Academic literature on the topic 'Phytophthora Zoospores'
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Journal articles on the topic "Phytophthora Zoospores"
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Erb, W. A., J. N. Moore, and R. E. Sterne. "Attraction of Phytophthora cinnamomi Zoospores to Blueberry Roots." HortScience 21, no. 6 (December 1986): 1361–63. http://dx.doi.org/10.21273/hortsci.21.6.1361.
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Abstract The attraction of zoospores of Phytophthora cinnamomi Rands to roots of three cultivars of rabbiteye blueberry (Vaccinium ashei Reade), two species hybrid cultivars of highbush blueberry, and one tetraploid species hybrid selection (US 109) was compared. Zoospores were attracted to the roots of all plants tested. Roots of highbush cultivars ‘Bluetta’ and ‘Patriot’ attracted more zoospores than the rabbiteye cultivars. The number of zoospores attracted to roots of US 109 was greater than the number attracted to the three rabbiteye cultivars, but less than the highbush cultivars. Increased zoospore attraction appeared to be related to root rot susceptibility in blueberries.
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Kong, Ping. "Carbon Dioxide as a Potential Water Disinfestant for Phytophthora Disease Risk Mitigation." Plant Disease 97, no. 3 (March 2013): 369–72. http://dx.doi.org/10.1094/pdis-09-12-0844-re.
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The spread of Phytophthora spp. through irrigation systems and natural waterways can have a significant impact on plant health and requires mitigation. Pressurized carbon dioxide (CO2) can inactivate Phytophthora nicotianae zoospores but its effectiveness at low pressure and on other species was unknown. This study evaluated the effect of injected CO2 at 63 to 4,000 ppm in irrigation water on zoospore survival of four Phytophthora spp. and infectivity of P. nicotianae zoospores. Zoospore survival of P. nicotianae, P. tropicalis, and P. pini was reduced by over 90% at 4,000 ppm and was reduced by 40% at 125 to 2,000 ppm after a 2-h exposure. Survival of P. megasperma was less affected by injected CO2, with a reduction of 37.1% at ≤4,000 ppm. CO2 treatments at 4,000 ppm for 30 or 120 min of water infested with P. nicotianae at zoospore concentrations of 1,000 and 5,000 ml−1 reduced disease incidence of annual vinca (Catharanthus roseus) by 92 and 75%. Comparable efficacy was observed in the CO2 treatment at 2,000 ppm. The CO2 treatments at <2,000 ppm also significantly reduced disease caused by water infested at 1,000 zoospores ml−1. These results indicate that CO2 may have potential as a safe and effective water disinfestant for Phytophthora spp.
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Kong, Ping, and Chuanxue Hong. "Zoospore Density-Dependent Behaviors of Phytophthora nicotianae Are Autoregulated by Extracellular Products." Phytopathology® 100, no. 7 (July 2010): 632–37. http://dx.doi.org/10.1094/phyto-100-7-0632.
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Phytophthora species are destructive fungus-like plant pathogens that use asexual single-celled flagellate zoospores for dispersal and plant infection. Many of the zoospore behaviors are density-dependent although the underlying mechanisms are poorly understood. Here, we use P. nicotianae as a model and demonstrate autoregulation of some zoospore behaviors using signal molecules that zoospores release into the environment. Specifically, zoospore aggregation, plant targeting, and infection required or were enhanced by threshold concentrations of these signal molecules. Below the threshold concentration, zoospores did not aggregate and move toward a cauline leaf of Arabidopsis thaliana (Col-0) and failed to individually attack annual vinca (Catharanthus roseus cv. Little Bright Eye). These processes were reversed when supplemented with zoospore-free fluid (ZFF) prepared from a zoospore suspension above threshold densities but not with calcium chloride at a concentration equivalent to extracellular Ca2+ in ZFF. These results suggest that Ca2+ is not a primary signal molecule regulating these communal behaviors. Zoospores coordinated their communal behaviors by releasing, detecting, and responding to signal molecules. This chemical communication mechanism raises the possibility that Phytophthora plant infection may not depend solely on zoospore number in the real world. Single zoospore infection may take place if it is signaled by a common molecule available in the environment which contributes to the destructiveness of these plant pathogens.
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von Broembsen, Sharon L., and J. W. Deacon. "Calcium Interference with Zoospore Biology and Infectivity of Phytophthora parasitica in Nutrient Irrigation Solutions." Phytopathology® 87, no. 5 (May 1997): 522–28. http://dx.doi.org/10.1094/phyto.1997.87.5.522.
