A detailed examination is made of the structure of human skin. Measures were drawn up to prevent skin contamination in nuclear installations as well as contaminated skin was decontaminated from the personnel. By systematically applying these measures a significant level of success was achieved in preventing contamination in nuclear installations. Cases where more far-reaching chemical methods had to be used were kept to a minimum. (R.P.)
Contamination is defined as anything other than cotton in cotton lint. Worldwide, contamination is on the rise and plastic contamination has increased at a faster rate than contamination overall. In the U.S., there are many sources of plastic contaminants, such as plastic trash that collects in cott...
Wang, Jun-Jie; He, Jiang-Tao; Lu, Yan; Liu, Li-Ya; Zhang, Xiao-Liang
Groundwater contamination prevention mapping is an important component of groundwater contamination geological survey and assessment work, which could provide the basis for making and implementing groundwater contamination prevention planning. A groundwater contamination prevention mapping system was constructed in view of the synthetic consideration on nature perspective derived from groundwater contamination sources and aquifer itself, social-economic perspective, policy perspective derived from outside. During the system construction process, analytic hierarchy process and relevant overlaying principles were used to couple groundwater contamination risk assessment, groundwater value as well as wellhead protection area zoning. Data processing and visualization of mapping results were achieved in the GIS environment. The research on groundwater contamination prevention mapping in Beijing Plain indicated that the final groundwater prevention map was in accordance with the actual conditions and well reflected the priorities of groundwater prevention, which could play a guidance role in designing and implementing further practical prevention and supervision measures. Besides, because of the dynamical properties of the system components, it was suggested to analyze the update frequency of the mapping.
The following industry recommended best management practices (BMPs), designed for growers and/or interstate shippers of host and associated host plants of Phytophthora ramorum, consists of biosecurity guidelines created by and for nursery growers in order to reduce the risks associated with P. ramorum. The control of P....
Cai, Guohong; Hillman, Bradley I
Phytophthora sp. is a genus in the oomycetes, which are similar to filamentous fungi in morphology and habitat, but phylogenetically more closely related to brown algae and diatoms and fall in the kingdom Stramenopila. In the past few years, several viruses have been characterized in Phytophthora species, including four viruses from Phytophthora infestans, the late blight pathogen, and an endornavirus from an unnamed Phytophthora species from Douglas fir. Studies on Phytophthora viruses have revealed several interesting systems. Phytophthora infestans RNA virus 1 (PiRV-1) and PiRV-2 are likely the first members of two new virus families; studies on PiRV-3 support the establishment of a new virus genus that is not affiliated with established virus families; PiRV-4 is a member of Narnaviridae, most likely in the genus Narnavirus; and Phytophthora endornavirus 1 (PEV1) was the first nonplant endornavirus at the time of reporting. Viral capsids have not been found in any of the above-mentioned viruses. PiRV-1 demonstrated a unique genome organization that requires further examination, and PiRV-2 may have played a role in late blight resurgence in 1980s-1990s. Copyright © 2013 Elsevier Inc. All rights reserved.
Purpose: To completely prevent the radioactive contaminations at the time of wearing or removing the airtight clothing, and further to facilitate wearing and removal of the same, air supply thereto and other works. Constitution: A duct having a large caliber and communicating with an air supply chamber is provided at the rear part of the airtight clothing. Since this duct is constituted in an expansible and contractible manner, the operator can pass the duct to wear or remove the airtight clothing. Since the airtight clothing according to the present invention is not cut off from its neck portion, the radiation protection is complete. Further, since the air supply duct has a great caliber, the wearing and removal of the airtight clothing become easy and further a large quantity of air can be supplied therein. (Kamimura, M.)
...] Notice of Request for Extension of Approval of an Information Collection; Phytophthora Ramorum... interstate movement of regulated articles to prevent the spread of Phytophthora ramorum. DATES: We will... for the interstate movement of regulated articles to prevent the spread of Phytophthora ramorum...
Dargère, Sylvie; Cormier, Hélène; Verdon, Renaud
Despite the development of new microbiological technologies, blood cultures remain the first line tool for the diagnosis of bloodstream infections. Their diagnostic value may be affected when a microorganism of questionable evidence is isolated, for example, coagulase-negative staphylococci, Bacillus spp., viridans group streptococci, Corynebacterium spp., Propionibacterium spp., and Micrococcus spp. Finally, making a correct diagnosis of pathogenicity (vs contamination) is very challenging. To review the current ways of dealing with the problem of blood culture contaminants and to provide practical suggestions to decrease blood culture contamination rates. PubMed electronic databases and existing reviews were searched up to December 2017 to retrieve relevant publications related to the topic. This review describes the burden of blood culture contamination, and analyses the main current issues and controversies in interpreting the occurrence of potential blood culture contaminants. It focuses on the best described approaches to decide whether blood culture contamination is present or not, and discusses the different strategies of prevention in adults. Each institution should have an efficient policy to prevent blood culture contamination, emphasizing the importance to follow guidelines for prescribing and collecting blood cultures. Training healthcare workers should focus on detrimental influence on patient care, and highlight the work and costs due to contaminants. The accurate differentiation of a contaminant from a true pathogen relies on a multidisciplinary approach and clinical judgment of experienced practitioners. Copyright © 2018. Published by Elsevier Ltd.
Waaij, D. van der; Andres, A.H.
The efficacy of horizontal and vertical laminar flow units (equipped with high-efficiency air filters) in the prevention of cross-contamination between cages and of contamination from outside has been demonstrated. With germ-free mice and using germ-free standard techniques for sterilization and for
Full Text Available The potato late blight pathogen Phytophthora infestans secretes an array of effector proteins thought to act in its hosts by disarming defences and promoting pathogen colonisation. However, little is known about the host targets of these effectors and how they are manipulated by the pathogen. This work describes the identification of two putative membrane-associated NAC transcription factors (TF as the host targets of the RxLR effector PITG_03192 (Pi03192. The effector interacts with NAC Targeted by Phytophthora (NTP 1 and NTP2 at the endoplasmic reticulum (ER membrane, where these proteins are localised. Transcripts of NTP1 and NTP2 rapidly accumulate following treatment with culture filtrate (CF from in vitro grown P. infestans, which acts as a mixture of Phytophthora PAMPs and elicitors, but significantly decrease during P. infestans infection, indicating that pathogen activity may prevent their up-regulation. Silencing of NTP1 or NTP2 in the model host plant Nicotiana benthamiana increases susceptibility to P. infestans, whereas silencing of Pi03192 in P. infestans reduces pathogenicity. Transient expression of Pi03192 in planta restores pathogenicity of the Pi03192-silenced line. Moreover, colonisation by the Pi03192-silenced line is significantly enhanced on N. benthamiana plants in which either NTP1 or NTP2 have been silenced. StNTP1 and StNTP2 proteins are released from the ER membrane following treatment with P. infestans CF and accumulate in the nucleus, after which they are rapidly turned over by the 26S proteasome. In contrast, treatment with the defined PAMP flg22 fails to up-regulate NTP1 and NTP2, or promote re-localisation of their protein products to the nucleus, indicating that these events follow perception of a component of CF that appears to be independent of the FLS2/flg22 pathway. Importantly, Pi03192 prevents CF-triggered re-localisation of StNTP1 and StNTP2 from the ER into the nucleus, revealing a novel effector mode
...] Notice of Request for Extension of Approval of an Information Collection; Phytophthora Ramorum... interstate movement of regulated articles to prevent the spread of Phytophthora ramorum. DATES: We will... spread of Phytophthora ramorum, contact Dr. Prakash K. Hebbar, National Policy Manager, PPQ, APHIS, 4700...
During the past two decades PCR and several other DNA/RNA amplification techniques have become important diagnostic tools in clinical laboratories. Amplification products contamination has been the main impediment to using these techniques routinely in diagnostic laboratories. Over the years, several creative pre- and post-amplification methods have been developed that prevent amplicon carryover contamination. These procedures, coupled with automated systems that employ real-time amplification and simultaneous detection in a closed system, have substantially reduced the possibility of false positive results due to amplification products carryover contamination.
Purpose: To prevent the contamination on the floor surface of working places by laying polyvinyl butyral sheets over the floor surface, replacing when the sheets are contaminated, followed by burning. Method: Polyvinyl butyral sheets comprising 50 - 70 mol% of butyral component are laid in a radioactive material handling facility, radioactive materials are handled on the polyvinyl butyral sheets and the sheets are replaced when contaminated. The polyvinyl butyral sheets used contain 62 - 68 mol% of butyral component and has 0.03 - 0.2 mm thickness. The contaminated sheets are subjected to burning processing. This can surely collect radioactive materials and the sheets have favorable burnability, releasing no corrosive or deleterious gases. In addition, they are inexpensive and give no hindrance to the workers walking. (Takahashi, M.)
Malawi Medical Journal. Wound Dressing Procedure and Prevention of Contamination and. Cross Infection. By: Chimwaza AF, MRN, MRN, Bsc (Hons) MSN Lecturer. Kachingwe-Sisya M., MRN, MRM. Bsc Nsg Edu. & Adm. MSN. Lecturer. Medical Surgical Nursing Department. Kamuzu College of Nursing. Blantyre. Malawi.
Capping is a common strategy for decreasing the risk associated with contaminated sediments in lakes and streams. Historically, caps have been designed to physically isolate contaminated sediments and prevent the transport of contaminants from sediments into the water above them...
This document gives basic information on potential pathways and mechanisms, by which radioactive materials from releases can reach man, and on modelling considerations to predict the behaviour of radioactive materials in the ground. The main objective is to present an overview of existing techniques for preventing the offsite releases of contaminants into the groundwater systems and techniques for mitigation of effects of such releases should they occur. The recommended techniques are fully applicable to any hazardous materials, such as organic liquids, and toxic materials or otherwise dangerous materials, the presence of which in the accessible biosphere can represent health risks as well as economic losses to the general public. 11 refs, 2 figs, 8 tabs
... contamination? 111.365 Section 111.365 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... contamination? You must take all the necessary precautions during the manufacture of a dietary supplement to prevent contamination of components or dietary supplements. These precautions include: (a) Performing...
Lee, Eric; Oki, Lorence R
Slow sand filtration has been shown to effectively reduce Phytophthora zoospores in irrigation water. This experiment tested the reduction of Phytophthora colony forming units (CFUs) by slow sand filtration systems after switching the pathogen contaminating plant leachate from Fusarium to Phytophthora and the resilience of the system to a short period without water, as might be caused by a pump failure. The slow sand filtration system greatly reduced Phytophthora CFUs and transmission after switching the pathogens. In addition, Phytophthora reduction by the slow sand filter was equally effective before and after the simulated pump failure. Reduction of Fusarium was not seen by the SSFs, before or after the simulated pump failure. The results suggest that slow sand filters are effective at reducing larger organisms, such as Phytophthora zoospores, even after a pump failure or a change in pathogens. Copyright © 2013 Elsevier Ltd. All rights reserved.
Phytophthora cinnamomi Rands is a ubiquitous soilborne pathogen associated with root rot in many woody perennial plant species, including highbush blueberry (Vaccinium sp.). To identify genotypes with resistance to the pathogen, cultivars and advanced selections of highbush blueberry were grown in a...
Downer, A J; Menge, J A; Pond, E
ABSTRACT Two enzyme systems, cellulase (beta-1,4-glucanase) and laminarinase (beta-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.
Baltrėnaitė, Edita; Lietuvninkas, Arvydas; Baltrėnas, Pranas
The intensive industrial development and urbanization, as well as the negligible return of hazardous components to the deeper layers of the Earth, increases the contamination load on the noosphere (i.e., the new status of the biosphere, the development of which is mainly controlled by the conscious activity of a human being). The need for reducing the spread and mobility of contaminants is growing. The insights into the role of the tree in the reduction of contaminant mobility through its life cycle are presented to show an important function performed by the living matter and its products in reducing contamination. For maintaining the sustainable development, natural materials are often used as the media in the environmental protection technologies. However, due to increasing contamination intensity, the capacity of natural materials is not sufficiently high. Therefore, the popularity of engineered materials, such as biochar which is the thermochemically modified lignocellulosic product, is growing. The new approaches, based on using the contaminant footprint, as well as natural (biogeochemical) and engineered barriers for reducing contaminant migration and their application, are described in the paper.
Butrón, Ana; Santiago, Rogelio; Mansilla, Pedro; Pintos-Varela, Cristina; Ordas, Amando; Malvar, Rosa Ana
Fusarium moniliforme and Fusarium proliferatum are the most frequently isolated fungi from maize (Zea mays L.) in Spain. Both Fusarium species produce toxins potentially dangerous for animals and humans, the fumonisins being the most significant of those toxins. White maize is preferred for human consumption, and extra care should be taken to avoid kernel mycotoxin contamination. The objectives of this study were to identify and quantify kernel infection by Fusarium spp. and contamination by fumonisin on white maize hybrids, to search for white maize sources of resistance to infection by Fusarium spp. and mycotoxin contamination, and to preliminarily study the genetics involved in such resistances. Ten F(1) single crosses derived from a diallel mating design among five white maize inbreds were evaluated in a randomized complete block design with three replications in 2002 at two locations. Fusarium verticilloides and F. proliferatum were detected on kernels of white maize hybrids cultivated in northwestern Spain. No differences in fungal infection were found among maize genotypes, but differences in fumonisin contamination were significant and could be related, in part, to differences in husk tightness. Among the genotypes studied, general combining ability (GCA) effects were the most important for resistance to fumonisin contamination. Inbreds EP10 and EC22 showed the most favorable GCA effects for husk tightness and fumonisin content, and the cross between them, EP10 x EC22, had the most favorable specific combining ability (SCA) effect for husk tightness. Inbreds EP10 and EC22 showed favorable GCA effects for fumonisin contamination and husk tightness, and the cross EP10 x EC22 was the only one with an average fumonisin level below 1 mug/g. Although this should be confirmed with more extensive studies, white maize inbreds developed from white maize landraces could be sources of resistance to fumonisin contamination.
This page describes EPA's goal in preventing animal waste from contaminating surface and ground Water. It is an EPA National Enforcement Initiative. Both enforcement cases, and a map of enforcement actions are provided.
Takahashi, Takeshi; Arai, Tomoyuki
In Fukushima Daiichi D and D activities, one of the most challenging issues is contaminated water management. In order to control ground water inflow into the buildings so that amount of contaminated water does not increase and prevent contaminated water spread out to the environment including into the ocean, TEPCO are taking various measures: In order to remove contamination sources, the removal of the highly contaminated water in the seaside trenches are being implemented. And also, the acceleration of water purification is planned by contaminated water clean-up facility. For the purpose of Isolating water from contaminated sources, construction of the frozen-soil land-side wall started in order to prevent the groundwater from flowing in the area and contaminated water from flowing out from the area. In order to prevent leakage of contaminated water into the ocean, soil improvement with sodium silicate (liquid glass) and Installation of the sea-side impermeable walls are implemented. Furthermore, replacement of the flange-type tanks with welded-joint tanks to mitigate leakage risks is underway. (author)
Steve Tjosvold; David Chambers; Gary Chastagner; Marianne. Elliott
Once Phytophthora ramorum is introduced into a nursery on a host, its local spread and establishment is primarily dependent on sporangia and zoospore production. Nursery operators commonly use fungicides to prevent the establishment of Phytophthora âcaused diseases, although current research only supports the use of fungicides...
Full Text Available To investigate susceptibility of young Scots pine seedlings to four Phytophthora species: Phytophthora cactorum, Phytophthora cambivora, Phytophthora plurivora and Phytophthora pini; seven-day-old seedlings of Scots pine (15 seedlings per experiment were infected using agar plugs of the respective species. Control group also consisted of 15 seedlings and was inoculated with sterile agar plugs. Results unambiguously show that after 4.5 days, all seedlings show clear signs of infection and display severe symptoms of tissue damage and necrosis. Moreover, three and two seedlings in the P. cactorum and P. cambivora infected seedlings groups, respectively, collapsed. The length of largest necrosis measured 13.4±3.90 mm and was caused by P. cactorum. To rule out any putative contamination or infection by secondary pathogens, re-isolations of pathogens from infection sites were performed and were positive in 100% of plated pieces of infected seedlings. All re-isolations were, however, negative in the case of the control group. Detailed microscopic analyses of infected tissues of young seedlings confirmed the presence of numerous Phytophthora species inside and on the surface of infected seedlings. Therefore, our results suggest Phytophthora spp. and mainly P. cactorum and P. cambivora as aggressive pathogens of Scots pine seedlings and highlight a putative involvement of these species in the damping off of young Scots pine seedlings frequently observed in forest nurseries.
Kizhnerov, L. V.; Konstantinov, Ye. A.; Prokopenko, V. A.; Sorokin, N. M.
The report presents the results of research in developing a low-waste technology of prevention, decontamination and localization of radioactive contamination founded on the of easily removed protective polymeric coating based on water and alcohol latexes and dispersion of polymers with special activating additives. The developed technology provides for the reduction of weakly fixed radioactive contamination of non-painted and painted surfaces to admissible levels (as a rule), it securely prevents and localizes contamination and does not generate secondary liquid radioactive wastes
Joan F. Webber
Following the recognition that Phytophthora ramorum (the cause of sudden oak death in the U.S.) was present in Europe as well as America, emergency European Community (EC) phytosanitary measures were put in place in September 2002 to prevent spread of P. ramorum, and also to stop introductions of the pathogen from elsewhere. A 3...
Londero, Alejandra; León Peláez, María A; Diosma, Gabriela; De Antoni, Graciela L; Abraham, Analía G; Garrote, Graciela L
Fungal contamination of poultry feed causes economic losses to industry and represents a potential risk to animal health. The aim of the present study was to analyze the effectiveness of whey fermented with kefir grains as additive to reduce fungal incidence, thus improving feed safety. Whey fermented for 24 h at 20 °C with kefir grains (100 g L(-1) ) reduced conidial germination of Aspergillus flavus, Aspergillus parasiticus, Aspergillus terreus, Aspergillus fumigatus, Penicillium crustosum, Trichoderma longibrachiatum and Rhizopus sp. Poultry feed supplemented with fermented whey (1 L kg(-1) ) was two to four times more resistant to fungal contamination than control feed depending on the fungal species. Additionally, it contained kefir microorganisms at levels of 1 × 10(8) colony-forming units (CFU) kg(-1) of lactic acid bacteria and 6 × 10(7) CFU kg(-1) of yeasts even after 30 days of storage. Fermented whey added to poultry feed acted as a biopreservative, improving its resistance to fungal contamination and increasing its shelf life. © 2014 Society of Chemical Industry.
Kong, Ping; Hong, Chuanxue; Richardson, Patricia A; Gallegly, Mannon E
Single-strand-conformation polymorphism (SSCP) of ribosomal DNA of 29 species (282 isolates) of Phytophthora was characterized in this study. Phytophthora boehmeriae, Phytophthora botryosa, Phytophthora cactorum, Phytophthora cambivora, Phytophthora capsici, Phytophthora cinnamomi, Phytophthora colocasiae, Phytophthora fragariae, Phytophthora heveae, Phytophthora hibernalis, Phytophthora ilicis, Phytophthora infestans, Phytophthora katsurae, Phytophthora lateralis, Phytophthora meadii, Phytophthora medicaginis, Phytophthora megakarya, Phytophthora nicotianae, Phytophthora palmivora, Phytophthora phaseoli, Phytophthora pseudotsugae, Phytophthora sojae, Phytophthora syringae, and Phytophthora tropicalis each showed a unique SSCP pattern. Phytophthora citricola, Phytophthora citrophthora, Phytophthora cryptogea, Phytophthora drechsleri, and Phytophthora megasperma each had more than one distinct pattern. A single-stranded DNA ladder also was developed, which facilitates comparison of SSCP patterns within and between gels. With a single DNA fingerprint, 277 isolates of Phytophthora recovered from irrigation water and plant tissues in Virginia were all correctly identified into eight species at substantially reduced time, labor, and cost. The SSCP analysis presented in this work will aid in studies on taxonomy, genetics, and ecology of the genus Phytophthora.
Xirasagar, Sudha; Kanwat, C P; Qu, Haiyan; Smith, Lillian U; Patterson, Nathaniel J; Shewchuk, Richard M
In the age of preparedness, public health agencies are concerned with intentional acts of food contamination in restaurants, in addition to food safety. Food safety consists of applying standard norms of practice and infrastructure, which, if violated, cause food-borne illness. In contrast, food defense requires an institutionalized mindset of informed alertness to unusual variations from the norms, combined with preemptive practices best suited to each restaurant. Therefore, while food safety lends itself to regulation to ensure standard practices, food defense is best served by advisory guidelines for autonomous application, preserving the restaurant industry's core values of hospitality and customer service. To address this challenge, public health agencies need survey tools that can yield action-relevant data on the knowledge and practice gaps in food defense preparedness and on educational messages and support services to be developed for maximum impact potential. This article presents a mail survey instrument, developed using qualitative research to ensure content and face validity. Instrument development involved drafting the survey on the basis of expert consultations, validating its content by using focus groups (representing all restaurant categories and geographic regions), and ensuring face validity through cognitive interviews. The resulting survey remains sensitive to the hospitality industry while encompassing all vulnerable points.
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...
Romero G, E.T.
In this work was studied the separation of uranium from the phosphate rock to decrease the level of radioactivity in the phosphate fertilizers, this prevents the redistribution of uranium in the environment. The uranium leaching conditions from phosphate rock were estimated using alkaline solutions. The changes in the natural phosphate rock after leaching were studied. The amenability to separate the uranium from phosphate rock with ammonium carbonate / bicarbonate solution was determined. The uranium extraction was approximately 40%. The leaching conditions showed high selectivity for uranium without changes in the ore structure. The bulk ore was not dissolved. (Author)
Full Text Available During oil and natural gas production, so-called “produced water” comprises the largest byproduct stream. In addition, many oil and gas operations are augmented via injection of hydraulic fracturing (HF fluids into the formation. Both produced water and HF fluids may contain hundreds of individual chemicals, some known to be detrimental to public health and the environment. Oil and gas production wastewater may serve a range of beneficial purposes, particularly in arid regions, if managed correctly. Numerous treatment technologies have been developed that allow for injection, discharge to the land surface, or beneficial reuse. Although many papers have addressed the effects of oil and gas production wastewater (OGPW on groundwater and surface water quality, significantly less information is available on the effects of these fluids on the soil resource. This review paper compiles fundamental information on numerous chemicals used and produced during oil and gas development and their effects on the soil environment. Additionally, pollution prevention technologies relating to OGPW are presented. An understanding of the effects of OGPW on soil chemical, physical, and biological properties can provide a foundation for effective remediation of OGPW-affected soils; additionally, sustainable reuse of oil and gas water for irrigation and industrial purposes may be enhanced.
B.J. Knaus; K.A. Graham; Niklaus J. Grünwald; Valerie J. Fieland
The genus Phytophthora contains some of the most notorious plant pathogens affecting nursery crops. Given the recent emergence of the sudden oak death pathogen Phytophthora ramorum, particularly in association with Rhododendron spp., characterization of Phytophthora communities...
Hsi Huo-Wang; Wu Ching-Hwa; Chou Kei-Den; Yeh Chin-Shiun
At the end of July 1992, Atomic Energy Council (AEC) received tips-off from Taipei local residents, saying some buildings in Taipei had their rebar been contaminated by radioactive materials. Regarding causes and sources of those radioactively contaminated rebar, views from every aspects were pointing toward that scraps mixed with radioactive source smelting in the steel mill as the most possible reason. After investigating houses and constructors, AEC found that most contaminated buildings were constructed during the period of 1982 and 1984. For protection of public rights, AEC then actively undertook nation-wide survey of more than forty thousand buildings constructed between 1982 and 1984. Thermal Luminescent Dosimeters (TLD) and house by house surveying were major methods to investigate houses contamination. Finally, it was found that radiation contaminated houses are concentrated in Taipei City, Taipei County, Tauoyen County, Keelung County. According to data collected up to December 31, 1999, there were 180 cases, with a total of 1601 contaminated housing units. Based on information data of dose assessment, distribution of annual dose are as the following: higher than 15 mSv -143 housing units (9.21%), 5-15 mSv -117 housing units (7.53%), less than 5 mSv -1293 housing units (83.26%). Except actively conducting remodeling of contaminated houses and granting compensation to house owners, AEC has established following measures to prevent rebars from being radioactively contaminated. (1) Radiation detection training of iron and steel detectors (2) Strengthening controls over radioactive sources (3) Enforcing examination of radioactive levels for imported rebars (4) Requesting domestic steel companies establish radiation detection capability (5) Promoting installation of portal type radiation detectors for steel companies having smelting furnace (6) Enforcing no-radioactive contamination certificate system. The radiation detection training of iron and steel
Chen, Wen; Djama, Zeinab Robleh; Coffey, Michael D; Martin, Frank N; Bilodeau, Guillaume J; Radmer, Lorien; Denton, Geoff; Lévesque, C André
Most Phytophthora spp. are destructive plant pathogens; therefore, effective monitoring and accurate early detection are important means of preventing potential epidemics and outbreaks of diseases. In the current study, a membrane-based oligonucleotide array was developed that can detect Phytophthora spp. reliably using three DNA regions; namely, the internal transcribed spacer (ITS), the 5' end of cytochrome c oxidase 1 gene (cox1), and the intergenic region between cytochrome c oxidase 2 gene (cox2) and cox1 (cox2-1 spacer). Each sequence data set contained ≈250 sequences representing 98 described and 15 undescribed species of Phytophthora. The array was validated with 143 pure cultures and 35 field samples. Together, nonrejected oligonucleotides from all three markers have the ability to reliably detect 82 described and 8 undescribed Phytophthora spp., including several quarantine or regulated pathogens such as Phytophthora ramorum. Our results showed that a DNA array containing signature oligonucleotides designed from multiple genomic regions provided robustness and redundancy for the detection and differentiation of closely related taxon groups. This array has the potential to be used as a routine diagnostic tool for Phytophthora spp. from complex environmental samples without the need for extensive growth of cultures.
Full Text Available Newly discovered Phytophthora species include invasive pathogens that threaten trees and shrubs. We present draft genome assemblies for three isolates of Phytophthora kernoviae and one isolate of the EU2 lineage of Phytophthora ramorum, collected from outbreak sites in Scotland.
Nandy, Poulomi; Young, Megan; Haugen, Shanil P; Katzenmeyer-Pleuss, Kristy; Gordon, Edward A; Retta, Stephen M; Wood, Steven C; Lucas, Anne D
One-way valves used in day use devices (used on multiple patients throughout a day without reprocessing between patients) are intended to reduce the potential for cross-contamination between patients resulting from the backflow of patient fluids. One-way valves are typically designed to withstand high levels of back pressure before failure; however, they may not be explicitly designed as a means of infection control as used in medical device applications. Five different medical grade one-way valves were placed in low pressure configurations. After flushing in the intended direction of flow, bacteriophage, bacteria, or dye was placed patient side for 24 hours. The upstream device side of the valve was then evaluated for microbial growth or presence of visible dye. Leakage (ie, backflow) of the microorganisms occurred with a variety of one-way valve designs across a range of fluid properties tested. This study describes testing of the one-way valves (component-level testing) for the potential of cross-contamination. Although day use medical device systems may use numerous other factors to prevent patient cross-contamination, this work demonstrates that one-way valves themselves may not prevent leakage of contaminated fluid if the fluid is able to reach the upstream side of the one-way valve. Published by Elsevier Inc.
Jennifer L. Banach
Full Text Available The potential cross-contamination of pathogens between clean and contaminated produce in the washing tank is highly dependent on the water quality. Process wash water disinfectants are applied to maintain the water quality during processing. The review examines the efficacy of process wash water disinfectants during produce processing with the aim to prevent cross-contamination of pathogens. Process wash water disinfection requires short contact times so microorganisms are rapidly inactivated. Free chlorine, chlorine dioxide, ozone, and peracetic acid were considered suitable disinfectants. A disinfectant’s reactivity with the organic matter will determine the disinfectant residual, which is of paramount importance for microbial inactivation and should be monitored in situ. Furthermore, the chemical and worker safety, and the legislative framework will determine the suitability of a disinfection technique. Current research often focuses on produce decontamination and to a lesser extent on preventing cross-contamination. Further research on a sanitizer’s efficacy in the washing water is recommended at the laboratory scale, in particular with experimental designs reflecting industrial conditions. Validation on the industrial scale is warranted to better understand the overall effects of a sanitizer.
