novel Oomycide Oxathiapiprolin Inhibits All Stages in the Asexual Life Cycle of Pseudoperonospora cubensis - Causal Agent of Cucurbit Downy Mildew.

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    Yigal Cohen

    Full Text Available Oxathiapiprolin is a new oomycide (piperidinyl thiazole isoxazoline class discovered by DuPont which controls diseases caused by oomycete plant pathogens. It binds in the oxysterol-binding protein domain of Oomycetes. Growth chambers studies with detached leaves and potted plants showed remarkable activity of oxathiapiprolin against Pseudoperonospora cubensis in cucurbits. The compound affected all stages in the asexual life cycle of the pathogen. It inhibited zoospore release, cystospore germination, lesion formation, lesion expansion, sporangiophore development and sporangial production. When applied to the foliage as a preventive spray no lesions developed due to inhibition of zoospore release and cystospore germination, and when applied curatively, at one or two days after inoculation, small restricted lesions developed but no sporulation occurred. When applied later to mature lesions, sporulation was strongly inhibited. Oxathiapiprolin suppressed sporulation of P. cubensis in naturally-infected leaves. It exhibited trans-laminar activity, translocated acropetaly from older to younger leaves, and moved from the root system to the foliage. Seed coating was highly effective in protecting the developed cucumber plants against downy mildew. UV microscopy observations made with cucumber leaves infected with P. cubensis revealed that inhibition of mycelium growth and sporulation induced by oxathiapiprolin was associated with callose encasement of the haustoria.

  10. Insight into the adsorption profiles of the Saprolegnia monoica chitin synthase MIT domain on POPA and POPC membranes by molecular dynamics simulation studies.

    Science.gov (United States)

    Kuang, Guanglin; Liang, Lijun; Brown, Christian; Wang, Qi; Bulone, Vincent; Tu, Yaoquan

    2016-02-21

    The critical role of chitin synthases in oomycete hyphal tip growth has been established. A microtubule interacting and trafficking (MIT) domain was discovered in the chitin synthases of the oomycete model organism, Saprolegnia monoica. MIT domains have been identified in diverse proteins and may play a role in intracellular trafficking. The structure of the Saprolegnia monoica chitin synthase 1 (SmChs1) MIT domain has been recently determined by our group. However, although our in vitro assay identified increased strength in interactions between the MIT domain and phosphatidic acid (PA) relative to other phospholipids including phosphatidylcholine (PC), the mechanism used by the MIT domain remains unknown. In this work, the adsorption behavior of the SmChs1 MIT domain on POPA and POPC membranes was systematically investigated by molecular dynamics simulations. Our results indicate that the MIT domain can adsorb onto the tested membranes in varying orientations. Interestingly, due to the specific interactions between MIT residues and lipid molecules, the binding affinity to the POPA membrane is much higher than that to the POPC membrane. A binding hotspot, which is critical for the adsorption of the MIT domain onto the POPA membrane, was also identified. The lower binding affinity to the POPC membrane can be attributed to the self-saturated membrane surface, which is unfavorable for hydrogen-bond and electrostatic interactions. The present study provides insight into the adsorption profile of SmChs1 and additionally has the potential to improve our understanding of other proteins containing MIT domains.

  11. 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.

  12. 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.

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

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    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.

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

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    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.

  15. Development of eukaryotic zoospores within polycyclic aromatic hydrocarbon (PAH)-polluted environments: a set of behaviors that are relevant for bioremediation.

    Science.gov (United States)

    Sungthong, Rungroch; van West, Pieter; Cantos, Manuel; Ortega-Calvo, Jose Julio

    2015-04-01

    In this study, we assessed the development (formation, taxis and settlement) of eukaryotic zoospores under different regimes of exposure to polycyclic aromatic hydrocarbons (PAHs), which imitated environmental scenarios of pollution and bioremediation. With this aim, we used an oomycete, Pythium aphanidermatum, as a source of zoospores and two PAH-degrading bacteria (Mycobacterium gilvum VM552 and Pseudomonas putida G7). The oomycete and both bacteria were not antagonistic, and zoospore formation was diminished only in the presence of the highest bacterial cell density (10(8)-10(10) colony-forming units mL(-1)). A negative influence of PAHs on zoospore formation and taxis was observed when PAHs were exposed in combination with organic solutions and polar solvents. Co-exposure of PAHs with non-polar solvents [hexadecane (HD) and 2,2,4,4,6,8,8-heptamethylnonane (HMN)] did not affect zoospore settlement at the interfaces of the organic solvents and water. However, zoospores settled and created mycelial networks only at HD-water interfaces. Both bacteria diminished the toxic influence of PAHs on zoospore formation and taxis, and they did not interrupt zoospore settlement. The results suggest that zoospore development could be applicable for toxicity assessment of PAHs and enhancement of their bioavailability. Microbial interactions during both swimming modes and community formation at pollutant interfaces were revealed as major factors that have potential relevance to bioremediation.

  16. Activation of Pathogenesis-related Genes by the Rhizobacterium, Bacillus sp. JS, Which Induces Systemic Resistance in Tobacco Plants

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    Ji-Seong Kim

    2015-06-01

    Full Text Available Plant growth promoting rhizobacteria (PGPR are known to confer disease resistance to plants. Bacillus sp. JS demonstrated antifungal activities against five fungal pathogens in in vitro assays. To verify whether the volatiles of Bacillus sp. JS confer disease resistance, tobacco leaves pre-treated with the volatiles were damaged by the fungal pathogen, Rhizoctonia solani and oomycete Phytophthora nicotianae. Pre-treated tobacco leaves had smaller lesion than the control plant leaves. In pathogenesis-related (PR gene expression analysis, volatiles of Bacillus sp. JS caused the up-regulation of PR-2 encoding β-1,3-glucanase and acidic PR-3 encoding chitinase. Expression of acidic PR-4 encoding chitinase and acidic PR-9 encoding peroxidase increased gradually after exposure of the volatiles to Bacillus sp. JS. Basic PR-14 encoding lipid transfer protein was also increased. However, PR-1 genes, as markers of salicylic acid (SA induced resistance, were not expressed. These results suggested that the volatiles of Bacillus sp. JS confer disease resistance against fungal and oomycete pathogens through PR genes expression.

  17. Scientifically advanced solutions for chestnut ink disease.

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    Choupina, Altino Branco; Estevinho, Letícia; Martins, Ivone M

    2014-05-01

    On the north regions of Portugal and Spain, the Castanea sativa Mill. culture is extremely important. The biggest productivity and yield break occurs due to the ink disease, the causal agent being the oomycete Phytophthora cinnamomi. This oomycete is also responsible for the decline of many other plant species in Europe and worldwide. P. cinnamomi and Phytophthora cambivora are considered, by the generality of the authors, as the C. sativa ink disease causal agents. Most Phytophthora species secrete large amounts of elicitins, a group of unique highly conserved proteins that are able to induce hypersensitive response (HR) and enhances plant defense responses in a systemic acquired resistance (SAR) manner against infection by different pathogens. Some other proteins involved in mechanisms of infection by P. cinnamomi were identified by our group: endo-1,3-beta-glucanase (complete cds); exo-glucanase (partial cds) responsible by adhesion, penetration, and colonization of host tissues; glucanase inhibitor protein (GIP) (complete cds) responsible by the suppression of host defense responses; necrosis-inducing Phytophthora protein 1 (NPP1) (partial cds); and transglutaminase (partial cds) which inducts defense responses and disease-like symptoms. In this mini-review, we present some scientifically advanced solutions that can contribute to the resolution of ink disease.

  18. Eukaryotic pathogens (Chytridiomycota and Oomycota) infecting marine microphytobenthic diatoms - a methodological comparison.

    Science.gov (United States)

    Scholz, Bettina; Küpper, Frithjof C; Vyverman, Wim; Karsten, Ulf

    2014-12-01

    Using sediment samples from the Solthörn tidal flat (southern North Sea, Germany), collected in bi-weekly intervals from June to July 2012, a range of qualitative and quantitative screening methods for oomycete and chytrid pathogens infecting benthic diatoms were evaluated. Pre-treatment of sediment samples using short ultrasound pulses and gradient centrifugation, in combination with CalcoFluor White, showed the best results in the visualization of both pathogen groups. The highest number of infected benthic diatoms was observed in mid July (5.8% of the total benthic diatom community). Most infections were caused by chytrids and, in a few cases, oomycetes (Lagenisma Drebes (host: Coscinodiscus radiatus Ehrenberg) and Ectrogella Zopf (hosts: Dimeregramma minor in Pritchard and Gyrosigma peisonis). Among the chytrids, sporangium morphology indicated the presence of five different morphotypes, infecting mainly epipelic taxa of the orders Naviculales (e.g., Navicula digitoradiata) and Achnanthales (e.g., Achnanthes brevipes Agardh). The presence of multiple pathogens in several epipelic diatom taxa suggests a significant role for fungal parasitism in affecting microphytobenthic diatom succession. © 2014 Phycological Society of America.

  19. A role in immunity for Arabidopsis cysteine protease RD21, the ortholog of the tomato immune protease C14.

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    Takayuki Shindo

    Full Text Available Secreted papain-like Cys proteases are important players in plant immunity. We previously reported that the C14 protease of tomato is targeted by cystatin-like EPIC proteins that are secreted by the oomycete pathogen Phytophthora infestans (Pinf during infection. C14 has been under diversifying selection in wild potato species coevolving with Pinf and reduced C14 levels result in enhanced susceptibility for Pinf. Here, we investigated the role C14-EPIC-like interactions in the natural pathosystem of Arabidopsis with the oomycete pathogen Hyaloperonospora arabidopsidis (Hpa. In contrast to the Pinf-solanaceae pathosystem, the C14 orthologous protease of Arabidopsis, RD21, does not evolve under diversifying selection in Arabidopsis, and rd21 null mutants do not show phenotypes upon compatible and incompatible Hpa interactions, despite the evident lack of a major leaf protease. Hpa isolates express highly conserved EPIC-like proteins during infections, but it is unknown if these HpaEPICs can inhibit RD21 and one of these HpaEPICs even lacks the canonical cystatin motifs. The rd21 mutants are unaffected in compatible and incompatible interactions with Pseudomonas syringae pv. tomato, but are significantly more susceptible for the necrotrophic fungal pathogen Botrytis cinerea, demonstrating that RD21 provides immunity to a necrotrophic pathogen.

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

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    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

  1. A novel murrel Channa striatus mitochondrial manganese superoxide dismutase: gene silencing, SOD activity, superoxide anion production and expression.

    Science.gov (United States)

    Arockiaraj, Jesu; Palanisamy, Rajesh; Bhatt, Prasanth; Kumaresan, Venkatesh; Gnanam, Annie J; Pasupuleti, Mukesh; Kasi, Marimuthu

    2014-12-01

    We have reported the molecular characterization including gene silencing, superoxide activity, superoxide anion production, gene expression and molecular characterization of a mitochondrial manganese superoxide dismutase (mMnSOD) from striped murrel Channa striatus (named as CsmMnSOD). The CsmMnSOD polypeptide contains 225 amino acids with a molecular weight of 25 kDa and a theoretical isoelectric point of 8.3. In the N-terminal region, CsmMnSOD carries a mitochondrial targeting sequence and a superoxide dismutases (SOD) Fe domain (28-109), and in C-terminal region, it carries another SOD Fe domain (114-220). The CsmMnSOD protein sequence shared significant similarity with its homolog of MnSOD from rock bream Oplegnathus fasciatus (96%). The phylogenetic analysis showed that the CsmMnSOD fell in the clade of fish mMnSOD group. The monomeric structure of CsmMnSOD possesses 9 α-helices (52.4%), 3 β-sheets (8.8%) and 38.8% random coils. The highest gene expression was noticed in liver, and its expression was inducted with fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila) infections. The gene silencing results show that the fish that received dsRNA exhibited significant (P superoxide anion production was determined by calculating the granular blood cell count during infection in murrel. It shows that the infection influenced the superoxide radical production which plays a major role in killing the pathogens. Overall, this study indicated the defense potentiality of CsmMnSOD; however, further research is necessary to explore its capability at protein level.

  2. Inhibitory effects of macrotetrolides from Streptomyces spp. on zoosporogenesis and motility of peronosporomycete zoospores are likely linked with enhanced ATPase activity in mitochondria

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    Md Tofazzal Islam

    2016-11-01

    Full Text Available The release of zoospores from sporangia and motility of the released zoospores are critical in the disease cycle of the Peronosporomycetes that cause devastating diseases in plants, fishes, animals and humans. Disruption of any of these asexual life stages eliminates the possibility of pathogenesis. In the course of screening novel bioactive secondary metabolites, we found that extracts of some strains of marine Streptomyces spp. rapidly impaired motility and caused subsequent lysis of zoospores of the grapevine downy mildew pathogen Plasmopara viticola at 10 g/ml. We tested a number of secondary metabolites previously isolated from these strains and found that macrotetrolide antibiotics such as nonactin, monactin, dinactin and trinactin, and nactic acids such as (+-nonactic acid, (+-homonactic acid, nonactic acid methyl ester, homonactic acid methyl ester, bonactin and feigrisolide C impaired motility and caused subsequent lysis of P. viticola zoospores in a dose- and time-dependent manners with dinactin being the most active compound (MIC 0.3 g/ml. A cation channel-forming compound, gramicidin, and a carrier of monovalent cations, nigericin also showed similar biological activities. Among all 12 compounds tested, gramicidin most potently arrested the motility of zoospores at concentrations starting from 0.1 g/ml. All macrotetrolide antibiotics also displayed similar motility impairing activities against P. viticola, Phytophthora capsici and Aphanomyces cochlioides zoospores indicating non-specific biological effects of these compounds towards peronosporomyctes. Furthermore, macrotetrolide antibiotics and gramicidin also markedly suppressed the release of zoospores from sporangia of P. viticola in a dose-dependent manner. As macrotetrolide antibiotics and gramicidin are known as enhancers of mitochondrial ATPase activity, inhibition of zoosporogenesis and motility of zoospores by these compounds are likely linked with hydrolysis of ATP

  3. Coagulation profile, gene expression and bioinformatics characterization of coagulation factor X of striped murrel Channa striatus.

    Science.gov (United States)

    Arasu, Abirami; Kumaresan, Venkatesh; Sathyamoorthi, Akila; Arasu, Mariadhas Valan; Al-Dhabi, Naif Abdullah; Arockiaraj, Jesu

    2016-08-01

    A transcriptome wide analysis of the constructed cDNA library of snakehead murrel Channa striatus revealed a full length cDNA sequence of coagulation factor X. Sequence analysis of C. striatus coagulation factor X (CsFX) showed that the cDNA contained 1232 base pairs (bp) comprising 1209 bp open reading frame (ORF). The ORF region encodes 424 amino acids with a molecular mass of 59 kDa. The polypeptide contains γ-carboxyglutamic acid (GLA) rich domain and two epidermal growth factor (EGF) like domains including EGF-CA domain and serine proteases trypsin signature profile. CsFX exhibited the maximum similarity with fish species such as Stegastes partitus (78%), Poecilia formosa (76%) and Cynoglossus semilaevis (74%). Phylogenetically, CsFX is clustered together with the fish group belonging to Actinopterygii. Secondary structure of factor X includes alpha helix 28.54%, extended strand 20.75%, beta turn 7.78% and random coil 42.92%. A predicted 3D model of CsFX revealed a short α-helix and a Ca(2+) (Gla domain) binding site in the coil. Four disulfide bridges were found in serine protease trypsin profile. Obviously, the highest gene expression (P < 0.05) was noticed in blood. Further, the changes in expression of CsFX was observed after inducing with bacterial (Aeromonas hydrophila) and fungal (Aphanomyces invadans) infections and other synthetic immune stimulants. Variation in blood clotting time (CT), prothrombin time (PT) and activated prothromboplastin time (APTT) was analyzed and compared between healthy and bacterial infected fishes. During infection, PT and APTT showed a declined clotting time due to the raised level of thrombocytes.

  4. An upstream initiator caspase 10 of snakehead murrel Channa striatus, containing DED, p20 and p10 subunits: molecular cloning, gene expression and proteolytic activity.

    Science.gov (United States)

    Arockiaraj, Jesu; Gnanam, Annie J; Muthukrishnan, Dhanaraj; Pasupuleti, Mukesh; Milton, James; Singh, Arun

    2013-02-01

    Caspase 10 (CsCasp10) was identified from a constructed cDNA library of freshwater murrel (otherwise called snakehead) Channa striatus. The CsCasp10 is 1838 base pairs (bp) in length and it is encoding 549 amino acid (aa) residues. CsCasp10 amino acid contains two death effector domains (DED) in the N-terminal at 2-77 and 87-154 and it contains caspase family p20 domain (large subunit) and caspase family p10 domain (small subunit) in the C-terminal at 299-425 and 449-536 respectively. Pairwise analysis of CsCasp10 showed the highest sequence similarity (79%) with caspase 10 of Paralichthys olivaceus. Moreover, the phylogenetic analysis showed that CsCasp10 is clustered together with other fish caspase 10, formed a sister group with caspase 10 from other lower vertebrates including amphibian, reptile and birds and finally clustered together with higher vertebrates such as mammals. Significantly (P < 0.05) highest CsCasp10 gene expression was noticed in gills and lowest in intestine. Furthermore, the CsCasp10 gene expression in C. striatus was up-regulated in gills by fungus Aphanomyces invadans and bacteria Aeromonas hydrophila induction. The proteolytic activity was analyzed using the purified recombinant CsCasp10 protein. The results showed the proteolytic activity of CsCasp10 for caspase 10 substrate was 2.5 units per μg protein. Moreover, the proteolytic activities of CsCasp10 in kidney and spleen induced by A. invadans and A. hydrophila stimulation were analyzed by caspase 10 activity assay kit. All these results showed that CsCasp10 are participated in immunity of C. striatus against A. invadans and A. hydrophila infection.