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Calcium, applied as either CaCl2 or Ca(NO3)2 to water or calcium-free soluble fertilizer solution (Peters 20-10-20 Peat Lite Special), affected several important stages of Phytophthora parasitica zoospore behavior relevant to infection and disease spread. Release of zoospores from sporangia was suppressed by Ca2+ concentrations in the range of 10 to 50 meq. These concentrations also curtailed zoospore motility; 20 meq of Ca2+ in fertilizer solution caused all zoospores to encyst within 4 h, whereas 94% of zoospores remained motile in unamended solution. In addition, Ca2+ in the range of 10 to 30 meq stimulated zoospore cysts to germinate in the absence of an organic nutrient trigger, while suppressing the release of a single zoospore (diplanetism) from cysts that did not germinate. In growth chamber experiments, the amendment of the fertilizer solution with 10 or 20 mM Ca(NO3)2 greatly suppressed infection of flood-irrigated, containerized vinca seedlings in a peat-based mix by motile or encysted zoospores of P. parasitica. These results demonstrate that Ca2+ amendments interfere with P. parasitica zoospore biology at multiple stages, with compounding effects on epidemiology, and suggest that manipulation of Ca2+ levels in irrigation water or fertilizer solutions could contribute to management of Phytophthora in recirculating irrigation systems.
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Downer, A. J., J. A. Menge, and E. Pond. "Effects of Cellulytic Enzymes on Phytophthora cinnamomi." Phytopathology® 91, no. 9 (September 2001): 839–46. http://dx.doi.org/10.1094/phyto.2001.91.9.839.
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Two enzyme systems, cellulase (β-1,4-glucanase) and laminarinase (β-1,3-glucanase), were added to soil extracts to simulate (in vitro) lytic components found in mulches suppressive to Phytophthora cinnamomi. Concentration ranges of each enzyme were incubated with Phytophthora cinnamomi mycelium, zoospores, zoospores cysts, and zoospore-infected excised roots to evaluate the roles of each enzyme in potential control of avocado root rot disease. Cellulase significantly retarded the development of zoosporangia and chlamydospores when mycelia were incubated in soil extract containing the enzyme at concentrations greater than 10 units/ml. Zoospore production was also reduced by cellulase but not by laminarinase. Laminarinase had little effect on zoosporangia or chlamydospore formation. At high concentrations, laminarinase was consistently more effective at preventing encystment than cellulase. Chlamydospores preformed in root tips were immune to the lytic effects of all treatments except cellulase at 100 units/ml. Zoospores placed in enzyme solutions and plated on a selective medium survived high cellulase concentrations and formed colonies, but there were fewer surviving zoospores when laminarinase was present at greater than 10 units/ml. Low concentrations of cellulase stimulated infection of excised roots, however, low concentrations of laminarinase prevented infection. Cellulase and laminarinase have different effects on the structures of the Phytophthora cinnamomi life history, however, each enzyme may have a role in reduction of inoculum.
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Widmer, T. L. "Infective Potential of Sporangia and Zoospores of Phytophthora ramorum." Plant Disease 93, no. 1 (January 2009): 30–35. http://dx.doi.org/10.1094/pdis-93-1-0030.
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Phytophthora species produce sporangia that either germinate directly or release zoospores, depending upon environmental conditions. Previous Phytophthora spp. inoculation trials have used both sporangia and zoospores as the inoculum type. However, it is unknown what impact propagule type has on disease. Rhododendron leaf disks were inoculated with P. ramorum zoospores (75, 500, or 2,400 per disk), sporangia (75 per disk), or sporangia plus trifluoperazine hydrochloride (TFP) (75 per disk), a chemical that inhibits zoospore formation. Combining results from two different isolates, the highest concentration of zoospores (2,400 per disk) induced a significantly higher percentage of necrotic leaf disk area (96.6%) than sporangia (87.6%) and 500 zoospores per disk (88.7%). The sporangia plus TFP treatment had the lowest necrosis at 47.5%. Rooted rhododendron cuttings had a higher percentage of necrotic leaves per plant when inoculated with zoospores (3,000 or 50,000 per ml) or cysts (50,000 per ml) than with sporangia (3,000 per ml) with or without TFP. The percentage of necrotic leaf area was significantly higher when cysts or zoospores were inoculated at 50,000 per ml than sporangia without TFP and zoospores at 3,000 per ml. All treatments were significantly higher in the percentage of necrotic leaf area than the leaves treated with sporangia plus TFP. This demonstrates that the full inoculum potential may not be achieved when sporangia are used as the inoculum propagule.
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Granke, L. L., and M. K. Hausbeck. "Effects of Temperature, Concentration, Age, and Algaecides on Phytophthora capsici Zoospore Infectivity." Plant Disease 94, no. 1 (January 2010): 54–60. http://dx.doi.org/10.1094/pdis-94-1-0054.
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Controlled laboratory studies were undertaken to determine the effects of water temperature (2, 9, 12, 19, 22, and 32°C), inoculum concentration (1 × 102, 1 × 103, 5 × 103, 1 × 104, 2 × 104, and 4 × 104 zoospores/ml), and zoospore suspension age (0, 1, 3, and 5 days old) on infection of pickling cucumbers (Cucumis sativus) by Phytophthora capsici. Zoospore motility and mortality in response to commercial algaecides were also investigated. Cucumbers became infected at all temperatures tested, except 2°C, and the highest infection incidence was observed for cucumbers incubated in suspensions held at ≥19°C. Fewer fruit (<40% at ≥19°C, 0% at ≤12°C) became infected when water contained 1 × 102 zoospores/ml. Almost 100% of fruit were infected when water contained ≥5 × 103 zoospores/ml at temperatures ≥12°C. While the incidence of fruit infection declined with the zoospore suspension age, infection still occurred when 5-day-old suspensions were used. Commercial algaecides inhibited zoospore motility and caused significant zoospore mortality in laboratory assays, and show promise for treatment of infested irrigation water. Avoidance of infested irrigation water throughout the growing season is warranted until effective and economically acceptable water treatments are developed for field use.