Banach, Jennifer L.; Sampers, Imca; Van Haute, Sam; van der Fels-Klerx, H.J. (Ine)
The potential cross-contamination of pathogens between clean and contaminated produce in the washing tank is highly dependent on the water quality. Process wash water disinfectants are applied to maintain the water quality during processing. The review examines the efficacy of process wash water disinfectants during produce processing with the aim to prevent cross-contamination of pathogens. Process wash water disinfection requires short contact times so microorganisms are rapidly inactivated. Free chlorine, chlorine dioxide, ozone, and peracetic acid were considered suitable disinfectants. A disinfectant’s reactivity with the organic matter will determine the disinfectant residual, which is of paramount importance for microbial inactivation and should be monitored in situ. Furthermore, the chemical and worker safety, and the legislative framework will determine the suitability of a disinfection technique. Current research often focuses on produce decontamination and to a lesser extent on preventing cross-contamination. Further research on a sanitizer’s efficacy in the washing water is recommended at the laboratory scale, in particular with experimental designs reflecting industrial conditions. Validation on the industrial scale is warranted to better understand the overall effects of a sanitizer. PMID:26213953
Scanlan, Francis P
Contaminants are a vast subject area of food safety and quality. They are generally divided into chemical, microbiological and physical classes and are present in our food chain from raw materials to finished products. They are the subject of international and national legislation that has widened to cover more and more contaminant classes and food categories. In addition, consumers have become increasingly aware of and alarmed by their risks, whether rightly or not. What is the food industry doing to ensure the safety and quality of the products we feed our children? This is a valid question which this article attempts to address from an industrial viewpoint. Chemical food safety is considered a complex field where the risk perception of consumers is often the highest. The effects of chronic or acute exposure to chemical carcinogens may cause disease conditions long after exposure that can be permanently debilitating or even fatal. It is also a moving target, as knowledge about the toxicity and occurrence data of new chemical contaminants continues to be generated. Their identification, prevention and management are challenges to the food industry as a whole. A reminder of the known chemical hazards in the food chain will be presented with an emphasis on the use of early warning to identify potential new contaminants. Early warning is also a means of prevention, anticipating food safety concerns before they become issues to manage. Current best management practices including Hazard Analysis and Critical Control Points relating to the supply chain of baby foods and infant formulae will be developed. Finally, key lessons from a case study on recent contamination issues in baby food products will be presented.
Parke, Jennifer L; Knaus, Brian J; Fieland, Valerie J; Lewis, Carrie; Grünwald, Niklaus J
Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to the development of integrated systems approaches. Four horticultural nurseries in Oregon were sampled every 2 months for 4 years to determine the identity and community structure of Phytophthora spp. associated with different sources and stages in the nursery production cycle. Plants, potting media, used containers, water, greenhouse soil, and container yard substrates were systematically sampled from propagation to the field. From 674 Phytophthora isolates recovered, 28 different species or taxa were identified. The most commonly isolated species from plants were Phytophthora plurivora (33%), P. cinnamomi (26%), P. syringae (19%), and P. citrophthora (11%). From soil and gravel substrates, P. plurivora accounted for 25% of the isolates, with P. taxon Pgchlamydo, P. cryptogea, and P. cinnamomi accounting for 18, 17, and 15%, respectively. Five species (P. plurivora, P. syringae, P. taxon Pgchlamydo, P. gonapodyides, and P. cryptogea) were found in all nurseries. The greatest diversity of taxa occurred in irrigation water reservoirs (20 taxa), with the majority of isolates belonging to internal transcribed spacer clade 6, typically including aquatic opportunists. Nurseries differed in composition of Phytophthora communities across years, seasons, and source within the nursery. These findings suggest likely contamination hazards and target critical control points for management of Phytophthora disease using a systems approach.
Jung, Yangjin; Jang, Hyein; Guo, Mengqi; Gao, Jingwen; Matthews, Karl R
This study was conducted to provide information regarding mitigation of cross-contamination through the use of sanitizer during crisping at retail outlets. Seven non-inoculated heads and one inoculated head (≈5 log CFU/g) of lettuce were placed into commercial sink filled with 76 L of tap water (TW), electrolyzed water (EW, free chlorine: 43 ± 6 ppm), lactic acid and phosphoric acid-based sanitizer (LPA, pH 2.89), or citric acid-based sanitizer (CA, pH 2.78) and soaked for 5 min. Two subsequent batches (eight non-inoculated heads per batch) were soaked in the same solution. Soaking with EW significantly reduced the population of S. enterica (2.8 ± 1.5 log CFU/g), E. coli O157:H7 (3.4 ± 1.1 log CFU/g), and L. monocytogenes (2.6 ± 0.7 log CFU/g) inoculated on Romaine lettuce compared to TW, LPA, and CA (p 0.05) or preventing cross-contamination. Soaking with EW prevented cross-contamination among lettuce heads and controlled bacterial populations in crisping water for three consecutive batches. EW may be an effective option as a sanitizer to minimizing the cross-contamination of leafy greens during the retail crisping. Copyright Â© 2017 Elsevier Ltd. All rights reserved.
Frequent outbreaks of citrus gummosis in Kenyan citrus orchards have been reported, yet the identity and distribution of the Phytophthora species causing the disease are unknown. Work was carried out to (i) characterize and identify Phytophthora species associated with citrus gummosis based on cultural and ...
Everett Hansen; Paul Reeser; Wendy Sutton
Phytophthora taxon Pg chlamydo is perhaps the second most abundant Phytophthora species in the world, after P. gonapodyides, although it is commonly misidentified. Pg chlamydo is frequently encountered in streams and rivers in western North America, Argentina, China, and Europe. It has occasionally been...
Preliminary results from the survey for fungicide resistance in Phytophthora were reported at the 2016 Washington Small Fruit Conference. Phytophthora was isolated from diseased plants in 28 red raspberry fields and tested against mefenoxam, the active ingredient of Ridomil. Most isolates were ident...
Full Text Available This research aims to control Seedling damping off disease in plants by using antagonistic actinomycetes against the causative fungi. Phytophthora infestans was isolated from the infected tomato plant seedling obtained from an economic plant nursery in Amphoe Pak Chong, Nakhon Ratchasima Province, Thailand. The chitinolytic Streptomyces rubrolavendulae S4, isolated from termite mounds at the grove of Amphoe Si-Sawat, Kanchanaburi Province, Thailand, was proven to be the most effective growth inhibition of fungal pathogens tested on potato dextrose agar. Tomato and chili seedlings that colonized with antagonistic S. rubrolavendulae S4 were grown in P. infestans artificial inoculated peat moss. Percents of noninfested seedling in fungal contaminated peat moss were compared to the controls with uninoculated peat moss. In P. infestans contaminated peat moss, the percents of survival of tomato and chili seedling were significantly increased (0.05. It was clearly demonstrated that S. rubrolavendulae S4 can prevent the tomato and chili seedling damping off disease in economic plant nurseries.
Full Text Available As Japan depends on imports for most ingredients used to manufacture feed products, close co-operation is indispensable between importers and manufacturers of feed and feed ingredients to effectively mitigate the risk associated with feed safety. Guidelines were issued by the Ministry of Agriculture, Forestry and Fisheries (MAFF in March 2008 to prevent feed products from being contaminated with undesirable substances. These guidelines identify the responsibilities of feed ingredient importers, feed manufacturers and distributors, as well as the roles of the MAFF and the Food and Agricultural Materials Inspection Centre.
Silva Pastura, Valeria Fonseca da; Wieland, Patricia
Aiming at increasing awareness of radiation health effects, environmental issues and preventive measures, the Nuclear Energy National Commission (CNEN) launched in 2004 an education and public outreach programme for mine workers, students, teachers, governmental leaders, labor representatives and members of communities nearby small mining sites at the North and Northeast regions. Many Brazilian conventional mines present a significant risk of exposure to radiation due to Uranium and Thorium. CNEN inspects the mines but there are several small mining sites dedicated to open pit short term mineral extraction, called 'garimpagem', that are of difficult control. Therefore, information at large about preventive measures to avoid contamination during exploration, transportation and storage is necessary. CNEN developed an educational campaign which includes a series of open seminars, talks, folders, booklets and posters. The objective of this paper is to present the Brazilian educational campaign to avoid contamination risks at those small mineral exploration sites and its results. This campaign is a joint task that receives collaboration of other organizations such as federal police, schools and universities
Seys, Scott A; Sampedro, Fernando; Hedberg, Craig W
Data from the recalls of meat and poultry products from 2000 through 2012 due to Salmonella contamination were used to assess the factors associated with the recovery of the recalled product and to develop quantitative models to estimate the number of illnesses prevented by recalls. The percentage of product recovered following a recall action was not dependent on establishment size, recall expansions, complexity of the distribution chain, type of distribution, amount of time between the production and recall dates, or number of pounds of product recalled. However, illness-related recalls were associated with larger amounts of recalled product, smaller percentages of recalled product recovered, a greater number of days between the production date and recall date, and nationwide distribution than were recalls that were not illness related. In addition, the detection of recall-associated illnesses appeared to be enhanced in states with strong foodborne illness investigation systems. The number of Salmonella illnesses prevented by recalls was based on the number of illnesses occurring relative to the number of pounds consumed, which was then extrapolated to the number of pounds of recalled product recovered. A simulation using a program evaluation and review technique probability distribution with illness-related recalls from 2003 through 2012 estimated that there were 19,000 prevented Salmonella illnesses, after adjusting for underdiagnosis. Recalls not associated with illnesses from 2000 through 2012 prevented an estimated additional 8,300 Salmonella illnesses, after adjusting for underdiagnosis. Although further improvements to ensure accurate and complete reporting should be undertaken, our study demonstrates that recalls are an important tool for preventing additional Salmonella illnesses. Moreover, additional training resources dedicated to public health agencies for enhancing foodborne illness detection, investigations, and rapid response and reporting would
Kessel, G.J.T.; Veloso, S.; Forch, M.G.; Latorse, M.P.
Phytophthora infestans, the causal agent of potato- and tomato late blight, remains a serious threat for (commercial) potato and tomato production. In North Western Europe, frequent fungicide applications, mostly aimed to prevent infection, form the back bone of potato late blight control. Modern
Ebba K. Peterson; Eric Larson
Phytophthora ramorum, causal agent of sudden oak death (SOD) and ramorum leaf blight, remains a persistent problem of regulatory concern within the horticultural industry. Damages to nurseries have been realized as a result of enforced quarantine and sanitation efforts designed to prevent the spread and establishment of this invasive pathogen....
Full Text Available Phytophthora root rot is considered to be the most destructive disease to citrus production in Egypt. Phytophthora species are generally present in citrus nurseries, where soil pots containing the survival propagules are considered responsible for their spread into new orchards. The goal of this study was to investigate the distribution and seasonal variation of Phytophthora species in soil and feeder roots in two Egyptian citrus nurseries, characterized by different management, and to identify Phytophthora species associated with root rot. Soil and root samples were collected at monthly intervals from Sour orange and Volkameriana lemon rootstocks during March-July period. The inoculum density of Phytophthora species, and the percentage of infected feeder roots, were estimated using the plate dilution method in conjunction with selective media. Phytophthora isolates were identified according to their morphological characteristics and on the basis of the ITS regions of the rDNA. Phytophthora nicotianae was the predominant isolated species, followed by P. citrophthora and P. palmivora. Phytophthora nicotianae was detected in both nurseries, while P. citrophthora and P. palmivora were recovered only in one nursery. Inoculum density of Phytophthora species fluctuated during spring and summer according to the environmental conditions, rootstock, and nursery management practices.
Phytophthora stem and root rot disease, caused by Phytophthora sojae, is one of the most destructive diseases of soybean (Glycine max (L.) Merr.), and has been increasing in several soybean-producing areas around the world. This disease induces serious limitations on soybean production, with yield l...
Kelly L. Ivors; Frank Martin; Michael Coffey; Izabela Makalowska; David M. Geiser; Seogchan Kang
Its virulence and ability to spread rapidly throughout the world by various means establishes Phytophthora as one of the most important groups of plant pathogens. Discoveries of interspecific hybridization among Phytophthora species in nature, which could yield novel pathogens, further underscore the threat posed by members of this genus. The ability...
Drake, Ben; Jones, Glyn
Heritage gardens, heathland and woodland are increasingly under threat from the non-native tree and plant diseases Phytophthora ramorum and Phytophthora kernoviae. However, there exist only limited literature that estimates the public non-market value that may be lost from a continued spread of Phytophthora ramorum and Phytophthora kernoviae into these habitats. This paper therefore uses a contingent valuation survey to assess the non-extractive public use and non-use values at risk from an uncontrolled spread of these diseases in England and Wales. Results estimate that £1.446bn of public value is at risk in England and Wales per year from an uncontrolled spread of Phytophthora ramorum and Phytophthora kernoviae. The greatest public value at risk, of £578 m/year, is from an uncontrolled spread of these diseases to heritage gardens, while the lowest public value at risk, of £386 m/year, is from disease spread to heathland. The findings of this paper should help policymakers make informed decisions as to the public resources to dedicate towards Phytophthora ramorum and Phytophthora kernoviae control in England and Wales. In this regard, the current control programme to contain these diseases appears cost-effective in light of the public value at risk estimates produced by this paper. Copyright © 2017 Elsevier Ltd. All rights reserved.
Frank N. Martin; Paul Richardson
The mitochondrial genomes of Phytophthora infestans, P. ramorum and P. sojae have been sequenced and comparative genomics has provided an opportunity to examine the processes involved with genome evolution in the genus Phytophthora. This approach can also be useful in assessing intraspecific...
Talgø, Venche; Thomsen, Iben Margrete
Phytophthora rotråte forårsaket av ulike arter av Phytophthora er et stort problem i juletreproduksjonen iUSA. I Norge er det også rapportert om flere tilfeller av skade på grunn av Phytophthora både i juletrær og klippegrønt, men så langt ikke i Danmark. I begge landene er flere arter av...... Phytophthora funnet på treaktige vekster i grøntanlegg. Vi har også sett en urovekkende spredning av Phytophthora til løvtrær i bynære skoger, vassdrag og naturområder det siste tiåret, spesielt i Norge. Både i Norge og Danmark har vi undersøkt vann i eller like ved juletreplantinger og funnet flere...... Phytophthora-arter, så dette er en skadegjører juletredyrkere må være på vakt overfor...
Uggioni, Paula Lazzarin; Salay, Elisabette
Objective: The objective of this study was to develop a validated and reliable questionnaire to measure consumer knowledge regarding safe practices to prevent microbiological contamination in restaurants and commercial kitchens. Methods: Non-probabilistic samples of individuals were interviewed in the city of Campinas, Brazil. Questionnaire items…
U.S. cotton is considered to have some of the lowest levels of contamination in the world. However, that reputation is in jeopardy as complaints of contamination from domestic and foreign mills are on the rise. Cotton contamination is classified by the International Textile Manufacturers Federation ...
Mulholland, Vincent; Elliot, Matthew; Green, Sarah
We present methods for the detection and quantification of four Phytophthora species which are pathogenic on trees; Phytophthora ramorum, Phytophthora kernoviae, Phytophthora lateralis, and Phytophthora austrocedri. Nucleic acid extraction methods are presented for phloem tissue from trees, soil, and pure cultures on agar plates. Real-time PCR methods are presented and include primer and probe sets for each species, general advice on real-time PCR setup and data analysis. A method for sequence-based identification, useful for pure cultures, is also included.
Walter Martin Widmer
Full Text Available In this study, hypotheses concerning the use of beach ashtrays were experimentally tested. Results indicated that the mean rate of abandonment of this equipment was low (1.5%. The mean amount of cigarette stubs (3.4 items/ashtray was greater than mean amounts of other types of litter. People with different socioeconomic profiles had different perceptions regarding the issues associated with beach debris. These results indicated that beach ashtrays could be useful to prevent the contamination of these environments and that differences in socioeconomic characteristics of beachgoers could partially explain the differences in perceptions regarding the presence of waste on the beaches. This information could now be used by coastal managers to plan strategies to reduce the marine contamination.A presença de resíduos sólidos no ambiente marinho é extensa. Praias são tipicamente contaminadas com esses materiais, que podem causar impactos ecológicos. Resíduos sólidos nas praias podem causar ferimentos nas pessoas e podem prejudicar a atividade turística. Neste estudo, hipóteses relativas ao uso de cinzeiros de praia foram testadas. Os resultados indicam que a taxa de abandono desse equipamento é pequena (1,5% e que a quantidade média de pontas de cigarro (3,4 itens/cinzeiro é maior do que as quantidades médias de outros tipos de lixo. Também se observou que pessoas com diferentes perfis socioeconômicos apresentaram percepções diferentes relativas à presença de resíduos sólidos nas praias. Estes resultados sugerem que cinzeiros portáteis podem ser um equipamento importante na redução da contaminação das praias e que diferenças socioeconômicas dos freqüentadores das praias podem explicar parcialmente as diferentes percepções relativas à presença de resíduos no ambiente praial. Sugere-se que os gerentes costeiros usem esse tipo de informação para planejar estratégias de redução desse problema.
Phytophthora is a genus comprised of over 65 destructive plant pathogenic species that cause severe damages in agriculture, forestry and natural habitats. Economically important pathogens are Phytophthora infestans (causing potato late blight) and Phytophthora sojae (causing soybean root and stem
Full Text Available Chemical control trials against Phytophthora capsici (Leon on pepper cultivations in Morocco. Pepper protection trials against collar and root rot have been undertaken under laboratory and culture conditions using Aliette (80 % of phosethylaluminium and Ridomil M 58 (10 % of metalaxyl associated to 48 % of maneb. It has been proved that, contrary to Ridomil M 58, Aliette does not protect the hostplant when the Phytophthora capsici (Leon zoospores are used as inoculum. But both fongicides are active when inoculating with a mycelian suspension. Trials undertaken under plastic glasshouses confirmed the laboratory results both with an artificial inoculation and with a natural one on contaminated soil. Only Ridomil M 58 provides satisfactory protection during the first weeks after the treatment. When disease propagation conditions are particularly favorable (permanent presence of an active inoculum source, the protection given by repeated Ridomil M 58 applications gradually disappears after a few weeks.
Calfee, David P.; Farr, Barry M.
A number of skin antiseptics have been used to prevent the contamination of blood cultures, but the comparative efficacies of these agents have not been extensively evaluated. We therefore sought to compare the efficacy of four skin antiseptics in preventing blood culture contamination in a randomized, crossover, investigator-blinded study conducted in an emergency department and the inpatient wards of a university hospital. The patient group included all patients from whom blood samples were obtained percutaneously for culture. Skin antisepsis was performed with 10% povidone-iodine, 70% isopropyl alcohol, tincture of iodine, or povidone-iodine with 70% ethyl alcohol (i.e., Persist). The blood culture contamination rate associated with each antiseptic was then determined. A total of 333 (2.62%) of 12,692 blood cultures were contaminated during the study period compared to 413 (3.21%) of 12,859 blood cultures obtained during the previous 12-month period (relative risk = 0.82; 95% confidence interval, 0.71 to 0.94; P = 0.006). During the study, the contamination rates were determined to be 2.93% with povidone-iodine, 2.58% with tincture of iodine, 2.50% with isopropyl alcohol, and 2.46% with Persist (P = 0.62). We detected no significant differences in the blood culture contamination rates among these four antiseptics, although there was some evidence suggesting greater efficacy among the alcohol-containing antiseptics. Among the evaluated antiseptics, isopropyl alcohol may be the optimal antiseptic for use prior to obtaining blood for culture, given its convenience, low cost, and tolerability. PMID:11980938
G.J. Bilodeau; C.A. Lévesque; A.W.A.M. De Cock; C. Duchaine; G. Kristjansson; R.C. Hamelin
Sudden oak death, caused by Phytophthora ramorum, is a severe disease that can affect numerous species of trees and shrubs. This pathogen has been spread via nursery stock, and quarantine measures are currently in place to prevent further spread. Molecular assays have been developed to rapidly detect and identify P. ramorum, but...
N. J. Grünwald; S. Werres; E. M. Goss; C. R. Taylor; V. J. Fieland
A new Phytophthora species was detected (i) in the USA, infecting foliage of Kalmia latifolia, (ii) in substrate underneath Pieris, and (iii) in Germany in soil samples underneath Aesculus hippocastanum showing disease symptoms. The new...
R.E. Linzer; M. Garbelotto
Two recently described pathogenic oomycetes, Phytophthora nemorosa and P. pseudosyringae, have overlapping host and geographic ranges in California and Oregon forests with P. ramorum, causal agent of ?sudden oak death? disease. Preliminary genetic evidence indicates P. nemorosa and P....
Banach, J.L.; Sampers, I.; Haute, van S.; Fels, van der H.J.
The potential cross-contamination of pathogens between clean and contaminated produce in the washing tank is highly dependent on the water quality. Process wash water disinfectants are applied to maintain the water quality during processing. The review examines the efficacy of process wash water
Sugimoto, Takuma; Kato, Masayasu; Yoshida, Shinya; Matsumoto, Isao; Kobayashi, Tamotsu; Kaga, Akito; Hajika, Makita; Yamamoto, Ryo; Watanabe, Kazuhiko; Aino, Masataka; Matoh, Toru; Walker, David R.; Biggs, Alan R.; Ishimoto, Masao
Phytophthora stem and root rot, caused by Phytophthora sojae, is one of the most destructive diseases of soybean [Glycine max (L.) Merr.], and the incidence of this disease has been increasing in several soybean-producing areas around the world. This presents serious limitations for soybean production, with yield losses from 4 to 100%. The most effective method to reduce damage would be to grow Phytophthora-resistant soybean cultivars, and two types of host resistance have been described. Race-specific resistance conditioned by single dominant Rps (“resistance to Phytophthora sojae”) genes and quantitatively inherited partial resistance conferred by multiple genes could both provide protection from the pathogen. Molecular markers linked to Rps genes or quantitative trait loci (QTLs) underlying partial resistance have been identified on several molecular linkage groups corresponding to chromosomes. These markers can be used to screen for Phytophthora-resistant plants rapidly and efficiently, and to combine multiple resistance genes in the same background. This paper reviews what is currently known about pathogenic races of P. sojae in the USA and Japan, selection of sources of Rps genes or minor genes providing partial resistance, and the current state and future scope of breeding Phytophthora-resistant soybean cultivars. PMID:23136490
This fact sheet provides tips on how to reduce the mismanagement of used oil contaminated with PCBs, a recurring issue faced by EPA and states, commercial and municipal used oil collection centers and recyclers.
Ambi, Ashwin; Bryan, Julia; Borbon, Katherine; Centeno, Daniel; Liu, Tianchi; Chen, Tung Po; Cattabiani, Thomas; Traba, Christian
Most studies reveal that the mechanism of action of propolis against bacteria is functional rather than structural and is attributed to a synergism between the compounds in the extracts. Propolis is said to inhibit bacterial adherence, division, inhibition of water-insoluble glucan formation, and protein synthesis. However, it has been shown that the mechanism of action of Russian propolis ethanol extracts is structural rather than functional and may be attributed to the metals found in propolis. If the metals found in propolis are removed, cell lysis still occurs and these modified extracts may be used in the prevention of medical and biomedical implant contaminations. The antibacterial activity of metal-free Russian propolis ethanol extracts (MFRPEE) on two biofilm forming bacteria: penicillin-resistant Staphylococcus aureus and Escherichia coli was evaluated using MTT and a Live/Dead staining technique. Toxicity studies were conducted on mouse osteoblast (MC-3T3) cells using the same viability assays. In the MTT assay, biofilms were incubated with MTT at 37°C for 30min. After washing, the purple formazan formed inside the bacterial cells was dissolved by SDS and then measured using a microplate reader by setting the detecting and reference wavelengths at 570nm and 630nm, respectively. Live and dead distributions of cells were studied by confocal laser scanning microscopy. Complete biofilm inactivation was observed when biofilms were treated for 40h with 2µg/ml of MFRPEE. Results indicate that the metals present in propolis possess antibacterial activity, but do not have an essential role in the antibacterial mechanism of action. Additionally, the same concentration of metals found in propolis samples, were toxic to tissue cells. Comparable to samples with metals, metal free samples caused damage to the cell membrane structures of both bacterial species, resulting in cell lysis. Results suggest that the structural mechanism of action of Russian propolis ethanol
Annelies Vercauteren; Isabelle De Dobbelaere; Martine Maes; Kurt Heungens
Phytophthora ramorum is thought to be an introduced pathogen in North America and in Europe based on the presence of only three clonal lineages. The North American lineages (NA1 and NA2) are responsible for infections in North American forests and nurseries, while the European lineage (EU1) is responsible for infections in Europe, mostly in...
Xavier Boutet; Annelies Vercauteren; Chandelier Heungens; Anne Kurt
Phytophthora ramorum (Werres, De Cock, Man inât Veld), which causes âsudden oak deathâ in the United States and dieback and leaf necrosis in ornamental plants (mainly Rhododendron and Viburnum) in Europe, is a heterothallic species with two mating types, A1 and A2 (Werres and others 2001, Rizzo and...
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
Lamour, Kurt H [ORNL; McDonald, W Hayes [ORNL; Savidor, Alon [ORNL
Genome sequences of the soybean pathogen, Phytophthora sojae, and the sudden oak death pathogen, Phytophthora ramorum, suggest a photosynthetic past and reveal recent massive expansion and diversification of potential pathogenicity gene families. Abstract: Draft genome sequences of the soybean pathogen, Phytophthora sojae, and the sudden oak death pathogen, Phytophthora ramorum, have been determined. O mycetes such as these Phytophthora species share the kingdom Stramenopila with photosynthetic algae such as diatoms and the presence of many Phytophthora genes of probable phototroph origin support a photosynthetic ancestry for the stramenopiles. Comparison of the two species' genomes reveals a rapid expansion and diversification of many protein families associated with plant infection such as hydrolases, ABC transporters, protein toxins, proteinase inhibitors and, in particular, a superfamily of 700 proteins with similarity to known o mycete avirulence genes.
Tyler, Brett M.; Tripathy, Sucheta; Zhang, Xuemin; Dehal, Paramvir; Jiang, Rays H. Y.; Aerts, Andrea; Arredondo, Felipe D.; Baxter, Laura; Bensasson, Douda; Beynon, JIm L.; Chapman, Jarrod; Damasceno, Cynthia M. B.; Dorrance, Anne E.; Dou, Daolong; Dickerman, Allan W.; Dubchak, Inna L.; Garbelotto, Matteo; Gijzen, Mark; Gordon, Stuart G.; Govers, Francine; Grunwald, NIklaus J.; Huang, Wayne; Ivors, Kelly L.; Jones, Richard W.; Kamoun, Sophien; Krampis, Konstantinos; Lamour, Kurt H.; Lee, Mi-Kyung; McDonald, W. Hayes; Medina, Monica; Meijer, Harold J. G.; Nordberg, Erik K.; Maclean, Donald J.; Ospina-Giraldo, Manuel D.; Morris, Paul F.; Phuntumart, Vipaporn; Putnam, Nicholas J.; Rash, Sam; Rose, Jocelyn K. C.; Sakihama, Yasuko; Salamov, Asaf A.; Savidor, Alon; Scheuring, Chantel F.; Smith, Brian M.; Sobral, Bruno W. S.; Terry, Astrid; Torto-Alalibo, Trudy A.; Win, Joe; Xu, Zhanyou; Zhang, Hongbin; Grigoriev, Igor V.; Rokhsar, Daniel S.; Boore, Jeffrey L.
Draft genome sequences have been determined for the soybean pathogen Phytophthora sojae and the sudden oak death pathogen Phytophthora ramorum. Oömycetes such as these Phytophthora species share the kingdom Stramenopila with photosynthetic algae such as diatoms, and the presence of many Phytophthora genes of probable phototroph origin supports a photosynthetic ancestry for the stramenopiles. Comparison of the two species' genomes reveals a rapid expansion and diversification of many protein families associated with plant infection such as hydrolases, ABC transporters, protein toxins, proteinase inhibitors, and, in particular, a superfamily of 700 proteins with similarity to known oömycete avirulence genes.
Farage, Priscila; Puppin Zandonadi, Renata; Cortez Ginani, Ver?nica; Gandolfi, Lenora; Pratesi, Riccardo; de Medeiros N?brega, Yanna Karla
Conditions associated to the consumption of gluten have emerged as a major health care concern and the treatment consists on a lifelong gluten-free diet. Providing safe food for these individuals includes adapting to safety procedures within the food chain and preventing gluten cross-contamination in gluten-free food. However, a gluten cross-contamination prevention protocol or check-list has not yet been validated. Therefore, the aim of this study was to perform the content validation and se...
Haque, M. M.; Diez, J. J.
Phytophthora alni is a highly destructive host specific pathogen to alders (Alnus spp.) spreading all over Europe. Recently this pathogen has been reported to cause diseases in common alder (Alnus glutinosa) in Spain. Seeds and seedlings of A. glutinosa were tested in vitro for their susceptibility to alder Phytophthora and other Phytophthora species. Isolates of P. alni ssp. alni, P. cinnamomi, P. citrophthora, P. nicotianae and P. palmivora were used in the experiments. Seeds and seedlings were inoculated with a zoospore suspension and uniform mycelial blocks of agar of the Phytophthora species. Susceptibility was calculated in terms of pathogen virulence on seed germination and seedling mortality 42 and 67 days after inoculation respectively. Seed germination and seedling mortality rates varied differently among the isolates used. Results implied that common alder and its seeds and seedlings are at risk to be infected by P. alni. In addition, other Phytophthora species are able to infect this kind of material showing their relative host non-specificity. This is one important finding concerning alder regeneration in infected areas, and the possibility of disease spread on this plant material. (Author) 42 refs.