  5. The alternative Medicago truncatula defense proteome of ROS – defective transgenic roots during early microbial infection

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    Leonard Muriithi Kiirika

    2014-07-01

    Full Text Available ROP-type GTPases of plants function as molecular switches within elementary signal transduction pathways such as the regulation of ROS synthesis via activation of NADPH oxidases (RBOH-respiratory burst oxidase homologue in plants. Previously, we reported that silencing of the Medicago truncatula GTPase MtROP9 led to reduced ROS production and suppressed induction of ROS-related enzymes in transgenic roots (MtROP9i infected with pathogenic (Aphanomyces euteiches and symbiotic microorganisms (Glomus intraradices, Sinorhizobium meliloti. While fungal infections were enhanced, S. meliloti infection was drastically impaired. In this study, we investigate the temporal proteome response of M. truncatula MtROP9i transgenic roots during the same microbial interactions under conditions of deprived potential to synthesize ROS. In comparison with control roots (Mtvector, we present a comprehensive proteomic analysis using sensitive MS protein identification. For four early infection time-points (1, 3, 5, 24 hpi, 733 spots were found to be different in abundance: 213 spots comprising 984 proteins (607 unique were identified after S. meliloti infection, 230 spots comprising 796 proteins (580 unique after G. intraradices infection, and 290 spots comprising 1240 proteins (828 unique after A. euteiches infection. Data evaluation by GelMap in combination with a heatmap tool allowed recognition of key proteome changes during microbial interactions under conditions of hampered ROS synthesis. Overall, the number of induced proteins in MtROP9i was low as compared with controls, indicating a dual function of ROS in defense signaling as well as alternative response patterns activated during microbial infection. Qualitative analysis of induced proteins showed that enzymes linked to ROS production and scavenging were highly induced in control roots, while in MtROP9i the majority of proteins were involved in alternative defense pathways such as cell wall and protein

  6. Parasitism of Xiphinema rivesi and X. americanum by Zoosporic Fungi.

    Science.gov (United States)

    Jafee, B A

    1986-01-01

    Living Xiphinema americanum (Xa) and X. rivesi (Xr) extracted from soil samples and stored for 1-5 days at 4 or 20 C contained aseptate fungal hyphae. The fungi directly penetrated the nematode's cuticle from spores encysted near the head. Penetration through the stoma, vulva, or anus was rare. Catenaria anguillulae (Cat), Lagenidium caudatura (Lag), Aphanomyces sp. (Aph), and Leptolegnia sp. (Lep) were isolated into pure culture from infected nematodes. The pathogenicity of these zoosporic fungi was determined by incubating mixed freshly extracted Xa and Xr in 2% soil extract (pH = 6.7, conductivity = 48 mumhos, 20 +/- 2 C) containing zoospores obtained from single-spore isolates. After 4 days, Cat, Lag, Aph, and Lep had infected 78, 18, 13, and 22%, respectively, of the nematodes. Both Xa and Xr were infected by every fungus; however, the relative susceptibility of Xa and Xr to these fungi was not determined. All noninoculated control nematodes remained uninfected and alive. In a second experiment, parasitism of Xa and Xr by Aph and Lep was increased when nematodes were incubated in 2% soil extract for 4 days before exposure to zoospores. In a third experiment, parasitism of Xa and Xr by Cat was greater in diluted saturation soil extract (conductivity = 100-400 mumhos) than in undiluted saturation extract (conductivity = 780 mumhos). Cat produced small zoospores (4-mum-d), bulbous infection hyphae, and assimilative hyphae of varying diameters in nematodes, whereas Lag, Aph, and Lep produced large zoospores (8-mum-d) and tubular, uniform infection and assimilative hyphae in nematodes.

  7. The nucleotide sequence and genome organization of Plasmopara halstedii virus

    Directory of Open Access Journals (Sweden)

    Göpfert Jens C

    2011-03-01

    Full Text Available Abstract Background Only very few viruses of Oomycetes have been studied in detail. Isometric virions were found in different isolates of the oomycete Plasmopara halstedii, the downy mildew pathogen of sunflower. However, complete nucleotide sequences and data on the genome organization were lacking. Methods Viral RNA of different P. halstedii isolates was subjected to nucleotide sequencing and analysis of the viral genome. The N-terminal sequence of the viral coat protein was determined using Top-Down MALDI-TOF analysis. Results The complete nucleotide sequences of both single-stranded RNA segments (RNA1 and RNA2 were established. RNA1 consisted of 2793 nucleotides (nt exclusive its 3' poly(A tract and a single open-reading frame (ORF1 of 2745 nt. ORF1 was framed by a 5' untranslated region (5' UTR of 18 nt and a 3' untranslated region (3' UTR of 30 nt. ORF1 contained motifs of RNA-dependent RNA polymerases (RdRp and showed similarities to RdRp of Scleropthora macrospora virus A (SmV A and viruses within the Nodaviridae family. RNA2 consisted of 1526 nt exclusive its 3' poly(A tract and a second ORF (ORF2 of 1128 nt. ORF2 coded for the single viral coat protein (CP and was framed by a 5' UTR of 164 nt and a 3' UTR of 234 nt. The deduced amino acid sequence of ORF2 was verified by nano-LC-ESI-MS/MS experiments. Top-Down MALDI-TOF analysis revealed the N-terminal sequence of the CP. The N-terminal sequence represented a region within ORF2 suggesting a proteolytic processing of the CP in vivo. The CP showed similarities to CP of SmV A and viruses within the Tombusviridae family. Fragments of RNA1 (ca. 1.9 kb and RNA2 (ca. 1.4 kb were used to analyze the nucleotide sequence variation of virions in different P. halstedii isolates. Viral sequence variation was 0.3% or less regardless of their host's pathotypes, the geographical origin and the sensitivity towards the fungicide metalaxyl. Conclusions The results showed the presence of a single and new

  8. The nucleotide sequence and genome organization of Plasmopara halstedii virus

    Science.gov (United States)

    2011-01-01

    Background Only very few viruses of Oomycetes have been studied in detail. Isometric virions were found in different isolates of the oomycete Plasmopara halstedii, the downy mildew pathogen of sunflower. However, complete nucleotide sequences and data on the genome organization were lacking. Methods Viral RNA of different P. halstedii isolates was subjected to nucleotide sequencing and analysis of the viral genome. The N-terminal sequence of the viral coat protein was determined using Top-Down MALDI-TOF analysis. Results The complete nucleotide sequences of both single-stranded RNA segments (RNA1 and RNA2) were established. RNA1 consisted of 2793 nucleotides (nt) exclusive its 3' poly(A) tract and a single open-reading frame (ORF1) of 2745 nt. ORF1 was framed by a 5' untranslated region (5' UTR) of 18 nt and a 3' untranslated region (3' UTR) of 30 nt. ORF1 contained motifs of RNA-dependent RNA polymerases (RdRp) and showed similarities to RdRp of Scleropthora macrospora virus A (SmV A) and viruses within the Nodaviridae family. RNA2 consisted of 1526 nt exclusive its 3' poly(A) tract and a second ORF (ORF2) of 1128 nt. ORF2 coded for the single viral coat protein (CP) and was framed by a 5' UTR of 164 nt and a 3' UTR of 234 nt. The deduced amino acid sequence of ORF2 was verified by nano-LC-ESI-MS/MS experiments. Top-Down MALDI-TOF analysis revealed the N-terminal sequence of the CP. The N-terminal sequence represented a region within ORF2 suggesting a proteolytic processing of the CP in vivo. The CP showed similarities to CP of SmV A and viruses within the Tombusviridae family. Fragments of RNA1 (ca. 1.9 kb) and RNA2 (ca. 1.4 kb) were used to analyze the nucleotide sequence variation of virions in different P. halstedii isolates. Viral sequence variation was 0.3% or less regardless of their host's pathotypes, the geographical origin and the sensitivity towards the fungicide metalaxyl. Conclusions The results showed the presence of a single and new virus type in

  9. 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.

  10. 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.

  11. Glycyrrhiza glabra extract protects plants against important phytopathogenic fungi.

    Science.gov (United States)

    Schuster, C; Konstantinidou-Doltsinis, S; Schmitt, A

    2010-01-01

    In previous investigations an ethanolic plant extract from Glycyrrhiza glabra (2.5% w/v) showed 100% efficacy against late blight (Phytophthora infestans) on detached tomato leaves. Based on these findings, the objective of this work was to investigate the effect of this extract against different important plant pathogenic fungi. Tests were carried out on potted plants. Against P. infestans, efficacies of 75% and 58% were achieved on tomato and potato plants with 5% extract concentration, respectively. Against another Oomycete, Pseudoperonospora cubensis, on cucumber, application of a 2.5% extract led to an efficacy of above 90%. The EC50-value was calculated to be 0.5% In a trial on beans against bean rust (Uromyces appendiculatus), G. glabra extract (5% concentration) showed 92% efficacy. In contrast, against powdery mildew on cucumber (Podosphaera xanthii), no disease reduction was found. Overall, the results indicate a high potential for the extract of G. glabra to control a number of important plant pathogens.

  12. Fighting fish (Betta splendens) bubble nests do not inhibit microbial growth.

    Science.gov (United States)

    Brown, Alexandria C; Clotfelter, Ethan D

    2012-12-01

    Some organisms produce antimicrobial substances in nesting foam to favorably manipulate the environment to which their developing offspring are exposed. We tested if fighting fish Betta splendens foamy nest material, which is comprised of bubbles produced in the oral cavity of nesting males, has antimicrobial properties against a pathogenic bacteria (Edwardsiella tarda), a nonpathogenic bacteria (Escherichia coli), or a pathogenic oomycete (Saprolegnia parasitica). We also tested if exposure to nest material increases larval survival by performing in vitro fertilizations and individually incubating eggs in bubble nest extract or tank water (control). Our results show no evidence of antimicrobial properties of bubble nests. On the contrary, bubble nests provided favorable microenvironments for the growth of Saprolegnia parasitica. Our results confirm earlier work citing the importance of male nest attendance, and suggest that the mechanism responsible for decreased survival in the absence of attending males is pathogenic microbes.

  13. Cytolytic toxins as triggers of plant immune response

    Science.gov (United States)

    Küfner, Isabell; Ottmann, Christian

    2009-01-01

    NEP1-like proteins (NLPs) are secreted proteins from fungi, oomycetes and bacteria, triggering immune responses and cell death in dicotyledonous plants. It has been unclear for a long time, whether NLPs are toxins or triggers of plant immunity. In a recent study we report that NLPs are toxins that exert cytolytic activity on dicotyledonous plants. Mutational analysis revealed a causal link between membrane damaging, cell death inducing and virulence promoting properties of NLPs. Interestingly, also induction of immune responses by NLPs required the same protein fold, providing evidence for damage-induced immunity in plants. Structural similarity to pore forming toxins from marine invertebrates allows the proposal of a model for the mode of NLP interaction with the host's membrane. PMID:19826219

  14. Novel, Pseudomonas-derived Antifungal Lipopeptides From A Disease Suppressive Soil In Greenlandic Potato Fields

    DEFF Research Database (Denmark)

    Hennessy, Rosanna Catherine; Michelsen, Charlotte F.; Glaring, Mikkel A.;

    2015-01-01

    Potato cultivation in southwest Greenland omits the use of pesticides, relies on limited crop rotations, and despite the presence of plant pathogenic fungi in the soil, has not suffered from severe disease outbreaks. In this presentation, the bacterial strain Pseudomonas sp. In5 which significantly...... contributes to the suppressiveness of soil at Inneruulalik in southern Greenland will be explored. A combination of molecular genetics and genomics coupled with matrix-assisted laser desorption ionization – time of flight (MALDI-TOF) imaging mass spectrometry (IMS) identified a large genomic island encoding...... the two non-ribosomal peptides nunapeptin and nunamycin, which are key components of the antifungal activity of In5. Bacterial-fungal interaction studies uncovered a complex interaction whereby nunamycin appears most active against Rhizoctonia solani with no antimicrobial effect against the oomycete...

  15. RNA-protein interactions in plant disease: hackers at the dinner table.

    Science.gov (United States)

    Spanu, Pietro D

    2015-09-01

    Plants are the source of most of our food, whether directly or as feed for the animals we eat. Our dinner table is a trophic level we share with the microbes that also feed on the primary photosynthetic producers. Microbes that enter into close interactions with plants need to evade or suppress detection and host immunity to access nutrients. They do this by deploying molecular tools - effectors - which target host processes. The mode of action of effector proteins in these events is varied and complex. Recent data from diverse systems indicate that RNA-interacting proteins and RNA itself are delivered by eukaryotic microbes, such as fungi and oomycetes, to host plants and contribute to the establishment of successful interactions. This is evidence that pathogenic microbes can interfere with the host software. We are beginning to see that pathogenic microbes are capable of hacking into the plants' immunity programs. © 2015 The Author. New Phytologist © 2015 New Phytologist Trust.

  16. Evolution of parasitic symbioses between plants and filamentous microorganisms.

    Science.gov (United States)

    Holub, Eric B

    2006-08-01

    Innate defense in wild plant populations is an invaluable resource for understanding how sustainable disease control can be achieved in crops through research that is rooted in molecular and evolutionary biology. Much progress has been made from molecular research into pathogen detection and defense induction. Bacterial pathology of the wild species Arabidopsis thaliana is at the forefront in revealing parallels with animal innate immunity against infectious diseases. In plants, unlike in animals, however, expansion in biodiversity has been mirrored by tremendous diversification in filamentous parasites. The fungal and oomycete pathology of Arabidopsis is exposing opportunities to investigate the molecular bases of compatibility, plant-driven speciation of parasites, and molecular epidemiology. Such research might reveal evidence that an arms race did occur in the evolution of plant-parasite symbioses.

  17. Phytopathogen effectors subverting host immunity: different foes, similar battleground.

    Science.gov (United States)

    Dou, Daolong; Zhou, Jian-Min

    2012-10-18

    Phytopathogenic bacteria, fungi, and oomycetes invade and colonize their host plants through distinct routes. These pathogens secrete diverse groups of effector proteins that aid infection and establishment of different parasitic lifestyles. Despite this diversity, a comparison of different plant-pathogen systems has revealed remarkable similarities in the host immune pathways targeted by effectors from distinct pathogen groups. Immune signaling pathways mediated by pattern recognition receptors, phytohormone homeostasis or signaling, defenses associated with host secretory pathways and pathogen penetrations, and plant cell death represent some of the key processes controlling disease resistance against diverse pathogens. These immune pathways are targeted by effectors that carry a wide range of biochemical functions and are secreted by completely different pathogen groups, suggesting that these pathways are a common battleground encountered by many plant pathogens. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. The Arabidopsis leucine-rich repeat receptor-like kinases BAK1/SERK3 and BKK1/SERK4 are required for innate immunity to hemibiotrophic and biotrophic pathogens

    DEFF Research Database (Denmark)

    Roux, Milena Edna; Schwessinger, Benjamin; Albrecht, Catherine;

    2011-01-01

    Recognition of pathogen-associated molecular patterns (PAMPs) by surface-localized pattern recognition receptors (PRRs) constitutes an important layer of innate immunity in plants. The leucine-rich repeat (LRR) receptor kinases EF-TU RECEPTOR (EFR) and FLAGELLIN SENSING2 (FLS2) are the PRRs...... and BKK1 cooperate genetically to achieve full signaling capability in response to elf18 and flg22 and to the damage-associated molecular pattern AtPep1. Furthermore, we demonstrated that BAK1 and BKK1 contribute to disease resistance against the hemibiotrophic bacterium Pseudomonas syringae...... and the obligate biotrophic oomycete Hyaloperonospora arabidopsidis. Our work reveals that the establishment of PAMP-triggered immunity (PTI) relies on the rapid ligand-induced recruitment of multiple SERKs within PRR complexes and provides insight into the early PTI signaling events underlying this important...

  19. Heterologous Production of the Marine Myxobacterial Antibiotic Haliangicin and Its Unnatural Analogues Generated by Engineering of the Biochemical Pathway

    Science.gov (United States)

    Sun, Yuwei; Feng, Zhiyang; Tomura, Tomohiko; Suzuki, Akira; Miyano, Seishi; Tsuge, Takashi; Mori, Hitoshi; Suh, Joo-Won; Iizuka, Takashi; Fudou, Ryosuke; Ojika, Makoto

    2016-01-01

    Despite their fastidious nature, marine myxobacteria have considerable genetic potential to produce novel secondary metabolites. The marine myxobacterium Haliangium ochraceum SMP-2 produces the antifungal polyketide haliangicin (1), but its productivity is unsatisfactory. The biosynthetic gene cluster hli (47.8 kbp) associated with 1 was identified and heterologously expressed in Myxococcus xanthus to permit the production of 1 with high efficiency (tenfold greater amount and threefold faster in growth speed compared with the original producer), as well as the generation of bioactive unnatural analogues of 1 through gene manipulation. A unique acyl-CoA dehydrogenase was found to catalyse an unusual γ,δ-dehydrogenation of the diketide starter unit, leading to the formation of the terminal alkene moiety of 1. Biological evaluation of the analogues obtained through this study revealed that their bioactivities (anti-oomycete and cytotoxic activities) can be modified by manipulating the vinyl epoxide at the terminus opposite the β-methoxyacrylate pharmacophore. PMID:26915413

  20. The Synthetic Elicitor DPMP (2,4-dichloro-6-{(E)-[(3-methoxyphenyl)imino]methyl}phenol) Triggers Strong Immunity in Arabidopsis thaliana and Tomato

    Science.gov (United States)

    Bektas, Yasemin; Rodriguez-Salus, Melinda; Schroeder, Mercedes; Gomez, Adilene; Kaloshian, Isgouhi; Eulgem, Thomas

    2016-01-01

    Synthetic elicitors are drug-like compounds that are structurally distinct from natural defense elicitors. They can protect plants from diseases by activating host immune responses and can serve as tools for the dissection of the plant immune system as well as leads for the development of environmentally-safe pesticide alternatives. By high-throughput screening, we previously identified 114 synthetic elicitors that activate expression of the pathogen-responsive CaBP22−333::GUS reporter gene in Arabidopsis thaliana (Arabidopsis), 33 of which are [(phenylimino)methyl]phenol (PMP) derivatives or PMP-related compounds. Here we report on the characterization of one of these compounds, 2,4-dichloro-6-{(E)-[(3-methoxyphenyl)imino]methyl}phenol (DPMP). DPMP strongly triggers disease resistance of Arabidopsis against bacterial and oomycete pathogens. By mRNA-seq analysis we found transcriptional profiles triggered by DPMP to resemble typical defense-related responses. PMID:27412821

  1. An update on polygalacturonase-inhibiting protein (PGIP), a leucine-rich repeat protein that protects crop plants against pathogens.