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Liu, Fang, Bao-hua Li, Sen Lian, Xiang-li Dong, Cai-xia Wang, Zhen-fang Zhang, and Wen-xing Liang. "Effects of Temperature and Moisture on the Infection and Development of Apple Fruit Rot Caused by Phytophthora cactorum." Plant Disease 102, no. 9 (September 2018): 1811–19. http://dx.doi.org/10.1094/pdis-07-17-1028-re.
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Phytophthora fruit rot, caused by Phytophthora cactorum, is an important disease of apple in China, often causing more than 50% fruit rot in rainy years. We examined the effects of temperature and moisture on the development of the disease and effects of the variables on zoospore release and germination, infection, and lesion development. In vitro, a temperature range of 5 to 20°C had no significant effects on zoospore release dynamics but did significantly affect the quantities of released zoospores. The largest quantity of zoospores was released at 9.9°C according to a fitted model. Zoosporangia released zoospores within 15 min at the test temperatures (0 to 20°C), which peaked at the fourth hour. Zoospores germinated in vitro, requiring free water, at temperatures from 5 to 35°C. The optimum germination temperature was 25.1°C according to a fitted model. The minimum wetness duration required for zoospores to complete the infection process and induce visible lesions on Fuji fruit was 0.40 h at the optimal temperature of 23.0°C according to the fitted model, whereas observed values were 4.5, 1.5, 0.5, 1.5 and 8.5 h at 10, 15, 20, 25, and 30°C, respectively. The number of zoospore infections on fruit at various temperatures and wetness durations were well fitted by the modified Weibull model; based on the model, the optimal temperature for zoospore infections was 23.0°C. Young apple fruit infected by zoospores developed visible lesions from 10 to 30°C, with a predicted optimum of 23.5°C; no lesions developed at 5 or 35°C. The shortest incubation period of the disease was 4 days. These results can be used to develop disease forecasting models for improved fungicide control.
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Bassani, Ilaria, Corinne Rancurel, Sophie Pagnotta, François Orange, Nicolas Pons, Kevin Lebrigand, Franck Panabières, Laurent Counillon, Xavier Noblin, and Eric Galiana. "Transcriptomic and Ultrastructural Signatures of K+-Induced Aggregation in Phytophthora parasitica Zoospores." Microorganisms 8, no. 7 (July 7, 2020): 1012. http://dx.doi.org/10.3390/microorganisms8071012.
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Most pathogenic oomycetes of the genus Phytophthora spread in water films as flagellated zoospores. Zoospores perceive and produce signals attracting other zoospores, resulting in autoaggregation in vitro or biofilm formation on plant surface. The mechanisms underlying intercellular communication and consequent attraction, adhesion and aggregation are largely unknown. In Phytophthora parasitica, the perception of a K+ gradient induces coordinated motion and aggregation. To define cellular and molecular events associated with oomycete aggregation, we combined transcriptomic and ultrastructural analyses. Results indicate involvement of electroception in K+ sensing. They establish that the transcriptome repertoire required for swimming and aggregation is already fully functional at zoospore release. At the time points analyzed, aggregates are mainly constituted of zoospores. They produce vesicular and fibrillary material discharged at cell-to-cell contacts. Consistently, the signature of transcriptome dynamics during transition to aggregates is an upregulation of genes potentially related to vesicular trafficking. Moreover, transcriptomic and functional analyses show a strong enhancement of carbonic anhydrase activity, indicating that pH homeostasis may contribute to aggregation by acting on both zoospore movement and adhesion. This study poses the molecular and cellular bases of aggregative behavior within oomycetes and expands the current knowledge of ion perception-mediated dissemination of propagules in the rhizosphere.
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Bishop-Hurley, Sharon L., Sarah A. Mounter, James Laskey, Roy O. Morris, Jim Elder, Philip Roop, Chris Rouse, Francis J. Schmidt, and James T. English. "Phage-Displayed Peptides as Developmental Agonists for Phytophthora capsici Zoospores." Applied and Environmental Microbiology 68, no. 7 (July 2002): 3315–20. http://dx.doi.org/10.1128/aem.68.7.3315-3320.2002.
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ABSTRACT As part of its pathogenic life cycle, Phytophthora capsici disperses to plants through a motile zoospore stage. Molecules on the zoospore surface are involved in reception of environmental signals that direct preinfection behavior. We developed a phage display protocol to identify peptides that bind to the surface molecules of P. capsici zoospores in vitro. The selected phage-displayed peptides contained an abundance of polar amino acids and proline but were otherwise not conserved. About half of the selected phage that were tested concomitantly induced zoospore encystment in the absence of other signaling agents. A display phage was shown to bind to the zoospore but not to the cyst form of P. capsici. Two free peptides corresponding to active phage were similarly able to induce encystment of zoospores, indicating that their ability to serve as signaling ligands did not depend on their exact molecular context. Isolation and subsequent expression of peptides that act on pathogens could allow the identification of receptor molecules on the zoospore surface, in addition to forming the basis for a novel plant disease resistance strategy.