Jin, Song [Fort Collins, CO; Fallgren, Paul H [Laramie, WY; Morris, Jeffrey M [Laramie, WY
Embodiments include treatments for acid mine drainage generation sources (10 perhaps by injection of at least one substrate (11) and biologically constructing a protective biofilm (13) on acid mine drainage generation source materials (14). Further embodiments include treatments for degradation of contaminated water environments (17) with substrates such as returned milk and the like.
Garcia, Robert A; Spitzer, Eric D; Kranz, Barbara; Barnes, Sue
The scientific literature indicates that blood culture contamination often leads to inappropriate antimicrobial treatment, adverse patient occurrences, and potential reporting of false-positive central line-associated bloodstream infections. The findings of a national infection prevention survey of blood culture practices and related interventions in hospitals support the need for infection preventionists to expand their participation in the review of topics related to the ordering and collection of blood for culture. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Lyubenova Aneta B.
Full Text Available Our aim was to examine the virulence of eight Phytophthora isolates belonging to three species (Phytophthora cryptogea, Phytophthora plurivora and Phytophthora quercina obtained from diverse European ecosystems (in Bulgaria, Poland and Germany towards three forest tree hosts – English oak (Quercus robur L., Turkey oak (Quercus cerris L. and European beech (Fagus sylvatica L..
Full Text Available Pseudomonas fluorescens strain 3JW1, which has a broad-spectrum antimicrobial activity, was studied to investigate whether it affects the amounts of aflatoxin B1 (AFB1 produced by Aspergillus flavus. It was found that the bacterium reduced the amounts of AFB1 in potato dextrose broth (PDB and peanut medium by 97.8% and 99.4%, respectively. It also reduced AFB1 by ~183 μg/kg (55.8% when applied onto peanut kernels. This strain reduced AFB1 via three mechanisms. First, it significantly inhibited A. flavus growth; second, our data showed that strain 3JW1 inhibits aflatoxin biosynthesis by A. flavus; and third, P. fluorescens strain 3JW1 is capable of degrading AFB1 at a rate as high as 88.3% in 96 hours. This is the first report demonstrating that Pseudomonas fluorescens can reduce toxin contamination caused by A. flavus on peanut kernels. Our findings indicate that P. fluorescens strain 3JW1 had multiple effects including reducing A. flavus infection and aflatoxin contamination. And the results also highlight the potential applications of the strain 3JW1 for the biological control of aflatoxin contamination in peanuts and other susceptible crops.
Full Text Available Phytophthora palmivora causes serious losses on cocoa in Indonesia and world-wide. The research aimed to assess the potential of soil as source of inocula for Phytophthora diseases in cocoa. Soil samples were baited using a healthy cocoa pod tissue, and the pathogen was isolated for morphological and molecular identification. Baiting technique was successfully used to detect the presence of P. palmivora in soil samples, and this was confirmed by morphological and molecular identification. P. palmivora can be detected in soil in all year around in wet areas indicating that soil is a massive and consistent source of inocula. Surveys conducted on the soil of Amazonian, Amelonado and Trinitario blocks of various ages showed that P. palmivora can be found in old and young cocoa blocks, even as young as 3 or 4 years. P. palmivora infection from soil to the pods appears to be mainly through contact or rain splash. Baiting with whole healthy pods exposed at different heights above undisturbed litter and above bare soil showed that the infection still occurred at 100 cm above the soil, even though it decreased gradually with the height. Infection from litter was not different to that from bare soil, indicating that the litter layer is not acting physically as a shield preventing rain from splashing the inocula up from wet soil to the pods. However, in tests for the possibility of P. palmivora carried through air convection, no pod was found to be infected, suggesting that the pathogen was not carried through convective accend of aerosol droplets from soil surface up to pods in the canopy.Key words : Theobroma cacao, pod rot, stem canker, baiting.
J.F. Webber; J. Rose
Two new Phytophthora pathogens, Phytophthora kernoviae and P. ramorum, have recently established in parts of the U.K. They are most prevalent in the south west of England where they cause intense episodes of foliar blight and dieback on both ornamental and naturalised rhododendron such as Rhododendron ponticum,...
Jiang, R.H.Y.; Govers, F.
Phytophthora is a genus entirely comprised of destructive plant pathogens. It belongs to the Stramenopila, a unique branch of eukaryotes, phylogenetically distinct from plants, animals, or fungi. Phytophthora genes show a strong preference for usage of codons ending with G or C (high GC3). The
A severe black pod disease of cocoa in Ghana caused by Phytophthora megakarya was first reported in 1985, even though there is evidence that the fungus might have existed earlier. Until then, only Phytophthora palmivora which causes a less severe black pod disease was known in Ghana. P. megakarya has changed ...
Webster, Joan; Bell-Syer, Sally E M; Foxlee, Ruth
Blood for transfusion may become contaminated at any point between collection and transfusion and may result in bacteraemia (the presence of bacteria in the blood), severe illness or even death for the blood recipient. Donor arm skin is one potential source of blood contamination, so it is usual to cleanse the skin with an antiseptic before blood donation. One-step and two-step alcohol based antiseptic regimens are both commonly advocated but there is uncertainty as to which is most effective. To assess the effects of cleansing the skin of blood donors with alcohol in a one-step compared with alcohol in a two-step procedure to prevent contamination of collected blood or bacteraemia in the recipient. In December 2014, for this third update, we searched the Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library; Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE; and EBSCO CINAHL. All randomised trials (RCTs) comparing alcohol based donor skin cleansing in a one-step versus a two-step process that includes alcohol and any other antiseptic for pre-venepuncture skin cleansing were considered. Quasi randomised trials were to have been considered in the absence of RCTs. Two review authors independently assessed studies for inclusion. No studies (RCTs or quasi RCTs) met the inclusion criteria. We did not identify any eligible studies for inclusion in this review. It is therefore unclear whether a two-step, alcohol followed by antiseptic skin cleansing process prior to blood donation confers any reduction in the risk of blood contamination or bacteraemia in blood recipients, or conversely whether a one-step process increases risk above that associated with a two-step process.
Dias, M.D.; Trivellato, S.V.; Quintas, M.L.; Birolini, D.
Nosocomial respiratory tract infections due to contamination of mechanical ventilators is a major problem complicating the management of intensive care unit patients. A significant source of such infection seems to be water contained in the nebulizers. Its decontamination by various means has been unsatisfactory up to date. In order to control this source of infection, the authors suggest the utilization of a small dose of a 2% iodine alcoholic solution added to the water of the nebulizers in the proportion of 0.125ml of iodine solution to 500ml of water. The results show that the procedure is safe, efficient and unexpensive. (author) [pt
Watermelon is an important crop grown in 44 states in the United States. Phytophthora fruit rot caused by Phytophthora capsici is a serious disease in the southeastern U.S., where over 50% of the watermelons are produced. The disease has resulted in severe losses to watermelon growers, especially in...
Yeshi A. Wamishe; Steven N. Jeffers; Jaesoon Hwang
Nurseries in the southeastern United States that received ornamental plants in 2004 colonized by Phytophthora ramorum and the surrounding urban areas are being monitored to determine if this pathogen has escaped and become established. At the same time, the prevalence and diversity of other species of Phytophthora are being...
Ellger, B.; Kiski, D.; Diem, E.; van den Heuvel, I.; Freise, H.; Van Aken, H.; Hinder, F.; Friedrich, A. W.
Non-return valves (NRVs) are designed to avoid backflow of infusion fluid against the designated direction of flow (DDF) when more than one infusion is delivered via one venous access. We tested in vitro whether NRVs reliably prevent flow against the DDF at clinically relevant low flow rates. Since
N.J. Grünwald; F.N. Martin; M.M. Larsen; C.M. Sullivan; C.M. Press; M.D. Coffey; E.M. Hansen; J.L. Parke
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...
Keith Walters; Claire Sansford; David. Slawson
Since the first reports in Great Britain (GB) of Phytophthora ramorum (2002) and P. kernoviae (2003), the death of a small number of infected trees and of heathland Vaccinium has been recorded. Initial policy against these pathogens was one of containment, with a view to eradication...
Giannakopoulou, Artemis; Schornack, Sebastian; Bozkurt, Tolga O; Haart, Dave; Ro, Dae-Kyun; Faraldos, Juan A; Kamoun, Sophien; O'Maille, Paul E
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.
Kritzer, P. [Freudenberg Nonwovens KG, Technical Nonwovens Div., Weinheim (Germany); Diel, W.; Barber, P.H. [IBM Speichersysteme Deutschland GmbH, Mainz (Germany); Romankiw, L.T. [IBM Watson Research Center, Yorktown Heights, NY (United States)
Electroplating of Nickel-Iron alloys is widely used in the production of magnetic heads for storage systems. Usually, the plating process is performed in acidic, salt-containing solutions. After the plating step, a complete removal of the plating salts is necessary to receive a clean surface. In disadvantageous cases, a precipitation of sticky particles is observed that cannot be removed from the plated surface without damaging the surface. Some of these substances (esp. nickel sulfates) might lead to severe local corrosion and thus might act as ''time-bomb'' in the later product. Non-corrosive precipitations (i.e. nickel hydroxides) strongly hinder or even prevent the following production steps. In the present paper, the mechanisms of the origin of the different kinds of precipitation are described and the principle actions for their prevention are given. An outlook is given for other possible technical applications. (orig.)
Studholme, D.J.; McDougal, R.L.; Sambles, C.; Hansen, E.; Hardy, G.; Grant, M.; Ganley, R.J.; Williams, N.M.
In New Zealand there has been a long association of Phytophthora diseases in forests, nurseries, remnant plantings and horticultural crops. However, new Phytophthora diseases of trees have recently emerged. Genome sequencing has been performed for 12 Phytophthora isolates, from six species: Phytophthora pluvialis, Phytophthora kernoviae, Phytophthora cinnamomi, Phytophthora agathidicida, Phytophthora multivora and Phytophthora taxon Totara. These sequences will enable comparative analyses to identify potential virulence strategies and ultimately facilitate better control strategies. This Whole Genome Shotgun data have been deposited in DDBJ/ENA/GenBank under the accession numbers LGTT00000000, LGTU00000000, JPWV00000000, JPWU00000000, LGSK00000000, LGSJ00000000, LGTR00000000, LGTS00000000, LGSM00000000, LGSL00000000, LGSO00000000, and LGSN00000000. PMID:26981359
Samantha Storer Pesani Pereira
Full Text Available OBJECTIVETo search for evidence of the efficiency of sodium hypochlorite on environmental surfaces in reducing contamination and prevention of healthcare-associated infection HAIs.METHODSystematic review in accordance with the Cochrane Collaboration.RESULTSWe analyzed 14 studies, all controlled trials, published between 1989-2013. Most studies resulted in inhibition of microorganism growth. Some decreased infection, microorganism resistance and colonization, loss of efficiency in the presence of dirty and surface-dried viruses.CONCLUSIONThe hypochlorite is an effective disinfectant, however, the issue of the direct relation with the reduction of HAIs remains. The absence of control for confounding variables in the analyzed studies made the meta-analysis performance inadequate. The evaluation of internal validity using CONSORT and TREND was not possible because its contents were not appropriate to laboratory and microbiological studies. As a result, there is an urgent need for developing specific protocol for evaluating such studies.
Full Text Available We have utilized patients' own oral mucosa as a cell source for the fabrication of transplantable epithelial cell sheets to treat limbal stem cell deficiency and mucosal defects after endoscopic submucosal dissection of esophageal cancer. Because there are abundant microbiotas in the human oral cavity, the oral mucosa was sterilized and 40 μg/mL gentamicin and 0.27 μg/mL amphotericin B were added to the culture medium in our protocol. Although an oral surgeon carefully checked each patient's oral cavity and although candidiasis was not observed before taking the biopsy, contamination with Candida albicans (C. albicans was detected in the conditioned medium during cell sheet fabrication. After adding 1 μg/mL amphotericin B to the transportation medium during transport from Nagasaki University Hospital to Tokyo Women's Medical University, which are 1200 km apart, no proliferation of C. albicans was observed. These results indicated that the supplementation of transportation medium with antimycotics would be useful for preventing contamination with C. albicans derived from the oral mucosa without hampering cell proliferation.
Full text: It is well known that Semipalatinsk Test Site has been contaminated by radionuclides mainly as a result of atmospheric, aboveground and underground intensive nuclear tests during more than 40 years. Survey of residual radioactivity in the soil at ten Semipalatinsk Test Site areas showed that a great number of Plutonium-239, 240, Strontium-90 and Cesium-137 are concentrated in the depth of soil layer 0-8 cm. The residual radioactivity within the Semipalatinsk Test Site is tightly bound to the topsoil as a result of extreme heating and melting of the soils during the tests. The maximal amount of radionuclides is accumulated on the fine soil particles having 0.1-1.0 mm size. Wind erosion is responsible for suspension of contaminated soil particles in the air and further spreading of contamination far away. For instance, dust particles of diameter 0,05-0,1 mm are dropped within a couple of kilometers of the erosion site, while particles of about 0.005-0.01 mm diameter can move hundreds and thousands of kilometers. According to the results of the Institute of Radiation Safety and Ecology, Kazakhstan, in “Degelen” massive, where the intensive nuclear tests were carried out, the concentration of radionuclides in air increases for Sr-90 up to 5 times, for Pu-239,240 up to 100-250 times during the elevation of thin dust from the ground surface. In this connection agglomeration of thin dust containing radionuclides is of primary importance to protect the population from inhalation of re-suspended dust. Inter-polymer complexes are water-insoluble, moisture and gas permeable substances that form a “cobweb” on the surface of soil particles and consequently leading to formation of protective crust. Inter-polymer complexes enhance the intrusion of water into the soil, resulting in increased soil moisture to promote seed germination and plant growth. Inter-polymer complexes are also able to accumulate radionuclides via inclusion of metal ions into the Inter
Kamyar Aram; David M. Rizzo
The prevalence of Phytophthora species in surface waters has earned increasing attention in the past decades, in great part as a result of âstream monitoringâ programs for detection and monitoring of Phytophthora ramorum and other invasive species. The potential for Phytophthora ...
Nawar, Lubna Saleh
To evaluate the contamination risk of the improper storage of pistachio nuts was studied in the major location of Saudi Arabia by studying the fungi associated with non and salted pistachio nuts. The infection with Aspergillus flavus and A. niger and treatment of this infection with some abiotic factors , salting and fumigation with acetic acid on the invasion and colonization were also stu ded. High percentage infection (100%) were found in salted pistachio of Maidenhead , while low infection (68.75%) was found in non salted pistachio of Jihad. Referring to the total fungal counts (9845.5 and 5681.8 CFU/g nuts) were detected on malt extract yeast agar and rose bengal agar media respectively. Aspergillus niger and A. flavus were found common in all pistachio samples collected from the three locations on the two media used. The both fungi were grew at temperatures between 20 and 35 degree C, also as the relative humidity increased the fungal growth increased reached its maximum at 100% RH. Sodium chloride at 20 and 25 % completely stopped the linear of the both fungi on malt yeast extract agar medium. Application of nuts with sodium chloride was found to increased the resistance of pistachio nut to invasion and colonization by the fungi during storage. Also, the resistance to invasion was increased by increasing the doses of fumigation with acetic acid applied to the pistachio nuts reached 0% infection at the higher dose of acetic acid (60%). (author)
Balderacchi, M.; Vischetti, C.; di Guardo, A.; Trevisan, M.
Sustainable development is a fundamental objective of the European Union. Since 1991, the use of numerical models has been used to assess the environmental fate of pesticides (directive 91/414 EC). Since then, new approaches to assess pesticide contamination have been developed. This is an ongoing process, with approaches getting increasingly close to reality. Actually, there is a new challenge to integrate the most advanced and cost-effective monitoring strategies with simulation models so that reliable indicators of unsaturated flow and transport can be suitably mapped and coupled with other indicators related to productivity and sustainability. The most relevant role of GIS in the analysis of pesticide fate in soil is its application to process together input data and the results of distribution model based simulations of pesticide transport. FitoMarche is a GIS-based software tool that estimates pesticide movement in the unsaturated zone using MACRO 5 and it is able to simulate complex and real crop rotations at the regional scale. Crop rotation involves the sequential production of different plant species on the same land, every crop is characterized by different agricultural practices that involve the use of different pesticides at different doses. FitoMarche extracts MACRO input data from a series of geographic data sets (shapefiles) and an internal database, writes input files for MACRO, executes the simulation and extracts solute and water fluxes from MACRO output files. The study has been performed in the Marche region, located in central Italy along the Adriatic coast. Soil, climate, land use shapefiles were provided from public authorities, crop rotation schemes were estimated from ISTAT (the national statistics institute) 5th agricultural census database using a municipality detail and agricultural practices following the local customs. Two herbicides have been tested: "A" is employed on maize crop, and "B" on maize, sunflower and sugarbeet. In the
Patel, Tanvi G; Shukla, Rinku V; Gupte, Snehalata C
Transfusion associated sepsis cases are encountered occasionally and bacterial transmission remains the major cause. The goal of our study was to compare the efficacy of disinfectants in phlebotomy site preparation. After selection of donor the antecubital fossa area of the arm was disinfected with different types of disinfectants namely sprit (70% isopropyl alcohol), povidone iodine (0.5% w/v available iodine in distilled water), savlon (1.5% v/v chlorhexidine gluconate solution and 3.0% cetrimide solution) and combination of sprit and povidone iodine. Swabs were collected from 20 donors using a sterile forceps, after cleaning with different antiseptic solutions. Swab was streaked on blood agar plate aseptically and the plate was incubated at 37°C for 24 h. Colonies were counted and a single colony was re-cultured by growing on nutrient and Mac-Conkey agar. The biochemical characteristics were determined by performing Gram staining, Motility, Catalase and Oxidase tests. The mean values of colonies were significantly higher with savlon compared to other three solutions. The difference was statistically significant by "t" test (t values 1.7-3.0; P bag were aseptically inoculated in aerobic and anaerobic culture bottles to be tested on BacT/Alert system. The bag containing donor's blood did not show any contamination when three cleanings were carried out using sprit, povidone iodine and spirit respectively.
Huang, Guobang; Chen, Yi; Zhang, Jin, E-mail: firstname.lastname@example.org
Graphical abstract: Nanocomposited-coating was deposited on silicone hydrogel by using the matrix-assisted pulsed laser evaporation (MAPLE) process. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel, and can inhibit the bacterial growth efficiently. - Highlights: • We developed a nanocomposited coating to prevent silicone hydrogel from biofouling. • Matrix-assisted pulsed laser evaporation can deposit inorganic–organic nanomaterials. • The designed nanocomposited coating reduces protein absorption by over 50%. • The designed nanocomposited coating shows significant antimicrobial efficiency. - Abstract: Zinc oxide (ZnO) nanoparticles incorporating with polyethylene glycol (PEG) were deposited together on the surface of silicone hydrogel through matrix-assisted pulsed laser evaporation (MAPLE). In this process, frozen nanocomposites (ZnO–PEG) in isopropanol were irradiated under a pulsed Nd:YAG laser at 532 nm for 1 h. Our results indicate that the MAPLE process is able to maintain the chemical backbone of polymer and prevent the nanocomposite coating from contamination. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel. The cytotoxicity study shows that the ZnO–PEG nanocomposites deposited on silicone hydrogels do not impose the toxic effect on mouse NIH/3T3 cells. In addition, MAPLE-deposited ZnO–PEG nanocomposites can inhibit the bacterial growth significantly.
Bak, Jimmy; Ladefoged, Søren D.; Begovic, Tanja
tubes. Light propagation enhancement in tubes can be obtained if the refractive index of the intra-luminal saline solution is higher than that of the polymer. This condition is achieved by using Teflon tubes with a low refractive index (1.34) instead of the polymers with a high refractive index (1...... is demonstrated to be a preventative disinfection treatment on tubes made of Teflon, which enhances the UVC light propagation, and on tubes made of a softer material, ethylene vinyl acetate (EVA), which is suitable for catheters but much less suitable for UVC light propagation. Simulating an aseptic breach (∼103...... mJ cm-2 killed the bacteria present in the tubes and kept them disinfected for a period of 3-4 days....
Bak, Jimmy; Ladefoged, Søren D; Begovic, Tanja
tubes. Light propagation enhancement in tubes can be obtained if the refractive index of the intra-luminal saline solution is higher than that of the polymer. This condition is achieved by using Teflon tubes with a low refractive index (1.34) instead of the polymers with a high refractive index (1...... is demonstrated to be a preventative disinfection treatment on tubes made of Teflon, which enhances the UVC light propagation, and on tubes made of a softer material, ethylene vinyl acetate (EVA), which is suitable for catheters but much less suitable for UVC light propagation. Simulating an aseptic breach (~10......, that a fluence of 21 mJ cm(-2) killed the bacteria present in the tubes and kept them disinfected for a period of 3-4 days....
Si-Ammour, Azeddine; Mauch, Felix; Métraux, Jean-Pierre
Afin de mieux comprendre l´interaction Phytophthora-plante, nous avons développé un nouveau pathosystème: Arabidopsis thaliana-Phytophthora porri. Jusqu´à présent, Phytophthora infestans, qui a causé famine et désolation en Irlande voilà 150 ans, a été le mieux étudié. Etudier le pathosystème Pomme de terre-Phytophthora infestans a, sans aucun doute, des avantages surtout parce que la pomme de terre est très cultivée de par le monde. Toutefois, utiliser Arabidopsis comme plante modèle pour de...
. The objective of this study was to identify QTLs for partial resistance to Phytophthora sojae. In this study, we evaluated a total of 214 soybean accessions by the hypocotyl inoculation method, and 175 were susceptible. The 175 susceptible ...
Z. Wu (Zhouqiao); K.A. Vakalopoulos (Konstantinos); G.S.A. ter Hoeve-Boersema (Simone); L.F. Kroese (Leonard); K.H. Lam (King); P.H. van der Horst (Paul); I.M. Mulder (Irene); Y.M. Bastiaansen-Jenniskens (Yvonne); G.J. Kleinrensink (Gert Jan); J. Jeekel (Johannes); J.F. Lange (Johan)
textabstractBackground: Colorectal anastomoses created in a contaminated environment result in a high leakage rate. This study investigated whether using anastomotic sealants (TissuCol®, Histoacryl® Flex, and Duraseal®) prevents leakage in a rat peritonitis model. Study design: Sixty-seven Wistar
Sreedharan, Aswathy; Li, You; De, Jaysankar; Gutierrez, Alan; Silverberg, Rachael; Schneider, Keith R
Salmonella has been reported to be involved in several foodborne illness outbreaks, many of which resulted from consumption of raw tomatoes. This research aimed to optimize and evaluate the concentration of free chlorine (hypochlorous acid [HOCl]) used as a sanitizer to prevent cross-contamination of tomatoes inoculated with a cocktail of five rifampin-resistant Salmonella enterica serovars in a laboratory-based model flume system. Organic load, prepared using sterilized Scotts Premium Topsoil, was added in different quantities to the flume wash water to simulate real-world packinghouse conditions. In a typical packinghouse operation utilizing a recirculating flume system, the organic matter washed from tomato surfaces accumulates over time. In this study, different concentrations (0, 25, 50, 75, and 100 ppm) of HOCl were used as sanitizers under three organic load conditions (0, 650, and 1,000 mg/L chemical oxygen demand). Results showed that 100 ppm of HOCl was necessary to prevent Salmonella cross-contamination of uninoculated tomatoes in the model flume system in the presence of organic loading. Also, when treated with 100 ppm of HOCl, Salmonella levels were reduced by >4.5 log CFU per tomato from inoculated tomatoes in the presence of organic load. At 75 ppm of HOCl, Salmonella cross-contamination was prevented, but only in the absence of organic loading. In studies in which plate counts were negative, whole tomato enrichment studies were performed. No cross-contamination of uninoculated tomatoes was recorded when 100 ppm of HOCl was used, even in the presence of high organic load (1,000 mg/L chemical oxygen demand). Although sanitizer application reduces contamination on tomato surfaces, the primary function of sanitizers in the wash water is to prevent cross-contamination.
Y. Balci; S. Balci; W.L. MacDonald; K.W. Gottschalk
Pathogenicity of seven Phytophthora species was assessed by inoculation of stem and foliar tissues of oak species (Quercus spp.) native to the eastern United States. Phytophthora cambivora, P. cinnamomi, P. citricola, P. europaea, P. quercina...
Hyun, Ik-Hwa; Choi, Woobong
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.
Full Text Available Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries into Korea from 1900 to 2010. The genus Phytophthora, classified in oomycetes, includes more than 120 species that are mostly recognized worldwide as highly invasive plant pathogens. After 2000, over 50 new species of Phytophthora were identified internationally as plant pathogens occurring in crops and forest trees. In Korea, Phytophthora is also one of the most serious plant pathogens. To date, 22 species (about one-fifth of known species of the genus have been identified and reported as plant pathogens in the country. The likelihood of new exotic Phytophthora species being introduced into Korea continues to increase, thus necessitating intensive plant quarantine inspections. As new potential threats to plant health in Korea, six Phytophthora species, namely, P. alni, P. inundata, P. kernoviae, P. pinifolia, P. quercina, and P. ramorum, are discussed in this review with focus on history, disease, biology, management, and plant quarantine issues.
Full Text Available This study was conducted to determine the Phytophthora rot resistance of 514 accessions of watermelon germplasm, Citrullus lanatus var lanatus. About 46% of the 514 accessions tested were collections from Uzbekistan, Turkey, China, U.S.A., and Ukraine. Phytophthora capsici was inoculated to 45-day-old watermelon seedlings by drenching with 5 ml of sporangial suspension (10⁶ sporangia/ml. At 7 days after inoculation, 21 accessions showed no disease symptoms while 291 accessions of susceptible watermelon germplasm showed more than 60.1% disease severity. A total of 510 accessions of watermelon germplasm showed significant disease symptoms and were rated as susceptible to highly susceptible 35 days after inoculation. The highly susceptible watermelon germplasm exhibited white fungal hyphae on the lesion or damping off with water-soaked and browning symptoms. One accession (IT032840 showed moderate resistance and two accessions (IT185446 and IT187904 were resistant to P. capsici. Results suggest that these two resistant germplasm can be used as a rootstock and as a source of resistance in breeding resistant watermelon varieties against Phytophthora.
Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok
We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit. PMID:25288942
Mee Kyung Sang
Full Text Available We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107 among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05 reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05 reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.
Valois, D.; Fayad, K.; Barasubiye, T.; Garon, M.; Dery, C.; Brzezinski, R.; Beaulieu, C.
A collection of about 200 actinomycete strains was screened for the ability to grow on fragmented Phytophthora mycelium and to produce metabolites that inhibit Phytophthora growth. Thirteen strains were selected, and all produced (beta)-1,3-, (beta)-1,4-, and (beta)-1,6-glucanases. These enzymes could hydrolyze glucans from Phytophthora cell walls and cause lysis of Phytophthora cells. These enzymes also degraded other glucan substrates, such as cellulose, laminarin, pustulan, and yeast cell ...
Battersby, Tara; Walsh, D; Whyte, P; Bolton, D
The objectives of this study were to evaluate current cleaning practices in broiler houses by testing a range of sites after cleaning and disinfection and to test the efficacy of the most commonly used methods in a commercial broiler house after flock harvesting. Cleaning procedures on 20 broiler houses (10 separate farms) were examined by testing a range of sampling points (feeders, drinkers, walls, etc.) for total viable count (TVC), total Enterobacteriaceae count (TEC) and Campylobacter spp. after cleaning and disinfection, using culture based methods. In a second experiment, the six most commonly used commercially available disinfectants and/or detergent products were evaluated. The results of the first study demonstrated that critical areas in 12 of the 20 broiler houses were not effectively cleaned and disinfected between flocks as the tarmac apron, ante-room, house door, feeders, drinkers, walls, columns, barriers and/or bird weighs were Campylobacter positive. Thermal fogging with the combination of potassium peroxymonosulfate, sulfamic acid and sodium chloride (5%, v/v) or the glutaraldehyde and quaternary ammonium complex (0.3%, v/v) were the most effective treatments while other disinfectant treatments were considerably less effective. It was therefore concluded that farmers should review their broiler house cleaning and disinfection procedures if Campylobacter cross-contamination between successive flocks is to be prevented. Copyright Â© 2016 Elsevier Ltd. All rights reserved.
Phytophthora megakarya Brasier & Griffin, is one of the Oomycete pathogens reported on Theobroma cacao, and it is the most virulent of the Phytophthora species that causes black pod disease. Phytophthora megakarya was first reported as the causal agent of black pod disease in 1979 after the reclassification of ...