    Science.gov (United States)

    Kalunke, Raviraj M; Tundo, Silvio; Benedetti, Manuel; Cervone, Felice; De Lorenzo, Giulia; D'Ovidio, Renato

    2015-01-01

    Polygalacturonase inhibiting proteins (PGIPs) are cell wall proteins that inhibit the pectin-depolymerizing activity of polygalacturonases secreted by microbial pathogens and insects. These ubiquitous inhibitors have a leucine-rich repeat structure that is strongly conserved in monocot and dicot plants. Previous reviews have summarized the importance of PGIP in plant defense and the structural basis of PG-PGIP interaction; here we update the current knowledge about PGIPs with the recent findings on the composition and evolution of pgip gene families, with a special emphasis on legume and cereal crops. We also update the information about the inhibition properties of single pgip gene products against microbial PGs and the results, including field tests, showing the capacity of PGIP to protect crop plants against fungal, oomycetes and bacterial pathogens.

  2. Aislamiento e identificación de hongos nematófagos nativos de zonas arroceras de Costa Rica

    Directory of Open Access Journals (Sweden)

    Walter Peraza-Padilla

    2011-01-01

    Full Text Available El objetivo de la presente investigación fue identifi car hongos nematófagos en fi ncas arroceras de Costa Rica. El estudio se realizó entre los meses de abril del 2008 a agosto de 2009. Fueron analizadas muestras de suelo provenientes de tres regiones productoras de arroz de Costa Rica: Pacífi co Central, Huetar Atlántica y Chorotega, mediante el método de espolvoreado en placa en búsqueda de hongos nematófagos. Los hongos aislados fueron identifi cados como Trichoderma sp., Penicillium sp., Paecilomyces sp., Fusarium oxysporum, Fusarium tabacinum, Fusarium sp., Aspergillus sp., Monacrosporium sp., Gonatobotrys sp., Geotrichium sp., Phythium sp., Cladosporium sp., Curvularia sp., Phoma sp., Oomycete y micelio estéril. Los resultados sugieren una alta diversidad de hongos nematófagos con potencial para ser utilizados como agentes de control biológico.

  3. Use of suppression subtractive hybridization to identify downy mildew genes expressed during infection of Arabidopsis thaliana.

    Science.gov (United States)

    Bittner-Eddy, Peter D; Allen, Rebecca L; Rehmany, Anne P; Birch, Paul; Beynon, Jim L

    2003-11-01

    SUMMARY Peronospora parasitica is an obligate biotrophic oomycete that causes downy mildew in Arabidopsis thaliana and Brassica species. Our goal is to identify P. parasitica (At) genes that are involved in pathogenicity. We used suppression subtractive hybridization (SSH) to generate cDNA libraries enriched for in planta-expressed parasite genes and up-regulated host genes. A total of 1345 clones were sequenced representing cDNA fragments from 25 putative P. parasitica (At) genes (Ppat 1-25) and 618 Arabidopsis genes. Analyses of expression patterns showed that 15 Ppats were expressed only in planta. Eleven Ppats encoded peptides with homology (BlastP values planta-expressed genes from P. parasitica (At) that complements other gene discovery approaches such as EST sequencing.

  4. Imported pythium insidiosum keratitis after a swim in Thailand by a contact lens-wearing traveler.

    Science.gov (United States)

    Lelievre, Lucie; Borderie, Vincent; Garcia-Hermoso, Dea; Brignier, Anne C; Sterkers, Margaret; Chaumeil, Christine; Lortholary, Olivier; Lanternier, Fanny

    2015-02-01

    A 30-year-old woman with a history of contact lens wear and exposure to swimming pool water in Thailand presented with a non-responsive, progressive corneal ulcer of the right eye. Confocal microscopy evidenced septate linear branching structures, raising suspicion of fungal keratitis. She was promptly treated with topical antibiotics and both topical and intravenous caspofungin plus voriconazole. Worsening of the clinical picture after 1 month of intensive medical therapy led to a large therapeutic penetrating keratoplasty being performed. Corneal cultures grew a mold-like organism, which was identified by sequencing as Pythium insidiosum, an aquatic oomycete. After 4 years of follow-up, the graft exhibits no infection relapse, but graft transparency has been lost after two rejection episodes. Keratoplasty combined with antifungal treatment may offer a cure to P. insidiosum keratitis, although long-term preservation of corneal transparency is difficult to obtain. © The American Society of Tropical Medicine and Hygiene.

  5. Understanding the plant-pathogen interactions in the context of proteomics-generated apoplastic proteins inventory.

    Science.gov (United States)

    Gupta, Ravi; Lee, So Eui; Agrawal, Ganesh K; Rakwal, Randeep; Park, Sangryeol; Wang, Yiming; Kim, Sun T

    2015-01-01

    The extracellular space between cell wall and plasma membrane acts as the first battle field between plants and pathogens. Bacteria, fungi, and oomycetes that colonize the living plant tissues are encased in this narrow region in the initial step of infection. Therefore, the apoplastic region is believed to be an interface which mediates the first crosstalk between host and pathogen. The secreted proteins and other metabolites, derived from both host and pathogen, interact in this apoplastic region and govern the final relationship between them. Hence, investigation of protein secretion and apoplastic interaction could provide a better understanding of plant-microbe interaction. Here, we are briefly discussing the methods available for the isolation and normalization of the apoplastic proteins, as well as the current state of secretome studies focused on the in-planta interaction between the host and the pathogen.

  6. Heterologous Production of the Marine Myxobacterial Antibiotic Haliangicin and Its Unnatural Analogues Generated by Engineering of the Biochemical Pathway.

    Science.gov (United States)

    Sun, Yuwei; Feng, Zhiyang; Tomura, Tomohiko; Suzuki, Akira; Miyano, Seishi; Tsuge, Takashi; Mori, Hitoshi; Suh, Joo-Won; Iizuka, Takashi; Fudou, Ryosuke; Ojika, Makoto

    2016-02-26

    Despite their fastidious nature, marine myxobacteria have considerable genetic potential to produce novel secondary metabolites. The marine myxobacterium Haliangium ochraceum SMP-2 produces the antifungal polyketide haliangicin (1), but its productivity is unsatisfactory. The biosynthetic gene cluster hli (47.8 kbp) associated with 1 was identified and heterologously expressed in Myxococcus xanthus to permit the production of 1 with high efficiency (tenfold greater amount and threefold faster in growth speed compared with the original producer), as well as the generation of bioactive unnatural analogues of 1 through gene manipulation. A unique acyl-CoA dehydrogenase was found to catalyse an unusual γ,δ-dehydrogenation of the diketide starter unit, leading to the formation of the terminal alkene moiety of 1. Biological evaluation of the analogues obtained through this study revealed that their bioactivities (anti-oomycete and cytotoxic activities) can be modified by manipulating the vinyl epoxide at the terminus opposite the β-methoxyacrylate pharmacophore.

  7. A systems biology perspective on plant-microbe interactions: biochemical and structural targets of pathogen effectors.

    Science.gov (United States)

    Pritchard, Leighton; Birch, Paul

    2011-04-01

    Plants have biochemical defences against stresses from predators, parasites and pathogens. In this review we discuss the interaction of plant defences with microbial pathogens such as bacteria, fungi and oomycetes, and viruses. We examine principles of complex dynamic networks that allow identification of network components that are differentially and predictably sensitive to perturbation, thus making them likely effector targets. We relate these principles to recent developments in our understanding of known effector targets in plant-pathogen systems, and propose a systems-level framework for the interpretation and modelling of host-microbe interactions mediated by effectors. We describe this framework briefly, and conclude by discussing useful experimental approaches for populating this framework.

  8. Antifungal activity of storage 2S albumins from seeds of the invasive weed dandelion Taraxacum officinale Wigg.

    Science.gov (United States)

    Odintsova, T I; Rogozhin, E A; Sklyar, I V; Musolyamov, A K; Kudryavtsev, A M; Pukhalsky, V A; Smirnov, A N; Grishin, E V; Egorov, T A

    2010-04-01

    In this work, we isolated and characterized novel antifungal proteins from seeds of dandelion (Taraxacum officinale Wigg.). We showed that they are represented by five isoforms, each consisting of two disulphide-bonded large and small subunits. One of them, To-A1 was studied in detail, including N-terminal amino acid sequencing of both subunits, and shown to display sequence homology with the sunflower 2S albumin. Using different assays we demonstrated that dandelion 2S albumins possess inhibitory activity against phytopathogenic fungi and the oomycete Phytophtora infestans at micromolar concentrations with various isoforms differing in their antifungal activity. Thus, 2S albumins of dandelion seeds represent a novel example of storage proteins with defense functions.

  9. Phytophthora nicotianae diseases worldwide: new knowledge of a long-recognised pathogen

    Directory of Open Access Journals (Sweden)

    Franck PANABIERES

    2016-05-01

    Full Text Available Phytophthora nicotianae was first isolated from tobacco at the end of the 19th century. This organism is now considered as one of the most devastating oomycete plant pathogens, with a recognized host range of more than 255 species over five continents and a wide diversity of climates. The economic losses caused by P. nicotianae are difficult to estimate, because of the diversity of its hosts and ecological niches. For these reasons, this pathogen represents a continuous challenge to plant disease management programmes, which frequently rely solely on the use of chemicals. Phytophthora nicotianae is better adapted than its competitors to abiotic stresses, especially to climate warming. As a result, its importance is increasing. This review illustrates, with some examples, how P. nicotianae currently impacts plant economies worldwide, and how it may constitute more severe threats to agriculture and natural ecosystems in the context of global climate change.

  10. 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.

  11. Alga-PrAS (Algal Protein Annotation Suite): A Database of Comprehensive Annotation in Algal Proteomes

    Science.gov (United States)

    Kurotani, Atsushi; Yamada, Yutaka

    2017-01-01

    Algae are smaller organisms than land plants and offer clear advantages in research over terrestrial species in terms of rapid production, short generation time and varied commercial applications. Thus, studies investigating the practical development of effective algal production are important and will improve our understanding of both aquatic and terrestrial plants. In this study we estimated multiple physicochemical and secondary structural properties of protein sequences, the predicted presence of post-translational modification (PTM) sites, and subcellular localization using a total of 510,123 protein sequences from the proteomes of 31 algal and three plant species. Algal species were broadly selected from green and red algae, glaucophytes, oomycetes, diatoms and other microalgal groups. The results were deposited in the Algal Protein Annotation Suite database (Alga-PrAS; http://alga-pras.riken.jp/), which can be freely accessed online. PMID:28069893

  12. Pythium insidiosum: morphological and molecular identification of Brazilian isolates

    Directory of Open Access Journals (Sweden)

    Maria Isabel de Azevedo

    2012-07-01

    Full Text Available Pythium insidiosum is an oomycete belonging to the kingdom Stramenipila and it is the etiologic agent of pythiosis. Pythiosis is a life-threatening infectious disease characterized by the development of chronic lesions on cutaneous and subcutaneous, intestinal, and bone tissues in humans and many species of animals. The identification of P. insidiosum is important in order to implement a rapid and definitive diagnosis and an effective treatment. This study reports the identification of 54 isolates of P. insidiosum of horses, dogs and sheep that presented suspicious clinical lesions of pythiosis from different regions in Brazil, by using morphological and molecular assays. Throughout the PCR it was possible to confirm the identity of all Brazilian isolates as being P. insidiosum.

  13. [Effect of terrazol on the ultrastructure of Mucor mucedo].

    Science.gov (United States)

    Casperson, G; Lyr, H

    1975-01-01

    Terrazol, a systemic fungicide showing high specifity to oomycetes, inhibits the apical growth of hyphae and promotes at lower concentrations the thickening of the cell wall in Mucor mucedo. As revealed by ultrastructural analysis, particularly the fine structure of some membrane systems is influenced. In the first place the inner membrane of the mitochondria is attacked leading to a complete lysis of mitochondria. However, the sensitivities within a given population are different. The plasmalemma enlarges, forms several invaginations, partly redraws from the cell wall, but remains intact. Only after an extensive treatment with relatively high concentrations of terrazol the nuclear envelope shows vesicles between the double membranes. The mechanism of action of terrazol is discussed.

  14. Glycoconjugates as elicitors or suppressors of plant innate immunity

    DEFF Research Database (Denmark)

    Silipo, Alba; Erbs, Gitte; Shinya, Tomonori

    2010-01-01

    Innate immunity is the first line of defense against invading microorganisms in vertebrates and the only line of defense in invertebrates and plants. Bacterial glyco-conjugates, such as lipopolysaccharides (LPS) from the outer membrane of Gram-negative bacteria and peptidoglycan (PGN) from the cell...... walls of both Gram-positive and Gram-negative bacteria, and fungal and oomycete glycoconjugates such as oligosaccharides derived from the cell wall components ß-glucan, chitin and chitosan, have been found to act as elicitors of plant innate immunity. These conserved indispensable microbe......-specific molecules are also referred to as microbe-associated molecular patterns (MAMPs). Other glyco-conjugates such as bacterial extracellular polysaccharides (EPS) and cyclic glucan have been shown to suppress innate immune responses, thus conversely promoting pathogenesis. MAMPs are recognized by the plant...

  15. 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...... different fields using nine simple-sequence repeat (SSR) markers. Forty-nine alleles were detected among the nine SSR loci and isolates from all four Nordic countries shared the most common alleles across the loci. In total 169 multilocus genotypes (based on seven loci) were identified among 191 isolates....... The genotypic diversities, quantified by a normalized Shannon’s diversity index (Hs), were 0.95 for the four Nordic countries. The low FST value of 0.04 indicates that the majority of variation is found within the four Nordic countries. The large number of genotypes and the frequency distribution of mating...

  16. Analysis of the Pythium ultimum transcriptome using Sanger and Pyrosequencing approaches

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    André Lévesque C

    2008-11-01

    Full Text Available Abstract Background Pythium species are an agriculturally important genus of plant pathogens, yet are not understood well at the molecular, genetic, or genomic level. They are closely related to other oomycete plant pathogens such as Phytophthora species and are ubiquitous in their geographic distribution and host rage. To gain a better understanding of its gene complement, we generated Expressed Sequence Tags (ESTs from the transcriptome of Pythium ultimum DAOM BR144 (= ATCC 200006 = CBS 805.95 using two high throughput sequencing methods, Sanger-based chain termination sequencing and pyrosequencing-based sequencing-by-synthesis. Results A single half-plate pyrosequencing (454 FLX run on adapter-ligated cDNA from a normalized cDNA population generated 90,664 reads with an average read length of 190 nucleotides following cleaning and removal of sequences shorter than 100 base pairs. After clustering and assembly, a total of 35,507 unique sequences were generated. In parallel, 9,578 reads were generated from a library constructed from the same normalized cDNA population using dideoxy chain termination Sanger sequencing, which upon clustering and assembly generated 4,689 unique sequences. A hybrid assembly of both Sanger- and pyrosequencing-derived ESTs resulted in 34,495 unique sequences with 1,110 sequences (3.2% that were solely derived from Sanger sequencing alone. A high degree of similarity was seen between P. ultimum sequences and other sequenced plant pathogenic oomycetes with 91% of the hybrid assembly derived sequences > 500 bp having similarity to sequences from plant pathogenic Phytophthora species. An analysis of Gene Ontology assignments revealed a similar representation of molecular function ontologies in the hybrid assembly in comparison to the predicted proteomes of three Phytophthora species, suggesting a broad representation of the P. ultimum transcriptome was present in the normalized cDNA population. P. ultimum sequences with

  17. The two-speed genomes of filamentous pathogens: waltz with plants.

    Science.gov (United States)

    Dong, Suomeng; Raffaele, Sylvain; Kamoun, Sophien

    2015-12-01

    Fungi and oomycetes include deep and diverse lineages of eukaryotic plant pathogens. The last 10 years have seen the sequencing of the genomes of a multitude of species of these so-called filamentous plant pathogens. Already, fundamental concepts have emerged. Filamentous plant pathogen genomes tend to harbor large repertoires of genes encoding virulence effectors that modulate host plant processes. Effector genes are not randomly distributed across the genomes but tend to be associated with compartments enriched in repetitive sequences and transposable elements. These findings have led to the 'two-speed genome' model in which filamentous pathogen genomes have a bipartite architecture with gene sparse, repeat rich compartments serving as a cradle for adaptive evolution. Here, we review this concept and discuss how plant pathogens are great model systems to study evolutionary adaptations at multiple time scales. We will also introduce the next phase of research on this topic.

  18. 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.

  19. Phylogenetic evidence for a fusion of archaeal and bacterial SemiSWEETs to form eukaryotic SWEETs and identification of SWEET hexose transporters in the amphibian chytrid pathogen Batrachochytrium dendrobatidis.