Dissertations / Theses on the topic "Phytophthora Zoospores"
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Osborne, Meave Catherine. "The spatial ecology of phytopathogenic zoospores in the rhizosphere." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369560.
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This thesis is concerned with an analysis of swimming of oomycete zoospores, particularly in relation to the hypothesis that electrotaxis mediated host root colonisation. A correlation was found between the electrotactic behaviour of zoospores of Phytophthora palmivora and Pythium aphanidermatum and their localisation relative to anodic or cathodic regions of the majority of non-host roots. Cathodotropic P. aphanidermatum zoospores were found to be attracted to the cathode generated at the wound site on monocotyledonous and dicotyledonous plant roots studied. Zoospores of P. aphanidermatum were also found to become gradually less attracted to these wound sites as they dissipated over time. Anodotropic P. palmivora zoospores were found to be repelled by the cathodic wound sites on roots of all plants investigated, with the exception of Petunia hybrida. In addition to this zoospores of P. aphanidermatum were found not exhibit chemotaxis or encystment in gradients of the wound-specific metabolite acetosyringone. This suggests that electrotaxis and chemotaxis both operate in directing zoospore accumulation around roots. This reduction of the conductivity of the bathing medium by the addition of different concentrations of sodium chloride salts did not appear to affect the accumulation of both zoospore species around roots of rye grass. The results of this study supports the hypothesis that zoospores use electrotaxis as one means to locate new plant hosts in the rhizosphere. However, chemotaxis may still augment the regulation of zoospore colonisation and encystment.
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Riggs, Kara. "Chemotaxis of Phytophthora sojae zoospores to soybean roots is altered by isoflavone silencing." Connect to resource, 2010. http://hdl.handle.net/1811/45485.
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Sykes, Melissa. "Do zoospores of Phytophthora cinnamomi produce enzymes such as cutinases, cellulases and pectinases?" Thesis, Sykes, Melissa (1995) Do zoospores of Phytophthora cinnamomi produce enzymes such as cutinases, cellulases and pectinases? Honours thesis, Murdoch University, 1995. https://researchrepository.murdoch.edu.au/id/eprint/32817/.
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Santos, Paulo Cézar das Mercês. "Phytophthora nicotianae: ação de meios de cultura e da qualidade da luz no crescimento e esporulação e aspectos fisiológicos e bioquímicos da interação com porta-enxertos cítricos." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-05012016-105803/.
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A citricultura brasileira apresenta números bastante significativos e expressivos, refletindo a grande importância social e econômica que essa atividade agrícola e industrial tem para a economia do país. O Brasil se destaca como o maior produtor de laranja do mundo. As plantas cítricas podem ser produzidas e multiplicadas de várias formas e a enxertia é a forma de propagação vegetativa mais utilizada comercialmente no Brasil. Dentre os porta-enxertos mais empregados, sobressaem-se o citrumeleiro Swingle e a tangerineira Sunki. Apesar das vantagens presentes nesses dois genótipos, a produção deles está sendo limitada por doenças causadas por fungos e estraminipilas. Em citros, as diversas espécies de Phytophthora são responsáveis pelas doenças gomose e podridões, principalmente de radicelas. P. nicotianae é a espécie que mais afeta as plantas cítricas no Brasil. Não obstante a grande importância de P. nicotianae para os porta-enxertos, alguns mecanismos de resistência ou susceptibilidade ainda requerem mais investigações cientificas. O presente trabalho visa a elucidação de alguns mecanismos de resistência dos citros a P. nicotianae, por meio de estudos fisiológicos e bioquímicos dos porta-enxertos, além da ação de meios de cultura e da qualidade da luz no estudo da fisiologia desse estraminipila. Para isso realizou-se a detecção de alguns equivalentes de compostos fenólicos através da técnica HPLC e o comportamento do genótipo resistente frente à possível inibição da síntese de compostos fenólicos através do tratamento das raízes do porta-enxerto Swingle com Pro-Ca; avaliou-se a atração de zoósporos de P. nicotianae por exsudatos radiculares provenientes dos dois porta-enxertos com o uso de uma armadilha adaptada; verificou-se o comportamento do zoósporo, a motilidade e a zoosporogênese frente à ação de vários compostos fenólicos e testou-se a ação de diferentes meios de culturas e da qualidade da luz no crescimento micelial e na esporulação de P. nicotianae. Os resultados revelaram que a tangerineira Sunki possui maiores quantidades de equivalentes em apigenina que o citrumeleiro Swingle nos dois períodos de avaliação, para o HPLC. O porta-enxerto resistente apresentou mais equivalentes de ácido clorogênico que o genótipo susceptível. Quanto ao Pro-Ca, os equivalentes de compostos fenólicos em raízes de plântulas do citrumeleiro Swingle não diferiram daquelas plantas tratadas com água. O Pro-Ca não inibiu e não desativou a síntese de compostos fenólicos. O uso do