The presence of Phytophthora megakarya, which until 1985 was unknown in Ghana, has changed the status of black pod disease of cocoa in the country. Hitherto, only Phytophthora palmivora was known to be present. This paper reviews the Phytophthora pod disease situation, the origin, distribution, incidence and ...
... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Phytophthora palmivora; exemption from... From Tolerances § 180.1057 Phytophthora palmivora; exemption from requirement of tolerance. Phytophthora palmivora is exempted from the requirement of a tolerance in or on the raw agricultural commodity...
Hasegawa, Toru; Hashimoto, Tadao; Hashimoto, Manabu
In order to prevent radioactive materials from spreading contamination from nuclear power plants outside the radiation control area, the surface contamination of all material transferred outside from the control area is monitored. This paper presents an overview and describes features of: (1) personnel surface contamination monitoring assemblies for measuring the surface contamination on workers, (2) article surface contamination monitoring assemblies for measuring the surface contamination on articles, (3) laundry monitors for measuring the surface contamination on worker clothes worn inside the control area, and (4) hand-foot-clothing contamination monitors for measuring the surface contamination on hands, feet and clothing. (author)
Banh, T.; Li, J.; El-Askary, H. M.
There has been a plant pathogen, Phytophthora Ramorum that has been causing trouble for the plant species in the forests of California and Oregon. Phytophthora is essentially a water mold that infects oak species like California black oak, coast live oak as well as California bay laurel (Lamsal). What this project aims to accomplish is to observe any changes in NDVI values between the years of 2002 and 1994. What the project hopes to observe is a decline of NDVI values between the two years because the infection of Phytophtora Ramorum will cause stress to the plant or kill the plant, which will lower the values of NDVI. The project will utilizes satellite data to create NDVI images over the study area and two types of change detection methods to observe the differences between the NDVI values of the two years. Preliminary results for the project, data obtained from Landsat 7 ETM+ with a resolution of 240 meters, was not able to observe any significant changes. A finer resolution to differentiate the NDVI values would be needed. In addition the best way to keep the pathogen from getting out of control is with ground level management, or complete eradication of the pathogen. These eradication methods include burning the infected host plants and spreading herbicide (Alexander). With that in mind it would be ideal to have an early detection of the pathogen infestation. Therefore another goal of the project is to continue to research if remote sensing could play a role in an early detection method for the presence of Phytophtora Ramorum.
Haraguchi, Yoshikura; Tomoyasu, Y.; Yamamoto, Yasuhiro; Ishihara, Toru
The authors has continued researches on countermeasures against various disasters including nuclear or radiation accident. Present paper deals with the following items; (1) Significance of preparation of a manual on countermeasures against disasters in relation to medical drills, (2) Status and prospects of disaster simulations and disaster drills, (3) Promotion and education on medical knowledge when nuclear disasters occur, (4) Network system study of broad area medicines throughout the country. (5) Study on how to approach mental an psychological cares, (6) Specialities of radioactive contamination in the general contamination of NBC (Nuclear, Biological and Chemical) disasters, (7) New concept and preparation of triage tags, and (8) Queueing theory application to many patients in a hospital. (H. Yokoo)
Scott A. Lawrence
Full Text Available Oomycetes in the genus Phytophthora are among the most damaging plant pathogens worldwide. Two important species are Phytophthora cinnamomi, which causes root rot in thousands of native and agricultural plants, and Phytophthora agathidicida, which causes kauri dieback disease in New Zealand. As is the case for other Phytophthora species, management options for these two pathogens are limited. Here, we have screened over 100 compounds for their anti-oomycete activity, as a potential first step toward identifying new control strategies. Our screening identified eight compounds that showed activity against both Phytophthora species. These included five antibiotics, two copper compounds and a quaternary ammonium cation. These compounds were tested for their inhibitory action against three stages of the Phytophthora life cycle: mycelial growth, zoospore germination, and zoospore motility. The inhibitory effects of the compounds were broadly similar between the two Phytophthora species, but their effectiveness varied widely among life cycle stages. Mycelial growth was most successfully inhibited by the antibiotics chlortetracycline and paromomycin, and the quaternary ammonium salt benzethonium chloride. Copper chloride and copper sulfate were most effective at inhibiting zoospore germination and motility, whereas the five antibiotics showed relatively poor zoospore inhibition. Benzethonium chloride was identified as a promising antimicrobial, as it is effective across all three life cycle stages. While further testing is required to determine their efficacy and potential phytotoxicity in planta, we have provided new data on those agents that are, and those that are not, effective against P. agathidicida and P. cinnamomi. Additionally, we present here the first published protocol for producing zoospores from P. agathidicida, which will aid in the further study of this emerging pathogen.
Lawrence, Scott A; Armstrong, Charlotte B; Patrick, Wayne M; Gerth, Monica L
Oomycetes in the genus Phytophthora are among the most damaging plant pathogens worldwide. Two important species are Phytophthora cinnamomi , which causes root rot in thousands of native and agricultural plants, and Phytophthora agathidicida , which causes kauri dieback disease in New Zealand. As is the case for other Phytophthora species, management options for these two pathogens are limited. Here, we have screened over 100 compounds for their anti-oomycete activity, as a potential first step toward identifying new control strategies. Our screening identified eight compounds that showed activity against both Phytophthora species. These included five antibiotics, two copper compounds and a quaternary ammonium cation. These compounds were tested for their inhibitory action against three stages of the Phytophthora life cycle: mycelial growth, zoospore germination, and zoospore motility. The inhibitory effects of the compounds were broadly similar between the two Phytophthora species, but their effectiveness varied widely among life cycle stages. Mycelial growth was most successfully inhibited by the antibiotics chlortetracycline and paromomycin, and the quaternary ammonium salt benzethonium chloride. Copper chloride and copper sulfate were most effective at inhibiting zoospore germination and motility, whereas the five antibiotics showed relatively poor zoospore inhibition. Benzethonium chloride was identified as a promising antimicrobial, as it is effective across all three life cycle stages. While further testing is required to determine their efficacy and potential phytotoxicity in planta , we have provided new data on those agents that are, and those that are not, effective against P. agathidicida and P. cinnamomi . Additionally, we present here the first published protocol for producing zoospores from P. agathidicida , which will aid in the further study of this emerging pathogen.
Ali, Mohammad; Kim, Bosung; Belfield, Kevin D; Norman, David; Brennan, Mary; Ali, Gul Shad
Application of nanoparticles for controlling plant pathogens is a rapidly emerging area in plant disease management, and nanoparticles synthesis methods that are economical and ecofriendly are extensively investigated. In this project, we investigated the potential of silver nanoparticles (AgNPs) synthesized with aqueous extract of Artemisia absinthium against several Phytophthora spp., which cause many economically important crop diseases. In in vitro dose-response tests conducted in microtiter plates, 10 µg ml⁻¹ of AgNPs inhibited mycelial growth of P. parasitica, P. infestans, P. palmivora, P. cinnamomi, P. tropicalis, P. capsici, and P. katsurae. Detailed in vitro dose-response analyses conducted with P. parasitica and P. capsici revealed that AgNPs synthesized with A. absinthium extract were highly potent (IC50: 2.1 to 8.3 µg ml⁻¹) and efficacious (100%) in inhibiting mycelial growth, zoospore germination, germ tube elongation, and zoospore production. Interestingly, AgNP treatment accelerated encystment of zoospores. Consistent with in vitro results, in planta experiments conducted in a greenhouse revealed that AgNP treatments prevented Phytophthora infection and improved plant survival. Moreover, AgNP in in planta experiments did not produce any adverse effects on plant growth. These investigations provide a simple and economical method for controlling Phytophthora with AgNP without affecting normal plant physiology.
Mizgajska-Wiktor, Hanna; Jarosz, Wojciech; Fogt-Wyrwas, Renata; Drzewiecka, Agnieszka
The studies conducted in the years 1994-2013 allowed to determine the distribution of Toxocara spp. eggs in the soil of different types of urban and rural areas in Poland and to establish seasonal and multi-year dynamics of soil contamination with T. cati and T. canis eggs. Out of 3309 soil samples examined, 14.9% contained the eggs and the average density was 3.43 eggs/100g of soil. The level of soil contamination was the highest in cities, lower in villages, and lowest in small towns. In urban areas eggs of T. cati were found more frequently than of T. canis, while in rural areas the opposite was true. Both, in urban and rural areas, the sites most heavily contaminated with Toxocara spp. eggs were household surroundings (backyards). Recreation areas (parks, playgrounds, lake beaches) were significantly less contaminated. In older parts of Poznań, in backyards, soil contamination with the eggs was generally high each month, being lowest in July and highest in December and the prevalence of T. cati eggs was much higher than of T. canis. The prevention policy introduced in the city thus far - paying great attention to dog faeces but not to cats was unsatisfactory. After 18 years of such policy, the number of Toxocara spp. eggs dropped significantly but it was not a linear phenomenon - the intensity of soil contamination fluctuated. To be more effective, preventive measures should be preceded with discrimination of T. canis and T. cati eggs recovered in the soil and for this purpose the new molecular techniques should be applied. A survey conducted in the population in 2010 showed that people's awareness on the significance of pets in the transmission of dangerous zoonoses to humans was unsatisfactory. We recommend to expand the knowledge of the subject among the populace. Copyright © 2016. Published by Elsevier B.V.
ten Have Arjen
Full Text Available Abstract Background Phytophthora species are oomycete plant pathogens with such major social and economic impact that genome sequences have been determined for Phytophthora infestans, P. sojae and P. ramorum. Pepsin-like aspartic proteinases (APs are produced in a wide variety of species (from bacteria to humans and contain conserved motifs and landmark residues. APs fulfil critical roles in infectious organisms and their host cells. Annotation of Phytophthora APs would provide invaluable information for studies into their roles in the physiology of Phytophthora species and interactions with their hosts. Results Genomes of Phytophthora infestans, P. sojae and P. ramorum contain 11-12 genes encoding APs. Nine of the original gene models in the P. infestans database and several in P. sojae and P. ramorum (three and four, respectively were erroneous. Gene models were corrected on the basis of EST data, consistent positioning of introns between orthologues and conservation of hallmark motifs. Phylogenetic analysis resolved the Phytophthora APs into 5 clades. Of the 12 sub-families, several contained an unconventional architecture, as they either lacked a signal peptide or a propart region. Remarkably, almost all APs are predicted to be membrane-bound. Conclusions One of the twelve Phytophthora APs is an unprecedented fusion protein with a putative G-protein coupled receptor as the C-terminal partner. The others appear to be related to well-documented enzymes from other species, including a vacuolar enzyme that is encoded in every fungal genome sequenced to date. Unexpectedly, however, the oomycetes were found to have both active and probably-inactive forms of an AP similar to vertebrate BACE, the enzyme responsible for initiating the processing cascade that generates the Aβ peptide central to Alzheimer's Disease. The oomycetes also encode enzymes similar to plasmepsin V, a membrane-bound AP that cleaves effector proteins of the malaria parasite
Background Phytophthora species are oomycete plant pathogens with such major social and economic impact that genome sequences have been determined for Phytophthora infestans, P. sojae and P. ramorum. Pepsin-like aspartic proteinases (APs) are produced in a wide variety of species (from bacteria to humans) and contain conserved motifs and landmark residues. APs fulfil critical roles in infectious organisms and their host cells. Annotation of Phytophthora APs would provide invaluable information for studies into their roles in the physiology of Phytophthora species and interactions with their hosts. Results Genomes of Phytophthora infestans, P. sojae and P. ramorum contain 11-12 genes encoding APs. Nine of the original gene models in the P. infestans database and several in P. sojae and P. ramorum (three and four, respectively) were erroneous. Gene models were corrected on the basis of EST data, consistent positioning of introns between orthologues and conservation of hallmark motifs. Phylogenetic analysis resolved the Phytophthora APs into 5 clades. Of the 12 sub-families, several contained an unconventional architecture, as they either lacked a signal peptide or a propart region. Remarkably, almost all APs are predicted to be membrane-bound. Conclusions One of the twelve Phytophthora APs is an unprecedented fusion protein with a putative G-protein coupled receptor as the C-terminal partner. The others appear to be related to well-documented enzymes from other species, including a vacuolar enzyme that is encoded in every fungal genome sequenced to date. Unexpectedly, however, the oomycetes were found to have both active and probably-inactive forms of an AP similar to vertebrate BACE, the enzyme responsible for initiating the processing cascade that generates the Aβ peptide central to Alzheimer's Disease. The oomycetes also encode enzymes similar to plasmepsin V, a membrane-bound AP that cleaves effector proteins of the malaria parasite Plasmodium falciparum during
Borst, A; Box, ATA; Fluit, AC
Contamination of samples with DNA is still a major problem in microbiology laboratories, despite the wide acceptance of PCR and other amplification techniques for the detection of frequently low amounts of target DNA. This review focuses on the implications of contamination in the diagnosis and
Farage, Priscila; Puppin Zandonadi, Renata; Cortez Ginani, Verônica; Gandolfi, Lenora; Pratesi, Riccardo; de Medeiros Nóbrega, Yanna Karla
Conditions associated to the consumption of gluten have emerged as a major health care concern and the treatment consists on a lifelong gluten-free diet. Providing safe food for these individuals includes adapting to safety procedures within the food chain and preventing gluten cross-contamination in gluten-free food. However, a gluten cross-contamination prevention protocol or check-list has not yet been validated. Therefore, the aim of this study was to perform the content validation and semantic evaluation of a check-list elaborated for the prevention of gluten cross-contamination in food services. The preliminary version of the check-list was elaborated based on the Brazilian resolution for food safety Collegiate Board Resolution 216 (RDC 216) and Collegiate Board Resolution 275 (RDC 275), the standard 22000 from the International Organization for Standardization (ISO 22000) and the Canadian Celiac Association Gluten-Free Certification Program documents. Seven experts with experience in the area participated in the check-list validation and semantic evaluation. The criteria used for the approval of the items, as to their importance for the prevention of gluten cross-contamination and clarity of the wording, was the achievement of a minimal of 80% of agreement between the experts (W-values ≥ 0.8). Moreover, items should have a mean ≥4 in the evaluation of importance (Likert scale from 1 to 5) and clarity (Likert scale from 0 to 5) in order to be maintained in the instrument. The final version of the check-list was composed of 84 items, divided into 12 sections. After being redesigned and re-evaluated, the items were considered important and comprehensive by the experts (both with W-values ≥ 0.89). The check-list developed was validated with respect to content and approved in the semantic evaluation.
Full Text Available Conditions associated to the consumption of gluten have emerged as a major health care concern and the treatment consists on a lifelong gluten-free diet. Providing safe food for these individuals includes adapting to safety procedures within the food chain and preventing gluten cross-contamination in gluten-free food. However, a gluten cross-contamination prevention protocol or check-list has not yet been validated. Therefore, the aim of this study was to perform the content validation and semantic evaluation of a check-list elaborated for the prevention of gluten cross-contamination in food services. The preliminary version of the check-list was elaborated based on the Brazilian resolution for food safety Collegiate Board Resolution 216 (RDC 216 and Collegiate Board Resolution 275 (RDC 275, the standard 22000 from the International Organization for Standardization (ISO 22000 and the Canadian Celiac Association Gluten-Free Certification Program documents. Seven experts with experience in the area participated in the check-list validation and semantic evaluation. The criteria used for the approval of the items, as to their importance for the prevention of gluten cross-contamination and clarity of the wording, was the achievement of a minimal of 80% of agreement between the experts (W-values ≥ 0.8. Moreover, items should have a mean ≥4 in the evaluation of importance (Likert scale from 1 to 5 and clarity (Likert scale from 0 to 5 in order to be maintained in the instrument. The final version of the check-list was composed of 84 items, divided into 12 sections. After being redesigned and re-evaluated, the items were considered important and comprehensive by the experts (both with W-values ≥ 0.89. The check-list developed was validated with respect to content and approved in the semantic evaluation.
Phytophthora fragariae i P. cactorum pripadaju među najdestruktivnije uzročnike bolesti u proizvodnji jagode. To su gljivicama slični organizmi koji napadaju podzemni dio biljke i uzrokuju venuće i sušenje jagode. Štete koje uzrokuju mogu biti drastične. Za razliku od P. fragariae, koja nikad nije zabilježena, P. cactorum često uzrokuje propadanje nasada jagode u Hrvatskoj. U radu su opisani etiologija i simptomi bolesti koje izazivaju te osnovna morfološka obilježja, naročito razlike među pa...
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Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok
We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.
Miller, S A; Madden, L V; Schmitthenner, A F
ABSTRACT Populations of Phytophthora spp. were determined by enzyme-linked immunosorbent assay (ELISA) in field soils used for pepper and soybean production in Ohio. Soybean fields were sampled extensively (64 fields, n = 6 samples per field over 2 years) and intensively (4 fields, n = 64 samples per field in 1 year) to assess heterogeneity of P. sojae populations. Four pepper fields (n = 64), three of which had a history of Phytophthora blight (caused by P. capsici), also were sampled intensively during a 6-month period. Mean (m), variance (v), and measures of aggregation (e.g., variance-to-mean ratio [v/m]) of immunoassay values, translated to Phytophthora antigen units (PAU), were related to the disease history in each of the pepper and soybean fields. Mean PAU values for fields in which Phytophthora root rot (soybean) or blight (pepper) had been moderate to severe were higher than in fields in which disease incidence had been low or not observed. A detection threshold value of 11.3 PAU was calculated with values for 64 samples from one pepper field, all of which tested negative for Phytophthora by bioassay and ELISA. Seven of the eight intensively sampled fields contained at least some detectable Phytophthora propagules, with the percentage of positive samples ranging from 1.6 to 73.4. Mean PAU values ranged from 1 to 84 (extensive soybean field sampling), 6 to 24 (intensive soybean field sampling), and 4 to 30 (intensive pepper field sampling); however, variances ranged from 0 to 7,774 (extensive sampling), 30 to 848 (intensive soybean field sampling), and 5 to 2,401 (intensive pepper field sampling). Heterogeneity of PAU was high in most individual soybean and pepper fields, with values of v/m greater than 1, and log(v) increasing with log(m), with a slope of about 2.0. Spatial autocorrelation coefficients were not significant, indicating there was no relationship of PAU values in neighboring sampling units (i.e., field locations) of the intensively sampled
Full Text Available Phytophthora ramorum is a quarantine pathogen that causes leaf blight and shoot dieback of the crown, bark cankers and death on a number of both ornamental and forest trees, especially in North America and northern Europe, where it has produced severe outbreaks.In Italy it was first reported in 2002, on Rhodondendron yakushimanum in a Piedmont nursery; after that it seemed to have disappeared, only to re-emerge in 2013 when numerous isolates were detected on batches of Viburnum tinus plants growing in some nurseries in the Pistoia area (Tuscany, which is an important district in the trade of nursery plants world-wide. This work reports on a number of laboratory tests that were carried out on isolates from infected plant samples. The micromorphological and macromorphological characteristics of the pathogen growing on carrot agar (CA, corn meal agar (CMA, malt extract agar (MEA potato dextrose agar, and V8 agar with added PARPNH (see text were determined, as was the growth rate at 10º, 15º, 20º, 25°, 30º, 32º and 35ºC. Molecular analysis was employed to identify the isolates more precisely. Inoculation trials under the bark were also carried out to ascertain the isolate virulence and the Koch’s Postulates.The Plant Protection Service of the Tuscan Region (SFR, Servizio Fitosanitario Regionale was alerted as soon as the pathogen infection was detected and it took the prescribed steps to eradicate the infection in the field and prevent the recurrence of an epidemic.
Martha Cárdenas Toquica
Full Text Available Phytophthora infestans, the causal agent of late blight disease in potato and other members of the Solanaceae family, is responsible for causing the Irish potato famine and, even today, it causes enormous economic losses all over the world. For the establishment of an adequate pest management strategy, the determination of population structure is required. To characterize P. infestans populations worldwide two allozymes, Gpi (Glucose-6-phospate isomerase and Pep (Peptidase, the RG57 DNA RFLP fingerprinting probe, as well as resistance to the fungicide metalaxyl and the mating type, have been used as markers. P. infestans populations in Mexico have been one of the main focuses of research in the population biology of this pathogen because this country has been considered as one of the possible centers of origin of this oomycete. In this review we present the population structure of P. infestans in Mexico, Europe, Africa, Asia, North America, and South America expanding on the present situation of P. infestans in Colombia. Finally, we will discuss different lines of research that are being carried out today with respect to P. infestans in Colombia, which have shown the importance of continuing the study of this devastating plant pathogen in our country.
Cardenas, Martha; Danies, Giovanna; Tabima, Javier; Bernal, Adriana; Restrepo, Silvia
Phytophthora infestans, the causal agent of late blight disease in potato and other members of the Solanaceae family, is responsible for causing the Irish potato famine and, even today, it causes enormous economic losses all over the world. For the establishment of an adequate pest management strategy, the determination of the pathogen's population structure is required. To characterize P. infestans populations worldwide two allozymes, Gpi (Glucose-6-phospate isomerase) and Pep (Pep tidase), the RG57 DNA RFLP fingerprinting probe, as well as resistance to the fungicide metalaxyl and mating type, have been used as markers. P. infestans populations in Mexico have been one of the main focuses of research in the population biology of this pathogen because this country has been considered as one of the possible centers of origin of this oomycete. In this review we present the population structure of P. infestans in Mexico, Europe, Africa, Asia, North America, and South America, expanding it on the present situation of P. infestans in Colombia. Finally, we will discuss different lines of research that are being carried out today with respect to P. infestans in Colombia, which have shown the importance of continuing the study of this devastating plant pathogen in our country.
Sharma, Mamta; Ghosh, Raju; Tarafdar, Avijit; Telangre, Rameshwar
Phytophthora blight caused by Phytophthora cajani is an emerging disease of pigeonpea (Cajanus cajan L.) affecting the crop irrespective of cropping system, cultivar grown and soil types. Current detection and identification methods for Phytophthora species rely primarily on cultural and morphological characteristics, the assessment of which is time-consuming and not always suitable. Sensitive and reliable methods for isolation, identification, zoospore production and estimating infection severity are therefore desirable in case of Phytophthora blight of pigeonpea. In this study, protocols for isolation and identification of Phytophthora blight of pigeonpea were standardized. Also the method for zoospore production and in planta infection of P. cajani was developed. Quantification of fungal colonization by P. cajani using real-time PCR was further standardized. Phytophthora species infecting pigeonpea was identified based on mycological characters such as growth pattern, mycelium structure and sporangial morphology of the isolates and confirmed through molecular characterization (sequence deposited in GenBank). For Phytophthora disease development, zoospore suspension of 1 × 10(5) zoospores per ml was found optimum. Phytophthora specific real-time PCR assay was developed using specific primers based on internal transcribed spacer (ITS) 1 and 2. Use of real-time PCR allowed the quantitative estimation of fungal biomass in plant tissues. Detection sensitivities were within the range of 0.001 pg fungal DNA. A study to see the effect of elevated CO₂ on Phytophthora blight incidence was also conducted which indicated no significant difference in disease incidence, but incubation period delayed under elevated CO₂ as compared to ambient level. The zoospore infection method for Phytophthora blight of pigeonpea will facilitate the small and large scale inoculation experiments and thus devise a platform for rapid and reliable screening against Phytophthora blight
del Castillo-Múnera, Johanna; Cárdenas, Martha; Pinzón, Andrés; Castañeda, Adriana; Bernal, Adriana J; Restrepo, Silvia
Phytophthora is the most important genus of the Oomycete plant pathogens. Nowadays, there are 117 described species in this genus, most of them being primary invaders of plant tissues. The different species are causal agents of diseases in a wide range of crops and plants in natural environments. In order to develop control strategies against Phytophthoraspecies, it is important to know the biology, ecology and evolutionary processes of these important pathogens. The aim of this study was to propose and validate a low cost identification system for Phytophthora species based on a set of polymorphic microsatellite (SSRs) markers. Thirty-three isolates representing Phytophthora infestans, Phytophthora andina, Phytophthora sojae, Phytophthora cryptogea, Phytophthora nicotianae, Phytophthora capsici and Phytophthora cinnamomi species were obtained, and 13 SSRs were selected as potentially transferable markers between these species. Amplification conditions, including annealing temperatures, were standardized for several markers. A subset of these markers amplified in all species, showing species-specific alleles. The adaptability and impact of the identification system in Colombia, an Andean agricultural country where different Phytophthora species co-exist in the same or in several hosts grown together, are discussed. Copyright © 2012 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.
Comparison of the efficacy of chlorhexidine gluconate versus povidone iodine as preoperative skin preparation for the prevention of surgical site infections in clean-contaminated upper abdominal surgeries.
Srinivas, Anirudh; Kaman, Lileswar; Raj, Prithivi; Gautam, Vikas; Dahiya, Divya; Singh, Gurpreet; Singh, Rajinder; Medhi, Bikash
To compare the efficacy of chlorhexidine-gluconate versus povidone iodine in preoperative skin preparation in the prevention of surgical site infections (SSIs) in clean-contaminated upper abdominal surgeries. This was a prospective randomized controlled trial conducted on patients undergoing clean-contaminated upper abdominal surgeries. A total of 351 patients 18-70 years old were randomized into two groups; chlorhexidine and povidone iodine skin preparation before surgery. The incidence of SSIs in the chlorhexidine group was 10.8 %, in comparison to 17.9 % in the povidone iodine group. The odds ratio was 0.6 in favor of chlorhexidine use, but the results were not statistically significant (P = 0.06). In the first postoperative week, SSIs developed in 7 % of patients in the chlorhexidine group and 14.1 % in the povidone iodine group (P = 0.03), and in the second postoperative week, SSIs were present in 4.1 % of the patients in the chlorhexidine group and 4.4 % in the povidone iodine group, which was not statistically significant (P = 0.88). The incidence of SSIs after clean-contaminated upper abdominal surgeries was lower with the use of chlorhexidine skin preparation than with povidone iodine preparation, although the results were not statistically significant. However, the odds ratio between the two groups favored the use of chlorhexidine over povidone iodine for preventing SSIs.
Recommendations for sampling for prevention of hazards in civil defense. On analytics of chemical, biological and radioactive contaminations. 2. ed.; Empfehlungen fuer die Probenahme zur Gefahrenabwehr im Bevoelkerungsschutz. Zur Analytik von chemischen, biologischen und radioaktiven Kontaminationen
Bachmann, Udo; Derakshani, Nahid; Drobig, Matthias; Koenig, Mario; Mentfewitz, Joachim; Prast, Hartmut; Uelpenich, Gerhard; Vidmayer, Marc; Wilbert, Stefan; Wolf, Manfred
The recommendations for sampling for prevention of hazards in civil defense (analytics of chemical, biological and radioactive contaminations) cover the following topics: Requirements for sampling, description of the materials (chemical, biological and radioactive contaminated materials), decontamination, sample transport and protocol documents.
Bond, Tiziana C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center of Micro and Nano Technology, Material Engineering Division; Chang, Allan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center of Micro and Nano Technology, Material Engineering Division; Zhou, Jenny [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center of Micro and Nano Technology, Material Engineering Division
The objective in this project is to provide a proof of concept will demonstrate the feasibility of a Raman, in-situ warning system for detecting and removing developing fungal hot spots from pistachio stockpiles and transit containers, thus decreasing human health risks and product loss as a result of contamination. The proposed project has the following goals: to calibrate the Raman fingerprinting of biomarkers, standalone and in premixed samples, to build a database with the vibrational profiles distinctive to the signatures of the bouquet emitted by the contaminated pistachios; to test the improvement in the detection of the detectable markers with enhanced Raman on a small probe.
The effects of potassium nitrate (KNO3) application on Phytophthora stem rot disease reduction of Glycine max (L.) Merr. cvs. Chusei-Hikarikuro and Sachiyutaka, and fungal growth and zoospore release of a Phytophthora sojae isolate were investigated under laboratory conditions. The application of 4-...
Phytophthora root rot of soybean, caused by Phytophthora sojae is one of the most important diseases in the Midwest US, causing losses of up to 44 million bushels per year. Disease may also be caused by P. sansomeana, however the prevalence and damage caused by this species is not well known, partl...
Balci, Y.; Brazee, N. J.; Loyd, A. L.; Hong, C. X.