    Science.gov (United States)

    Hu, Yi-Bing; Sosso, Davide; Qu, Xiao-Qing; Chen, Li-Qing; Ma, Lai; Chermak, Diane; Zhang, De-Chun; Frommer, Wolf B

    2016-10-01

    SWEETs represent a new class of sugar transporters first described in plants, animals, and humans and later in prokaryotes. Plant SWEETs play key roles in phloem loading, seed filling, and nectar secretion, whereas the role of archaeal, bacterial, and animal transporters remains elusive. Structural analyses show that eukaryotic SWEETs are composed of 2 triple-helix bundles (THBs) fused via an inversion linker helix, whereas prokaryotic SemiSWEETs contain only a single THB and require homodimerization to form transport pores. This study indicates that SWEETs retained sugar transport activity in all kingdoms of life, and that SemiSWEETs are likely their ancestral units. Fusion of oligomeric subunits into single polypeptides during evolution of eukaryotes is commonly found for transporters. Phylogenetic analyses indicate that THBs of eukaryotic SWEETs may not have evolved by tandem duplication of an open reading frame, but rather originated by fusion between an archaeal and a bacterial SemiSWEET, which potentially explains the asymmetry of eukaryotic SWEETs. Moreover, despite the ancient ancestry, SWEETs had not been identified in fungi or oomycetes. Here, we report the identification of SWEETs in oomycetes as well as SWEETs and a potential SemiSWEET in primitive fungi. BdSWEET1 and BdSWEET2 from Batrachochytrium dendrobatidis, a nonhyphal zoosporic fungus that causes global decline in amphibians, showed glucose and fructose transport activities.-Hu, Y.-B., Sosso, D., Qu, X.-Q., Chen, L.-Q., Ma, L., Chermak, D., Zhang, D.-C., Frommer, W. B. Phylogenetic evidence for a fusion of archaeal and bacterial SemiSWEETs to form eukaryotic SWEETs and identification of SWEET hexose transporters in the amphibian chytrid pathogen Batrachochytrium dendrobatidis. © FASEB.

  20. Cloning and analysis of a constitutive heat shock (cognate) protein 70 gene inducible by L-glutamine.

    Science.gov (United States)

    LéJohn, H B; Cameron, L E; Yang, B; MacBeath, G; Barker, D S; Williams, S A

    1994-02-11

    An intronless gene encoding a protein of 652 amino acid residues with an M(r) of 71,266, showing between 79% and 59% identity in nucleotide sequence with heat shock protein 70 (HSP 70) genes of Bremia lactucae (a parasitic Oomycete of lettuce) and a wide range of organisms that include humans, was isolated from the nonparasitic Oomycete Achlya klebsiana. While the gene appears to be constitutively expressed, L-glutamine augmented its expression particularly under conditions of nutritional stress. L-Glutamine enhanced the transcription of a 2.4-kilobase poly(A)+ RNA simultaneously in the same way as it elevated the cellular level of the HSP 70-like protein. A polyclonal antibody (affinity-purified) raised in rabbit against the purified monomeric (M(r) 120,000) form of an NAD-specific glutamate dehydrogenase (Yang, B., and LéJohn, H.B. (1994) J. Biol. Chem. 269, 4506-4512) immunoprecipitated the HSP 70-like protein, and it was used to study the kinetics of induction of this stress-related protein and the effect of proteinase inhibitors on its metabolism. By using as probes four partial length cDNA clones, nine overlapping DNA fragments of the organism's genome carrying the HSP 70-like protein gene were isolated from a genomic library. The nucleotide sequence of the gene, including its boundaries, was determined by using these genomic clones. The 5'-untranslated boundary of the gene displayed the classical nucleotide arrangement of heat shock elements as well as CCAAT and TATA box motifs. Within the coding region are the typical conserved amino acid heat shock protein signatures 1 and 2 at the predicted locations. By primer extension and S1 nuclease protection mapping system, we estimated that the gene is probably transcribed into a message of 2.2 kilobases.

  1. A conserved peptide pattern from a widespread microbial virulence factor triggers pattern-induced immunity in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Hannah Böhm

    2014-11-01

    Full Text Available Microbe- or host damage-derived patterns mediate activation of pattern-triggered immunity (PTI in plants. Microbial virulence factor (effector-triggered immunity (ETI constitutes a second layer of plant protection against microbial attack. Various necrosis and ethylene-inducing peptide 1 (Nep1-like proteins (NLPs produced by bacterial, oomycete and fungal microbes are phytotoxic virulence factors that exert immunogenic activities through phytotoxin-induced host cell damage. We here show that multiple cytotoxic NLPs also carry a pattern of 20 amino acid residues (nlp20 that triggers immunity-associated plant defenses and immunity to microbial infection in Arabidopsis thaliana and related plant species with similar characteristics as the prototype pattern, bacterial flagellin. Characteristic differences in flagellin and nlp20 plant responses exist however, as nlp20s fail to trigger extracellular alkalinization in Arabidopsis cell suspensions and seedling growth inhibition. Immunogenic nlp20 peptide motifs are frequently found in bacterial, oomycete and fungal NLPs. Such an unusually broad taxonomic distribution within three phylogenetic kingdoms is unprecedented among microbe-derived triggers of immune responses in either metazoans or plants. Our findings suggest that cytotoxic NLPs carrying immunogenic nlp20 motifs trigger PTI in two ways as typical patterns and by inflicting host cell damage. We further propose that conserved structures within a microbial virulence factor might have driven the emergence of a plant pattern recognition system mediating PTI. As this is reminiscent of the evolution of immune receptors mediating ETI, our findings support the idea that there is a continuum between PTI and ETI.

  2. Phylogenetic relationships of Brazilian isolates of Pythium insidiosum based on ITS rDNA and cytochrome oxidase II gene sequences.

    Science.gov (United States)

    Azevedo, M I; Botton, S A; Pereira, D I B; Robe, L J; Jesus, F P K; Mahl, C D; Costa, M M; Alves, S H; Santurio, J M

    2012-09-14

    Pythium insidiosum is an aquatic oomycete that is the causative agent of pythiosis. Advances in molecular methods have enabled increased accuracy in the diagnosis of pythiosis, and in studies of the phylogenetic relationships of this oomycete. To evaluate the phylogenetic relationships among isolates of P. insidiosum from different regions of Brazil, and also regarding to other American and Thai isolates, in this study a total of thirty isolates of P. insidiosum from different regions of Brazil was used and had their ITS1, 5.8S rRNA and ITS2 rDNA (ITS) region and the partial sequence of cytochrome oxidase II (COX II) gene sequenced and analyzed. The outgroup consisted of six isolates of other Pythium species and one of Lagenidium giganteum. Phylogenetic analyses of ITS and COX II genes were conducted, both individually and in combination, using four different methods: Maximum parsimony (MP); Neighbor-joining (NJ); Maximum likelihood (ML); and Bayesian analysis (BA). Our data supported P. insidiosum as monophyletic in relation to the other Pythium species, and COX II showed that P. insidiosum appears to be subdivided into three major polytomous groups, whose arrangement provides the Thai isolates as paraphyletic in relation to the Brazilian ones. The molecular analyses performed in this study suggest an evolutionary proximity among all American isolates, including the Brazilian and the Central and North America isolates, which were grouped together in a single entirely polytomous clade. The COX II network results presented signals of a recent expansion for the American isolates, probably originated from an Asian invasion source. Here, COX II showed higher levels bias, although it was the source of higher levels of phylogenetic information when compared to ITS. Nevertheless, the two markers chosen for this study proved to be entirely congruent, at least with respect to phylogenetic relationships between different isolates of P. insidiosum. Copyright © 2012 Elsevier

  3. Volatiles in Inter-Specific Bacterial Interactions.

    Science.gov (United States)

    Tyc, Olaf; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well-described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium, and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal, and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide) were tested for their effect on three target bacteria. Here, we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  4. Repression of the Auxin Response Pathway Increases Arabidopsis Susceptibility to Necrotrophic Fungi

    Institute of Scientific and Technical Information of China (English)

    Francisco Llorente; Paul Muskett; Andrea Sánchez-Vallet; Gemma López; Brisa Ramos; Clara Sánchez-Rodríguez; Lucia Jordá; Jane Parker; Antonio Molina

    2008-01-01

    In plants, resistance to necrotrophic pathogens depends on the interplay between different hormone systems, such as those regulated by salicylic acid (SA), jasmonic acid (JA), ethylene, and abscisic acid. Repression of auxin signaling by the SA pathway was recently shown to contribute to antibacterial resistance. Here, we demonstrate that Arabidopsis auxin signaling mutants axrl, axr2, and axr6 that have defects in the auxin-stimulated SCF (Skpl-Cullin-F-box) ubiquitination pathway exhibit increased susceptibility to the necrotrophic fungi Plectosphaerella cucumerina and Botrytis cinerea. Also, stabilization of the auxin transcriptional repressor AXR3 that is normally targeted for removal by the SCF-ubiquitin/proteasome machinery occurs upon P. cucumerina infection. Pharmacological inhibition of auxin transport or proteasome function each compromise necrotroph resistance of wild-type plants to a similar extent as in non-treated auxin response mutants. These results suggest that auxin signaling is important for resistance to the necrotrophic fungi P. cucumerina and B. cinerea. SGTlb (one of two Arabidopsis SGT1 genes encoding HSP90/HSC70 co-chaperones) promotes the functions of SCF E3-ubiquitin ligase complexes in auxin and JA responses and resistance conditioned by certain Resistance (R) genes to biotrophic pathogens. We find that sgtlb mutants are as resistant to P. cucumerina as wild-type plants. Conversely, auxin/SCF signaling mutants are uncompromised in RPP4-triggered resistance to the obligate biotrophic oomycete, Hyaloperonospora parasitica. Thus, the predominant action of SGTlb in R gene-conditioned resistance to oomycetes appears to be at a site other than assisting SCF E3-ubiquitin ligases. However, genetic additivity of sgtlb axr1 double mutants in susceptibility to H. parasitica suggests that SCF-mediated ubiquitination contributes to limiting biotrophic pathogen colonization once plant-pathogen compatibility is established.

  5. The anti-Phytophthora effect of selected potato-associated Pseudomonas strains: from the laboratory to the field

    Directory of Open Access Journals (Sweden)

    Anouk eGuyer

    2015-11-01

    Full Text Available Late blight, caused by the oomycete Phytophthora infestans, is the most devastating disease of potato. In organic farming, late Late blight, caused by the oomycete Phytophthora infestans, is the most devastating disease of potato. In organic farming, late blight is controlled by repeated applications of copper-based products, which negatively impact the environment. To find alternative solutions for late blight management, we have previously isolated a large collection of bacteria from the phyllosphere and the rhizosphere of potatoes. Here we report the antagonistic potential of these strains when co-cultivated with P. infestans as well as with other potato pathogens. We then focused on three Pseudomonas strains and compared their protective impact against late blight to that of well-known biocontrol strains in planta using a high-throughput leaf disc assay with automated picture analysis. When sprayed on the leaves of potatoes in the greenhouse, the strains were able to survive for at least 15 days. Under field conditions, populations decreased faster but all tested strains could still be retrieved after 8 days. The most active strain in vitro, P. chlororaphis R47, was also the best protectant on leaf discs from plants grown in the greenhouse experiment, but its protection potential could not be verified in the field due to unfavourable infection conditions. However, its protective effect against P. infestans in planta, its survival in the phyllosphere as well as its ability to colonise the potato rhizosphere in very high population densities, suggest a potential for field application, e.g. in the form of tuber treatment or leaf spray.

  6. Are algal genes in nonphotosynthetic protists evidence of historical plastid endosymbioses?

    Directory of Open Access Journals (Sweden)

    Tian Jing

    2009-10-01

    Full Text Available Abstract Background How photosynthetic organelles, or plastids, were acquired by diverse eukaryotes is among the most hotly debated topics in broad scale eukaryotic evolution. The history of plastid endosymbioses commonly is interpreted under the "chromalveolate" hypothesis, which requires numerous plastid losses from certain heterotrophic groups that now are entirely aplastidic. In this context, discoveries of putatively algal genes in plastid-lacking protists have been cited as evidence of gene transfer from a photosynthetic endosymbiont that subsequently was lost completely. Here we examine this evidence, as it pertains to the chromalveolate hypothesis, through genome-level statistical analyses of similarity scores from queries with two diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana, and two aplastidic sister taxa, Phytophthora ramorum and P. sojae. Results Contingency tests of specific predictions of the chromalveolate model find no evidence for an unusual red algal contribution to Phytophthora genomes, nor that putative cyanobacterial sequences that are present entered these genomes through a red algal endosymbiosis. Examination of genes unrelated to plastid function provide extraordinarily significant support for both of these predictions in diatoms, the control group where a red endosymbiosis is known to have occurred, but none of that support is present in genes specifically conserved between diatoms and oomycetes. In addition, we uncovered a strong association between overall sequence similarities among taxa and relative sizes of genomic data sets in numbers of genes. Conclusion Signal from "algal" genes in oomycete genomes is inconsistent with the chromalveolate hypothesis, and better explained by alternative models of sequence and genome evolution. Combined with the numerous sources of intragenomic phylogenetic conflict characterized previously, our results underscore the potential to be mislead by a posteriori

  7. Estructura espacial y estacional de la comunidad de hongos asociada al abrigo de hojas muertas de Espeletia grandiflora H & B en el páramo El Granizo, Monserrate-Cundinamarca, Colombia

    Directory of Open Access Journals (Sweden)

    Sabogal Rodríguez Sandra Patricia

    2002-11-01

    Full Text Available RESUMENSe caracterizó la comunidad de hongos asociada a la necromasa de Espeletia grandiflora, segúnlas siguientes variables: Grado de descomposición de la necromasa, segmentos foliares,tamaño de la planta y época climática. El muestreo se realizó durante los meses marzo - abril(seca-húmeda, agosto (seca y octubre (húmeda del año 2001. Las muestras de roseta y denecromasa a diferentes alturas con respecto al suelo (distribución vertical, fueron subdivididasen secciones foliares (distribución horizontal, procesadas según la técnica de aislamiento demicelio activo en medios de cultivo PDA y luego determinadas hasta especie. La clase-forma:Deuteromycete presentó cuatro familias, Moniliaceae, Dematiaceae, Melanconiaceae yActa Sphaeropsidaceae, donde la familia Moniliaceae exhibió la mayor riqueza de especies (4,seguida por la Dematiaceae (3; de igual forma la clase Ascomicete con cuatro familias,Sordariaceae, Chaetomiaceae, Lasiosphaerinaceae y Nectriaceae, siendo Sordariaceae la másrepresentativa en especies (2. Las clases Oomycetes y Zigomycetes presentaron una familia,Pytiaceae y Mortierelaceae respectivamente; la familia Pytiaceae estuvo representada por tresespecies. Es de anotar que, la clase-forma Deuteromycetes presenta la mayor riqueza enfamilias, especies y la mayor abundancia de individuos, sin embargo, los individuos con lasmayores frecuencias y una amplia distribución corresponden a las clases Ascomycetes yOomycete. Las especies de hongos siguieron un patrón de distribución fundamentado en laheterogeneidad espacial como temporal de los hábitats en estudio. -Pythium vexansy Sordariafimicolarepresentaron el 33% de la abundancia total de las especies de hongos asociadas a lanecromasa de Espeletia grandiflora.

  8. Estructura espacial y estacional de la comunidad de hongos asociada al abrigo de hojas muertas de Espeletia grandiflora H & B en el páramo El Granizo, Monserrate - Cundinamarca, Colombia

    Directory of Open Access Journals (Sweden)

    Anacona Chicangana Amalfy

    2002-06-01

    Full Text Available Se caracterizó la comunidad de hongos asociada a la necromasa de Espeletia grandiflora, segúnlas siguientes variables: Grado de descomposición de la necromasa, segmentos foliares, tama-ño de la planta y época climática. El muestreo se realizó durante los meses marzo-abril (seca-húmeda, agosto (seca y octubre (húmeda del año 2001. Las muestras de roseta y denecromasa a diferentes alturas con respecto al suelo (distribución vertical, fueron subdivididasen secciones foliares (distribución horizontal, procesadas según la técnica de aislamiento demicelio activo en medios de cultivo PDA y luego determinadas hasta especie. La clase-forma:Deuteromycete presentó cuatro familias, Moniliaceae, Dematiaceae, Melanconiaceae ySphaeropsidaceae, donde la familia Moniliaceae exhibió la mayor riqueza de especies (4,seguida por la Dematiaceae (3; de igual forma la clase Ascomicete con cuatro familias,Sordariaceae, Chaetomiaceae, Lasiosphaerinaceae y Nectriaceae, siendo Sordariaceae la másrepresentativa en especies (2. Las clases Oomycetes y Zigomycetes presentaron una familia,Pytiaceae y Mortierelaceae respectivamente; la familia Pytiaceae estuvo representada por tresespecies. Es de anotar que, la clase-forma Deuteromycetes presenta la mayor riqueza en fami-lias, especies y la mayor abundancia de individuos, sin embargo, los individuos con las mayoresfrecuencias y una amplia distribución correspondes a las clases Ascomycetes y Oomycete.Las especies de hongos siguieron un patrón de distribución fundamentado en la heteroge-neidad espacial como temporal de los hábitats en estudio. Pythium vexansy Sordaria fimicolarepresentaron 33% de la abundancia total de las especies de hongos asociadas a la necromasade Espeletia grandiflora.

  9. Volatiles in inter-specific bacterial interactions

    Directory of Open Access Journals (Sweden)

    Olaf eTyc

    2015-12-01

    Full Text Available The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide were tested for their effect on three target bacteria. Here we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  10. An antibiotic complex from Lysobacter enzymogenes strain C3: antimicrobial activity and role in plant disease control.