anticorpo contra a elicitina \"α-plurivorina\" teve resultados intermediários no consumo de água por plântulas de tangerineira Sunki e a atividade zoosporicida dos compostos fenólicos apresentou resultados variáveis no comportamento da motilidade de zoósporos. Os compostos fenólicos escopoletina e tricetinpentametoxi conseguiram paralisar a motilidade e proporcionaram as menores porcentagens de zoosporogênese. O meio de cultura AA permitiu a maior TCMD, seguido de CA e V8-CaCO3-Ágar. Os maiores valores de esporulação foram encontrados nesses dois últimos meios, respectivamente. Todas as faixas de luzes (e a ausência de luz) estudadas no presente trabalho podem ser avaliadas para o crescimento micelial, porém o tratamento claro foi aquele que mais induziu a esporulação de zoósporos de P. nicotianae.The Brazilian citrus industry has very significant and expressive numbers, reflecting the great social and economic importance of this industrial and agricultural activity has for the economy. Brazil stands out as the world\'s largest orange producer. Citrus plants can be produced and multiplied in various ways and the bud is the form of vegetative propagation more commercially used in Brazil. Among the most commonly used rootstocks, stand up the Swingle citrumelo and Sunki mandarin. Despite the advantages these two genotypes present, their production is being limited by diseases caused by fungi and estraminipilas. In citrus, all species of Phytophthora are responsible for diseases gummosis and fibrous root rot, especially. P. nicotianae is the kind that affects citrus plants in Brazil. Regardless of the great importance of P. nicotianae for rootstocks, some mechanisms of resistance or susceptibility still require further scientific investigation. This study aims to elucidate some mechanisms of resistance of citrus to P. nicotianae, through physiological and biochemical studies of rootstocks, beyond of action culture media and quality of light in the physiological study of this estraminipila. To this was carried out to detect certain equivalent of phenolic compounds by HPLC and genotype resistant behavior against the possible inhibition of the synthesis of phenolic compounds by treatment of the roots of Swingle rootstock with Pro-Ca; evaluated the zoospores attraction P. nicotianae by exudates from the two rootstocks using an adapted trap; it was the zoospore behavior, motility and zoosporogenesis to the action of various phenolic compounds and tested the action of different culture media and quality of light on mycelial growth and sporulation of P. nicotianae. The results for HPLC revealed that Sunki mandarin has larger amounts of apigenin equivalents Swingle citrumelo in that the two periods. The sturdy rootstock had more chlorogenic acid equivalents of the susceptible genotype. As for the Pro-Ca equivalent of phenolic compounds in Swingle seedling roots not differ from those plants treated with water. The Pro-Ca not inhibited and not disabled the synthesis of phenolic compounds. The use of the antibody against elicitin \"α-plurivorin\" had intermediate results in water consumption by Sunki mandarin seedlings and zoosporicide activity of phenolic compounds showed variable results in the behavior of zoospore motility. The scopoletin and tricetinpentametoxi phenolic compounds managed to paralyze the motility and provided the smallest percentages of zoosporogenesis. The culture medium AA allowed greater DMGR, followed by CA and V8-CaCO3-Agar. The highest sporulation values were found in the last two media, respectively. All lights tracks (and the absence of light) studied in this work can be evaluated for mycelial growth, but the treatment light was that more induced sporulation of zoospores of P. nicotianae.
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Raftoyannis, Yannis. "Comparative study of the patterns of encystment and pathogenicity of zoospores of Phytophthora and Pythium spp. on a range of axenically-grown angiosperm roots." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287382.
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Guérin, Valérie. "Effets du silicium dans la réduction du stress biotique causé par Phytophthora sojae chez le soya évalué grâce à une nouvelle méthode d'inoculation par zoospores." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30547/30547.pdf.
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L'objectif de ce projet visait à déterminer si le silicium (Si), reconnu pour son effet prophylactique contre les agents biotrophes, pouvait protéger le soja contre Phytophthora sojae, un oomycète hemi-biotrophe. Le défi initial consistait à développer une méthode d'inoculation qui reproduisait le processus d'infection naturelle tout en permettant aux plants d'absorber le Si. Dans un premier temps, l'inoculation de zoospores dans une solution hydroponique a permis de générer des infections reproductibles conséquentes avec les réponses phénotypiques attendues. Dans un deuxième temps, l'ajout de Si a permis de réduire significativement l'incidence de la maladie tout en augmentant le rendement des plants. Cet effet était surtout manifeste sur les cultivars possédant un niveau de résistance contre P. sojae ou sur ceux absorbant plus de Si. Nous proposons ainsi une nouvelle méthode d'inoculation de P. sojae représentative de l'infection naturelle et démontrons que le Si peut servir pour la lutte contre cet oomycète.