A novel species of the genus Phytophthora was recovered during surveys of stream and nursery irrigation water in Maryland, Massachusetts, North Carolina, Virginia and West Virginia in the USA. The novel species is heterothallic, and all examined isolates were A1 mating type. It produced rare ornamented oogonia and amphigynous antheridia when paired with A2 mating type testers of Phytophthora cinnamomi and Phytophthora cryptogea. Sporangia of this novel species were non-papillate and non-caducous. Thin-walled intercalary chlamydospores were abundant in hemp seed agar and carrot agar, while they were produced only rarely in aged cultures grown in clarified V8 juice agar. Phylogenetic analyses based on sequences of the internal transcribed spacer region and the β-tubulin and mitochondrial cytochrome-c oxidase 1 (cox1) genes indicated that the novel species is phylogenetically close to Phytophthora gallica in Phytophthora clade 10. The novel species has morphological and molecular features that are distinct from those of other species in Phytophthora clade 10. It is formally described here as Phytophthora intercalaris sp. nov. Description of this unique clade-10 species is important for understanding the phylogeny and evolution of Phytophthora clade 10. PMID:26620125
Late blight, caused by Phytophthora infestans is the most important disease of potato (Solanum tuberosum). This study reveals the genetic diversity of P. infestans population in north China. A total of 134 strains of P. infestans were isolated from different agricultural fields in Hebei, Liaoning, Jinlin and Heilongjiang Provinces ...
Potato tuber blight caused by Phytophthora infestans accounts for significant losses in storage. There is limited published quantitative data on predicting tuber blight. We validated a tuber blight prediction model developed in New York with cultivars Allegany, NY 101, and Katahdin using independent...
G. Calmin; M. Riedel; L. Belbahri; S. Wagner; S. Werres; F. Lefort
The important quarantine organism Phytophthora ramorum has been dramatically increasing its host range in the past years and most of the studies concerning P. ramorum focus on these issues. Very little is known about the latency period. For sampling and analyzing potentially infected plant material,...
Aaron L. Smith; Everett M. Hansen
Chlamydospores are a distinctive feature of Phytophthora ramorum. They are formed quickly in agar, and within colonized leaves. We followed their development and maturation in vitro and in vivo, and studied conditions affecting their germination. Cell walls of mature P. ramorum chlamydospores...
This study reveals the genetic diversity of P. infestans population in north China. A total of. 134 strains of P. ... Key words: Phytophthora infestans, population genetics, simple-sequence repeat (SSR), potato late blight. INTRODUCTION .... growth (about 5 to 7 days), the white mycelia of P. infestans were transferred to fresh ...
Prakash Hebbar; Scott Pfister; Stacy Scott; Anthony Man-Son-Hing; Russ Bulluck
Sudden oak death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), and threatens this species throughout its range in Oregon. The disease was first discovered in coastal southwest Oregon forests in July 2001. Since then an interagency team...
Potato (Solanum tuberosum L.) is nowadays the most important non-cereal food crop in the world. It is prone to huge annual losses due to late blight, the disease caused by the oomycete pathogen Phytophthora infestans. Modern management of late blight necessitates the use of multiple resistance (R)
Jun 28, 2012 ... found among citrus species in the percentage of root colonization by the AM fungi and in the severity of root rot disease ... Key words: Phytophthora parasitica, citrus, rootstock, arbuscular mycorrhizal (AM) fungi, root rot. INTRODUCTION ..... caused by Fusarium oxysporum f.sp. lycopersici by AMF Glomus.
Grünwald, N.J.; Flier, W.G.
The central highlands of Mexico are considered to be a center of genetic diversity for both the potato late blight pathogen and for tuber-bearing Solanum spp. Recent work conducted in Mexico and South America sheds new light on the biology and evolution of Phytophthora infestans and other related
Katherine J. Hayden; Matteo Garbelotto; Hardeep Fai; Brian Knaus; Richard Cronn; Jessica W. Wright
Disease processes are dynamic, involving a suite of gene expression changes in both the host and the pathogen, all within a single tissue. As such, they lend themselves well to transcriptomic analysis. Here we focus on a generalist invasive pathogen (Phytophthora ramorum) and its most susceptible California Floristic Province native host, tanoak (...
John Frampton; Fikret Isik; Mike Benson; Jaroslav Kobliha; Jan Stjskal
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 ...
S. Murphy; C. Lee; Y. Valachovic; A. Jirka; D.R. Owen; D. Rizzo; W. Mark
One hundred eighty-seven sites were established in perennial watercourses and sampled for one to four years between 2004 and 2007 to monitor for the presence of Phytophthora ramorum throughout coastal central and northern California watersheds as well as portions of the Sierra Nevada mountain range. In 2007, 132 sites...
S.K. Murphy; C. Lee; Y. Valachovic; J. Bienapfl; W. Mark; A. Jirka; D.R. Owen; T.F. Smith; D.M. Rizzo
One hundred-thirteen sites were established in perennial watercourses and sampled for 1 to 3 years between 2004 and 2006 to monitor for presence of Phytophthora ramorum throughout coastal central and northern California watersheds as well as portions of the Sierra Nevada mountain range (Murphy and others 2006). The majority of the monitored...
Govers, F.; Meijer, H.J.G.; Tran, H.; Wagemakers, L.; Raaijmakers, J.M.
Oomycetes cause devastating diseases on plants and animals. They cause major yield losses in many crop plants and their control heavily depends on agrochemicals. This is certainly true for the potato late blight pathogen Phytophthora infestans. Strong concerns about adverse effects of agrochemicals
Full Text Available Pathogens of Phytophthora genus are common not only in forest nurseries and stands, but also in water courses. Species of Phytophthora spread with plants for plantings (and soil attached to them and with water courses as well, attacking the plants growing in riparian ecosystems. Several specialized organisms damaging only one tree species were identified like P. alni on alders or P. quercina on oaks. Some Phytophthora species can develop on several hosts like P. plurivora and P. cactorum on oaks, beeches, alders, ashes and horse chestnuts. Other oomycetes like P. gallica species was found for the first time in Poland in water used for plant watering in forest nursery. Species P. lacustris and P. gonapodyides were found in superficial water. Phytophthora species P. polonica was identified in the declining alder stands for the first time in the world, and P. taxon hungarica and P. megasperma were found in the rhizosphere of seriously damaged ash stands for the first time in Poland. The most often isolated species were P. plurivora (clade 2 with frequency 37% and P. lacustris with frequency 33% (clade 6. The best represented clade 6 revealed the occurrence of 6 species: P. gonapodyides, P. lacustris, P. megasperma, P. sp. raspberry, P. taxon hungarica and P. taxon oak soil.
Elizabeth J. Fichtner; David M. Rizzo; Shannon C. Lynch; Jennifer Davidson; Gerri Buckles; Jennifer Parker
Sudden oak death manifests as non-lethal foliar lesions on bay laurel (Umbellularia californica), which support sporulation and survival of Phytophthora ramorum in forest ecosystems. Infected bay laurel leaves are more likely to abscise than uninfected leaves, resulting in an accumulation of inoculum at the forest floor. The pathogen survives the dry...
Fluorescent Pseudomonas bacteria produce a wide variety of antimicrobial metabolites, including soap-like compounds referred to as biosurfactants. The results of this thesis showed that biosurfactant-producing Pseudomonas bacteria are effective in controlling Phytophthora foot rot
Discovering the origins of Phytophthora ramorum remains a challenge. To improve our chances of finding the origin of P. ramorum or any other introduced organism, we need to be sure of our motivation, because success will require persistence. We need to be able to distinguish indigenous from exotic organisms, to know what to...
N.K. Osterbauer; M. Lujan; G. McAninch; A. Trippe; S. Lane
The Oregon Department of Agriculture implemented the Grower Assisted Inspection Program (GAIP) for nurseries in 2007. Participants in GAIP adopted best management practices (BMP) for five critical control points (CCP) (used containers, irrigation water, soil substrate, potting media, and incoming plants), where foliar Phytophthora can be introduced...
K.L. Riley; G.A. Chastagner
In 2005 and 2006, white fir and Douglas-fir growing in a Christmas tree plantation near Los Gatos, CA, under a black walnut tree infected with mistletoe tested positive for Phytophthora ramorum, the cause of Sudden Oak Death. Isolation from a symptomatic mistletoe inflorescence stalk was positive for P. ramorum. In 2007,...
K.L. Riley; G.A. Chastagner
Phytophthora ramorum was detected on grand fir in 2003 and 2005 in a Christmas tree plantation near Los Gatos, CA, in association with infected California bay laurel. Isolates derived from stem lesions were used to inoculate grand fir seedlings in two tests. Isolations from lesions on inoculated plants were positive for P. ramorum...
Aug 22, 2014 ... resistance, and facilitate future marker-assistant selection aimed to improve resistance to P. sojae and reduce disease-related mortality in soybean. [Sun J., Guo N., Lei J., Li L., Hu G. and Xing H. 2014 Association mapping for partial resistance to Phytophthora sojae in soybean. (Glycine max (L.) Merr.).
Pánek, Matěj; Fér, Tomáš; Mráček, Jaroslav; Tomšovský, Michal
The Phytophthora cactorum species complex in Europe is composed of P. cactorum, Phytophthora hedraiandra, and a hybrid species Phytophthora × serendipita. Evolutionary analyses using the amplified fragment length polymorphism (AFLP) method were carried out on 133 isolates from 19 countries. The AFLP data were complemented by sequence analysis of three genes (ITS region of ribosomal RNA gene, phenolic acid decarboxylase - Pheca I, and Cytochrome oxidase - Cox I), morphometric analysis and cardinal temperature data. The high proportion of clonal genotypes, low gene flow among groups, which was defined by the structure analysis, and low Nei's gene diversity confirms the homothallic life cycle of the groups. On the other hand, the ITS, Cox I and Pheca I sequence data support occasional hybridization between species. The structure K = 5 grouping revealed two groups of hybrid origin (C2 and F). While the C2 group resembles P. × serendipita, the F group includes Finnish isolates characterized by high oogonial abortion rates and slow growth. The morphological characters routinely used in identification of Phytophthora species are not useful for delimitation of species from the P. cactorum complex. Therefore, we discuss the status of P. hedraiandra as a separate species. The epitypification of P. cactorum is proposed. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.
During a survey in October 2013, in the Michaux State Forest in Pennsylvania , necrotic Rhododendron maximum leaves were noticed on mature plants alongside a stream. Symptoms were nondescript necrotic lesions at the tips of mature leaves. Colonies resembling a Phytophthora sp. were observed from c...
Cocoyam (Colocasia esculenta L). is an important edible tuber crop, but taro leaf blight caused by Phytophthora colocasiae has been the greatest constraint to cocoyam production in Nigeria since 2009. Field trials were conducted to determine the effect of fungicides and the spray regimes on leaf growth, disease incidence, ...
Brouwer, Henk; Coutinho, Pedro M; Henrissat, Bernard; de Vries, Ronald P
Carbohydrate-Active enZymes (CAZymes) form particularly interesting targets to study in plant pathogens. Despite the fact that many CAZymes are pathogenicity factors, oomycete CAZymes have received significantly less attention than effectors in the literature. Here we present an analysis of the CAZymes present in the Phytophthora infestans, Ph. ramorum, Ph. sojae and Pythium ultimum genomes compared to growth of these species on a range of different carbon sources. Growth on these carbon sources indicates that the size of enzyme families involved in degradation of cell-wall related substrates like cellulose, xylan and pectin is not always a good predictor of growth on these substrates. While a capacity to degrade xylan and cellulose exists the products are not fully saccharified and used as a carbon source. The Phytophthora genomes encode larger CAZyme sets when compared to Py. ultimum, and encode putative cutinases, GH12 xyloglucanases and GH10 xylanases that are missing in the Py. ultimum genome. Phytophthora spp. also encode a larger number of enzyme families and genes involved in pectin degradation. No loss or gain of complete enzyme families was found between the Phytophthora genomes, but there are some marked differences in the size of some enzyme families. Copyright © 2014 Elsevier Inc. All rights reserved.
Cvitanich, Cristina; Judelson, Howard S.
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...
Skottrup, Peter; Frøkiær, Hanne; Hejgaard, Jørn
In this study we focused on the development of a Surface Plasmon Resonance (SPR) immunosensor for Phytophthora infestans detection. The fungus-like organism is the cause of potato late blight and is a major problem in potato growing regions of the world. Efficient control is dependent on early...
This study was performed to investigate the frequency with which P. ramorum would be isolated from host tissue co-infected with P. ramorum as well as an indigenous Phytophthora species or P. kernoviae. Three separate experiments were tested in a similar manner using different combinations of pathog...
Lehtinen, A; Hannukkala, A; Andersson, B
A total of 743 single-lesion isolates of Phytophthora infestans were collected in summer 2003 from Denmark, Finland, Norway and Sweden. Most of the isolates were tested for mating type, and subsets were tested for sensitivity to fungicides and virulence (host specific pathogenicity). Approximately...
Montes, Melanie Sarah
Phytophthora infestans is the potato late blight pathogen, most famous for its role in the Great Famine in Ireland in the 1840s. It is still a large problem today, costing about a billion Euros in yield loss and chemical control each year on potatoes in Europe alone. It also has a profound enviro...
Catherine Eyre; Matteo Garbelotto
Sudden oak death, the tree disease caused by Phytophthora ramorum, has significant environmental and economic impacts on natural forests on the U.S. west coast, plantations in the United Kingdom, and in the worldwide nursery trade. Stream baiting is vital for monitoring and early detection of the pathogen in high-risk areas and is performed...
Yang, Xiao; Copes, Warren E; Hong, Chuanxue
Phytophthora stricta sp. nov. and Phytophthora macilentosa sp. nov. are described based on morphological, physiological and molecular characters in this study. Phytophthora stricta represents a previously unknown clade in the rRNA internal transcribed spacer (ITS)-based phylogeny. Phytophthora macilentosa, along with nine other species, consistently forms a high temperature-tolerant cluster within ITS clade 9. These observations are supported by the sequence analysis of the mitochondrial cytochrome c oxidase 1 gene. Both species are heterothallic and all examined isolates are A1 mating type. Phytophthora stricta produces nonpapillate and slightly caducous sporangia. This species is named after its characteristic constrictions on sporangiophores. Phytophthora macilentosa produces nonpapillate and noncaducous sporangia, which are mostly elongated obpyriform with a high length to breadth ratio. Both species were recovered from irrigation water of an ornamental plant nursery in Mississippi, USA and P. stricta was also recovered from stream water in Virginia, USA. Copyright © 2013 The British Mycological Society. All rights reserved.
Kabukoba, J J; Pearce, J M
1. To design a device that would reduce contamination of staff during obstetric procedures. 2. To undertake clinical trials to assess the effectiveness and acceptability of such a device. A prospective study. The arm sleeve is made of a nonwoven material laminated on polyethylene film making it waterproof. It has an elastomeric cuff with adhesive that ensures a watertight seal between it and the glove. Delivery suite in a teaching hospital. Doctors and midwives were requested to wear the sleeve on top of the standard gown and gloves. Each user was assessed for blood contamination at the end of the procedure and a questionnaire detailing the extent of contamination and the views of the user was completed. Eighty questionnaires were completed. The contamination of arms and hands was 3.8% and 5%, respectively. Eighty-nine percent thought the sleeve had served its purpose and 76% said they would use it regularly. The sleeve is an effective protective device which complements the glove and gown. We recommend that it should be used during all obstetric procedures.
Etxeberria, Aitzol; Mendarte, Sorkunde; Larregla, Santiago
Phytophthora capsici is a major fungal plant pathogen that causes root and crown rot of pepper crops and its oospores are the most resistant propagules. To evaluate the effect of different temperature regimes and exposure times on the survival of P. capsici oospores. Thermal inactivation treatments simulated field conditions, through the use of different constant and cycling temperature regimes, in moistened sterilized soil (15-53 °C) and sterilized water (45-53 °C). The plasmolysis method evaluated oospore viability. Relationships between oospores viability and exposure time were statistically determined by linear regression. Interpolation was used to calculate the estimated times required to kill a determined percentage of the population. The required time to reduce P. capsici oospores viability decreased with increasing temperatures. Times required to kill 100% of oospores were 199-22-6.6-4.7-1.0 hours at 40-45-47.5-50-53°C respectively in moistened soil and 31-1.0-0.2 hours at 45-50-53 °C in water. Oospores were scarcely affected at temperatures ≤ 35 °C. With 1,680 hours at 15-35 °C, oospores survival in soil ranged from 88 to 36%. The 4 hours-40 °C regime killed 100% of oospores after 28days, while the 5 hours-35°C regime after 70 days killed only 75%. Time required to achieve total oospores death was remarkably shortened in water when compared with moistened soil. The developed models can be used to predict survival values at any exposure time with constant temperatures ranging from 40 to 53 °C in moistened soil and from 45 to 53 °C in water. The weakening of P. capsici oospores under sublethal heating, is a useful observation that can be applied for pathogen control with solarization. Copyright © 2010 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.
Guido, Fellbrich; Beatrix, Blume; Frederic, Brunner; Heribert, Hirt; Thomas, Kroj; Wilco, Ligterink; Annette, Romanski; Thorsten, Nurnberger; Institute of Plant Biochemistry, Department of Stress and Developmental Biology; Institute of Plant Biochemistry, Department of Stress and Developmental Biology:(Present address)LION Bioscience AG; Institute of Plant Biochemistry, Department of Stress and Developmental Biology; Institute of Microbiology and Genetics, Vienna Biocenter; Institute of Plant Biochemistry, Department of Stress and Developmental Biology:(Present address)Centre National de la Recherche Scientifique, Institut des Sciences Vegetales; Institute of Microbiology and Genetics, Vienna Biocenter; Institute of Plant Biochemistry, Department of Stress and Developmental Biology
Cultured parsley(Petroselinum crispum)cells respond to treatment with elicitors derived from different species of the genus Phytophthora with transcript accumulation of defense-associated genes and the production of furanocoumarin phytoalexins. Pep-25, an oligopeptide fragment of a Phytophthora sojae 42-kDa cell wall protein, and a cell wall elicitor preparation derived from Phytophthora parasitica(Pp-elicitor)stimulate accumulation of the same gene transcripts and formation of the same patte...
Juanita Engelbrecht; Noalani van den Berg
Avocado (Persea americana) – a major fruit crop worldwide – is threatened by root rot caused by Phytophthora cinnamomi. This pathogen is known to infect the plant via the feeder roots leading to branch dieback, and eventually tree mortality. While it is known that different avocado rootstocks have varying degrees of susceptibility to Phytophthora root rot, little research has been done on the avocado–Phytophthora interaction. In this study, transcript abundance levels of defence-related genes...
Mideros, M.F.; Turissini, D.A.; Guayazán, N.; Ibarra-Avila, H.; Danies, G.; Cárdenas, M.; Myers, K.; Tabima, J.; Goss, E.M.; Bernal, A.; Lagos, L.E.; Grajales, A.; Gonzalez, L.N.; Cooke, D.E.L.; Fry, W.E.; Grünwald, N.; Matute, D.R.; Restrepo, S.
Over the past few years, symptoms akin to late blight disease have been reported on a variety of crop plants in South America. Despite the economic importance of these crops, the causal agents of the diseases belonging to the genus Phytophthora have not been completely characterized. In this study,
Francisco J. Avila; Barbara Schoedel; Z. Gloria Abad; Michael D. Coffey; Cheryl Blomquist
The goal of this work was to develop improved tools for the detection of Phytophthora ramorum and P. kernoviae for field and the laboratory use. ImmunoStripÂ® and ELISA were selected as the test formats for development. Presently, the diagnosis of sudden oak death (SOD) in the national survey of P. ramorum ...
Martin, Michael David; Garrett Vieira, Filipe Jorge; Ho, Simon Y. W.
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...
Kong, Ping; Lea-Cox, John D; Moorman, Gary W; Hong, Chuanxue
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.
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Valois, D; Fayad, K; Barasubiye, T; Garon, M; Dery, C; Brzezinski, R; Beaulieu, C
A collection of about 200 actinomycete strains was screened for the ability to grow on fragmented Phytophthora mycelium and to produce metabolites that inhibit Phytophthora growth. Thirteen strains were selected, and all produced (beta)-1,3-, (beta)-1,4-, and (beta)-1,6-glucanases. These enzymes could hydrolyze glucans from Phytophthora cell walls and cause lysis of Phytophthora cells. These enzymes also degraded other glucan substrates, such as cellulose, laminarin, pustulan, and yeast cell walls. Eleven strains significantly reduced the root rot index when inoculated on raspberry plantlets.
James S Haudenshield
Full Text Available Phytophthora root rot of soybean [Glycine max (L. Merr.] is caused by the oomycete Phytophthora sojae (Kaufm. & Gerd.. P. sojae has a narrow host range, consisting primarily of soybean, and it is a serious pathogen worldwide. It exists in root and stem tissues as mycelium, wherein it can form oospores which subsequently germinate to release motile, infectious zoospores. Molecular assays detecting DNA of P. sojae are useful in disease diagnostics, and for determining the presence of the organism in host tissues, soils, and runoff or ponded water from potentially infested fields. Such assays as published have utilized ITS sequences from the nuclear ribosomal RNA genes in conventional PCR or dye-binding quantitative PCR (Q-PCR but are not amenable to multiplexing, and some of these assays did not utilize control strategies for type I or type II errors. In this study, we describe primers and a bifunctional probe with specificity to a gypsy-like retroelement in the P. sojae genome to create a fluorogenic 5'-exonuclease linear hydrolysis assay, with a multiplexed internal control reaction detecting an exogenous target to validate negative calls, and with uracil-deglycosylase-mediated protection against carryover contamination. The assay specifically detected 13 different P. sojae isolates, and excluded 17 other Phytophthora species along with 20 non-Phytophthora fungal and oomycete species pathogenic on soybean. A diagnostic limit of detection of 34 fg total P. sojae DNA was observed in serial dilutions, equivalent to 0.3 genome, and a practical detection sensitivity of four zoospores per sample was achieved, despite losses during DNA extraction.
Haudenshield, James S; Song, Jeong Y; Hartman, Glen L
Phytophthora root rot of soybean [Glycine max (L.) Merr.] is caused by the oomycete Phytophthora sojae (Kaufm. & Gerd.). P. sojae has a narrow host range, consisting primarily of soybean, and it is a serious pathogen worldwide. It exists in root and stem tissues as mycelium, wherein it can form oospores which subsequently germinate to release motile, infectious zoospores. Molecular assays detecting DNA of P. sojae are useful in disease diagnostics, and for determining the presence of the organism in host tissues, soils, and runoff or ponded water from potentially infested fields. Such assays as published have utilized ITS sequences from the nuclear ribosomal RNA genes in conventional PCR or dye-binding quantitative PCR (Q-PCR) but are not amenable to multiplexing, and some of these assays did not utilize control strategies for type I or type II errors. In this study, we describe primers and a bifunctional probe with specificity to a gypsy-like retroelement in the P. sojae genome to create a fluorogenic 5'-exonuclease linear hydrolysis assay, with a multiplexed internal control reaction detecting an exogenous target to validate negative calls, and with uracil-deglycosylase-mediated protection against carryover contamination. The assay specifically detected 13 different P. sojae isolates, and excluded 17 other Phytophthora species along with 20 non-Phytophthora fungal and oomycete species pathogenic on soybean. A diagnostic limit of detection of 34 fg total P. sojae DNA was observed in serial dilutions, equivalent to 0.3 genome, and a practical detection sensitivity of four zoospores per sample was achieved, despite losses during DNA extraction.
Halken, S; Høst, A
, breastfeeding should be encouraged for 4-6 months. In high-risk infants a documented extensively hydrolysed formula is recommended if exclusive breastfeeding is not possible for the first 4 months of life. There is no evidence for preventive dietary intervention neither during pregnancy nor lactation...... populations. These theories remain to be documented in proper, controlled and prospective studies. Breastfeeding and the late introduction of solid foods (>4 months) is associated with a reduced risk of food allergy, atopic dermatitis, and recurrent wheezing and asthma in early childhood. In all infants....... Preventive dietary restrictions after the age of 4-6 months are not scientifically documented....
Full Text Available Phytophthora is a genus of Oomycota responsible for some of the most serious diseases with great economic impact (Judelson and Blanco, 2005. While 54 species were found in the 20th century (Erwin and Ribeiro, 1996 another 51-54 new species have been identified(Brasier, 2008 since the year 2000. They are spread worldwide and have broad range of host plants – fruit trees, citrus, forest and park species. Phytophthora can cause serious damages in orchards and nurseries of apples, cherries, etc. In Bulgaria they have been found first on young apples and cherries (1998-1999 in Plovdiv region (Nakova, 2003. Surveys have been done for discovering disease symptoms in Plovdiv and Kjustendil regions. Isolates have been obtained from infected plant material (roots and stem bases applying baiting bioassay (green apples, variety Granny Smith and/or PARP 10 selective media. Phytophthora strains were identified based on standard morphology methods – types of colonies on PDA, CMA, V 8, type and size of sporangia, oogonia and antheridia, andoospores. Cardial temperatures for their growth were tested on CMA and PDA.For molecular studies, DNA was extracted from mycelium using the DNA extraction kit.DNA was amplified using universal primers ITS 6 and ITS 4. Amplification products concentrations were estimated by comparison with the standard DNA. Sequencing was done at the Scottish Crop Research Institute (SCRI, Dundee, Scotland. Phytophthora root and crown rot symptoms first appear in early spring. Infected trees show bud break delay, have small chlorotic leaves, and branches die all of a sudden. Later symptoms are found in August-September. Leaves of the infected trees show reddish discoloration and drop down. Both symptoms are connected with lesions (wet, necrotic in appearance at stem bases of the trees.Disease spread was 2-3% in most gardens, only in an apple orchard in Bjaga (Plovdiv region it was up to 8-10%. Morphologically, the isolates acquired from
Jankowiak, R; Stępniewska, H; Bilański, P; Kolařík, M
Phytophthora plurivora and other Phytophthora species are known to be serious pathogens of forest trees. Little is known, however, about the presence of P. plurivora in Polish oak forests and their role in oak decline. The aims of this study were to identify P. plurivora in healthy and declining Quercus robur stands in southern Poland and to demonstrate the relationship between different site factors and the occurrence of P. plurivora. In addition, the virulence of P. plurivora and other Phytophthora species was evaluated through inoculations using 2-year-old oak seedlings. Rhizosphere soil was investigated from 39 oak stands representing different healthy tree statuses. The morphology and DNA sequences of the internal transcribed spacer regions (ITS) of the ribosomal DNA and the mitochondrial cox1 gene were used for identifications. P. plurivora, an oak fine root pathogen, was isolated from rhizosphere soil samples in 6 out of 39 stands. Additionally, Phytophthora cambivora, Phytophthora polonica and Phytophthora rosacearum-like were also obtained from several stands. The results showed a significant association between the presence of P. plurivora and the health status of oak trees. Similar relationships were also observed for all identified Phytophthora species. In addition, there was evidence for a connection between the presence of all identified Phytophthora species and some site conditions. Phytophthora spp. occurred more frequently in declining stands and in silt loam and sandy loam soils with pH ≥ 3.66. P. plurivora and P. cambivora were the only species capable of killing whole plants, producing extensive necrosis on seedling stems.
Lamour, Kurt H; Stam, Remco; Jupe, Julietta; Huitema, Edgar
Phytophthora capsici is a highly dynamic and destructive pathogen of vegetables. It attacks all cucurbits, pepper, tomato and eggplant, and, more recently, snap and lima beans. The disease incidence and severity have increased significantly in recent decades and the molecular resources to study this pathogen are growing and now include a reference genome. At the population level, the epidemiology varies according to the geographical location, with populations in South America dominated by clonal reproduction, and populations in the USA and South Africa composed of many unique genotypes in which sexual reproduction is common. Just as the impact of crop loss as a result of P. capsici has increased in recent decades, there has been a similar increase in the development of new tools and resources to study this devastating pathogen. Phytophthora capsici presents an attractive model for understanding broad-host-range oomycetes, the impact of sexual recombination in field populations and the basic mechanisms of Phytophthora virulence. Kingdom Chromista; Phylum Oomycota; Class Oomycetes; Order Peronosporales; Family Peronosporaceae; Genus Phytophthora; Species capsici. Symptoms vary considerably according to the host, plant part infected and environmental conditions. For example, in dry areas (e.g. southwestern USA and southern France), infection on tomato and bell or chilli pepper is generally on the roots and crown, and the infected plants have a distinctive black/brown lesion visible at the soil line (Fig. 1). In areas in which rainfall is more common (e.g. eastern USA), all parts of the plant are infected, including the roots, crown, foliage and fruit (Fig. 1). Root infections cause damping off in seedlings, whereas, in older plants, it is common to see stunted growth, wilting and, eventually, death. For tomatoes, it is common to see significant adventitious root growth just above an infected tap root, and the stunted plants, although severely compromised, may not die
Vetukuri, Ramesh Raju; Kushwaha, Sandeep; Sen, Diya; Whisson, Stephen C; Lamour, Kurt; Grenville-Briggs, Laura
Phytophthora colocasiae is a phytopathogenic oomycete that causes leaf blight and corm rot on taro (Colocasia esculenta), an important staple crop in the tropics. The impact of P. colocasiae is a serious concern for food security in Asian and Oceanic regions. Vietnamese strain 7290 of P. colocasiae was sequenced (Illumina) to assemble a draft genome of 56.6 Mb, comprised of 19853 scaffolds and 19984 predicted protein-coding genes. As in other Phytophthora species, P. colocasiae possesses numerous pathogenicity-related genes, such as the RxLR class of effectors. This draft genome sequence of P. colocasiae provides a resource for underpinning the first steps into determining the molecular mechanisms of disease development in this pathosystem.