    Science.gov (United States)

    Li, S; Jochum, C C; Yu, F; Zaleta-Rivera, K; Du, L; Harris, S D; Yuen, G Y

    2008-06-01

    Lysobacter enzymogenes C3 is a bacterial biological control agent that exhibits antagonism against multiple fungal pathogens. Its antifungal activity was attributed in part to lytic enzymes. In this study, a heat-stable antifungal factor (HSAF), an antibiotic complex consisting of dihydromaltophilin and structurally related macrocyclic lactams, was found to be responsible for antagonism by C3 against fungi and oomycetes in culture. HSAF in purified form exhibited inhibitory activity against a wide range of fungal and oomycetes species in vitro, inhibiting spore germination, and disrupting hyphal polarity in sensitive fungi. When applied to tall fescue leaves as a partially-purified extract, HSAF at 25 mug/ml and higher inhibited germination of conidia of Bipolaris sorokiniana compared with the control. Although application of HSAF at 12.5 mug/ml did not reduce the incidence of conidial germination, it inhibited appressorium formation and suppressed Bipolaris leaf spot development. Two mutant strains of C3 (K19 and DeltaNRPS) that were disrupted in different domains in the hybrid polyketide synthase-nonribosomal peptide synthetase gene for HSAF biosynthesis and had lost the ability to produce HSAF were compared with the wild-type strain for biological control efficacy against Bipolaris leaf spot on tall fescue and Fusarium head blight, caused by Fusarium graminearum, on wheat. Both mutant strains exhibited decreased capacity to reduce the incidence and severity of Bipolaris leaf spot compared with C3. In contrast, the mutant strains were as efficacious as the wild-type strain in reducing the severity of Fusarium head blight. Thus, HSAF appears to be a mechanism for biological control by strain C3 against some, but not all, plant pathogenic fungi.

  11. The Arabidopsis microtubule-associated protein MAP65-3 supports infection by filamentous biotrophic pathogens by down-regulating salicylic acid-dependent defenses.

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    Quentin, Michaël; Baurès, Isabelle; Hoefle, Caroline; Caillaud, Marie-Cécile; Allasia, Valérie; Panabières, Franck; Abad, Pierre; Hückelhoven, Ralph; Keller, Harald; Favery, Bruno

    2016-03-01

    The oomycete Hyaloperonospora arabidopsidis and the ascomycete Erysiphe cruciferarum are obligate biotrophic pathogens causing downy mildew and powdery mildew, respectively, on Arabidopsis. Upon infection, the filamentous pathogens induce the formation of intracellular bulbous structures called haustoria, which are required for the biotrophic lifestyle. We previously showed that the microtubule-associated protein AtMAP65-3 plays a critical role in organizing cytoskeleton microtubule arrays during mitosis and cytokinesis. This renders the protein essential for the development of giant cells, which are the feeding sites induced by root knot nematodes. Here, we show that AtMAP65-3 expression is also induced in leaves upon infection by the downy mildew oomycete and the powdery mildew fungus. Loss of AtMAP65-3 function in the map65-3 mutant dramatically reduced infection by both pathogens, predominantly at the stages of leaf penetration. Whole-transcriptome analysis showed an over-represented, constitutive activation of genes involved in salicylic acid (SA) biosynthesis, signaling, and defense execution in map65-3, whereas jasmonic acid (JA)-mediated signaling was down-regulated. Preventing SA synthesis and accumulation in map65-3 rescued plant susceptibility to pathogens, but not the developmental phenotype caused by cytoskeleton defaults. AtMAP65-3 thus has a dual role. It positively regulates cytokinesis, thus plant growth and development, and negatively interferes with plant defense against filamentous biotrophs. Our data suggest that downy mildew and powdery mildew stimulate AtMAP65-3 expression to down-regulate SA signaling for infection.

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

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    Angela Chaparro-Garcia

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

  13. Management of root diseases of annual pasture legumes in Mediterranean ecosystems - a case study of subterranean clover root diseases in the south-west of Western Australia

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    M. Barbetti

    2007-12-01

    Full Text Available Subterranean clover (Trifolium subterraneum is an important component of Mediterranean dryland pasture ecosystems, such as in the south-west of Western Australia, where it is utilised as a winter annual pasture that provides nitrogen as well as disease breaks for rotational crops. Necrotrophic soil-borne fungal pathogens dominate Mediterranean ecosystems because of the ease of survival of these pathogens on infested residues over the dry summer period, and because of low levels of microbial competition in the impoverished and nutrient-defi cient soils characteristic of these regions that predisposes plants to root diseases. In addition to herbage and seed yield losses from soil-borne fungal and nematode pathogens, changes in botanical composition, in the number of regenerating plants, their persistence, and factors affecting feed quality are signifi cantly affected. Further, where the causal organisms of the diseases on subterranean clover are also common on other rotational crops, the impact of these soilborne pathogens appears far wider in Mediterranean ecosystems than previously considered. Under these conditions, soil-borne pathogens pose a serious threat to the productivity of this self-seeding pasture legume, to the extent that reseeding may become necessary. Pathogens such as Phytophthora clandestina, various Pythium species particularly Pythium irregulare, Aphanomyces sp., Rhizoctonia solani, one or more Fusarium species, Phoma medicaginis and Cylindrocarpon didymium are of concern, as are the nematode parasites from the genera Meloidogyne, Heterodera, Pratylenchus, Trichodorus and Radopholus. In this ecosystem, root pathogens operate together as disease complexes and the challenge therefore has been to source host genotypes with resistance to multiple pathogens. In addition to plant nutrition, environmental factors, in particular rainfall (soil moisture and soil temperature, have a marked effect on both the disease severity caused by

  14. Immunological role of C4 CC chemokine-1 from snakehead murrel Channa striatus.

    Science.gov (United States)

    Bhatt, Prasanth; Kumaresan, Venkatesh; Palanisamy, Rajesh; Chaurasia, Mukesh Kumar; Gnanam, Annie J; Pasupuleti, Mukesh; Arockiaraj, Jesu

    2014-02-01

    In this study, we have reported a cDNA sequence of C4 CC chemokine identified from snakehead murrel (also known as striped murrel) Channa striatus (named as CsCC-Chem-1) normalized cDNA library constructed by Genome Sequencing FLX™ Technology (GS-FLX™). CsCC-Chem-1 is 641 base pairs (bp) long that contain 438 bp open reading frame (ORF). The ORF encodes a polypeptide of 146 amino acids with a molecular mass of 15 kDa. The polypeptide contains a small cytokine domain at 30-88. The domain carries the CC motif at Cys(33)-Cys(34). In addition, CsCC-Chem-1 consists of another two cysteine residues at C(59) and C(73), which, together with C(33) and C(34), make CsCC-Chem-1 as a C4-CC chemokine. CsCC-Chem-1 also contains a 'TCCT' motif at 32-35 as CC signature motif; this new motif may represent new characteristic features, which may lead to some unknown function that needs to be further focused on. Phylogenitically, CsCC-Chem-1 clustered together with CC-Chem-1 from rock bream Oplegnathus fasciatus and European sea bass Dicentrarchus labrax. Significantly (P<0.05) highest gene expression was noticed in spleen and is up-regulated upon fungus (Aphanomyces invadans), bacteria (Aeromonas hydrophila) and virus (poly I:C) infection at various time points. The gene expression results indicate the influence of CsCC-Chem-1 in the immune system of murrel. Overall, the gene expression study showed that the CsCC-Chem-1 is a capable gene to increase the cellular response against various microbial infections. Further, we cloned the coding sequence of CsCC-Chem-1 in pMAL vector and purified the recombinant protein to study the functional properties. The cell proliferation activity of recombinant CsCC-Chem-1 protein showed a significant metabolic activity in a concentration dependent manner. Moreover, the chemotaxis assay showed the capability of recombinant CsCC-Chem-1 protein which can induce the migration of spleen leukocytes in C. striatus. However, this remains to be verified

  15. The phytosanitary form and fighting measures diseases and pests of sugar beet from Republic of Moldova

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    Timus Asea M.

    2006-01-01

    Full Text Available Sugar beet is one of the most important agricultural crops in the Republic of Moldova. The North and Central regions have good enough pedoclimatic conditions. The genetic potential of sorts and hybrids can be created through the application of modern technologies in order to grow at least 32-35 tons/ha of sugar beet roots. In the Republic of Moldova, sugar beet vegetates between 160 and 180 days in the first year and needs approximately an amount of 2400-2900°C, average of 15.3-15.4°C. Each phenological phase needs different temperatures: at least 4C° is necessary for planting and springing an amount of 650°C is necessary for foliar apparatus; an amount of 1150- 1800°C is necessary to grow the volume of roots and for sugar depositing the average of 2400 to 2600°C is necessary. The mentioned temperatures ensure a normal development of sugar beet plants. If these temperatures fluctuate, the pathogens and pests are stimulated to develop. The most frequent diseases of sugar beet are: Pythium de baryanum Hesse., Aphanomyces cochlioides Dresch. Peronospora schachtii Fuck., Phoma betae Fr. Cercospora beticola Sacc. Erysiphe communis Grev. f. betae Jacz., virosis - Beta virus 2, 3 si 4 etc. The main pests belong to the following categories: Homoptera: Aphis fabae Scop. (fam. Aphididae, Pemphigus fuscicornis Koch. (fam. Pemphigidae Coleoptera: Agriotes sp. (fam. Elateridae, Chaetocnema concinna M. Ch. breviuscula Fld., Cassida nebulosa L. (fam. Chrysomelidae, Atomaria linearis Step. (fam. Cryptophagidae; Bothynoderes punctiventris Germ., Tanymechus dilaticollis Gyll., T. palliatus F., Psalidium maxillosum F. (Curculionidae; Lepidoptera: Agrotis segetum Den. et Schiff., Authographa gamma L. Mamestra (Barathra brassicae L. (Noctuidae, Loxostege sticticalis L. (Pyralidae, Gnorimoschema ocellatella Boyd.; Diptera Pegomyia betae Curtis. (fam. Anthomyidae. Heterodera schachtii Schmidt (Heteroderidae. The most recommended insecticides for fighting the

  16. VARIABILIDAD GENÉTICA DE AISLAMIENTOS COLOMBIANOS DE Phytophthora infestans (Mont de Bary EN SOLANÁCEAS CULTIVADAS EN COLOMBIA GENETIC VARIABILITY OF ISOLATES OF Phytophthora infestans (Mont. de Bary IN SOLANACEOUS CROPS FROM COLOMBIA

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    Natalia Raigosa Gómez

    2009-06-01

    Full Text Available Se estudio el nivel de variabilidad genética de una población de 35 aislamientos de Phytophthora infestans obtenidos en diferentes hospedantes y regiones geográficas de Colombia, mediante las técnicas de haplotipos mitocondriales y RAPD. Los resultados encontrados sugieren la existencia en el país de los haplotipos mitocondriales Ia en los aislamientos que afectan tomate de árbol (Solanum betaceum y IIa en cultivos de papa; dichos haplotipos están asociados a los linajes genéticos EC-3 y EC-1, respectivamente. Sin embargo, tres aislamientos obtenidos en tomate de mesa (S. lycopersicum, pimentón (Capsicum sp. y pepino de agua (S. muricatum requieren de un análisis posterior, debido a la falta de correlación entre los perfiles de restricción generados con los cuatro pares de cebadores utilizados en esta prueba y los haplotipos mitocondriales mencionados en la literatura. De otra parte, mediante cuatro cebadores RAPD, fue posible encontrar variabilidad al interior de los dos linajes genéticos, siendo interesante el hecho que los aislamientos obtenidos en tomate de árbol (EC-3 fueron divididos en dos grupos, relacionados con una distancia genética de 0,17. Estos hallazgos indican que es importante contemplar las fuentes de variación asexual en el análisis de la estructura poblacional de este oomycete y por tanto en el diseño de las estrategias de control de las enfermedades que causa P. infestans en cultivos de solanáceas de importancia económica.The level of genetic variability of 35 isolates of Phytophthora infestans obtained from different hosts and geographical regions of Colombia was studied through mitochondrial haplotypes and RAPD techniques. Results suggested the existence of mitochondrial haplotypes Ia affecting tree tomato (Solanum betaceum and IIa in potato, which are associated with genetic lineages EC-3 and EC-1, respectively. However, three isolates obtained from tomato (S. lycopersicum, capsicum (Capsicum sp. and

  17. The malarial host-targeting signal is conserved in the Irish potato famine pathogen.

    Directory of Open Access Journals (Sweden)

    2006-05-01

    Full Text Available Animal and plant eukaryotic pathogens, such as the human malaria parasite Plasmodium falciparum and the potato late blight agent Phytophthora infestans, are widely divergent eukaryotic microbes. Yet they both produce secretory virulence and pathogenic proteins that alter host cell functions. In P. falciparum, export of parasite proteins to the host erythrocyte is mediated by leader sequences shown to contain a host-targeting (HT motif centered on an RxLx (E, D, or Q core: this motif appears to signify a major pathogenic export pathway with hundreds of putative effectors. Here we show that a secretory protein of P. infestans, which is perceived by plant disease resistance proteins and induces hypersensitive plant cell death, contains a leader sequence that is equivalent to the Plasmodium HT-leader in its ability to export fusion of green fluorescent protein (GFP from the P. falciparum parasite to the host erythrocyte. This export is dependent on an RxLR sequence conserved in P. infestans leaders, as well as in leaders of all ten secretory oomycete proteins shown to function inside plant cells. The RxLR motif is also detected in hundreds of secretory proteins of P. infestans, Phytophthora sojae, and Phytophthora ramorum and has high value in predicting host-targeted leaders. A consensus motif further reveals E/D residues enriched within approximately 25 amino acids downstream of the RxLR, which are also needed for export. Together the data suggest that in these plant pathogenic oomycetes, a consensus HT motif may reside in an extended sequence of approximately 25-30 amino acids, rather than in a short linear sequence. Evidence is presented that although the consensus is much shorter in P. falciparum, information sufficient for vacuolar export is contained in a region of approximately 30 amino acids, which includes sequences flanking the HT core. Finally, positional conservation between Phytophthora RxLR and P. falciparum RxLx (E, D, Q is

  18. Microbial Hub Taxa Link Host and Abiotic Factors to Plant Microbiome Variation.

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    Matthew T Agler

    2016-01-01

    Full Text Available Plant-associated microorganisms have been shown to critically affect host physiology and performance, suggesting that evolution and ecology of plants and animals can only be understood in a holobiont (host and its associated organisms context. Host-associated microbial community structures are affected by abiotic and host factors, and increased attention is given to the role of the microbiome in interactions such as pathogen inhibition. However, little is known about how these factors act on the microbial community, and especially what role microbe-microbe interaction dynamics play. We have begun to address this knowledge gap for phyllosphere microbiomes of plants by simultaneously studying three major groups of Arabidopsis thaliana symbionts (bacteria, fungi and oomycetes using a systems biology approach. We evaluated multiple potential factors of microbial community control: we sampled various wild A. thaliana populations at different times, performed field plantings with different host genotypes, and implemented successive host colonization experiments under lab conditions where abiotic factors, host genotype, and pathogen colonization was manipulated. Our results indicate that both abiotic factors and host genotype interact to affect plant colonization by all three groups of microbes. Considering microbe-microbe interactions, however, uncovered a network of interkingdom interactions with significant contributions to community structure. As in other scale-free networks, a small number of taxa, which we call microbial "hubs," are strongly interconnected and have a severe effect on communities. By documenting these microbe-microbe interactions, we uncover an important mechanism explaining how abiotic factors and host genotypic signatures control microbial communities. In short, they act directly on "hub" microbes, which, via microbe-microbe interactions, transmit the effects to the microbial community. We analyzed two "hub" microbes (the

  19. Resistance to Plasmopara viticola in a grapevine segregating population is associated with stilbenoid accumulation and with specific host transcriptional responses

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    Delledonne Massimo

    2011-08-01

    Full Text Available Abstract Background Downy mildew, caused by the oomycete Plasmopara viticola, is a serious disease in Vitis vinifera, the most commonly cultivated grapevine species. Several wild Vitis species have instead been found to be resistant to this pathogen and have been used as a source to introgress resistance into a V. vinifera background. Stilbenoids represent the major phytoalexins in grapevine, and their toxicity is closely related to the specific compound. The aim of this study was to assess the resistance response to P. viticola of the Merzling × Teroldego cross by profiling the stilbenoid content of the leaves of an entire population and the transcriptome of resistant and susceptible individuals following infection. Results A three-year analysis of the population's response to artificial inoculation showed that individuals were distributed in nine classes ranging from total resistance to total susceptibility. In addition, quantitative metabolite profiling of stilbenoids in the population, carried out using HPLC-DAD-MS, identified three distinct groups differing according to the concentrations present and the complexity of their profiles. The high producers were characterized by the presence of trans-resveratrol, trans-piceid, trans-pterostilbene and up to thirteen different viniferins, nine of them new in grapevine. Accumulation of these compounds is consistent with a resistant phenotype and suggests that they may contribute to the resistance response. A preliminary transcriptional study using cDNA-AFLP selected a set of genes modulated by the oomycete in a resistant genotype. The expression of this set of genes in resistant and susceptible genotypes of the progeny population was then assessed by comparative microarray analysis. A group of 57 genes was found to be exclusively modulated in the resistant genotype suggesting that they are involved in the grapevine-P. viticola incompatible interaction. Functional annotation of these transcripts

  20. Nonribosomal peptides, key biocontrol components for Pseudomonas fluorescens In5, isolated from a Greenlandic suppressive soil.

    Science.gov (United States)

    Michelsen, Charlotte F; Watrous, Jeramie; Glaring, Mikkel A; Kersten, Roland; Koyama, Nobuhiro; Dorrestein, Pieter C; Stougaard, Peter

    2015-03-17

    isolated from this Greenlandic suppressive soil. Using a combination of molecular genetics, genomics, and microbial imaging mass spectrometry, we show that two cyclic lipopeptides, nunamycin and nunapeptin, are important for the biocontrol activity of P. fluorescens In5 both in vitro and in microcosm assays. Furthermore, we demonstrate that the synthesis of nunamycin is repressed by the oomycete Pythium aphanidermatum. Overall, our report provides important insight into interkingdom interference between bacteria and fungi/oomycetes. Copyright © 2015 Michelsen et al.

  1. Characterization of eds1, a mutation in Arabidopsis suppressing resistance to Peronospora parasitica specified by several different RPP genes.