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Howard, Kay. "An in vitro investigation of the reduction in lesion development caused by infection with Phytophthora cinnamomi zoospores in young axenic Pisolithus tinctorius/Eucalyptus sieberi ectomycorrhizae." Thesis, Howard, Kay ORCID: 0000-0003-3977-1243 (1995) An in vitro investigation of the reduction in lesion development caused by infection with Phytophthora cinnamomi zoospores in young axenic Pisolithus tinctorius/Eucalyptus sieberi ectomycorrhizae. Honours thesis, Murdoch University, 1995. https://researchrepository.murdoch.edu.au/id/eprint/32816/.
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It has been suggested that ectomycorrhizae protect roots from invasion by soilborne plant pathogens. The present study tested this hypothesis with in vitro studies using axenic conditions. When Eucalyptus sieberi . roots were in association with Pisolithus tinctorius, a degree of protection was afforded, whereby lesion lengths caused by Phytophthora cinnamomi in primary roots are reduced. Exudates from P. tinctorius resulted in a significant increase in the number of lateral roots. Lateral root apices were observed as a popul,ar site for P. cinnamomi infection in control roots. By 48 h, lesion development in ectomycorrhizae was 1.96 - 4.58 and 0.26 - 4.75 mm.d-1 (P. tinctorius isolates H445 and M56, respectively), whereas the control lesion extenstion rate was 11.2 mm.d-1.
In non-mycorrhizal plants, P. cinnamomi caused a brown lesion, in the stele of the root, extending from the root tip within 12 h. At 5 mm beyond the visible lesion front, the amount and position of hyphae observed varied from root to root. Staining of embedded sections with methylene blue and azure II in borax detected lignin in the xylem and in large amounts in the metaxylem, of all inoculated roots. Lignin was only observed in the xylem of the non-inoculated control roots. Sudan black B detected suberin only within sections of visible lesions. Whole mounts stained with Trypan blue showed most hyphae were arranged randomly along the root surface, with many orientated along cell wall junctions. Hyphae were concentrated at the apex of newly formed lateral roots, and were detected growing intercellulary throughout the cortex and the phloem of primary roots.
The influence of the P. tinctorius hyphae on• zoospore germination and mycelial growth, on solid media, varied between the two P. cinnamomi isolates used in this study. The interaction between P. cinnamomi isolate MP112 and P. tinctorius isolate M56 resulted in the greatest inhibition of the pathogen's mycelium. In this reaction, P. cinnamomi hyphae tended to aggregate, but did not stop growing. Zoospore germination of P. cinnamomi isolate MP94048 were suppressed at 0.5 h only, while germination of zoospores of isolate MP112 were significantly reduced by both P. tinctorius isolates for the entire trial.
Staining of embedded sections revealed the ectomycorrhizae (P. tinctorius isolate M56) produced more elongated epidermal cells with approximately 30% more primary root tips covered by hyphae, than isolate H445. However, both isolates were observed to have a loose mantle. Isolate M56 produced some defence reactions, detected by aniline blue fluorescence in the cortex, and both isolates resulted in greater lignification in the metaxylem in comparison to the control roots.
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Shepherd, Samantha J. "Analysis of Phytophthora palmivora zoosporogenesis and zoospore chemotaxis." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327418.
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Warburton, Adrian John. "Role of calcium in zoospore biology of Phytophthora and Pythium species." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/13204.
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The work in this thesis was designed to study the role of Ca2+ in zoospore biology, and extends previous findings by comparing effects of Ca2+ and Ca2+ -modulating treatments in zoospores and zoospore cysts of Pythium spp., Phytophthora spp. and Aphanomyces euteiches. Zoospore motility was studied by videomicroscopy to compare the behaviour of Phytophthora infestans, Ph. parasiticia and Ph. plamivora aphanidermatum, Py. dissotocum, Py. catenulatum and A. euteiches. Zoospores of all fungi swam in an extended helix, but the Phytophthora spp. and A. euteiches made frequent changes of direction when swimming in water or buffer, whereas the Pythium spp. did not do so. Chelation of external Ca2+ with EGTA or BAPTA buffer caused zoospores of all fungi to swim in a straight path, reduced random turning, and prevented the spores from flanging direction when they collided with obstacles. Phytophthora zoospores accumulated at the surface of suspensions, but this was abolished in the presence of EGTA, whereas Pythium zoospores always accumulated at the base of suspensions. Isotropic backgrounds of some amino acids (e.g. L-glutamic acid) induced an irregular motility pattern; this was overridden by EGTA but restored by subsequent addition of Ca2+. These findings are discussed in relation to host-location behaviour by zoospores. A role of Ca2+ in germination of cysts, induced by agitation of zoospores of Py. aphanidermatum and Ph. parasitica, was demonstrated by reduced or suppressed germination in the presence of Ca2+ -uptake inhibitors (La3+, verapamil), Ca2+ chelators (BAPTA), calmodulin-antagonists (trifluoperazine, calmidazolium) or compounds that affect intracellular Ca2+ stores (caffeine, TMB-8). The critical concentrations and times of application of these treatments were determined, and some divalent cations and organic nutrients (sugars, amino acids) were shown partly to reverse the suppression of germination. A link was demonstrated between Ca2+ fluxes and zoospore development into cysts.