The following chapter describes a PCR method for the identification of the raspberry root rot pathogen Phytophthora fragariae var. rubi. Furthermore, a nested PCR suitable for the detection of the pathogen in infected raspberry roots and validated against the "Duncan bait test" (EPPO Bull 35:87-91, 2005) is explained. Protocols for different DNA extraction methods are given which can be transferred to other fungal pathogens.
Koprivica Mirjana; Dulić-Marković Ivana; Jevtić Radivoje; Cooke Dave E.L.
Phytophthora fragariae var. rubi (Wilcox and Duncan), a causal agent of raspberry root rot, is a serious soil-borne pathogen listed by EPPO as an A2 quarantine pest. Root samples were collected from badly diseased raspberry plants showing a variety of characteristic and often dramatic symptoms during surveys carried out in western Serbia in 2002. Identification of the causal agent was performed in collaboration work with the Scottish Crop Research Institute (S.C.R.I.), Dundee, UK. Necrotic ...
Fluorescent Pseudomonas bacteria produce a wide variety of antimicrobial metabolites, including soap-like compounds referred to as biosurfactants. The results of this thesis showed that biosurfactant-producing Pseudomonas bacteria are effective in controlling Phytophthora foot rot disease of black pepper in Vietnam and promote root and shoot development of the ‘King of Spices’. Biosurfactant-producing P. fluorescens strain SS101 was also effective in controlling tomato late blight caused by P...
Steven N. Jeffers; Inga M. Meadows; Joseph B. James; Paul H. Sisco
American chestnut (Castanea dentata (Marsh.) Borkh.) once was a primary hardwood species in forests of the eastern United States. Sometime during the late 18th century, it is speculated that Phytophthora cinnamomi, which causes Phytophthora root rot (PRR) on many woody plant species, was introduced to the southeast region of...
E. J. Fichtner; D. M. Rizzo; S. A. Kirk; J. F. Webber
Phytophthora kernoviae exhibits comparable epidemiology to Phytophthora ramorum in invaded UK woodlands. Because both pathogens have an overlapping geographic range in the UK and often concurrently invade the same site, it is speculated that P. kernoviae may also invade North American (NA) forests...
G. Curtis Colburn; Steven N. Jeffers
Many commercial algaecides contain copper compounds as active ingredients. Phytophthora spp. and other oomycetes are known to be sensitive to copper-based fungicides. Therefore, algaecides registered to manage algae in natural waterways and irrigation waters also might be effective for mitigating or even eradicating Phytophthora ...
Phytophthora encodes an unusually large number of glycosyl hydrolases (GH), with many large gene families resulting from duplication events. There are ten copies of GH 12 (cel12) present in Phytophthora sojae. This is the only pathogen endoglucanase family to which plants produce an inhibitory pr...
Phytophthora root and stem rot caused by Phytophthora sojae Kaufmann and Gerdmann is one of the most severe soybean [Glycine max (L.) Merr] diseases in the US. Partial resistance is as effective in managing this disease as single-gene (Rps) mediated resistance and is more durable. The objective of t...
Phytophthora infestans – the causal agent of potato late blight – secretes a plethora of effector proteins to facilitate plant infection. The central subject of this thesis is ipiO, one of the first cloned Phytophthora genes with a putative function in pathogenicity as was anticipated based on its
Jaesoon Hwang; Steven N. Jeffers; Steven W. Oak
Monitoring occurrence and distribution of Phytophthora species, including Phytophthora ramorum, in forest ecosystems can be achieved in several ways including sampling symptomatic plants, infested soils, and infested streams. Collecting plant and soil samples can be laborious and time consuming due to the distance surveyors...
Angela Dale; Nicolas Feau; Julien Ponchart; Guillaume Bilodeau; Jean Berube; R.C. Hamelin
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...
Tabima, Javier F; Kronmiller, Brent A; Press, Caroline M; Tyler, Brett M; Zasada, Inga A; Grünwald, Niklaus J
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.
Gaszczyk, K.; Mendes, O.; Verstappen, E.C.P.; Bonants, P.J.M.; Schoen, C.D.
Plant Research International heeft een diagnostische methode ontwikkeld die toe te passen is 'in planta', en ook de meest recent beschreven (quarantaine-) soorten omvat. De methode omvat de ontwikkeling van een generieke Phytophthora-methode gevolgd door een Phytophthora-identificatie.
In most parts of the world where Theobroma cacao is grown, Phytophthora palmivora is the major concern for causing black pod rot (BPR). Phytophthora megakarya, on the other hand, occurs only in Africa, but represents a major threat to cacao production, the countries of West Africa being the largest ...
Corina Junker; Sabine Werres
Bait tests are very helpful for diagnosis of Phytophthora in for example soil, substrate, water, sediment, and rootball samples (Werres and others 2014). By attracting the motile zoospores of the Phytophthora species with the baits these pathogens can be separated from other organisms. Bait tests are simple and cost...
Southeastern states produce about 50% of the watermelons in the United States (U.S.) where conditions are optimal for development of Phytophthora fruit rot prevail. Phytophthora fruit rot significantly limits watermelon production by causing serious yield losses to growers before and after harvest. ...
M.F. Cohen; E. Yamamoto; E. Condeso; B.L. Anacker; N. Rank; M. Mazzola
Plant pathogens of the oomycete lineage share common susceptibilities to many biotic and abiotic stresses. We are investigating the potential of antagonistic bacteria, isothiocyanates, and mycophagous amoebae to control diseases caused by Phytophthora spp., including the etiologic agent of sudden oak death, Phytophthora ramorum (...
S. Denman; E. Moralejo; S.A. Kirk; E. Orton; A. Whybrow
Phytophthora ramorum and P. kernoviae are newly discovered invasive Phytophthoras causing leaf necrosis, shoot tip dieback (mostly on ornamental and forest understorey host species) and bleeding cankers on tree trunks of a wide range of plant species. Both pathogens are now present in south-west England....
Rhododendron root rot, caused by several Phytophthora species, can cause devastating losses in nursery-grown plants. Most research on chemical control of root rot has focused on Phytophthora cinnamomi. However, it is unknown whether treatments recommended for P. cinnamomi are also effective for othe...
Khan, Salah Uddin; Gurley, Emily S.; Hossain, M. Jahangir; Nahar, Nazmun; Sharker, M. A. Yushuf; Luby, Stephen P.
Background Drinking raw date palm sap is a risk factor for human Nipah virus (NiV) infection. Fruit bats, the natural reservoir of NiV, commonly contaminate raw sap with saliva by licking date palm’s sap producing surface. We evaluated four types of physical barriers that may prevent bats from contacting sap. Methods During 2009, we used a crossover design and randomly selected 20 date palm sap producing trees and observed each tree for 2 nights: one night with a bamboo skirt intervention applied and one night without the intervention. During 2010, we selected 120 trees and randomly assigned four types of interventions to 15 trees each: bamboo, dhoincha (local plant), jute stick and polythene skirts covering the shaved part, sap stream, tap and collection pot. We enrolled the remaining 60 trees as controls. We used motion sensor activated infrared cameras to examine bat contact with sap. Results During 2009 bats contacted date palm sap in 85% of observation nights when no intervention was used compared with 35% of nights when the intervention was used [psap when the skirt did not entirely cover the sap producing surface. Therefore, in 2010 we requested the sap harvesters to use larger skirts. During 2010 bats contacted date palm sap [2% vs. 83%, psap in trees with bamboo (psap during one night (7%) with the jute stick skirt (psap producing areas of a tree effectively prevented bat-sap contact. Community interventions should promote applying these skirts to prevent occasional Nipah spillovers to human. PMID:22905160
Brasier, C M; Cooke, D E; Duncan, J M
Plant disease epidemics resulting from introductions of exotic fungal plant pathogens are a well known phenomenon. An associated risk-that accelerated pathogen evolution may be occurring as a consequence of genetic exchange between introduced, or introduced and resident, fungal pathogens-is largely unrecognized. This is, in part, because examples of natural, interspecific hybridization in fungi are very rare. Potential evolutionary developments range from the acquisition of new host specificities to emergence of entirely new pathogen taxa. We present evidence from cytological behavior, additive nucleotide bases in repetitive internal transcribed spacer regions of the rRNA-encoding DNA (rDNA), and amplified fragment length polymorphisms of total DNA that a new, aggressive Phytophthora pathogen of alder trees in Europe comprises a range of heteroploid-interspecific hybrids involving a Phytophthora cambivora-like species and an unknown taxon similar to Phytophthora fragariae. The hybrids' marked developmental instabilities, unusual morphological variability, and evidence for recombination in their internal transcribed spacer profiles indicates that they are of recent origin and that their evolution is continuing. The likelihood of such evolutionary events may be increasing as world trade in plants intensifies. However, routine diagnostic procedures currently in use are insufficiently sensitive to allow their detection.
Full Text Available Global climate change is associated with higher concentrations of atmospheric carbon dioxide (CO2. The ongoing changes are likely to have significant, direct or indirect effects on plant diseases caused by many biotic agents such as phytopathogenic fungi. This study results showed that increased CO2 concentration did not stimulate the growth of 1-year-old beech Fagus sylvatica L seedlings but it activated pathogenic Phytophthora species (P. plurivora and P. cactorum which caused significant reduction in the total number of fine roots as well as their length and area. The results of the greenhouse experiment indicated that pathogens once introduced into soil survived in pot soil, became periodically active (in sufficient water conditions and were able to damage beech fine roots. However, the trees mortality was not observed during the first year of experiment. DNA analyses performed on soil and beech tissue proved persistence of introduced Phytophthora isolates.
Fell, J.W.; Master, I.M.
Fungi of the genus Phytophthora were found to be associated with the initial stages of leaf litter decay of Rhizophora mangle L. and other Rhizophora species in estuarine and coastal marine waters. Phytophthora appears to be an important component of red-mangrove litter degradation systems throughout the tropics, which includes the Atlantic, Pacific, and Indian Oceans. The distributions of Phytophthora vesicula Anastasiou et Churchland and four new species of Phytophthora are discussed, as well as their occurrence in other tropical marine allochthonous spermatophytic leaf litter. The descriptions of the new species and varieties, Phytophthora bahamensis, P. epistomium, P. mycoparasitica, P. spinosa var. spinosa, and P. spinosa var. lobata, are presented. Pythium was rarely observed in the mangrove litter system, although one species, Pythium grandisporangium sp. nov., is described. (auth)
van Hooff, Jolien J E; Snel, Berend; Seidl, Michael F
Genomes of the plant-pathogenic genus Phytophthora are characterized by small duplicated blocks consisting of two consecutive genes (2HOM blocks) and by an elevated abundance of similarly aged gene duplicates. Both properties, in particular the presence of 2HOM blocks, have been attributed to a whole-genome duplication (WGD) at the last common ancestor of Phytophthora. However, large intraspecies synteny-compelling evidence for a WGD-has not been detected. Here, we revisited the WGD hypothesis by deducing the age of 2HOM blocks. Two independent timing methods reveal that the majority of 2HOM blocks arose after divergence of the Phytophthora lineages. In addition, a large proportion of the 2HOM block copies colocalize on the same scaffold. Therefore, the presence of 2HOM blocks does not support a WGD at the last common ancestor of Phytophthora. Thus, genome evolution of Phytophthora is likely driven by alternative mechanisms, such as bursts of transposon activity.
Moreau, R A; Young, D H; Danis, P O; Powell, M J; Quinn, C J; Beshah, K; Slawecki, R A; Dilliplane, R L
Cellular lipids were extracted from three species of Oomycete plant pathogens (Pythium ultimum, Phytophthora infestans, and Ph. capsici) and analyzed via normal-phase high-performance liquid chromatography with flame-ionization detection. The most abundant polar lipids in each of the three species were the polar membrane lipids, phosphatidylethanolamine (PE), phosphatidylcholine, and a phosphosphingolipid that eluted soon after PE. Structural analysis via mass spectrometry and nuclear magnetic resonance spectrometry revealed that the phosphosphingolipid was ceramide phosphorylethanolamine (Cer-PE). The most abundant molecular species of Cer-PE in P. ultimum had a molecular weight of 670.5, contained an unusual 19-carbon branched triunsaturated sphingoid (C19-delta 4, 8, 10, 9-methyl long-chain base) and palmitic acid as the amide-linked fatty acid. The most abundant molecular species of Cer-PE in Ph. infestans had a molecular weight of 714.5, contained a common 16-carbon 1,3 di-OH sphingoid, and erucic (cis 13-docosenoic, C22-delta 13) acid as the amide-linked fatty acid. The Cer-PE in Ph. capsici comprised a mixture of each of the two molecular species found in P. ultimum and Ph. infestans.
Reeksting, B. J.; Olivier, N. A.; van den Berg, N.
Background Avocado (Persea americana Mill.) is a commercially important fruit crop worldwide. A major limitation to production is the oomycete Phytophthora cinnamomi, which causes root rot leading to branch-dieback and tree death. The decline of orchards infected with P. cinnamomi occurs much faster when exposed to flooding, even if flooding is only transient. Flooding is a multifactorial stress compromised of several individual stresses, making breeding and selection for tolerant varieties c...
Scanu, Bruno; Linaldeddu, Benedetto T.; Deidda, Antonio; Jung, Thomas
The Mediterranean basin is recognized as a global biodiversity hotspot accounting for more than 25,000 plant species that represent almost 10% of the world’s vascular flora. In particular, the maquis vegetation on Mediterranean islands and archipelagos constitutes an important resource of the Mediterranean plant diversity due to its high rate of endemism. Since 2009, a severe and widespread dieback and mortality of Quercus ilex trees and several other plant species of the Mediterranean maquis has been observed in the National Park of La Maddalena archipelago (northeast Sardinia, Italy). Infected plants showed severe decline symptoms and a significant reduction of natural regeneration. First studies revealed the involvement of the highly invasive wide-host range pathogen Phytophthora cinnamomi and several fungal pathogens. Subsequent detailed research led to a better understanding of these epidemics showing that multiple Phytophthora spp. were involved, some of them unknown to science. In total, nine Phytophthora species were isolated from rhizosphere soil samples collected from around symptomatic trees and shrubs including Asparagus albus, Cistus sp., Juniperus phoenicea, J. oxycedrus, Pistacia lentiscus and Rhamnus alaternus. Based on morphological characters, growth-temperature relations and sequence analysis of the ITS and cox1 gene regions, the isolates were identified as Phytophthora asparagi, P. bilorbang, P. cinnamomi, P. cryptogea, P. gonapodyides, P. melonis, P. syringae and two new Clade 6 taxa which are here described as P. crassamura sp. nov. and P. ornamentata sp. nov. Pathogenicity tests supported their possible involvement in the severe decline that is currently threatening the Mediterranean maquis vegetation in the La Maddalena archipelago. PMID:26649428
Leónides Castellanos González
Full Text Available The objective of this research was to conduct a spatial analysis of the incidence of Phytophthora nicotianae Breda de Haan and Phytophthora infestans (Mont. De Bary, during five seasons of potato in Fields Company Miscellaneous Crops in Horquita, Cienfuegos (2003-2004 to 2007-2008. Information about pathogens, collected by the Plant Protection Station of Yaguaramas, was used in order to do so. An alpha numerical database was made, oriented to a group of areas under center pivot irrigation machines (Kubans and Bayamón and its quadrants. Parallel to this, mapping of center pivot machines and quadrants was generated in MapInfo GIS 8.5. Several automatic geo codifications were made in order to relate the alphanumeric database and the mapping, and thematic maps were generated in the presence or absence of pathogens. The two study agents have presented high spatial variability during the five planting seasons. Both have influenced the same geographical area with similar appearance date. P. infestans has not expressed a defined dispersion pattern and it has spread at random from the primary source of incidence, while Phytophthora nicotianae has become an endemic agent which shows a dispersion pattern towards neighboring areas or areas connected by the road network from the primary sources, which have been associated with poor land leveling and late or intermediate planting seasons.
This review summarizes pertinent data and opinions regarding the potential hazard of disease transmission through cryopreserved and banked embryos in liquid nitrogen (LN). Special attention is given to the survival of pathogens in LN, new vitrification methods, sterility of LN, risks associated with the use of straws and cryovials, and LN dewars including dry shippers. It was experimentally demonstrated that cross-contamination between LN and embryos may occur, when infectious agents are present in LN and embryos are not protected by a sealed container. It is important, therefore, to prevent direct contact of embryos with LN during cryopreservation and their banking. This includes the usage of hermetically sealed, high-quality, shatter-proof freezing containers and/or the application of a secondary enclosure such as "double bagging or straw in straw." A periodic disinfection of cryo-dewars should be considered as an additional precaution to diminish the potential for inadvertent cross-contamination. It might be advisable to use separate LN dewars to quarantine embryos derived from infected donors of valuable genotype or from unknown health status, extinction-threatened species. Nevertheless, in summary, it has been concluded that over 25 yr with no direct evidence of disease transmission by transferred cryopreserved human and animal embryos, that the present cryopreservation technology is sanitary sound, with the stipulation that biocontainment measures recommended by the International Embryo Transfer Society (IETS) and the World Organization for Animal Health - Office International des Epizooties (OIE), are strictly followed. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.
Stamler, Rio A; Sanogo, Soumalia; Goldberg, Natalie P; Randall, Jennifer J
Phytophthora species were isolated from rivers and streams in the southwestern United States by leaf baiting and identified by sequence analysis of internal transcribed spacer (ITS) ribosomal DNA (rDNA). The major waterways examined included the Rio Grande River, Gila River, Colorado River, and San Juan River. The most prevalent species identified in rivers and streams were Phytophthora lacustris and P. riparia, both members of Phytophthora ITS clade 6. P. gonapodyides, P. cinnamomi, and an uncharacterized Phytophthora species in clade 9 were also recovered. In addition, six isolates recovered from the Rio Grande River were shown to be hybrids of P. lacustris × P. riparia Pathogenicity assays using P. riparia and P. lacustris failed to produce any disease symptoms on commonly grown crops in the southwestern United States. Inoculation of Capsicum annuum with P. riparia was shown to inhibit disease symptom development when subsequently challenged with P. capsici, a pathogenic Phytophthora species. Many Phytophthora species are significant plant pathogens causing disease on a large variety of crops worldwide. Closer examinations of streams, rivers, and forest soils have also identified numerous Phytophthora species that do not appear to be phytopathogens and likely act as early saprophytes in aquatic and saturated environments. To date, the Phytophthora species composition in rivers and streams of the southwestern United States has not been evaluated. This article details a study to determine the identity and prevalence of Phytophthora species in rivers and streams located in New Mexico, Arizona, Colorado, Utah, and Texas. Isolated species were evaluated for pathogenicity on crop plants and for their potential to act as biological control agents. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
Full Text Available Phytophthora fragariae var. rubi (Wilcox & Duncan, a causal agent of raspberry root rot, is a serious soil-borne pathogen listed by EPPO as an A2 quarantine pest. Root samples were collected from badly diseased raspberry plants showing a variety of characteristic and often dramatic symptoms during surveys carried out in western Serbia in 2002. Identification of the causal agent was performed in collaboration work with the Scottish Crop Research Institute (S.C.R.I., Dundee, UK. Necrotic roots were plated on selective French bean agar (incorporating ampicilin, ryfamicin, bavistin and hymexasol. Detection of isolates was based on cultural and morphological features compared with referent cultures. DNA was extracted directly from the sampled roots using extraction buffer (200 mM Tris- HCl pH 8.5, 250 mM NaCl, 25 mM EDTA, 0.5% SDS, purified by multi spin separation columns [Thistle Scientific (Axygen] or in 24:1 mixture of chlorophorm- iso-amyl alcohol and amplified by nested PCR (ITS4 and DC6 for first round, DC1and DC5 for second round. Diluted DNA extracts were also amplified by conventional PCR with modified ”universal” Phytophthora primers (ITS 6, ITS 7 and ITS 8, Cooke et al., 2000 and digested with Msp1. Digestion patterns of the universal primers PCR product from infected roots matched those of Scottish strains. P. fragariae var. rubi occured on 8 out of 14 sites. Our results indicate that nested PCR (ITS4 and DC6 for first round, DC1 and DC5 for second round or digestion of the ”universal” Phytophthora primers PCR product for detection of P. fragariae var. rubi are more sensitive and less time-consuming and therefore recommended for use.
Bertier, Lien; Leus, Leen; D’hondt, Liesbet; de Cock, Arthur W. A. M.; Höfte, Monica
It is becoming increasingly evident that interspecific hybridization is a common event in phytophthora evolution. Yet, the fundamental processes underlying interspecific hybridization and the consequences for its ecological fitness and distribution are not well understood. We studied hybridization events in phytophthora clade 8b. This is a cold-tolerant group of plant pathogenic oomycetes in which six host-specific species have been described that mostly attack winter-grown vegetables. Hybrid characterization was done by sequencing and cloning of two nuclear (ITS and Ypt1) and two mitochondrial loci (Cox1 and Nadh1) combined with DNA content estimation using flow cytometry. Three different mtDNA haplotypes were recovered among the presumed hybrid isolates, dividing the hybrids into three types, with different parental species involved. In the nuclear genes, additivity, i.e. the presence of two alleles coming from different parents, was detected. Hybrid isolates showed large variations in DNA content, which was positively correlated with the additivity in nuclear loci, indicating allopolyploid hybridization followed by a process of diploidization. Moreover, indications of homeologous recombination were found in the hybrids by cloning ITS products. The hybrid isolates have been isolated from a range of hosts that have not been reported previously for clade 8b species, indicating that they have novel pathogenic potential. Next to this, DNA content measurements of the non-hybrid clade 8b species suggest that polyploidy is a common feature of this clade. We hypothesize that interspecific hybridization and polyploidy are two linked phenomena in phytophthora, and that these processes might play an important and ongoing role in the evolution of this genus. PMID:24386473
Mazzolini, A.P.; Sealock, R.M.; Legge, G.J.F.; Grant, B.R.
We have measured the elemental variations between zoospores and germinating cystospores of the fungus Phytophthora palmivora, using a scanning proton microprobe. Averaged over a number of individual cells, our results indicate that the level of Ca is much lower in germinating cystospores than in zoospores. The levels of S, Cl, and Zn also appear to be lower, and the level of K appears to be higher. The spatial distribution of elements within the germinating cystospore is very similar for P, S, Cl, K, Mn, Fe, and Cu, but significantly different for Ca and Zn. (orig.)
Mazzolini, A. P.; Grant, B. R.; Sealock, R. M.; Legge, G. J. F.
We have measured the elemental variations between zoospores and germinating cystospores of the fungus Phytophthora palmivora, using a scanning proton microprobe. Averaged over a number of individual cells, our results indicate that the level of Ca is much lower in germinating cystospores than in zoospores. The levels of S, Cl, and Zn also appear to be lower, and the level of K appears to be higher. The spatial distribution of elements within the germinating cystospore is very similar for P, S, Cl, K, Mn, Fe, and Cu, but significantly different for Ca and Zn.
US Agency for International Development — The data are the phenotypic host reactions of a recombinant inbred line population of Capsicum annuum developed to differentiate races of Phytophthora capsici. The...
Wang, Y.; Bouwmeester, K.; Mortel, van de J.E.; Shan, W.; Govers, F.
Recognition of pathogens by plants initiates defense responses including activation of defense-related genes and production of antimicrobial compounds. Recently, we reported that Phytophthora capsici can successfully infect Arabidopsis and revealed interaction specificity among various
Diana Elizabeth Toapanta-Gallegos
Full Text Available One of the most damaging diseases in cultivation of avocado (Persea americana Mill. is root rot associated with Phytophthora cinnamomi Rands. This disease causes progressive wilt and even death of the tree. The objective of this study was to identify the presence of P. cinnamomi in two productive areas of avocado in Ecuador using the molecular technique PCR-RFLP. Tree root samples were obtained with root rot symptoms in the production areas, from which 10 isolates were morphologically identified with Phytophthora spp. infection. To distinguish among the various Phytophthora species, a molecular analysis was performed using molecular markers in the ITSregion of the ribosomal DNA (rDNA. The ITSdigestion fragment obtained by PCR with the Ta qI enzyme confirmed the presence of Phytophthora cinnamomi in the isolated samples, and its association with root rot in the sampled production areas.
Tumwine, J.; Frinking, H.D.; Jeger, M.J.
Cultural control measures against tomato late blight (Phytophthora infestans) were evaluated in six field experiments over 3 years in Uganda. Each experiment included sanitation (removal of diseased plant tissues), fungicide (mancozeb) application, and an untreated control, as standard treatments.
Neefjes, H.; Noort, van F.R.
Toevoegen van plantversterker kaliumfosfiet maakt kalanchoë weerbaar tegen phytophthora. Onderzoek bij WUR Glastuinbouw heeft dit aangetoond in een deel van een proef. De praktijk is voorzichtig met het middel
Dijksterhuis, J; Deacon, J W
The behaviour of encysting zoospores of Phytophthora palmivora during leaching conditions was studied. Zoospores encysted and germinated successfully on polycarbonate membranes after mechanical agitation. Transient (10 min) leaching treatments with nutrient-free buffer underneath the membranes
Yana Valachovic; Richard Cobb; David Rizzo; Brendan Twieg; Chris Lee; Radoslaw Glebocki
In California, wildland hosts that support sporulation of Phytophthora ramorum, such as California bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.) and tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), also develop prolific basal sprouts following...
Rachel E. Linzer; David M. Rizzo; Santa Olga Cacciola; Matteo Garbelotto
In California and Oregon, two recently described oomycete forest pathogens, Phytophthora nemorosa and P. pseudosyringae, overlap in their host and geographic ranges with the virulent P. ramorum, causal agent of "sudden oak death." Epidemiological observations, namely broader geographic...
Werres, S.; Marwitz, R.; Man in 't Veld, W.; Cock, de A.W.A.M.; Bonants, P.J.M.; Weerdt, de M.; Themann, K.; Ilieva, E.; Baayen, R.P.
Since 1993, a hitherto unidentified Phytophthora species has been found associated with twig blight disease in Rhododendron and, sporadically, Viburnum. The morphology and growth characteristics of fourteen isolates from Germany and the Netherlands were investigated, together with their breeding
Kong, Ping; McDowell, John M; Hong, Chuanxue
Zoospore exudates play important roles in promoting zoospore communication, homing and germination during plant infection by Phytophthora. However, it is not clear whether exudates affect plant immunity. Zoospore-free fluid (ZFF) and zoospores of P. nicotianae were investigated comparatively for effects on resistance of Arabidopsis thaliana Col-0 and mutants that affect signaling mediated by salicylic acid (SA) and jasmonic acid (JA): eds16 (enhanced disease susceptibility16), pad4 (phytoalexin deficient4), and npr1 (nonexpressor of pathogenesis-related genes1). Col-0 attracted more zoospores and had severe tissue damage when flooded with a zoospore suspension in ZFF. Mutants treated with ZFF alone developed disease symptoms similar to those inoculated with zoospores and requirements of EDS16 and PAD4 for plant responses to zoospores and the exudates was apparent. Zoospore and ZFFs also induced expression of the PR1 and PDF1.2 marker genes for defense regulated by SA and JA, respectively. However, ZFF affected more JA defense signaling, down regulating PR1 when SA signaling or synthesis is deficient, which may be responsible for Arabidopsis mutant plants more susceptible to infection by high concentration of P. nicotianae zoospores. These results suggest that zoospore exudates can function as virulence factors and inducers of plant immune responses during plant infection by Phytophthora.
Full Text Available Zoospore exudates play important roles in promoting zoospore communication, homing and germination during plant infection by Phytophthora. However, it is not clear whether exudates affect plant immunity. Zoospore-free fluid (ZFF and zoospores of P. nicotianae were investigated comparatively for effects on resistance of Arabidopsis thaliana Col-0 and mutants that affect signaling mediated by salicylic acid (SA and jasmonic acid (JA: eds16 (enhanced disease susceptibility16, pad4 (phytoalexin deficient4, and npr1 (nonexpressor of pathogenesis-related genes1. Col-0 attracted more zoospores and had severe tissue damage when flooded with a zoospore suspension in ZFF. Mutants treated with ZFF alone developed disease symptoms similar to those inoculated with zoospores and requirements of EDS16 and PAD4 for plant responses to zoospores and the exudates was apparent. Zoospore and ZFFs also induced expression of the PR1 and PDF1.2 marker genes for defense regulated by SA and JA, respectively. However, ZFF affected more JA defense signaling, down regulating PR1 when SA signaling or synthesis is deficient, which may be responsible for Arabidopsis mutant plants more susceptible to infection by high concentration of P. nicotianae zoospores. These results suggest that zoospore exudates can function as virulence factors and inducers of plant immune responses during plant infection by Phytophthora.