    Science.gov (United States)

    Parker, J E; Holub, E B; Frost, L N; Falk, A; Gunn, N D; Daniels, M J

    1996-11-01

    The interaction between Arabidopsis and the biotrophic oomycete Peronospora parasitica (downy mildew) provides an attractive model pathosystem to identify molecular components of the host that are required for genotype-specific recognition of the parasite. These components are the so-called RPP genes (for resistance to P. parasitica). Mutational analysis of the ecotype Wassilewskija (Ws-0) revealed an RPP-nonspecific locus called EDS1 (for enhanced disease susceptibility) that is required for the function of RPP genes on chromosomes 3 (RPP1/RPP14 and RPP10) and 4 (RPP12). Genetic analyses demonstrated that the eds1 mutation is recessive and is not a defective allele of any known RPP gene, mapping to the bottom arm of chromosome 3 (approximately 13 centimorgans below RPP1/RPP14). Phenotypically, the Ws-eds1 mutant seedlings supported heavy sporulation by P. parasitica isolates that are each diagnostic for one of the RPP genes in wild-type Ws-0; none of the isolates is capable of sporulating on wild-type Ws-0. Ws-eds1 seedlings exhibited enhanced susceptibility to some P. parasitica isolates when compared with a compatible wild-type ecotype, Columbia, and the eds1 parental ecotype, Ws-0. This was observed as earlier initiation of sporulation and elevated production of conidiosporangia. Surprisingly, cotyledons of Ws-eds1 also supported low sporulation by five isolates of P. parasitica from Brassica oleracea. These isolates were unable to sporulate on > 100 ecotypes of Arabidopsis, including wild-type Ws-0. An isolate of Albugo candida (white blister) from B. oleracea also sporulated on Ws-eds1, but the mutant exhibited no alteration in phenotype when inoculated with several oomycete isolates from other host species. The bacterial resistance gene RPM1, conferring specific recognition of the avirulence gene avrB from Pseudomonas syringae pv glycinea, was not compromised in Ws-eds1 plants. The mutant also retained full responsiveness to the chemical inducer of systemic

  2. 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.

  3. Elicitin-Induced Distal Systemic Resistance in Plants is Mediated Through the Protein-Protein Interactions Influenced by Selected Lysine Residues.

    Science.gov (United States)

    Uhlíková, Hana; Obořil, Michal; Klempová, Jitka; Šedo, Ondrej; Zdráhal, Zbyněk; Kašparovský, Tomáš; Skládal, Petr; Lochman, Jan

    2016-01-01

    Elicitins are a family of small proteins with sterol-binding activity that are secreted by Phytophthora and Pythium sp. classified as oomycete PAMPs. Although α- and β-elicitins bind with the same affinity to one high affinity binding site on the plasma membrane, β-elicitins (possessing 6-7 lysine residues) are generally 50- to 100-fold more active at inducing distal HR and systemic resistance than the α-isoforms (with only 1-3 lysine residues). To examine the role of lysine residues in elicitin biological activity, we employed site-directed mutagenesis to prepare a series of β-elicitin cryptogein variants with mutations on specific lysine residues. In contrast to direct infiltration of protein into leaves, application to the stem revealed a rough correlation between protein's charge and biological activity, resulting in protection against Phytophthora parasitica. A detailed analysis of proteins' movement in plants showed no substantial differences in distribution through phloem indicating differences in consequent apoplastic or symplastic transport. In this process, an important role of homodimer formation together with the ability to form a heterodimer with potential partner represented by endogenous plants LTPs is suggested. Our work demonstrates a key role of selected lysine residues in these interactions and stresses the importance of processes preceding elicitin recognition responsible for induction of distal systemic resistance.

  4. Elicitin-induced distal systemic resistance in plants is mediated through the protein-protein interactions influenced by selected lysine residues

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    Hana eUhlíková

    2016-02-01

    Full Text Available Elicitins are a family of small proteins with sterol-binding activity that are secreted by Phytophthora and Pythium spp. classified as oomycete PAMPs. Although alfa- and beta-elicitins bind with the same affinity to one high affinity binding site on the plasma membrane, beta-elicitins (possessing 6-7 lysine residues are generally 50- to 100-fold more active at inducing distal HR and systemic resistance than the alfa-isoforms (with only 1-3 lysine residues.To examine the role of lysine residues in elicitin biological activity, we employed site-directed mutagenesis to prepare a series of beta-elicitin cryptogein variants with mutations on specific lysine residues. In contrast to direct infiltration of protein into leaves, application to the stem revealed a rough correlation between protein’s charge and biological activity, resulting in protection against Phytophthora parasitica. A detailed analysis of proteins’ movement in plants showed no substantial differences in distribution through phloem indicating differences in consequent apoplastic or symplastic transport. In this process, an important role of homodimer formation together with the ability to form a heterodimer with potential partner represented by endogenous plants LTPs is suggested. Our work demonstrates a key role of selected lysine residues in these interactions and stresses the importance of processes preceding elicitin recognition responsible for induction of distal systemic resistance.

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

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    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.

  6. 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.

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

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    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.

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

    Science.gov (United States)

    Roy, Sourav; Kagda, Meenakshi; Judelson, Howard S

    2013-03-01

    Most eukaryotic pathogens have complex life cycles in which gene expression networks orchestrate the formation of cells specialized for dissemination or host colonization. In the oomycete Phytophthora infestans, the potato late blight pathogen, major shifts in mRNA profiles during developmental transitions were identified using microarrays. We used those data with search algorithms to discover about 100 motifs that are over-represented in promoters of genes up-regulated in hyphae, sporangia, sporangia undergoing zoosporogenesis, swimming zoospores, or germinated cysts forming appressoria (infection structures). Most of the putative stage-specific transcription factor binding sites (TFBSs) thus identified had features typical of TFBSs such as position or orientation bias, palindromy, and conservation in related species. Each of six motifs tested in P. infestans transformants using the GUS reporter gene conferred the expected stage-specific expression pattern, and several were shown to bind nuclear proteins in gel-shift assays. Motifs linked to the appressoria-forming stage, including a functionally validated TFBS, were over-represented in promoters of genes encoding effectors and other pathogenesis-related proteins. To understand how promoter and genome architecture influence expression, we also mapped transcription patterns to the P. infestans genome assembly. Adjacent genes were not typically induced in the same stage, including genes transcribed in opposite directions from small intergenic regions, but co-regulated gene pairs occurred more than expected by random chance. These data help illuminate the processes regulating development and pathogenesis, and will enable future attempts to purify the cognate transcription factors.

  9. 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.

  10. Appraisal of artificial screening techniques of tomato to accurately reflect field performance of the late blight resistance.

    Directory of Open Access Journals (Sweden)

    Marzena Nowakowska

    Full Text Available Late blight (LB caused by the oomycete Phytophthora infestans continues to thwart global tomato production, while only few resistant cultivars have been introduced locally. In order to gain from the released tomato germplasm with LB resistance, we compared the 5-year field performance of LB resistance in several tomato cultigens, with the results of controlled conditions testing (i.e., detached leaflet/leaf, whole plant. In case of these artificial screening techniques, the effects of plant age and inoculum concentration were additionally considered. In the field trials, LA 1033, L 3707, L 3708 displayed the highest LB resistance, and could be used for cultivar development under Polish conditions. Of the three methods using controlled conditions, the detached leaf and the whole plant tests had the highest correlation with the field experiments. The plant age effect on LB resistance in tomato reported here, irrespective of the cultigen tested or inoculum concentration used, makes it important to standardize the test parameters when screening for resistance. Our results help show why other reports disagree on LB resistance in tomato.

  11. 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.

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

    Science.gov (United States)

    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.

  13. 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.

  14. GK4, a G-protein-coupled receptor with a phosphatidylinositol phosphate kinase domain in Phytophthora infestans, is involved in sporangia development and virulence.

    Science.gov (United States)

    Hua, Chenlei; Meijer, Harold J G; de Keijzer, Jeroen; Zhao, Wei; Wang, Yuanchao; Govers, Francine

    2013-04-01

    For dispersal and host infection plant pathogens largely depend on asexual spores. Pathogenesis and sporulation are complex processes that are governed by cellular signalling networks including G-protein and phospholipid signalling. Oomycetes possess a family of novel proteins called GPCR-PIPKs (GKs) that are composed of a seven-transmembrane spanning (7-TM) domain fused to a phosphatidylinositol phosphate kinase (PIPK) domain. Based on this domain structure GKs are anticipated to link G-protein and phospholipid signal pathways; however, their functions are currently unknown. Expression analyses of the 12 GK genes in Phytophthora infestans and their orthologues in Phytophthora sojae, revealed differential expression during asexual development. PiGK1 and PiGK4 were fused to monomeric red fluorescent protein (mRFP) and ectopically expressed in P. infestans. In growing hyphae different subcellular distribution patterns were observed indicating that these two GKs act independently during development. We focused on the functional analyses of PiGK4. Its localization suggested involvement in cell differentiation and elongation and its 7-TM domain showed a canonical GPCR membrane topology. Silencing of GK4 and overexpression of full-length and truncated constructs in P. infestans revealed that PiGK4 is not only involved in spore germination and hyphal elongation but also in sporangia cleavage and infection.

  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 Cell Death Triggered by the Nuclear Localized RxLR Effector PITG_22798 from Phytophthora infestans Is Suppressed by the Effector AVR3b.

    Science.gov (United States)

    Wang, Hongyang; Ren, Yajuan; Zhou, Jing; Du, Juan; Hou, Juan; Jiang, Rui; Wang, Haixia; Tian, Zhendong; Xie, Conghua

    2017-02-14

    Phytopathogenic oomycetes, such as Phytophthora infestans, potentially secrete many RxLR effector proteins into plant cells to modulate plant immune responses and promote colonization. However, the molecular mechanisms by which these RxLR effectors suppress plant immune responses are largely unknown. Here we describe an RxLR effector PITG_22798 (Gene accession: XM_002998349) that was upregulated during early infection of potato by P. infestans. By employment of agroinfiltration, we observed that PITG_22798 triggers cell death in Nicotiana benthamiana. Confocal microscopic examination showed that PITG_22798-GFP (Green Fluorescent Protein) located in the host nucleus when expressed transiently in N. benthamiana leaves. A nuclear localization signal (NLS) domain of PITG_22798 is important for nuclear localization and cell death-inducing activity. Sequence alignment and transient expression showed that PITG_22798 from diverse P. infestans isolates are conserved, and transient expression of PITG_22798 enhances P. infestans colonization of N. benthamiana leaves, which suggests that PITG_22798 contributes to P. infestans infection. PITG_22798-triggered cell death is dependent on SGT1-mediated signaling and is suppressed by the P. infestans avirulence effector 3b (AVR3b). The present research provides a clue for further investigation of how P. infestans effector PITG_22798 associates with and modulates host immunity.

  17. 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.

  18. In vitro translocation experiments with RxLR-reporter fusion proteins of Avr1b from Phytophthora sojae and AVR3a from Phytophthora infestans fail to demonstrate specific autonomous uptake in plant and animal cells.

    Science.gov (United States)

    Wawra, Stephan; Djamei, Armin; Albert, Isabell; Nürnberger, Thorsten; Kahmann, Regine; van West, Pieter

    2013-05-01

    Plant-pathogenic oomycetes have a large set of secreted effectors that can be translocated into their host cells during infection. One group of these effectors are the RxLR effectors for which it has been shown, in a few cases, that the RxLR motif is important for their translocation. It has been suggested that the RxLR-leader sequences alone are enough to translocate the respective effectors into eukaryotic cells through binding to surface-exposed phosphoinositol-3-phosphate. These conclusions were primary based on translocation experiments conducted with recombinant fusion proteins whereby the RxLR leader of RxLR effectors (i.e., Avr1b from Phytophthora sojae) were fused to the green fluorescent protein reporter-protein. However, we failed to observe specific cellular uptake for a comparable fusion protein where the RxLR leader of the P. infestans AVR3a was fused to monomeric red fluorescent protein. Therefore, we reexamined the ability of the reported P. sojae AVR1b RxLR leader to enter eukaryotic cells. Different relevant experiments were performed in three independent laboratories, using fluorescent reporter fusion constructs of AVR3a and Avr1b proteins in a side-by-side comparative study on plant tissue and human and animal cells. We report that we were unable to obtain conclusive evidence for specific RxLR-mediated translocation.

  19. 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.

  20. Phytophthora infestans RXLR effector PexRD2 interacts with host MAPKKK ε to suppress plant immune signaling.

    Science.gov (United States)

    King, Stuart R F; McLellan, Hazel; Boevink, Petra C; Armstrong, Miles R; Bukharova, Tatyana; Sukarta, Octavina; Win, Joe; Kamoun, Sophien; Birch, Paul R J; Banfield, Mark J

    2014-03-01

    Mitogen-activated protein kinase cascades are key players in plant immune signaling pathways, transducing the perception of invading pathogens into effective defense responses. Plant pathogenic oomycetes, such as the Irish potato famine pathogen Phytophthora infestans, deliver RXLR effector proteins to plant cells to modulate host immune signaling and promote colonization. Our understanding of the molecular mechanisms by which these effectors act in plant cells is limited. Here, we report that the P. infestans RXLR effector PexRD2 interacts with the kinase domain of MAPKKKε, a positive regulator of cell death associated with plant immunity. Expression of PexRD2 or silencing MAPKKKε in Nicotiana benthamiana enhances susceptibility to P. infestans. We show that PexRD2 perturbs signaling pathways triggered by or dependent on MAPKKKε. By contrast, homologs of PexRD2 from P. infestans had reduced or no interaction with MAPKKKε and did not promote disease susceptibility. Structure-led mutagenesis identified PexRD2 variants that do not interact with MAPKKKε and fail to support enhanced pathogen growth or perturb MAPKKKε signaling pathways. Our findings provide evidence that P. infestans RXLR effector PexRD2 has evolved to interact with a specific host MAPKKK to perturb plant immunity-related signaling.

  1. Mutations in the EDR1 Gene Alter the Response of Arabidopsis thaliana to Phytophthora infestans and the Bacterial PAMPs flg22 and elf18.

    Science.gov (United States)

    Geissler, Katrin; Eschen-Lippold, Lennart; Naumann, Kai; Schneeberger, Korbinian; Weigel, Detlef; Scheel, Dierk; Rosahl, Sabine; Westphal, Lore

    2015-02-01

    Mechanistically, nonhost resistance of Arabidopsis thaliana against the oomycete Phytophthora infestans is not well understood. Besides PEN2 and PEN3, which contribute to penetration resistance, no further components have been identified so far. In an ethylmethane sulphonate-mutant screen, we mutagenized pen2-1 and screened for mutants with an altered response to infection by P. infestans. One of the mutants obtained, enhanced response to Phytophthora infestans6 (erp6), was analyzed. Whole-genome sequencing of erp6 revealed a single nucleotide polymorphism in the coding region of the kinase domain of At1g08720, which encodes the putative MAPKKK ENHANCED DISEASE RESISTANCE1 (EDR1). We demonstrate that three independent lines with knock-out alleles of edr1 mount an enhanced response to P. infestans inoculation, mediated by increased salicylic acid signaling and callose deposition. Moreover, we show that the single amino acid substitution in erp6 causes the loss of in vitro autophosphorylation activity of EDR1. Furthermore, growth inhibition experiments suggest a so-far-unknown involvement of EDR1 in the response to the pathogen-associated molecular patterns flg22 and elf18. We conclude that EDR1 contributes to the defense response of A. thaliana against P. infestans. Our data position EDR1 as a negative regulator in postinvasive nonhost resistance.

  2. 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.

  3. 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.

  4. 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.

  5. Computational Prediction of Effector Proteins in Fungi: Opportunities and Challenges

    Directory of Open Access Journals (Sweden)

    Humira eSonah

    2016-02-01

    Full Text Available Effector proteins are mostly secretory proteins that stimulate plant infection by manipulating the host response. Identifying fungal effector proteins and understanding their function is of great importance in efforts to curb losses to plant diseases. Recent advances in high-throughput sequencing technologies have facilitated the availability of several fungal genomes and thousands of transcriptomes. As a result, the growing amount of genomic information has provided great opportunities to identify putative effector proteins in different fungal species. There is little consensus over the annotation and functionality of effector proteins, and mostly small secretory proteins are considered as effector proteins, a concept that tends to overestimate the number of proteins involved in a plant-pathogen interaction. With the characterization of Avr genes, criteria for computational prediction of effector proteins are becoming more efficient. There are hundreds of tools available for the identification of conserved motifs, signature sequences and structural features in the proteins. Many pipelines and online servers, which combine several tools, are made available to perform genome-wide identification of effector proteins. In this review, available tools and pipelines, their strength and limitations for effective identification of fungal effector proteins are discussed. We also present an exhaustive list of classically secreted proteins along with their key conserved motifs found in 12 common plant pathogens (11 fungi and one oomycete through an analytical pipeline.

  6. Grapevine Pathogenic Microorganisms: Understanding Infection Strategies and Host Response Scenarios.

    Science.gov (United States)

    Armijo, Grace; Schlechter, Rudolf; Agurto, Mario; Muñoz, Daniela; Nuñez, Constanza; Arce-Johnson, Patricio

    2016-01-01

    Grapevine (Vitis vinifera L.) is one of the most important fruit crop worldwide. Commercial cultivars are greatly affected by a large number of pathogenic microorganisms that cause diseases during pre- and/or post-harvest periods, affecting production, processing and export, along with fruit quality. Among the potential threats, we can find bacteria, fungi, oomycete, or viruses with different life cycles, infection mechanisms and evasion strategies. While plant-pathogen interactions are cycles of resistance and susceptibility, resistance traits from natural resources are selected and may be used for breeding purposes and for a sustainable agriculture. In this context, here we summarize some of the most important diseases affecting V. vinifera together with their causal agents. The aim of this work is to bring a comprehensive review of the infection strategies deployed by significant types of pathogens while understanding the host response in both resistance and susceptibility scenarios. New approaches being used to uncover grapevine status during biotic stresses and scientific-based procedures needed to control plant diseases and crop protection are also addressed.