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Grayson, David Edward. "Suppression of zoospore cyst and sporangial germination of Phytophthora infestans by treatments that might interfere with calcium-mediated functions." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/12199.
Full textAbstract:
In laboratory experiments, Ca2+, other divalent cations and various Ca2+-modulating treatments were tested for effects on germination of zoospore cysts and of sporangia of three isolates of Phytophthora infestans and sometimes for an isolate of P. palmivora. The aim was to determine whether manipulation of Ca2+ or Ca2+-mediated events has the potential for control of potato late blight caused by P. infestans. This work was based on previous evidence for a central role of Ca2+ in the infection sequence from zoospores of phytopathogenic Phytophthora, Pythium and Aphanomyces spp. Zoospore cyst germination of both P. infestans and P. palmivora was suppressed by early post-encystment addition of the chelators EGTA or BAPTA, indicating a requirement for external Ca2+ or other polyvalent cations, by calcium channel blockers (La3+, Gd3+, verapamil) or by amiloride, indicating a requirement for flux of Ca2+ or other ions across the cyst membrane, by calmodulin antagonists (calmidazolium, dibucaine, trifluoperazine) and by intracellular calcium antagonists (caffeine, TMB-8), indicating a role for both calmodulin and for Ca2+ release from intracellular stores. Supplements of Ca2+ or other divalent cations (Ba2+, Mg2+) also suppressed cyst germination, but sometimes partly or completely overcame the suppression by other treatments if applied early as post-treatments. Germination of sporangia of P. infestans by hyphal outgrowth (direct germination, at c. 20°C) or zoosporogenesis (indirect germination, at c. 12°C) was suppressed by the same treatments as applied to zoospore cysts. These treatments sometimes caused rapid sporangial death, assessed microscopically by irreversible changes in cytoplasmic organisation. Their suppressive or toxic effects were generally more pronounced when sporangia were incubated to induce indirect rather than direct germination. The suppression caused by Ca2+-modulating treatments could be rescued only partly by simultaneous or early post-application of divalent cations. Even potentially mild chemical treatments (0.1% pectin or 5 mM orthophosphate) caused rapid (20-30 min) death of sporangia (especially when incubated for indirect germination). Simultaneous or early post-treatments with divalent cations could only partly reverse the suppression.
Book chapters on the topic "Phytophthora Zoospores"
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Huitema, Edgar, Matthew Smoker, and Sophien Kamoun. "A Straightforward Protocol for Electro-transformation of Phytophthora capsici Zoospores." In Methods in Molecular Biology, 129–35. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61737-998-7_11.
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Gubler, Frank, and Adrienne R. Hardham. "The Fate of Peripheral Vesicles in Zoospores of Phytophthora cinnamomi During Infection of Plants." In Electron Microscopy of Plant Pathogens, 197–210. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75818-8_15.
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Stouvenakers, Gilles, Peter Dapprich, Sebastien Massart, and M. Haïssam Jijakli. "Plant Pathogens and Control Strategies in Aquaponics." In Aquaponics Food Production Systems, 353–78. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-15943-6_14.
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AbstractAmong the diversity of plant diseases occurring in aquaponics, soil-borne pathogens, such as Fusarium spp., Phytophthora spp. and Pythium spp., are the most problematic due to their preference for humid/aquatic environment conditions. Phytophthora spp. and Pythium spp. which belong to the Oomycetes pseudo-fungi require special attention because of their mobile form of dispersion, the so-called zoospores that can move freely and actively in liquid water. In coupled aquaponics, curative methods are still limited because of the possible toxicity of pesticides and chemical agents for fish and beneficial bacteria (e.g. nitrifying bacteria of the biofilter). Furthermore, the development of biocontrol agents for aquaponic use is still at its beginning. Consequently, ways to control the initial infection and the progression of a disease are mainly based on preventive actions and water physical treatments. However, suppressive action (suppression) could happen in aquaponic environment considering recent papers and the suppressive activity already highlighted in hydroponics. In addition, aquaponic water contains organic matter that could promote establishment and growth of heterotrophic bacteria in the system or even improve plant growth and viability directly. With regards to organic hydroponics (i.e. use of organic fertilisation and organic plant media), these bacteria could act as antagonist agents or as plant defence elicitors to protect plants from diseases. In the future, research on the disease suppressive ability of the aquaponic biotope must be increased, as well as isolation, characterisation and formulation of microbial plant pathogen antagonists. Finally, a good knowledge in the rapid identification of pathogens, combined with control methods and diseases monitoring, as recommended in integrated plant pest management, is the key to an efficient control of plant diseases in aquaponics.
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Gilbert, G. S., J. Handelsman, and J. L. Parke. "Role of ammonia and calcium in lysis of zoospores of Phytophthora spp. by Bacillus cereus strain UW85." In The Rhizosphere and Plant Growth, 300. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3336-4_58.