Anandhakumar, J.; Zeller, W.
After screening of several rhizosphere bacteria against the soilborne pathogens of red core and crown rot disease of strawberry Phytophthora fragariae var. fragariae and Phytophthora cactorum under in vitro conditions, three of the most active isolates which produced up to 63% of reduction in mycelium growth, such as Raoultella terrigena (G-584), Bacillus amyloliquefaciens (G-V1) and Pseudomonas fluorescens (2R1-7) were selected for further studies under in vivo conditions. In ...
Blaya, Josefa; Marhuenda, Frutos C.; Pascual, Jose A.; Ros, Margarita
Phytophthora root rot caused by Phytophthora nicotianae is an economically important disease in pepper crops. The use of suppressive composts is a low environmental impact method for its control. Although attempts have been made to reveal the relationship between microbiota and compost suppressiveness, little is known about the microorganisms associated with disease suppression. Here, an Ion Torrent platform was used to assess the microbial composition of composts made of different agro-indus...
It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination
Choudhury, Robin A.; Mehl, Heather K.; Blomquist, Cheryl L.; McRoberts, Neil; Rizzo, David M.
Phylogenetic relationships between thirteen species of downy mildew and 103 species of Phytophthora (plant-pathogenic oomycetes) were investigated with two nuclear and four mitochondrial loci, using several likelihood-based approaches. Three Phytophthora taxa and all downy mildew taxa were excluded from the previously recognized subgeneric clades of Phytophthora, though all were strongly supported within the paraphyletic genus. Downy mildews appear to be polyphyletic, with graminicolous downy mildews (GDM), brassicolous downy mildews (BDM) and downy mildews with colored conidia (DMCC) forming a clade with the previously unplaced Phytophthora taxon totara; downy mildews with pyriform haustoria (DMPH) were placed in their own clade with affinities to the obligate biotrophic P. cyperi. Results suggest the recognition of four additional clades within Phytophthora, but few relationships between clades could be resolved. Trees containing all twenty extant downy mildew genera were produced by adding partial coverage of seventeen additional downy mildew taxa; these trees supported the monophyly of the BDMs, DMCCs and DMPHs but suggested that the GDMs are paraphyletic in respect to the BDMs or polyphyletic. Incongruence between nuclear-only and mitochondrial-only trees suggests introgression may have occurred between several clades, particularly those containing biotrophs, questioning whether obligate biotrophic parasitism and other traits with polyphyletic distributions arose independently or were horizontally transferred. Phylogenetic approaches may be limited in their ability to resolve some of the complex relationships between the “subgeneric” clades of Phytophthora, which include twenty downy mildew genera and hundreds of species. PMID:29529094
Vannini, Andrea; Bruni, Natalia; Tomassini, Alessia; Franceschini, Selma; Vettraino, Anna Maria
Pyrosequencing analysis was performed on soils from Italian chestnut groves to evaluate the diversity of the resident Phytophthora community. Sequences analysed with a custom database discriminated 15 pathogenic Phytophthoras including species common to chestnut soils, while a total of nine species were detected with baiting. The two sites studied differed in Phytophthora diversity and the presence of specific taxa responded to specific ecological traits of the sites. Furthermore, some species not previously recorded were represented by a discrete number of reads; among these species, Phytophthora ramorum was detected at both sites. Pyrosequencing was demonstrated to be a very sensitive technique to describe the Phytophthora community in soil and was able to detect species not easy to be isolated from soil with standard baiting techniques. In particular, pyrosequencing is an highly efficient tool for investigating the colonization of new environments by alien species, and for ecological and adaptive studies coupled with biological detection methods. This study represents the first application of pyrosequencing for describing Phytophthoras in environmental soil samples. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
Full Text Available Potato (Solanum tuberosum L. has been remained an important agricultural crop in resolving global food issues through decades. The crop has experienced enormous growth in terms of production throughout the world in recent decades because of improvement in agricultural mechanization, fertilizers application and irrigation practices. Nevertheless, a significant proportion of this valuable crop is still vulnerable to losses due to prevalence of different viral, bacterial, fungal and nematodes infestations. Late blight, caused by Phytophthora infestans (Mont. de Bary, is one of the most threatening pathogenic diseases which not only results in direct crop losses but also cause farmers to embrace huge monetary expenses for disease control and preventive measures. The disease is well known for notorious ‘Irish Famine’ which resulted in drop of Irish population by more than 20% as result of hunger and potato starvation. Globally, annual losses of crop and money spend on fungicides for late blight control exceeds one trillion US dollars. This paper reviews the significance of late blight of potato and controlling strategies adopted for minimizing yield losses incurred by this disease by the use of synthetic fungicides. Advantages and disadvantages of fungicides application are discussed.
E.M. Goheen; S.J. Frankel
The fourth meeting of the International Union of Forest Research Organizations (IUFRO) Working Party S07.02.09, Phytophthoras in Forests and Natural Ecosystems provided a forum for current research on Phytophthora species worldwide. Seventy-eight submissions describing papers and posters on recent developments in Phytophthora diseases of trees and natural ecosystems in...
Effectiveness of silver dressing in preventing surgical site infections in contaminated wounds = Efectividad de los apósitos de plata en la prevención de la infección del sitio operatorio en heridas contaminadas
Cabrales, Rodolfo Adrián
Full Text Available Abstract Introduction: Silver gauzes are designed to treat infected wounds, but there is controversial evidence about their effectiveness in preventing surgical site infections in contaminated wounds. Objective: To evaluate the effect of silver gauzes in patients undergoing surgery with contaminated wounds at a university-based tertiary referral center. Methods: This was a prospective, controlled trial comparing a silver gauze dressing with saline gauze dressings in patients undergoing abdominal surgeries with contaminated wounds. Patients were randomly assigned to receive either silver gauze (SG dressing or saline gauze dressings (SD. The primary end point was surgical site infection occurring within 30 days of surgery. Results: 65 patients were enrolled in the review. The incidence of surgical site infection was 14% (9/65. No differences were observed among groups (15.2% vs. 12.5%, p = 0.75. Multivariate analysis revealed no relationship between the type of dressing and surgical site infection. Conclusion: Silver gauzes are safe and effective in preventing surgical site infections in surgeries with contaminated wounds. Further trials are required to find out if they have advantages over standard dressings.
Full Text Available Abstract Background Oomycetes of the genus Phytophthora are pathogens that infect a wide range of plant species. For dicot hosts such as tomato, potato and soybean, Phytophthora is even the most important pathogen. Previous analyses of Phytophthora genomes uncovered many genes, large gene families and large genome sizes that can partially be explained by significant repeat expansion patterns. Results Analysis of the complete genomes of three different Phytophthora species, using a newly developed approach, unveiled a large number of small duplicated blocks, mainly consisting of two or three consecutive genes. Further analysis of these duplicated genes and comparison with the known gene and genome duplication history of ten other eukaryotes including parasites, algae, plants, fungi, vertebrates and invertebrates, suggests that the ancestor of P. infestans, P. sojae and P. ramorum most likely underwent a whole genome duplication (WGD. Genes that have survived in duplicate are mainly genes that are known to be preferentially retained following WGDs, but also genes important for pathogenicity and infection of the different hosts seem to have been retained in excess. As a result, the WGD might have contributed to the evolutionary and pathogenic success of Phytophthora. Conclusions The fact that we find many small blocks of duplicated genes indicates that the genomes of Phytophthora species have been heavily rearranged following the WGD. Most likely, the high repeat content in these genomes have played an important role in this rearrangement process. As a consequence, the paucity of retained larger duplicated blocks has greatly complicated previous attempts to detect remnants of a large-scale duplication event in Phytophthora. However, as we show here, our newly developed strategy to identify very small duplicated blocks might be a useful approach to uncover ancient polyploidy events, in particular for heavily rearranged genomes.
Full Text Available Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis, a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana rootstocks grafted with 'King' mandarin (Citrus nobilis and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch's postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi, sweet orange (Citrus x sinensis and bergamot (Citrus x bergamia as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on 'Carrizo' citrange (C. sinensis 'Washington Navel' x Poncirus trifoliata. This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity.
Puglisi, Ivana; De Patrizio, Alessandro; Schena, Leonardo; Jung, Thomas; Evoli, Maria; Pane, Antonella; Van Hoa, Nguyen; Van Tri, Mai; Wright, Sandra; Ramstedt, Mauritz; Olsson, Christer; Faedda, Roberto; Magnano di San Lio, Gaetano; Cacciola, Santa Olga
Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis), a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI) as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana) rootstocks grafted with 'King' mandarin (Citrus nobilis) and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch's postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi), sweet orange (Citrus x sinensis) and bergamot (Citrus x bergamia) as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on 'Carrizo' citrange (C. sinensis 'Washington Navel' x Poncirus trifoliata). This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity.
Cheng, Yanbo; Ma, Qibin; Ren, Hailong; Xia, Qiuju; Song, Enliang; Tan, Zhiyuan; Li, Shuxian; Zhang, Gengyun; Nian, Hai
Using a combination of phenotypic screening, genetic and statistical analyses, and high-throughput genome-wide sequencing, we have finely mapped a dominant Phytophthora resistance gene in soybean cultivar Wayao. Phytophthora root rot (PRR) caused by Phytophthora sojae is one of the most important soil-borne diseases in many soybean-production regions in the world. Identification of resistant gene(s) and incorporating them into elite varieties are an effective way for breeding to prevent soybean from being harmed by this disease. Two soybean populations of 191 F 2 individuals and 196 F 7:8 recombinant inbred lines (RILs) were developed to map Rps gene by crossing a susceptible cultivar Huachun 2 with the resistant cultivar Wayao. Genetic analysis of the F 2 population indicated that PRR resistance in Wayao was controlled by a single dominant gene, temporarily named RpsWY, which was mapped on chromosome 3. A high-density genetic linkage bin map was constructed using 3469 recombination bins of the RILs to explore the candidate genes by the high-throughput genome-wide sequencing. The results of genotypic analysis showed that the RpsWY gene was located in bin 401 between 4466230 and 4502773 bp on chromosome 3 through line 71 and 100 of the RILs. Four predicted genes (Glyma03g04350, Glyma03g04360, Glyma03g04370, and Glyma03g04380) were found at the narrowed region of 36.5 kb in bin 401. These results suggest that the high-throughput genome-wide resequencing is an effective method to fine map PRR candidate genes.
Background Plant-microbe interactions feature complex signal interplay between pathogens and their hosts. Phytophthora species comprise a destructive group of fungus-like plant pathogens, collectively affecting a wide range of plants important to agriculture and natural ecosystems. Despite the availability of genome sequences of both hosts and microbes, little is known about the signal interplay between them during infection. In particular, accurate descriptions of coordinate relationships between host and microbe transcriptional programs are lacking. Results Here, we explore the molecular interaction between the hemi-biotrophic broad host range pathogen Phytophthora capsici and tomato. Infection assays and use of a composite microarray allowed us to unveil distinct changes in both P. capsici and tomato transcriptomes, associated with biotrophy and the subsequent switch to necrotrophy. These included two distinct transcriptional changes associated with early infection and the biotrophy to necrotrophy transition that may contribute to infection and completion of the P. capsici lifecycle Conclusions Our results suggest dynamic but highly regulated transcriptional programming in both host and pathogen that underpin P. capsici disease and hemi-biotrophy. Dynamic expression changes of both effector-coding genes and host factors involved in immunity, suggests modulation of host immune signaling by both host and pathogen. With new unprecedented detail on transcriptional reprogramming, we can now explore the coordinate relationships that drive host-microbe interactions and the basic processes that underpin pathogen lifestyles. Deliberate alteration of lifestyle-associated transcriptional changes may allow prevention or perhaps disruption of hemi-biotrophic disease cycles and limit damage caused by epidemics. PMID:23799990
Phytophthora root rot (PRR) caused by Phytophthora sojae Kaufm. & Gerd. and flooding can limit growth and productivity, of soybean [Glycine max (L.) Merr.], especially on poorly drained soils. The primary objective of this research project was to map quantitative trait loci (QTL) associated with f...
Phytophthora root and stem rot (PRR) of soybean, caused by Phytophthora sojae, is effectively controlled by Rps genes in soybean. Rps genes are race-specific, yet the mechanism of resistance, as well as susceptibility, remains largely unclear. Taking advantage of RNA-seq technology, we sequenced the...
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...
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...
Phytophthora capsici has been documented as a pathogen on a wide variety of vegetable crops in the family Solanaceae, Cucurbitaceae, Fabaceae, and plants belonging to 23 other families. Phytophthora fruit rot of watermelons caused by P. capsici is particularly severe in southeastern U.S where optima...
Four studies evaluated the effect of Phytophthora cinnamomi isolates, inoculum delivery methods, and flood and drought conditions on vigor, disease severity scores, and survival of blueberry plants grown in pots in the greenhouse. Phytophthora cinnamomi isolates were obtained from blueberry plants ...
E. Hansen; C. Hesse; P. Reeser; W. Sutton; L. Winton
Phytophthora species are abundant in streams, widespread in soils and occasionally found in diseased plants in the tanoak forests of southwestern Oregon. It is time-consuming and expensive to identify hundreds of isolates to species using morphology or internal transribed spacer (ITS) sequencing. We modified a published Phytophthora...
David Lockley; Judith Turner; Gillian Humphries; Phil Jennings
Soil samples were collected from quadrats marked out below the canopies of two rhododendrons, one infected by Phytophthora ramorum (Site 1) and the other (Site 2) infected by Phytophthora kernoviae and P. ramorum. Rainwater was collected in high-level and low level traps. Soil and rainwater were sampled at...
Man In 't Veld, Willem A; Rosendahl, Karin C H M; van Rijswick, Patricia C J; Meffert, Johan P; Westenberg, Marcel; van de Vossenberg, Bart T L H; Denton, Geoff; van Kuik, Fons A J
In the past decade several Phytophthora strains were isolated from diseased Pachysandra terminalis plants suffering stem base and root rot, originating from the Netherlands and Belgium. All isolates were homothallic and had a felt-like colony pattern, produced semi-papillate sporangia, globose oogonia and had a maximum growth at ~ 27 C. Several additional Phytophthora strains were isolated from diseased Buxus sempervirens plants, originating from the Netherlands and Belgium, which had sustained stem base and root rot; similar strains also were isolated from Acer palmatum, Choisya ternata and Taxus in the United Kingdom. All isolates were homothallic and had a stellate colony pattern, produced larger semi-papillate sporangia and smaller globose oogonia than the isolates from Pa. terminalis and had a maximum growth temperature of ~ 30 C. Phylogenetic analyses of both species using the internal transcribed spacer region of the nuc rDNA (ITS), mt cytochrome oxidases subunit I gene (CoxI) and nuc translation elongation factor 1-α gene (TEF1α) revealed that all sequences of each species were identical at each locus and unique to that species, forming two distinct clusters in subclade 2a. Sequence analysis of partial β-tubulin genes showed that both taxa share an identical sequence that is identical to that of Ph. himalsilva, a species originating from Asia, suggesting a common Asian origin. Pathogenicity trials demonstrated disease symptoms on their respective hosts, and re-isolation and re-identification of the inoculated pathogens confirmed Koch's postulates. © 2015 by The Mycological Society of America.
Durán, Alvaro; Slippers, Bernard; Gryzenhout, Marieka; Ahumada, Rodrigo; Drenth, Andre; Wingfield, Brenda D; Wingfield, Michael J
Phytophthora pinifolia causes a needle and shoot disease in Pinus radiata, referred to as 'Daño Foliar del Pino'. This newly discovered disease requires intensive research efforts that necessitate the processing of large numbers of samples for which accurate identification, often by people not experienced in Phytophthora taxonomy, is required. The aim of this study was, therefore, to develop species-specific primers for P. pinifolia that amplify the internal transcribed spacer region of the ribosomal operon and the nuclear Ypt1 gene, respectively. The primers were tested over several Phytophthora spp., as well as fungi isolated from P. radiata. In all cases, only P. pinifolia was amplified. In addition to the species-specific primers, a PCR-restriction fragment length polymorphism protocol using available Phytophthora genus-specific primers was also used to generate a species-specific profile for P. pinifolia. This provided a characteristic profile that allows the identification of P. pinifolia, and it could also discriminate between 27 different species of Phytophthora. Both techniques reported in this study make it possible to identify large numbers of P. pinifolia cultures accurately and efficiently, which will be important for both quarantine work and biological research on this important new pathogen.
Li, Wen-Wen; Zhao, Wen-Xia; Huai, Wen-Xia
A new species of the genus Phytophthora was isolated from stream water in the subtropical forests of China during a survey of forest Phytophthora from 2011 to 2013. This new species is formally described here and named Phytophthora pseudopolonica sp. nov. This new homothallic species is distinct from other known Phytophthora species in morphology and produces nonpapillate and noncaducous sporangia with internal proliferation. Spherical hyphal swellings and thin-walled chlamydospores are abundant when the species is kept in sterile water. The P. pseudopolonica sp. nov. forms smooth oogonia with paragynous and sometimes amphigynous antheridia. The optimum growth temperature of the species is 30 °C in V8-juice agar with β-sitosterol, yet it barely grows at 5 °C and 35 °C. Based on sequences of the internal transcribed spacer and the combined β-tubulin and elongation factor 1α gene sequence data, isolates of the new species cluster together into a single branch and are close to Phytophthora polonicabelonging to clade 9.
Nagel, Jan H; Slippers, Bernard; Wingfield, Michael J; Gryzenhout, Marieka
The diversity of Phytophthora spp. in rivers and riparian ecosystems has received considerable international attention, although little such research has been conducted in South Africa. This study determined the diversity of Phytophthora spp. within a single river in Gauteng province of South Africa. Samples were collected over 1 y including biweekly river baiting with Rhododendron indicum leaves. Phytophthora isolates were identified with phylogenetic analyses of sequences for the internal transcribed spacer (ITS) region of the ribosomal DNA and the mitochondrial cytochrome oxidase c subunit I (coxI) gene. Eight Phytophthora spp. were identified, including a new taxon, P. taxon Sisulu-river, and two hybrid species from Cooke's ITS clade 6. Of these, species from Clade 6 were the most abundant, including P. chlamydospora and P. lacustris. Species residing in Clade 2 also were encountered, including P. multivora, P. plurivora and P. citrophthora. The detection of eight species in this investigation of Phytophthora diversity in a single riparian river ecosystem in northern South Africa adds to the known diversity of this genus in South Africa and globally. © 2015 by The Mycological Society of America.
Prigigallo, Maria I; Abdelfattah, Ahmed; Cacciola, Santa O; Faedda, Roberto; Sanzani, Simona M; Cooke, David E L; Schena, L
A metabarcoding method based on genus-specific primers and 454 pyrosequencing was utilized to investigate the genetic diversity of Phytophthora spp. in soil and root samples of potted plants, from eight nurseries. Pyrosequencing enabled the detection of 25 Phytophthora phylotypes distributed in seven different clades and provided a much higher resolution than a corresponding cloning/Sanger sequencing approach. Eleven of these phylotypes, including P. cactorum, P. citricola s.str., P. palmivora, P. palmivora-like, P. megasperma or P. gonapodyides, P. ramorum, and five putative new Phytophthora species phylogenetically related to clades 1, 2, 4, 6, and 7 were detected only with the 454 pyrosequencing approach. We also found an additional 18 novel records of a phylotype in a particular nursery that were not detected with cloning/Sanger sequencing. Several aspects confirmed the reliability of the method: (i) many identical sequence types were identified independently in different nurseries, (ii) most sequence types identified with 454 pyrosequencing were identical to those from the cloning/Sanger sequencing approach and/or perfectly matched GenBank deposited sequences, and (iii) the divergence noted between sequence types of putative new Phytophthora species and all other detected sequences was sufficient to rule out sequencing errors. The proposed method represents a powerful tool to study Phytophthora diversity providing that particular attention is paid to the analysis of 454 pyrosequencing raw read sequences and to the identification of sequence types.
JAQUELINE FIGUEREDO DE OLIVEIRA COSTA
Full Text Available ABSTRACT In 2013, soursop trees showing symptoms of root rot were observed in a field in Maceió, state of Alagoas, Brazil. It was isolated Phytophthora sp. which pathogenicity was confirmed in the host seedlings. Morphological and physiological characteristics in carrot-agar modified medium were consistent with Phytophthora nicotianae description. The PCR sequences products obtained with ITS1/ITS4 primers were compared to sequences of ribosomal DNA of Phytophthora species from the GenBank database observing high identity with other P. nicotianae isolates. A phylogenetic tree was performed to compare the isolate with other sequences of P. nicotianae, which clustering has been verified with 99% of bootstrap, confirming the morphophysiological studies. This is the first report of this pathogen on annonaceous plants in the Northeastern Brazil.
Full Text Available Resistance test strains of transgenic potatoes transformed with RB gene to late blight (Phytophthora infestan in KP Pasirsarongge, Cianjur. Potato late blight caused by Phytophthora infestans (P. infestans (Mönt. de Barry continues to be one of the most important crop diseases of all time. Genetic engineering of potato using RB gene for resistant plant to this disease is the most effective and environmental friendly to prevent widespread of late blight. This research aims to perform resistance of transgenic potato lines containing RB gene to lateblight (P. infestans in Pasirsarongge, Cianjur field trial station. The first generation of transgenic lines were planted on polybag containing soil:manures using randomized complete block design. Tested plant inoculation was done naturaly from inoculum source from border row (Granola that has been planted at one month before. The symptom was observed at one month after planting and damage scoring was done every three days for five times. Twenty two transgenic lines of tested plant showed various resistance respond to late blight (P. infestans attack. Three transgenic lines showed highly resistance to late blight (P. infestans were lines 11, 24, and 25, one transgenic line has resistant level was line 6.
Schena, Leonardo; Cardle, Linda; Cooke, David E L
Microsatellites or single sequence repeats (SSRs) are a powerful choice of marker in the study of Phytophthora population biology, epidemiology, ecology, genetics and evolution. A strategy was tested in which the publicly available unigene datasets extracted from genome sequences of P. infestans, P. sojae and P. ramorum were mined for candidate SSR markers that could be applied to a wide range of Phytophthora species. A first approach, aimed at the identification of polymorphic SSR loci common to many Phytophthora species, yielded 171 reliable sequences containing 211 SSRs. Microsatellites were identified from 16 target species representing the breadth of diversity across the genus. Repeat number ranged from 3 to 16 with most having seven repeats or less and four being the most commonly found. Trinucleotide repeats such as (AAG)n, (AGG)n and (AGC)n were the most common followed by pentanucleotide, tetranucleotide and dinucleotide repeats. A second approach was aimed at the identification of useful loci common to a restricted number of species more closely related to P. sojae (P. alni, P. cambivora, P. europaea and P. fragariae). This analysis yielded 10 trinucleotide and 2 tetranucleotide SSRs which were repeated 4, 5 or 6 times. Key studies on inter- and intra-specific variation of selected microsatellites remain. Despite the screening of conserved gene coding regions, the sequence diversity between species was high and the identification of useful SSR loci applicable to anything other than the most closely related pairs of Phytophthora species was challenging. That said, many novel SSR loci for species other than the three 'source species' (P. infestans, P. sojae and P. ramorum) are reported, offering great potential for the investigation of Phytophthora populations. In addition to the presence of microsatellites, many of the amplified regions may represent useful molecular marker regions for other studies as they are highly variable and easily amplifiable from
Full Text Available Abstract Background Microsatellites or single sequence repeats (SSRs are a powerful choice of marker in the study of Phytophthora population biology, epidemiology, ecology, genetics and evolution. A strategy was tested in which the publicly available unigene datasets extracted from genome sequences of P. infestans, P. sojae and P. ramorum were mined for candidate SSR markers that could be applied to a wide range of Phytophthora species. Results A first approach, aimed at the identification of polymorphic SSR loci common to many Phytophthora species, yielded 171 reliable sequences containing 211 SSRs. Microsatellites were identified from 16 target species representing the breadth of diversity across the genus. Repeat number ranged from 3 to 16 with most having seven repeats or less and four being the most commonly found. Trinucleotide repeats such as (AAGn, (AGGn and (AGCn were the most common followed by pentanucleotide, tetranucleotide and dinucleotide repeats. A second approach was aimed at the identification of useful loci common to a restricted number of species more closely related to P. sojae (P. alni, P. cambivora, P. europaea and P. fragariae. This analysis yielded 10 trinucleotide and 2 tetranucleotide SSRs which were repeated 4, 5 or 6 times. Conclusion Key studies on inter- and intra-specific variation of selected microsatellites remain. Despite the screening of conserved gene coding regions, the sequence diversity between species was high and the identification of useful SSR loci applicable to anything other than the most closely related pairs of Phytophthora species was challenging. That said, many novel SSR loci for species other than the three 'source species' (P. infestans, P. sojae and P. ramorum are reported, offering great potential for the investigation of Phytophthora populations. In addition to the presence of microsatellites, many of the amplified regions may represent useful molecular marker regions for other studies as
Brazee, Nicholas J; Wick, Robert L; Hulvey, Jonathan P
Little is currently known about the assemblage of Phytophthora species in northeastern North America, representing a gap in our understanding of species incidence. Therefore, Phytophthora species were surveyed at 20 sites in Massachusetts, with 16 occurring in the Connecticut River Valley. Many of the sampled waterways were adjacent to active agricultural lands, yet were buffered by mature floodplain forests composed of Acer, Platanus, Populus and Ulmus. Isolates were recovered with three types of baits (rhododendron leaves, pear, green pepper) in 2013 and water filtration in 2014. Overall, 457 isolates of Phytophthora were recovered and based on morphological characters and rDNA internal transcribed spacer (ITS), β-tubulin (β-tub) and cytochrome oxidase c subunit I (cox1) sequences, 18 taxa were identified, including three new species: P. taxon intercalaris, P. taxon caryae and P. taxon pocumtuck. In addition, 49 isolates representing five species of Phytopythium also were identified. Water filtration captured a greater number of taxa (18) compared to leaf and fruit baits (12). Of the three bait types rhododendron leaves yielded the greatest number of isolates and taxa, followed by pear and green pepper, respectively. Despite the proximity to agricultural lands, none of the Phytophthora species baited are considered serious pathogens of vegetable crops in the region. However, many of the recovered species are known woody plant pathogens, including four species in the P. citricola s.l. complex that were identified: P. plurivora, P. citricola III, P. pini and a putative novel species, referred to here as P. taxon caryae. An additional novel species, P. taxon pocumtuck, is a close relative of P. borealis based on cox1 sequences. The results illustrate a high level of Phytophthora species richness in the Connecticut River Valley and that major rivers can serve as a source of inoculum for pathogenic Phytophthora species in the northeast. © 2016 by The Mycological
Ho, H H; Lu, J Y
To date, 26 species of Phytophthora have been reported in mainland China but only 23 are accepted as good taxa. Phytophthora nicotianae (P. parasitica) is the single most important species causing over 40 different plant diseases; P. boehmeriae is widespread attacking Gossypium, Boehmeria, Citrus, Broussonetia papyrifera and Pterocarya stenoptera; P. "fragariae var. oryzo-bladis" is unique to mainland China causing blight of Oryza sativa seedlings; P. megasperma sensu lato has been isolated from Glycine max, Asparagus officinalis and Spinacia oleracea. In Hainan Province, P. heveae is present in the soil without causing apparent diseases to Hevea brasiliensis there.
KOC, Esra; USTUN, Ayşen Sulun
In this study, PAL activity in stems of pepper (Capsicum annuum L.) plants infected by the root rot pathogen Phytophthora capsici-22 in a resistant (PM-702) and two susceptible (Kahramanmaraş-Hot (KM-Hot) and Demre-8) cultivar were studied. The response of the PAL activity in the resistant cultivar was faster and higher than in the susceptible cultivars (p < 0.01). The increase in production of PAL upon Phytophthora capsici-22 were higher in the infected plants compared to the non-in...
Fabritius, Anna-Liisa; Cvitanich, Cristina; Judelson, Howard S.
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...... revealed that the predicted products of three of the genes had similarity to proteins that influence RNA stability, namely a ribonuclease activator, the pumilio family of RNA-binding proteins and RNase H. The products of two other mating-induced genes resembled two types of Phytophthora proteins previously...