  7. Identifying beneficial qualities of Trichoderma parareesei for plants.

    Science.gov (United States)

    Rubio, M Belén; Quijada, Narciso M; Pérez, Esclaudys; Domínguez, Sara; Monte, Enrique; Hermosa, Rosa

    2014-03-01

    Trichoderma parareesei and Trichoderma reesei (teleomorph Hypocrea jecorina) produce cellulases and xylanases of industrial interest. Here, the anamorphic strain T6 (formerly T. reesei) has been identified as T. parareesei, showing biocontrol potential against fungal and oomycete phytopathogens and enhanced hyphal growth in the presence of tomato exudates or plant cell wall polymers in in vitro assays. A Trichoderma microarray was used to examine the transcriptomic changes in T6 at 20 h of interaction with tomato plants. Out of a total 34,138 Trichoderma probe sets deposited on the microarray, 250 showed a significant change of at least 2-fold in expression in the presence of tomato plants, with most of them being downregulated. T. parareesei T6 exerted beneficial effects on tomato plants in terms of seedling lateral root development, and in adult plants it improved defense against Botrytis cinerea and growth promotion under salt stress. Time course expression patterns (0 to 6 days) observed for defense-related genes suggest that T6 was able to prime defense responses in the tomato plants against biotic and abiotic stresses. Such responses undulated, with a maximum upregulation of the jasmonic acid (JA)/ethylene (ET)-related LOX1 and EIN2 genes and the salt tolerance SOS1 gene at 24 h and that of the salicylic acid (SA)-related PR-1 gene at 48 h after T6 inoculation. Our study demonstrates that the T. parareesei T6-tomato interaction is beneficial to both partners.

  8. Expression profiling of Cucumis sativus in response to infection by Pseudoperonospora cubensis.

    Science.gov (United States)

    Adhikari, Bishwo N; Savory, Elizabeth A; Vaillancourt, Brieanne; Childs, Kevin L; Hamilton, John P; Day, Brad; Buell, C Robin

    2012-01-01

    The oomycete pathogen, Pseudoperonospora cubensis, is the causal agent of downy mildew on cucurbits, and at present, no effective resistance to this pathogen is available in cultivated cucumber (Cucumis sativus). To better understand the host response to a virulent pathogen, we performed expression profiling throughout a time course of a compatible interaction using whole transcriptome sequencing. As described herein, we were able to detect the expression of 15,286 cucumber genes, of which 14,476 were expressed throughout the infection process from 1 day post-inoculation (dpi) to 8 dpi. A large number of genes, 1,612 to 3,286, were differentially expressed in pair-wise comparisons between time points. We observed the rapid induction of key defense related genes, including catalases, chitinases, lipoxygenases, peroxidases, and protease inhibitors within 1 dpi, suggesting detection of the pathogen by the host. Co-expression network analyses revealed transcriptional networks with distinct patterns of expression including down-regulation at 2 dpi of known defense response genes suggesting coordinated suppression of host responses by the pathogen. Comparative analyses of cucumber gene expression patterns with that of orthologous Arabidopsis thaliana genes following challenge with Hyaloperonospora arabidopsidis revealed correlated expression patterns of single copy orthologs suggesting that these two dicot hosts have similar transcriptional responses to related pathogens. In total, the work described herein presents an in-depth analysis of the interplay between host susceptibility and pathogen virulence in an agriculturally important pathosystem.

  9. Survival of Phytophthora alni, Phytophthora kernoviae, and Phytophthora ramorum in a simulated aquatic environment at different levels of pH.

    Science.gov (United States)

    Kong, Ping; Lea-Cox, John D; Moorman, Gary W; Hong, Chuanxue

    2012-07-01

    Phytophthora ramorum, Phytophthora alni, and Phytophthora kernoviae present significant threats to biosecurity. As zoosporic oomycetes, these plant pathogens may spread through natural waterways and irrigation systems. However, survival of these pathogens in aquatic systems in response to water quality is not well understood. In this study, we investigated their zoospore survival at pH 3-11 in a 10% Hoagland's solution over a 14-day period. The results showed that all three pathogens were most stable at pH 7, although the populations declined overnight irrespective of pH. Extended survival of these species depended on the tolerance of pH of their germinants. Germinants of P. alni ssp. alni and P. ramorum were more basic tolerant (pH 5-11), while those of P. kernoviae were more acidic tolerant (pH 3-9). These tolerant germinants formed compact hyphae or secondary sporangia to allow longer survival of these pathogens. Long-term survival at a broad pH range suggests that these pathogens, especially P. ramorum, are adapted to an aquatic environment and pose a threat to new production areas through water dispersal. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  10. Strain-level diversity of secondary metabolism in the biocontrol species Aneurinibacillus migulanus.

    Science.gov (United States)

    Alenezi, Faizah N; Rekik, Imen; Bełka, Marta; Ibrahim, Abrar F; Luptakova, Lenka; Jaspars, Marcel; Woodward, Steve; Belbahri, Lassaad

    2016-01-01

    Aneurinibacillus migulanus strains Nagano and NCTC 7096 show potential in biocontrol against fungal and fungus-like plant pathogens, including a wide range of Ascomycota, Basidiomycota, and Oomycetes. Differences in terms of the range of pathogens that each strain inhibits, however, suggested that production of a single antibiotic cyclic peptide, gramicidin S (GS), by the two strains, is not the sole mechanism of inhibition. The availability of four sequenced genomes of Aneurinibacillus prompted us to apply genome mining techniques to identify the bioactive potential of A. migulanus and to provide insights into the secondary metabolite arsenal of the genus Aneurinibacillus. Up to eleven secondary metabolite biosynthetic gene clusters were present in the three Aneurinibacillus species. Biosynthetic gene clusters specifying bacteriocins, microcins, non-ribosomal peptides, polyketides, terpenes, phosphonates, lasso peptides and linaridins were identified. Chitinolytic potential and iron metabolism regulation were also investigated. With increasing numbers of biocontrol bacterial genomes being sequenced and mined, the use of approaches similar to those described in this paper will lead to an increase in the numbers of environmentally friendly natural products available to use against plant diseases. Copyright © 2015 Elsevier GmbH. All rights reserved.

  11. Control of Plant Diseases by Extracts of Inula viscosa.

    Science.gov (United States)

    Wang, Wenqiao; Ben-Daniel, B H; Cohen, Yigal

    2004-10-01

    ABSTRACT Leaves of Inula viscosa were collected from the field, dried, and extracted with a mixture of acetone and n-hexane. The oily, water-insoluble pastes obtained after evaporation of the solvents were used for the control of foliar diseases in growth chambers. The pastes, either dissolved in acetone or emulsified in water, effectively controlled downy mildew of cucumber, late blight of potato or tomato, powdery mildew of wheat, and rust of sunflower. Mean effective dose (concentration) required for 90% inhibition of disease values for acetone solutions and water emulsions ranged from 0.68 to 1.02% and 0.65 to 1.00% (wt/vol), respectively. Dry matter content in fresh leaves, paste-extract yield in dry leaves, and disease control efficacy of paste extracts were similar in leaves of I. viscosa collected during May to October, suggesting that, for practical use, harvests can be conducted during most of the growing season. The results show that I. viscosa may be used as an herbal source for fungicidal preparations against foliar diseases caused by pathogens belonging to the families Oomycetes, Ascomycetes, and Basidiomycetes.

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

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    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.

  13. Daytime Solar Heating Controls Downy Mildew Peronospora belbahrii in Sweet Basil.

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    Yigal Cohen

    Full Text Available The biotrophic oomycete Peronospora belbahrii causes a devastating downy mildew disease in sweet basil. Due to the lack of resistant cultivars current control measures rely heavily on fungicides. However, resistance to fungicides and strict regulation on their deployment greatly restrict their use. Here we report on a 'green' method to control this disease. Growth chamber studies showed that P. belbahrii could hardly withstand exposure to high temperatures; exposure of spores, infected leaves, or infected plants to 35-45 °C for 6-9 hours suppressed its survival. Therefore, daytime solar heating was employed in the field to control the downy mildew disease it causes in basil. Covering growth houses of sweet basil already infected with downy mildew with transparent infra-red-impermeable, transparent polyethylene sheets raised the daily maximal temperature during sunny hours by 11-22 °C reaching 40-58 °C (greenhouse effect. Such coverage, applied for a few hours during 1-3 consecutive days, had a detrimental effect on the survival of P. belbahrii: killing the pathogen and/or suppressing disease progress while enhancing growth of the host basil plants.

  14. 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.

  15. Comparative and functional analysis of the widely occurring family of Nep1-like proteins.

    Science.gov (United States)

    Oome, Stan; Van den Ackerveken, Guido

    2014-10-01

    Nep1-like proteins (NLP) are best known for their cytotoxic activity in dicot plants. NLP are taxonomically widespread among microbes with very different lifestyles. To learn more about this enigmatic protein family, we analyzed more than 500 available NLP protein sequences from fungi, oomycetes, and bacteria. Phylogenetic clustering showed that, besides the previously documented two types, an additional, more divergent, third NLP type could be distinguished. By closely examining the three NLP types, we identified a noncytotoxic subgroup of type 1 NLP (designated type 1a), which have substitutions in amino acids making up a cation-binding pocket that is required for cytotoxicity. Type 2 NLP were found to contain a putative calcium-binding motif, which was shown to be required for cytotoxicity. Members of both type 1 and type 2 NLP were found to possess additional cysteine residues that, based on their predicted proximity, make up potential disulfide bridges that could provide additional stability to these secreted proteins. Type 1 and type 2 NLP, although both cytotoxic to plant cells, differ in their ability to induce necrosis when artificially targeted to different cellular compartments in planta, suggesting they have different mechanisms of cytotoxicity.

  16. Contribution of Multiple Inter-kingdom Horizontal Gene Transfers to Evolution and Adaptation of Amphibian-killing Chytrid, Batrachochytrium dendrobatidis

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    Baofa Sun

    2016-08-01

    Full Text Available Amphibian populations are experiencing catastrophic declines driven by the fungal pathogen Batrachochytrium dendrobatidis (Bd. Although horizontal gene transfer (HGT facilitates the evolution and adaptation in many fungi by conferring novel function genes to the recipient fungi, inter-kingdom HGT in Bd remains largely unexplored. In this study, our investigation detects 19 bacterial genes transferred to Bd, including metallo-beta-lactamase and arsenate reductase that play important roles in the resistance to antibiotics and arsenates. Moreover, three probable HGT gene families in Bd are from plants and one gene family coding the ankyrin repeat-containing protein appears to come from oomycetes. The observed multi-copy gene families associated with HGT are probably due to the independent transfer events or gene duplications. Five HGT genes with extracellular locations may relate to infection, and some other genes may participate in a variety of metabolic pathways, and in doing so add important metabolic traits to the recipient. The evolutionary analysis indicates that all the transferred genes evolved under purifying selection, suggesting that their functions in Bd are similar to those of the donors. Collectively, our results indicate that HGT from diverse donors may be an important evolutionary driver of Bd, and improve its adaptations for infecting and colonizing host amphibians.

  17. Revisiting Vitis vinifera subtilase gene family: a possible role in grapevine resistance against Plasmopara viticola

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    Joana Figueiredo

    2016-11-01

    Full Text Available Subtilisin-like proteases, also known as subtilases, are a very diverse family of serine peptidases present in many organisms. In grapevine, there are hints of the involvement of subtilases in defence mechanisms, but their role is not yet understood. The first characterization of the subtilase gene family was performed in 2014. However, simultaneously, the grapevine genome was re-annotated and several sequences were re-annotated or retrieved. We have performed a re-characterization of this family in grapevine and identified 82 genes coding for 97 putative proteins, as result of alternative splicing. All the subtilases identified present the characteristic S8 peptidase domain and the majority of them also have a pro-domain I9 inhibitor, a protease-associated (PA domain and a signal peptide for targeting to the secretory pathway. Phylogenetic studies revealed six subtilase groups denominated VvSBT1 to VvSBT6. As several evidences have highlighted the participation of plant subtilases in response to biotic stimulus, we have investigated subtilase participation in grapevine resistance to Plasmopara viticola, the causative agent of downy mildew. Fourteen grapevine subtilases presenting either high homology to P69C from tomato, SBT3.3 from Arabidopsis thaliana or located near the Resistance to Plasmopara viticola (RPV locus were selected. Expression studies were conducted in the grapevine-P. viticola pathosystem with resistant and susceptible cultivars. Our results may indicate that some of grapevine subtilisins are potentially participating in the defence response against this biotrophic oomycete.

  18. Photosynthetic responses of lettuce to downy mildew infection and cytokinin treatment.

    Science.gov (United States)

    Prokopová, Jitka; Spundová, Martina; Sedlárová, Michaela; Husicková, Alexandra; Novotný, Radko; Dolezal, Karel; Naus, Jan; Lebeda, Ales

    2010-08-01

    Changes in primary metabolism of lettuce, Lactuca sativa L. (cv. Cobham Green), induced by compatible interaction with the biotrophic oomycete pathogen Bremia lactucae Regel (race BL 16), under two intensities of illumination in the presence and absence of exogenous cytokinins were studied by chlorophyll fluorescence imaging. Thirteen days post-inoculation leaf discs infected by B. lactucae exhibited impairments of photosynthesis associated with biotrophic infections, including: reductions in photosynthetic pigment contents and the maximum quantum yield of photosystem II photochemistry (F(V)/F(M)), inhibition of electron transport (Phi(PSII)) and increased non-photochemical chlorophyll fluorescence quenching (NPQ). Detected changes in photosynthetic parameters correlated with the leaf area colonized by the pathogen's intercellular hyphae. Applications of two cytokinins, benzylaminopurine and meta-topolin, previously shown to suppress B. lactucae sporulation if applied 24 h prior to inoculation at a concentration of 200 microM, retarded the pathogen's asexual reproduction with no apparent negative effects on the host's photosynthetic apparatus. However, long-lasting treatment of healthy tissues with this high concentration of exogenous cytokinin led to effects parallel to pathogenesis: reductions in photosynthetic pigment contents accompanied by inhibition of photosystem II photochemistry and electron transport. These effects of both prolonged exposure to cytokinins and the pathogenesis were weaker in discs exposed to the lower photosynthetic photon flux density. The role of cytokinins in plant-biotrophic pathogen interactions and their potential as disease control agents are discussed.

  19. Genetic analysis of the fungus, Bremia lactucae, using restriction fragment length polymorphisms.

    Science.gov (United States)

    Hulbert, S H; Ilott, T W; Legg, E J; Lincoln, S E; Lander, E S; Michelmore, R W

    1988-12-01

    Restriction fragment length polymorphisms (RFLPs) were developed as genetic markers for Bremia lactucae, the biotrophic Oomycete fungus which causes lettuce downy mildew. By using 55 genomic and cDNA probes, a total of 61 RFLP loci were identified among three heterothallic isolates of B. lactucae. Of these 61 RFLP loci, 53 were heterozygous in at least one of the three strains and thus were informative for linkage analysis in at least one of two F1 crosses that were performed. Analysis of the cosegregation of these 53 RFLPs, eight avirulence loci and the mating type locus allowed the construction of a preliminary genetic linkage map consisting of 13 small linkage groups. Based on the extent of linkage detected among probes, the genome of B. lactucae can be estimated to be approximately 2000 cM. Linkage was detected between a RFLP locus and an avirulence gene, providing a potential starting point for chromosome walking to clone an avirulence gene. The high frequency of DNA polymorphism in naturally occurring isolates and the proper Mendelian segregation of loci detected by low copy number probes indicates that it will be possible to construct a detailed genetic map of B. lactucae using RFLPs as markers. The method of analysis employed here should be applicable to many other outbreeding, heterozygous species for which defined inbred lines are not available.

  20. The xylem as battleground for plant hosts and vascular wilt pathogens

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    Koste eYadeta

    2013-04-01

    Full Text Available Vascular wilts are among the most destructive plant diseases that occur in annual crops as well as in woody perennials. These diseases are generally caused by soil-borne bacteria, fungi and oomycetes that infect through the roots and enter the water-conducting xylem vessels where they proliferate and obstruct the transportation of water and minerals. As a consequence, leaves wilt and die, which may lead to impairment of the whole plant and eventually to death of the plant. Cultural, chemical and biological measures to control this group of plant pathogens are generally ineffective, and the most effective control strategy is the use of genetic resistance. Owing to the fact that vascular wilt pathogens live deep in the interior of their host plants, studies into the biology of vascular pathogens are complicated. However, to design novel strategies to combat vascular wilt diseases, understanding the (molecular biology of vascular pathogens and the molecular mechanisms underlying plant defense against these pathogens is crucial. In this review we discuss the current knowledge on interactions of vascular wilt pathogens with their host plants, with emphasis on host defense responses against this group of pathogens.

  1. Effect of road deicing salt on the susceptibility of amphibian embryos to infection by water molds.

    Science.gov (United States)

    Karraker, Nancy E; Ruthig, Gregory R

    2009-01-01

    Some causative agents of amphibian declines act synergistically to impact individual amphibians and their populations. In particular, pathogenic water molds (aquatic oomycetes) interact with environmental stressors and increase mortality in amphibian embryos. We documented colonization of eggs of three amphibian species, the wood frog (Rana sylvatica), the green frog (Rana clamitans), and the spotted salamander (Ambystoma maculatum), by water molds in the field and examined the interactive effects of road deicing salt and water molds, two known sources of mortality for amphibian embryos, on two species, R. clamitans and A. maculatum in the laboratory. We found that exposure to water molds did not affect embryonic survivorship in either A. maculatum or R. clamitans, regardless of the concentration of road salt to which their eggs were exposed. Road salt decreased survivorship of A. maculatum, but not R. clamitans, and frequency of malformations increased significantly in both species at the highest salinity concentration. The lack of an effect of water molds on survival of embryos and no interaction between road salt and water molds indicates that observations of colonization of these eggs by water molds in the field probably represent a secondary invasion of unfertilized eggs or of embryos that had died of other causes. Given increasing salinization of freshwater habitats on several continents and the global distribution of water molds, our results suggest that some amphibian species may not be susceptible to the combined effects of these factors, permitting amphibian decline researchers to devote their attention to other potential causes.