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"PROTOCOL 02-03.1: Production of Phytophthora zoospores." In Laboratory Protocols for Phytophthora Species, edited by Kelly Ivors, 1. The American Phytopathological Society, 2015. http://dx.doi.org/10.1094/9780890544969.02.03.1.
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"PROTOCOL 02-05.1: Obtaining and manipulating zoospores of Phytophthora infestans." In Laboratory Protocols for Phytophthora Species, edited by Howard Judelson, 1–2. The American Phytopathological Society, 2015. http://dx.doi.org/10.1094/9780890544969.02.05.1.
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"PROTOCOL 02-02.1: Mass production of Phytophthora nicotianae zoospores using a wet plate method." In Laboratory Protocols for Phytophthora Species, edited by Chuan Hong, 1. The American Phytopathological Society, 2015. http://dx.doi.org/10.1094/9780890544969.02.02.1.
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A. Moreira-Morrillo, Anthony, Álvaro Monteros-Altamirano, Ailton Reis, and Felipe R. Garcés-Fiallos. "Phytophthora capsici on Capsicum Plants: A Destructive Pathogen in Chili and Pepper Crops." In Capsicum - New Perspectives [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104726.
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Capsicum from tropical and subtropical America, is an important genus for the nutritional, economic and cultural values of its species. At the same time, the Capsicum species are affected by diseases caused by viruses, bacteria, fungi and pseudofungi, in particular the oomycete Phytophthora capsici. This phytopathogen causes great damage and losses in different Capsicum species, because it infects all plant organs causing root, crown and fruit rot; and, leaf blight. The polycyclic dispersion through zoospores and sporangia, the limited availability of resistant genotypes, and the reduced diversity of effective oomyceticides (fungicides), make P. capsici one of the most complex phytopathogens to be managed worldwide specially in field conditions. However, successful management of P. capsici depends on the knowledge of the pathogen, its interaction with the susceptible host and the methods of control used. Thus, this chapter addressed the etiology, symptomatology, occurrence and management of the disease. Additionally, the cycle of the disease is discussed in a holistic and simple way.
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"PROTOCOL 02-10.1: Inoculating detached leaves via a Phytophthora zoospore drop." In Laboratory Protocols for Phytophthora Species, edited by Rachel Linzer and Matteo Garbelotto, 1–4. The American Phytopathological Society, 2015. http://dx.doi.org/10.1094/9780890544969.02.10.1.
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"PROTOCOL 02-04.1: Induction of sporangia formation and zoospore release for Phytophthora ramorum and other Phytophthora spp." In Laboratory Protocols for Phytophthora Species, edited by Everett Hansen, 1–2. The American Phytopathological Society, 2015. http://dx.doi.org/10.1094/9780890544969.02.04.1.
Full textReports on the topic "Phytophthora Zoospores"
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Katan, Jaacov, and Michael E. Stanghellini. Clinical (Major) and Subclinical (Minor) Root-Infecting Pathogens in Plant Growth Substrates, and Integrated Strategies for their Control. United States Department of Agriculture, October 1993. http://dx.doi.org/10.32747/1993.7568089.bard.
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In intensive agriculture, harmful soilborne biotic agents, cause severe damage. These include both typical soilborne (clinical) major pathogens which destroy plants (e.g. Fusarium and Phytophthora pathogens), and subclinical ("minor") pathogens (e.g. Olpidium and Pythium). The latter cause growth retardation and yield decline. The objectives of this study were: (1) To study the behavior of clinical (major) and subclinical (minor) pathogens in plant growth substrate, with emphasis on zoosporic fungi, such as Pythium, Olipidium and Polymyxa. (2) To study the interaction between subclinical pathogens and plants, and those aspects of Pythium biology which are relevant to these systems. (3) To adopt a holistic-integrated approach for control that includes both eradicative and protective measures, based on a knowledge of the pathogens' biology. Zoospores were demonstrated as the primary, if not the sole propagule, responsible for pathogen spread in a recirculating hydroponic cultural system, as verified with P. aphanidermatum and Phytophthora capsici. P. aphanidermatum, in contrast to Phytophthora capsici, can also spread by hyphae from plant-to-plant. Synthetic surfactants, when added to the recirculating nutrient solutions provided 100% control of root rot of peppers by these fungi without any detrimental effects on plant growth or yield. A bacterium which produced a biosurfactant was proved as efficacious as synthetic surfactants in the control of zoosporic plant pathogens in the recirculating hydroponic cultural system. The biosurfactant was identified as a rhamnolipid. Olpidium and Polymyxa are widespread and were determined as subclinical pathogens since they cause growth retardation but no plant mortality. Pythium can induce both phenomena and is an occasional subclinical pathogen. Physiological and ultrastructural studies of the interaction between Olpidium and melon plants showed that this pathogen is not destructive but affects root hairs, respiration and plant nutrition. The infected roots constitute an amplified sink competing with the shoots and eventually leading to growth retardation. Space solarization, by solar heating of the greenhouse, is effective in the sanitation of the greenhouse from residual inoculum and should be used as a component in disease management, along with other strategies.