  2. Granulomatous pneumonia caused by Pythium insidiosum in a central American jaguar, Panthera onca.

    Science.gov (United States)

    Camus, Alvin C; Grooters, Amy M; Aquilar, Roberto E

    2004-11-01

    A 7-month-old, male jaguar presented with dyspnea and leukocytosis unresponsive to antibiotic therapy. Radiographs revealed unilateral pulmonary consolidation. An exploratory thoracotomy was performed, and the left lung, which contained a large multilobular mass with extensive fibrosis and numerous caseonecrotic foci, was removed. Microscopically, eosinophilic granulomatous inflammation surrounded broad (4.4-8.3 microm) rarely septate hyphae. A diagnosis of Pythium insidiosum infection was confirmed by immunohistochemistry, immunoblot serology, culture, and polymerase chain reaction. Dyspnea recurred despite treatment, and the animal succumbed 3 weeks after surgery. Necropsy findings indicated that death resulted from occlusion of the right main stem bronchus by a fungal granuloma. The oomycete P. insidiosum typically causes granulomatous disease of the skin or gastrointestinal tract in animals and arteritis, keratitis, or cellulitis in humans. Infection is uncommon in felines, and pulmonary involvement is rare. This report details the first case of P. insidiosum infection in an exotic felid and provides the first description of primary pulmonary pythiosis in any species.

  3. Taro Leaf Blight—A Threat to Food Security

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    Tom Okpul

    2012-07-01

    Full Text Available Taro leaf blight (caused by the Oomycete Phytophthora colocasiae is a disease of major importance in many regions of the world where taro is grown. Serious outbreaks of taro leaf blight in Samoa in 1993 and in the last few years in Cameroon, Ghana and Nigeria continue to demonstrate the devastating impact of this disease on the livelihoods and food security of small farmers and rural communities dependent on the crop. The spread of the disease to new geographical areas also poses a major threat to neighbouring countries and taro growing regions still free from the disease. Past research, particularly in the Pacific, has demonstrated that management measures such as chemical and cultural control are largely ineffective and that breeding for disease resistance is the most sustainable approach to manage the disease. Recently, the Pacific and South-east Asian regional taro networks have made excellent progress in developing cultivars resistant to taro leaf blight through enhanced utilization of taro genetic resources and close collaboration between farmers and researchers in breeding programs. These programs have secured vital taro genetic resources for future use. This paper provides an overview of the disease, its origin, distribution, biology, epidemiology, management and global impact. The paper will largely focus on breeding strategies to address the disease including challenges, opportunities and constraints. It also discusses how these breeding experiences and outputs can be scaled up to other geographical areas where the disease has been recently introduced or under threat of introduction.

  4. Identifying Beneficial Qualities of Trichoderma parareesei for Plants

    Science.gov (United States)

    Rubio, M. Belén; Quijada, Narciso M.; Pérez, Esclaudys; Domínguez, Sara; Hermosa, Rosa

    2014-01-01

    Trichoderma parareesei and Trichoderma reesei (teleomorph Hypocrea jecorina) produce cellulases and xylanases of industrial interest. Here, the anamorphic strain T6 (formerly T. reesei) has been identified as T. parareesei, showing biocontrol potential against fungal and oomycete phytopathogens and enhanced hyphal growth in the presence of tomato exudates or plant cell wall polymers in in vitro assays. A Trichoderma microarray was used to examine the transcriptomic changes in T6 at 20 h of interaction with tomato plants. Out of a total 34,138 Trichoderma probe sets deposited on the microarray, 250 showed a significant change of at least 2-fold in expression in the presence of tomato plants, with most of them being downregulated. T. parareesei T6 exerted beneficial effects on tomato plants in terms of seedling lateral root development, and in adult plants it improved defense against Botrytis cinerea and growth promotion under salt stress. Time course expression patterns (0 to 6 days) observed for defense-related genes suggest that T6 was able to prime defense responses in the tomato plants against biotic and abiotic stresses. Such responses undulated, with a maximum upregulation of the jasmonic acid (JA)/ethylene (ET)-related LOX1 and EIN2 genes and the salt tolerance SOS1 gene at 24 h and that of the salicylic acid (SA)-related PR-1 gene at 48 h after T6 inoculation. Our study demonstrates that the T. parareesei T6-tomato interaction is beneficial to both partners. PMID:24413597

  5. The chitin-binding Cladosporium fulvum effector protein Avr4 is a virulence factor.

    Science.gov (United States)

    van Esse, H Peter; Bolton, Melvin D; Stergiopoulos, Ioannis; de Wit, Pierre J G M; Thomma, Bart P H J

    2007-09-01

    The biotrophic fungal pathogen Cladosporium fulvum (syn. Passalora fulva) is the causal agent of tomato leaf mold. The Avr4 protein belongs to a set of effectors that is secreted by C. fulvum during infection and is thought to play a role in pathogen virulence. Previous studies have shown that Avr4 binds to chitin present in fungal cell walls and that, through this binding, Avr4 can protect these cell walls against hydrolysis by plant chitinases. In this study, we demonstrate that Avr4 expression in Arabidopsis results in increased virulence of several fungal pathogens with exposed chitin in their cell walls, whereas the virulence of a bacterium and an oomycete remained unaltered. Heterologous expression of Avr4 in tomato increased the virulence of Fusarium oxysporum f. sp. lycopersici. Through tomato GeneChip analyses, we demonstrate that Avr4 expression in tomato results in the induced expression of only a few genes. Finally, we demonstrate that silencing of the Avr4 gene in C. fulvum decreases its virulence on tomato. This is the first report on the intrinsic function of a fungal avirulence protein that has a counter-defensive activity required for full virulence of the pathogen.

  6. O-prenylated acridone alkaloids from the stems of Balsamocitrus paniculata (Rutaceae).

    Science.gov (United States)

    Happi, Emmanuel Ngeufa; Waffo, Alain François; Wansi, Jean Duplex; Ngadjui, Bonaventure Tchaleu; Sewald, Norbert

    2011-06-01

    Two new O-prenylated acridone alkaloids, balsacridone A (1) and B (2), together with eighteen known compounds were isolated from the methanol extract from the stems of Balsamocitrus paniculata, a Cameroonian medicinal plant. The structures of all compounds were determined by comprehensive analyses of their 1D and 2D NMR, mass spectral (EI and ESI) data, and chemical reactions. N-methyl-6-methoxybenzoxazolinone (16) was isolated for the first time from a natural source while compounds 13, 14, and 15 for the first time from this genus. Pure compounds were tested for their activity against bacteria, fungi, and plant pathogen oomycetes, using the paper disk agar diffusion assay. The agar diffusion test delivered low to missing antimicrobial activities, corresponding to MICs > 1 mg/mL. However, compounds 1-15 exhibited a strong suppressive effect on phagocytosis response upon activation with serum opsonized zymosan in the range of IC50 = 0.5-7.2 μM, and the acridone alkaloids (1-5), N-trans-p-coumaroyltyramine (13), and N-trans-pcoumaroyloctopamine (14) displayed weak cytotoxic activity against the human Caucasian prostate adenocarcinoma cell line PC-3, with IC₅₀ values ranging from 69.8 to 99.0 μM.

  7. UV Light Inactivation of Human and Plant Pathogens in Unfiltered Surface Irrigation Water

    Science.gov (United States)

    Jones, Lisa A.; Worobo, Randy W.

    2014-01-01

    Fruit and vegetable growers continually battle plant diseases and food safety concerns. Surface water is commonly used in the production of fruits and vegetables and can harbor both human- and plant-pathogenic microorganisms that can contaminate crops when used for irrigation or other agricultural purposes. Treatment methods for surface water are currently limited, and there is a need for suitable treatment options. A liquid-processing unit that uses UV light for the decontamination of turbid juices was analyzed for its efficacy in the treatment of surface waters contaminated with bacterial or oomycete pathogens, i.e., Escherichia coli, Salmonella enterica, Listeria monocytogenes, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, and Phytophthora capsici. Five-strain cocktails of each pathogen, containing approximately 108 or 109 CFU/liter for bacteria or 104 or 105 zoospores/liter for Ph. capsici, were inoculated into aliquots of two turbid surface water irrigation sources and processed with the UV unit. Pathogens were enumerated before and after treatment. In general, as the turbidity of the water source increased, the effectiveness of the UV treatment decreased, but in all cases, 99.9% or higher inactivation was achieved. Log reductions ranged from 10.0 to 6.1 and from 5.0 to 4.2 for bacterial pathogens and Ph. capsici, respectively. PMID:24242253

  8. The evolutionarily conserved E3 ubiquitin ligase AtCHIP contributes to plant immunity

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    Xin eLi

    2016-03-01

    Full Text Available Plants possess a sophisticated immune system to recognize and respond to microbial threats in their environment. The level of immune signaling must be tightly regulated so that immune responses can be quickly activated in the presence of pathogens, while avoiding autoimmunity. HSP90s, along with their diverse array of co-chaperones, forms chaperone complexes that have been shown to play both positive and negative roles in regulating the accumulation of immune receptors and regulators. In this study, we examined the role of AtCHIP, an evolutionarily conserved E3 ligase that was known to interact with chaperones including HSP90s in multicellular organisms including fruit fly, C. elegans, plants and human. Atchip knockout mutants display enhanced disease susceptibility to a virulent oomycete pathogen, and overexpression of AtCHIP causes enhanced disease resistance at low temperature. Although CHIP was reported to target HSP90 for ubiquitination and degradation, accumulation of HSP90.3 was not affected in Atchip plants. In addition, protein accumulation of nucleotide-binding, leucine-rich repeat domain immune receptor (NLR SNC1 is not altered in Atchip mutant. Thus, while AtCHIP plays a role in immunity, it does not seem to regulate the turnover of HSP90 or SNC1. Further investigation is needed in order to determine the exact mechanism behind AtCHIP’s role in regulating plant immune responses.

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

    Directory of Open Access Journals (Sweden)

    Brigida Pimentel Villar de Queiroz

    2006-12-01

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

  10. Accurate and adequate spatiotemporal expression and localization of RPW8.2 is key to activation of resistance at the host-pathogen interface.

    Science.gov (United States)

    Wang, Wenming; Berkey, Robert; Wen, Yingqiang; Xiao, Shunyuan

    2010-08-01

    Numerous fungal and oomycete pathogens penetrate the plant cell wall and extract nutrition from the host cells by a feeding structure called the haustorium. We recently revealed that the Arabidopsis resistance protein RPW8.2 is specifically targeted to the extrahaustorial membrane (EHM) for activation of haustorium-targeted resistance to powdery mildew pathogens. Consistent with its EHM-localization, RPW8.2 contains a putative transmembrane (TM) domain at its N-terminus. Here, we show that translational fusion of YFP to the N-terminus of RPW8.2 results in localization of YFP-RPW8.2 to both the plasma membrane and the EHM, and loss of RPW8.2's defense function. We also show that deletion of the TM domain results in mis-localization of the RPW8.2-YFP fusion protein and extremely low levels of accumulation. These results indicate that an intact N-terminal TM domain is necessary for EHM-specific localization and defense function of RPW8.2. In addition, we show that when expressed from the strong constitutive 35S viral promoter, RPW8.2 accumulates at low levels in the EHM insufficient to activate resistance, highlighting the importance of stronger spatiotemporal expression of RPW8.2 from its native promoter. Taken together, our results indicate that accurate and adequate spatiotemporal expression and localization of RPW8.2 is key to activation of resistance at the host-pathogen interface.

  11. A Novel Soybean ERF Transcription Factor, GmERF113, Increases Resistance to Phytophthora sojae Infection in Soybean

    Science.gov (United States)

    Zhao, Yuanling; Chang, Xin; Qi, Dongyue; Dong, Lidong; Wang, Guangjin; Fan, Sujie; Jiang, Liangyu; Cheng, Qun; Chen, Xi; Han, Dan; Xu, Pengfei; Zhang, Shuzhen

    2017-01-01

    Phytophthora root and stem rot of soybean caused by the oomycete Phytophthora sojae, is a destructive disease worldwide. Ethylene response factors (ERFs) play important roles in regulating plant biotic and abiotic stress tolerance. In this study, a new ERF gene, GmERF113, was isolated from the highly resistant soybean ‘Suinong 10.’ Sequence analysis suggested that the protein encoded by GmERF113 contained a conserved AP2/ERF domain of 58 amino acid and belonged to the B-4 subgroup of the ERF subfamily. Expression of GmERF113 was significantly induced by P. sojae, ethylene, and methyl jasmonate. GmERF113 protein localized to the nucleus when transiently expressed in Arabidopsis protoplasts, could bind to the GCC-box, and acted as a transcription activator. In addition, a region of the full-length GmERF113, GmERF113-II, interacted with a basic helix-loop-helix transcription factor (GmbHLH) in yeast cells. Full-length GmERF113 also interacted with GmbHLH in planta. GmERF113-overexpressing transgenic plants in susceptible cultivar ‘Dongnong 50’ soybean exhibited increased resistance to P. sojae and positively regulated the expression of the pathogenesis-related genes, PR1 and PR10-1. These results indicate that GmERF113 may play a crucial role in the defense of soybean against P. sojae infection. PMID:28326092

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

    Institute of Scientific and Technical Information of China (English)

    ZENG Juan; WANG Yuanchao; SHEN Gui; ZHENG Xiaobo

    2006-01-01

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

  13. Resistance Against Basil Downy Mildew in Ocimum Species.

    Science.gov (United States)

    Ben-Naim, Yariv; Falach, Lidan; Cohen, Yigal

    2015-06-01

    Downy mildew, caused by the oomycete Peronospora belbahrii, is a devastating disease of sweet basil. In this study, 113 accessions of Ocimum species (83 Plant Introduction entries and 30 commercial entries) were tested for resistance against downy mildew at the seedling stage in growth chambers, and during three seasons, in the field. Most entries belonging to O. basilicum were highly susceptible whereas most entries belonging to O. americanum, O. kilimanadascharicum, O. gratissimum, O. campechianum, or O. tenuiflorum were highly resistant at both the seedling stage and the field. Twenty-seven highly resistant individual plants were each crossed with the susceptible sweet basil 'Peri', and the F1 progeny plants were examined for disease resistance. The F1 plants of two crosses were highly resistant, F1 plants of 24 crosses were moderately resistant, and F1 plants of one cross were susceptible, suggesting full, partial, or no dominance of the resistance gene(s), respectively. These data confirm the feasibility of producing downy mildew-resistant cultivars of sweet basil by crossing with wild Ocimum species.

  14. 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.

  15. 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.

  16. Genome sequence of the stramenopile Blastocystis, a human anaerobic parasite

    Science.gov (United States)

    2011-01-01

    Background Blastocystis is a highly prevalent anaerobic eukaryotic parasite of humans and animals that is associated with various gastrointestinal and extraintestinal disorders. Epidemiological studies have identified different subtypes but no one subtype has been definitively correlated with disease. Results Here we report the 18.8 Mb genome sequence of a Blastocystis subtype 7 isolate, which is the smallest stramenopile genome sequenced to date. The genome is highly compact and contains intriguing rearrangements. Comparisons with other available stramenopile genomes (plant pathogenic oomycete and diatom genomes) revealed effector proteins potentially involved in the adaptation to the intestinal environment, which were likely acquired via horizontal gene transfer. Moreover, Blastocystis living in anaerobic conditions harbors mitochondria-like organelles. An incomplete oxidative phosphorylation chain, a partial Krebs cycle, amino acid and fatty acid metabolisms and an iron-sulfur cluster assembly are all predicted to occur in these organelles. Predicted secretory proteins possess putative activities that may alter host physiology, such as proteases, protease-inhibitors, immunophilins and glycosyltransferases. This parasite also possesses the enzymatic machinery to tolerate oxidative bursts resulting from its own metabolism or induced by the host immune system. Conclusions This study provides insights into the genome architecture of this unusual stramenopile. It also proposes candidate genes with which to study the physiopathology of this parasite and thus may lead to further investigations into Blastocystis-host interactions. PMID:21439036

  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. Foliar application of β-D-glucan nanoparticles to control rhizome rot disease of turmeric.

    Science.gov (United States)

    Anusuya, Sathiyanarayanan; Sathiyabama, Muthukrishnan

    2015-01-01

    The soilborne Oomycete Pythium aphanidermatum is the causal agent of rhizome rot disease, one of the most serious threats to turmeric crops. At present, effective fungicides are not available. Researches on nanoparticles in a number of crops have evidenced the positive changes in gene expression indicating their potential use in crop improvement. Hence, experiments were carried out to determine the effect of β-D-glucan nanoparticles (nanobiopolymer) in protection of turmeric plants against rot disease by the way of products that reinforce plant's own defense mechanism. Foliar spray of β-D-glucan nanoparticles (0.1%, w/v) elicited marked increase in the activity of defense enzymes such as peroxidases (E.C.1.11.1.7), polyphenol oxidases (E.C.1.14.18.1), protease inhibitors (E.C.3.4.21.1) and β-1,3-glucanases (E.C.3.2.1.39) at various age levels. Constitutive and induced isoforms of these enzymes were investigated during this time-course study. β-D-glucan nanoparticles (GNPs) significantly reduced the rot incidence offering 77% protection. Increased activities of defense enzymes in GNPs-applied turmeric plants may play a role in restricting the development of disease symptoms. These results demonstrated that GNPs could be used as an effective resistance activator in turmeric for control of rhizome rot disease.

  19. 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.

  20. 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.