Full Text Available Abstract Background The oomycete Phytophthora infestans causes late blight on potato and tomato. Despite extensive research, the P. infestans-host interaction is still poorly understood. To find new ways to further unravel this interaction we established a new infection system using MsK8 tomato cells. These cells grow in suspension and can be maintained as a stable cell line that is representative for tomato. Results MsK8 cells can host several Phytophthora species pathogenic on tomato. Species not pathogenic on tomato could not infect. Microscopy revealed that 16 h after inoculation up to 36% of the cells were infected. The majority were penetrated by a germ tube emerging from a cyst (i.e. primary infection while other cells were already showing secondary infections including haustoria. In incompatible interactions, MsK8 cells showed defense responses, namely reactive oxygen species production and cell death leading to a halt in pathogen spread at the single cell level. In compatible interactions, several P. infestans genes, including RXLR effector genes, were expressed and in both, compatible and incompatible interactions tomato genes involved in defense were differentially expressed. Conclusions Our results show that P. infestans can prosper as a pathogen in MsK8 cells; it not only infects, but also makes haustoria and sporulates, and it receives signals that activate gene expression. Moreover, MsK8 cells have the ability to support pathogen growth but also to defend themselves against infection in a similar way as whole plants. An advantage of MsK8 cells compared to leaves is the more synchronized infection, as all cells have an equal chance of being infected. Moreover, analyses and sampling of infected tissue can be performed in a non-destructive manner from early time points of infection onwards and as such the MsK8 infection system offers a potential platform for large-scale omics studies and activity screenings of inhibitory
Granke, L L; Windstam, S T; Hoch, H C; Smart, C D; Hausbeck, M K
Understanding the mechanisms of Phytophthora capsici sporangial dissemination is paramount to understanding epidemic initiation and development. Direct laboratory observations showed P. capsici sporangial dispersal occurred in water with capillary force, but did not occur in response to wind or a reduction in relative humidity. Atmospheric sporangial concentrations were monitored under field conditions using a volumetric spore sampler in a commercial cucurbit field and in an experimental setting where copious sporangia were continuously available in close proximity to the spore trap. Dispersal was infrequent (0.7% of total hours monitored) during sampling in a commercial field; 14 sporangia were detected during a 7.5-week sampling period. In the experimental field situation, dispersal occurred in 4.6% of the hours sampled and 438 sporangia were impacted onto tapes during a 7-week sampling period. Airborne sporangial concentrations were positively associated with rainfall at both sites, but not vapor pressure deficit. Furthermore, in the experimental field situation, wind speed was not significant in regression analysis. Wind speed was not measured in the commercial field. Hence, both direct laboratory observations and volumetric spore sampling indicate that dispersal of sporangia via wind currents is infrequent, and sporangia are unlikely to be naturally dispersed among fields by wind alone.
Vettraino, AnnaMaria; Brasier, Clive M; Webber, Joan F; Hansen, Everett M; Green, Sarah; Robin, Cecile; Tomassini, Alessia; Bruni, Natalia; Vannini, Andrea
Following recent discovery of Phytophthora lateralis on native Chamaecyparis obtusa in Taiwan, four phenotypically distinct lineages were discriminated: the Taiwan J (TWJ) and Taiwan K (TWK) in Taiwan, the Pacific Northwest (PNW) in North America and Europe and the UK in west Scotland. Across the four lineages, we analysed 88 isolates from multiple sites for microsatellite diversity. Twenty-one multilocus genotypes (MLGs) were resolved with high levels of diversity of the TWK and PNW lineages. No alleles were shared between the PNW and the Taiwanese lineages. TWK was heterozygous at three loci, whereas TWJ isolates were homozygous apart from one isolate, which exhibited a unique allele also present in the TWK lineage. PNW lineage was heterozygous at three loci. The evidence suggests its origin may be a yet unknown Asian source. North American and European PNW isolates shared all their alleles and also a dominant MLG, consistent with a previous proposal that this lineage is a recent introduction into Europe from North America. The UK lineage was monomorphic and homozygous at all loci. It shared its alleles with the PNW and the TWJ and TWK lineages, hence a possible origin in a recent hybridisation event between a Taiwan lineage and PNW cannot be ruled out. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.
Sirjana Devi Shrestha
Full Text Available The Phytophthora sojae avirulence gene Avr3a encodes an effector that is capable of triggering immunity on soybean plants carrying the resistance gene Rps3a. P. sojae strains that express Avr3a are avirulent to Rps3a plants, while strains that do not are virulent. To study the inheritance of Avr3a expression and virulence towards Rps3a, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 X P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F5 generation. However, test-crosses of F1 progeny (ACR10 X P7076 with strain P6497 result in the release of silencing of Avr3a. Expression of Avr3a in the progeny is variable and correlates with the phenotypic penetrance of the avirulence trait. The F1 progeny from a direct cross of P6497 X ACR10 segregate for inheritance for Avr3a expression, a result that could not be explained by parental imprinting or heterozygosity. Analysis of small RNA arising from the Avr3a gene sequence in the parental strains and hybrid progeny suggests that the presence of small RNA is necessary but not sufficient for gene silencing. Overall, we conclude that inheritance of the Avr3a gene silenced phenotype relies on factors that are variable among P. sojae strains.
Sahoo, Dipak K; Abeysekara, Nilwala S; Cianzio, Silvia R; Robertson, Alison E; Bhattacharyya, Madan K
Phytophthora sojae Kaufmann and Gerdemann, which causes Phytophthora root rot, is a widespread pathogen that limits soybean production worldwide. Development of Phytophthora resistant cultivars carrying Phytophthora resistance Rps genes is a cost-effective approach in controlling this disease. For this mapping study of a novel Rps gene, 290 recombinant inbred lines (RILs) (F7 families) were developed by crossing the P. sojae resistant cultivar PI399036 with the P. sojae susceptible AR2 line, and were phenotyped for responses to a mixture of three P. sojae isolates that overcome most of the known Rps genes. Of these 290 RILs, 130 were homozygous resistant, 12 heterzygous and segregating for Phytophthora resistance, and 148 were recessive homozygous and susceptible. From this population, 59 RILs homozygous for Phytophthora sojae resistance and 61 susceptible to a mixture of P. sojae isolates R17 and Val12-11 or P7074 that overcome resistance encoded by known Rps genes mapped to Chromosome 18 were selected for mapping novel Rps gene. A single gene accounted for the 1:1 segregation of resistance and susceptibility among the RILs. The gene encoding the Phytophthora resistance mapped to a 5.8 cM interval between the SSR markers BARCSOYSSR_18_1840 and Sat_064 located in the lower arm of Chromosome 18. The gene is mapped 2.2 cM proximal to the NBSRps4/6-like sequence that was reported to co-segregate with the Phytophthora resistance genes Rps4 and Rps6. The gene is mapped to a highly recombinogenic, gene-rich genomic region carrying several nucleotide binding site-leucine rich repeat (NBS-LRR)-like genes. We named this novel gene as Rps12, which is expected to be an invaluable resource in breeding soybeans for Phytophthora resistance.
Dipak K Sahoo
Full Text Available Phytophthora sojae Kaufmann and Gerdemann, which causes Phytophthora root rot, is a widespread pathogen that limits soybean production worldwide. Development of Phytophthora resistant cultivars carrying Phytophthora resistance Rps genes is a cost-effective approach in controlling this disease. For this mapping study of a novel Rps gene, 290 recombinant inbred lines (RILs (F7 families were developed by crossing the P. sojae resistant cultivar PI399036 with the P. sojae susceptible AR2 line, and were phenotyped for responses to a mixture of three P. sojae isolates that overcome most of the known Rps genes. Of these 290 RILs, 130 were homozygous resistant, 12 heterzygous and segregating for Phytophthora resistance, and 148 were recessive homozygous and susceptible. From this population, 59 RILs homozygous for Phytophthora sojae resistance and 61 susceptible to a mixture of P. sojae isolates R17 and Val12-11 or P7074 that overcome resistance encoded by known Rps genes mapped to Chromosome 18 were selected for mapping novel Rps gene. A single gene accounted for the 1:1 segregation of resistance and susceptibility among the RILs. The gene encoding the Phytophthora resistance mapped to a 5.8 cM interval between the SSR markers BARCSOYSSR_18_1840 and Sat_064 located in the lower arm of Chromosome 18. The gene is mapped 2.2 cM proximal to the NBSRps4/6-like sequence that was reported to co-segregate with the Phytophthora resistance genes Rps4 and Rps6. The gene is mapped to a highly recombinogenic, gene-rich genomic region carrying several nucleotide binding site-leucine rich repeat (NBS-LRR-like genes. We named this novel gene as Rps12, which is expected to be an invaluable resource in breeding soybeans for Phytophthora resistance.
Willscher, Sabine; Werner, Peter; Jablonski, Lukasz; Wittig, Juliane
In the presented scientific research project, the radiation protection of soil surfaces impacted by former industrial utilization or mining was investigated. This radiation protection of the contaminated soil surfaces was carried out by bioremediation techniques. The soil surfaces include larger agricultural or forestry areas useful for the production of sustainable plant-based raw materials and renewable energies. The contaminated areas show a positive climatic water balance with a subsequent impact of SM/R contaminants onto the adjacent ground water. During this scientific research project, the introduction of sustainable, biosphere conserving methods for a long-term remediation of slightly to moderately HM/R- contaminated areas was investigated; these areas are characterized by a radiotoxic amplifying potential due to a continued occurrence of radionuclides and heavy metals/ metalloids. The insights into transfer processes from the soil substrate over the mediating soil water phase and by microbes into the plant roots, into the shoots and the leaves of the plants represent necessary requirements for the control of SM/R transfer into the plants and its optimization. In this research project, considerable investigations were carried out for the understanding of binding of HM/R in the different plant compartments, also depending on different soil additives. The obtained first scientific results and their practical applicability were transformed onto experimental soil areas under natural field conditions. The transfer processes could be optimized and finally bioremediation efficiency could be enhanced due to the accompanying modifications (different soil additives of the field experiments). This new remediation method, further developed to a field application, represents a new tool for the stabilization / and extraction of HM/R on the field site and improves the efficiency of bioremediation processes. A pacification of the large areas with slightly to medium
Beone, G.; Carbone, A.I.; Zagaroli, M.
The paper deals with the problem of contaminated areas cleanup, in order to eliminate every possible damage for man safety and environment and to site recovery for some utilization, The first step of cleanup operation is site characterization, that is followed by a pianificazion activity for a better definition of staff qualification, technology to be used, protection and prevention instruments for the risks due to contaminants handling. The second section describes the different remedial technologies for contaminated sites. Remedial technologies may be divided into on-site/off-site and in-situ treatments, according to whether materials (waste, soil, water) are moved to another location or not, respectively. Finally, it is outlined that contaminated areas cleanup is a typical multidisciplinary activity because very different competences are required. (author)
Xiong, Qin; Ye, Wenwu; Choi, Duseok; Wong, James; Qiao, Yongli; Tao, Kai; Wang, Yuanchao; Ma, Wenbo
The genus Phytophthora consists of notorious and emerging pathogens of economically important crops. Each Phytophthora genome encodes several hundreds of cytoplasmic effectors, which are believed to manipulate plant immune response inside the host cells. However, the majority of Phytophthora effectors remain functionally uncharacterized. We recently discovered two effectors from the soybean stem and root rot pathogen Phytophthora sojae with the activity to suppress RNA silencing in plants. These effectors are designated Phytophthora suppressor of RNA silencing (PSRs). Here, we report that the P. sojae PSR2 (PsPSR2) belongs to a conserved and widespread effector family in Phytophthora. A PsPSR2-like effector produced by P. infestans (PiPSR2) can also suppress RNA silencing in plants and promote Phytophthora infection, suggesting that the PSR2 family effectors have conserved functions in plant hosts. Using Agrobacterium rhizogenes-mediated hairy roots induction, we demonstrated that the expression of PsPSR2 rendered hypersusceptibility of soybean to P. sojae. Enhanced susceptibility was also observed in PsPSR2-expressing Arabidopsis thaliana plants during Phytophthora but not bacterial infection. These experiments provide strong evidence that PSR2 is a conserved Phytophthora effector family that performs important virulence functions specifically during Phytophthora infection of various plant hosts.
Man in 't Veld, Willem A
Isozyme analysis and cytochrome oxidase sequences were used to examine whether differentiation of P. fragariae var. fragariae and P. fragariae var. rubi at the variety level is justified. In isozyme studies six strains of both P. fragariae varieties were analyzed with malate dehydrogenase (MDH), glucose phosphate isomerase (GPI), aconitase (ACO), isocitrate dehydrogenase (IDH) and phosphogluconate dehydrogenase (PGD), comprising altogether seven putative loci. Five unique alleles (Mdh-1(A), Mdh-2(B), Gpi(A), Aco(B) and Idh-1(B)) were found in strains of P. fragariae var. fragariae, whereas five unique alleles (Mdh-1(B), Mdh-2(A), Gpi(B), Aco(A) and Idh-1(A)) were present in strains of P. fragariae var. rubi. It was inferred from these data that there is no gene flow between the two P. fragariae varieties. Cytochrome oxidase I (Cox I) sequences showed consistent differences at 15 positions between strains of Fragaria and Rubus respectively. Based on isozyme data, cytochrome oxidase I sequences, and previously published differences in restyriction enzyme patterns of mitochondrial DNA, sequences of nuclear and mitochondrial genes, AFLP patterns and pathogenicity, it was concluded that both specific pathogenic varieties of P. fragariae are reproductively isolated and constitute a distinct species. Consequently strains isolated from Rubus idaeus are assigned to Phytophthora rubi comb. nov.
Erica M Goss
Full Text Available Emerging plant pathogens have largely been a consequence of the movement of pathogens to new geographic regions. Another documented mechanism for the emergence of plant pathogens is hybridization between individuals of different species or subspecies, which may allow rapid evolution and adaptation to new hosts or environments. Hybrid plant pathogens have traditionally been difficult to detect or confirm, but the increasing ease of cloning and sequencing PCR products now makes the identification of species that consistently have genes or alleles with phylogenetically divergent origins relatively straightforward. We investigated the genetic origin of Phytophthora andina, an increasingly common pathogen of Andean crops Solanum betaceum, S. muricatum, S. quitoense, and several wild Solanum spp. It has been hypothesized that P. andina is a hybrid between the potato late blight pathogen P. infestans and another Phytophthora species. We tested this hypothesis by cloning four nuclear loci to obtain haplotypes and using these loci to infer the phylogenetic relationships of P. andina to P. infestans and other related species. Sequencing of cloned PCR products in every case revealed two distinct haplotypes for each locus in P. andina, such that each isolate had one allele derived from a P. infestans parent and a second divergent allele derived from an unknown species that is closely related but distinct from P. infestans, P. mirabilis, and P. ipomoeae. To the best of our knowledge, the unknown parent has not yet been collected. We also observed sequence polymorphism among P. andina isolates at three of the four loci, many of which segregate between previously described P. andina clonal lineages. These results provide strong support that P. andina emerged via hybridization between P. infestans and another unknown Phytophthora species also belonging to Phytophthora clade 1c.
Erik Davis Fausak
Full Text Available Clinical bottom lineBased on very poor veterinary and human evidence, fluid bags and IV sets should be changed every 96 hours whether on one or multiple patients. Additionally, supportive evidence suggests that creating a routine of wiping ports with alcohol prior to injection or withdrawal may significantly decrease the likelihood of fluid contamination. This certainly seems to be an area that needs more research.
Niklaus J. Grünwald
Whole and partial genome sequences are becoming available at an ever-increasing pace. For many plant pathogen systems, we are moving into the era of genome resequencing. The first Phytophthora genomes, P. ramorum and P. sojae, became available in 2004, followed shortly by P. infestans...
Clive Brasier; Susan Kirk; Joan Rose
The comparative risk to trees posed by European (E.U.) versus North American (U.S.) isolates of Phytophthora ramorum, the possible risk posed by genetic recombination between them, and whether European versus North American isolates represented discrete sub-populations was investigated. Population samples of E.U. and U.S. isolates were compared for...
T. Ufer; M. Posner; H.-P. Wessels; S. Wagner; K. Kaminski; T. Brand; Werres S.
In a four year project, three different filtration systems were tested under commercial nursery conditions to eliminate Phytophthora spp. from irrigation water. Five nurseries were involved in the project. Slow sand filtration systems were tested in three nurseries. In the fourth nursery, a filtration system with lava grains (ShieerÂ® Bio filtration)...
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
Alan Kanaskie; Everett Hansen; Ellen Michaels Goheen; Nancy Osterbauer; Michael McWilliams; Jon Laine; Michael Thompson; Stacy Savona; Harvey Timeaus; Bill Woosley; Wendy Sutton; Paul Reeser; Rick Schultz; Dan Hilburn
Sudden Oak Death (SOD) disease caused by Phytophthora ramorum Werres, de Cock & Man in't Veld was first discovered in Oregon forests in July 2001. Since then, an interagency team has been attempting to eradicate the pathogen though a programme of early detection (aerial and ground surveys, stream baiting...
Jacob van Breda de Haan is known as the author of the name Phytophthora nicotianae n.sp., the causal agent of ‘black shank’, an important disease of tobacco. Who was he? Where did he work? What did he publish? He published in Dutch, 1896, in a Dutch colonial report series. Next question: what more
Vijn, I.; Govers, F.
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
John T. Kliejunas
Sudden oak death and Phytophthora ramorum, both first recognized about a decade ago, have been the subject of hundreds of scientific and popular press articles. This document presents a comprehensive, concise summary of sudden oak death and P. ramorum research findings and management activities. Topics covered include...
J.L. Parke; B.J. Knaus; V.J. Fieland; C. Lewis; N.J. Grünwald
Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to the development of integrated systems approaches. Four horticultural nurseries in Oregon were sampled every 2 months for 4 years to determine the identity and community structure of Phytophthora...
Robert C. Venette; Susan D. Cohen
Phytophthora ramorum has caused extensive mortality to tanoak and several oak species in coastal California. This pathogen has infected at least 72 plant species under natural conditions and 32 additional species in the laboratory. Many infected hosts have been distributed across the United States by the horticultural industry. We developed a...
Everett M. Hansen; Paul Reeser; Wendy Sutton; Richard A. Sniezko
Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl.) (POC) is an economically and ecologically valuable tree in the forests of southwest Oregon and northern California and in the horticultural trade worldwide. Phytophthora lateralis, the aggressive, invasive cause of POC root disease, was introduced to the native...
Full Text Available Ornamental plants play an important role in human life. Plants positively influence the psyche and improve the well-being of people around them. They produce oxygen, provide a barrier to dust and noise, lower the temperature and increase air humidity, thereby positively impacting the microclimate. The unmatched appeal of pelargonium, ease of cultivation and care, abundance of flowering from spring to late autumn and its decorative qualities make it a universal application. The aim of the study was to isolate the microorganisms that inhabit the cuttings of pelargonium, identify fungal isolates, investigate the pathogenicity of selected isolates and evaluate the influence of certain essential oils (Carum carvi L. essential oils, Citrus limon L. essential oils, Citrus reticulatae aetheroleum essential oils, essential oil of tea tree in in vitro circumstances on the linear growth of the mycelium: Phytophthora cryptogea, Phytophthora nicotianae var. nicotianae. Previcur Energy 840 SL was used as a standard chemical protection. The most numerous isolated fungi were: Phytophthora, Botrytis, Cylindrocladium, Alternaria and Cylindrocarpon. The highest efficiency in relation to Phytophthora cryptogea characterized the Citrus limon L. essential oils (concentration 0.1% and 1% and Carum carvi L. essential oil (concentration 1%.
Daniel Manter; Everett Hansen; Jennifer. Parke
Phytophthora ramorum populations are clonal and consist of three clonal lineages: EU1 is the only lineage found in Europe with a few isolated nursery infections in the USA; NA1 is associated with natural infestations in California and Oregon as well as some nursery infections in North America, and NA2 has a limited distribution and has only...
Govers, Laura L.; van der Zee, Els M.; Meffert, Johan P.; van Rijswick, Patricia C. J.; Man in't Veld, Willem A.; Heusinkveld, Jannes H. T.; van der Heide, Tjisse
Restoration is increasingly considered an essential tool to halt and reverse the rapid decline of vital coastal ecosystems dominated by habitat-forming foundation species such as seagrasses. However, two recently discovered pathogens of marine plants, Phytophthora gemini and Halophytophthora sp.
Karel A. Jacobs; James D. MacDonald; Alison M. Berry; Laurence R. Costello
The incidence and severity of Phytophthora cinnamomi Rands root disease was quantified in cork oak (Quercus suber L.) roots subjected to low oxygen (hypoxia) stress. Seedling root tips were inoculated with mycelial plugs of the fungus and incubated in ≤1, 3-4, or 21 percent oxygen for 5 days. Ninety-four percent of roots...
Phytophthora sojae causes damping off, root rot, and stem rot of soybean, particularly in poorly drained soils. The use of resistance has been one of the primary management tools used to control this disease, with the most commonly used genes being Rps1c and Rps1k, followed by Rps1a. The Varietal In...
Improving resistance for Phytophthora root and stem rot is an important goal in soybean [Glycine max (L.) Merr.] breeding. Partial resistance can be as effective in managing this disease as single-gene (Rps) mediated resistance and is more durable. The objective of this study was to identify QTL con...
Phytophthora sojae (Kaufm. & Gerd.) causes seed rot, pre- and post-emergence damping off, and sometimes foliar blight in soybean (Glycine max). Crop loss may approach 100% with susceptible cultivars. We report here the development of a unique quantitative PCR assay specific to DNA of P. sojae, and a...
Daniel K. Manter; Rick G. Kelsey; Joseph J. Karchesy
Infection of compatible plants by Phytophthora spp. often leads to a decline in stomatal conductance and photosynthesis, although the mechanistic basis for such declines is not completely understood. In many cases, declines in leaf gas exchange rates have been linked to losses in water supply capacity associated with root and/or xylem. However, the...
Laxalt, A.M.; Latijnhouwers, M.; Hulten, van M.; Govers, F.
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
Pieterse, C.M.J.; Risseeuw, E.P.; Davidse, L.C.
An in planta induced gene of Phytophthora infestans (the causal organism of potato late blight) was isolated from a genomic library by differential hybridization using labelled cDNA derived from poly(A)⁺ RNA of P. infestans grown in vitro and labelled cDNA made from potato-P,
C. Robin; D. Piou; N. Feau; G. Douzon; N. Schenck; E.M. Hansen
Phytophthora lateralis has been isolated from root and collar lesions in Port-Orford Cedar (POC) trees (Chamaecyparis lawsoniana) in north-western France (Brittany). These trees, planted in hedgerows, displayed symptoms similar to the typical symptoms of POC root disease. Until now, the disease has been found outside of the...
Poppel, van P.M.J.A.
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
J. Parke; B. Collins; G. Buckles; E. Hansen; B. Lachenbruch
In an experiment with mature naturally infected tanoak trees, Phytophthora ramorum was observed in sapwood and appeared to interfere with stem water transport (Parke and others 2007). We postulated that colonization of the xylem could contribute to rapid spread within the tree and lead to development of crown mortality symptomatic of...
Full Text Available Incidence of Phytophthora blight of hot pepper (Capsicum annuum and yield (fresh weight of pepper fruits were investigated at four separate fields located in Cheongwon, Boeun, Eumsung, and Goesan, which are major pepper production areas in Chungcheongbuk-Do. In all of the experimental fields except the Goesan field, increased incidence of Phytophthora blight led to decreased yield of pepper fruits. The harvest time in which the yield of red pepper fruits was highly correlated with the incidence of Phytophthora blight was different between areas: it was highly correlated in the third harvest in Cheongwon (y=-11.0x+435.2, r2= 0.99, but in the second harvest in Boeun (y=-15.0x+944.6, r2=0.76. In contrast, there was a very low correlation between the pepper yield and the disease incidence in Goesan in which pepper seedlings grafted on resistant stocks were planted. The final disease incidence in the Cheongwon experimental field reached 100% more than 40 days later in 2007 compared with that in 2006. The control threshold of Phytophthora blight in the pepper fields where disease incidence had been lower than 5% was set as 0.8% disease incidence, which caused less than 5% yield loss
Ellen Michaels Goheen; Everett Hansen; Alan Kanaskie; Wendy Sutton; Paul Reeser
Sudden oak death, caused by Phytophthora ramorum, was identified in late July 2001 in forest stands in Curry County on the southwest Oregon coast where it was killing tanoak (Lithocarpus densiflorus) and infecting Pacific rhododendron (Rhododendron macrophyllum) and evergreen huckleberry (Vaccinium...
Judith Turner; Philip Jennings; Sam McDonough; Debbie Liddell; Jackie Stonehouse
A range of fungicides have been tested for activity against P. ramorum using both in vitro and in vivo tests. All fungicides had proven activity against Phytophthora species and either had full approval for use on hardy ornamental nursery stock in the United Kingdom, or could be used under the Revised Long Term Arrangements for Extension of Use (2002...
Brice A. McPherson; Sylvia R. Mori; Anna O. Conrad; Stephen Opiyo; Pierluigi Bonello; David L. Wood
California coast live oaks (Quercus agrifolia) trees have suffered large losses from sudden oak death, caused by the introduced oomycete Phytophthora ramorum. In this review paper, we discuss oak plant chemistry as a potential predictor of disease susceptibility. We have recorded an annual mortality rate of three percent in...
Phytophthora pathogens are notorious for causing severe damage to many agriculturally and ornamentally important plants. Effective plant resistance depends largely on the capacity to perceive pathogens and to activate rapid defence. Cytoplasmic resistance
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
Govers, Laura L.; Man in 't Veld, Willem A.; Meffert, Johan P.; Bouma, Tjeerd J.; van Rijswick, Patricia C. J.; Heusinkveld, Jannes H. T.; Orth, Robert J.; van Katwijk, Marieke M.; van der Heide, Tjisse
Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is
Alan Kanaskie; Everett Hansen; Wendy Sutton
In Oregon, tanoak (Lithocarpus densiflorus) is the tree species most susceptible to Phytophthora ramorum, and Sudden Oak Death (SOD) occurs only in forests where tanoak is present. Oregon is attempting to eradicate the pathogen by complete destruction of host plants in and near infested sites. Although the eradication effort has...
A new method based on the analysis of mitochondrial intergenic regions characterized by intraspecific variation in DNA sequences was developed and applied to the study of the plant pathogen Phytophthora nicotianae. Two regions flanked by genes trny and rns and trnw and cox2 were identified by compa...
Marianne Elliott; Simon F. Shamoun; Grace Sumampong; Delano James; Stephan C. Briere; Saad Masri; Aniko Varga
A collection of 67 isolates of Phytophthora ramorum from the United States (U.S.), European Union (EU), and Canada was screened using differences in phenotypic traits (pathogenicity, growth rate at several temperatures, and sensitivity/resistance to metalaxyl, dimethomorph, and streptomycin) and for presence of cytoplasmic elements (dsRNA and...
F.N. Martin; M. Coffey; R. Hamelin; P. Tooley; M. Garbelotto; K. Hughes; T. Kubisiak
A number of molecular diagnostic procedures for detection of Phytophthora ramorum have been reported in the literature. In an effort to evaluate the specificity of 10 of these techniques a standardized DNA library for 317 isolates was assembled that included 60 described species as well as 22 taxonomically unclassified isolates. These were sent blind...
Katherine J. Hayden; Matteo Garbelotto; Brian J. Knaus; Richard C. Cronn; Hardeep Rai; Jessica W. Wright
Emergent diseases are an ever-increasing threat to forests and forest ecosystems and necessitate the development of research tools for species that often may have few preexisting resources. We sequenced the mRNA expressed by the sudden oak death pathogen Phytophthora ramorum and its most susceptible forest host, tanoak, within the same tissue at two time points after...
Grünwald, N.J.; Flier, W.G.; Sturbaum, A.K.; Garay-Serrano, E.; Bosch, van den G.B.M.; Smart, C.D.; Matuszak, J.M.; Turkensteen, L.J.; Fry, W.E.
We tested the hypothesis that the population of Phytophthora infestans in the Toluca valley region is genetically differentiated according to habitat. Isolates were sampled in three habitats from (i) wild Solanum spp. (WILD), (ii) land-race varieties in low-input production systems (RURAL), and
Marko Riedel; Gautier Calmin; Lassaad Belbahri; Francois Lefort; Monika Gotz; Stefan Wagner; Sabine. Werres
Transgenic Phytophthora ramorum strains that produce green fluorescent protein (GFP) constitutively were obtained after stable DNA integration using a polyethylene glycol and CaCl2-based transformation protocol. Green fluorescent protein production was studied in developing colonies and in different propagules of the pathogen...
Burgess, T.I.; Simamora, A.V.; White, D.; Wiliams, B.; Schwager, M.; Stukely, M.J.C.; Hardy, G.E.St.J.
During routine vegetation health surveys in the southwest of Western Australia (SWWA), several Phytophthora isolates with affinity to Clade 6a have been recovered. In this study, all known taxa from Clade 6a, P. inundata, P. humicola, P. gemini, P. ‘walnut’ and P. ‘personii’, and the new isolates
Jennifer Britt; Simone Prospero; Niklaus Grünwald; Alan Kanaskie; Everett Hansen
Since the discovery of Phytophthora ramorum in southern Oregon forests in 2001, newly infested areas are located each year. We tracked the spread and dispersal using DNA fingerprinting. While among site genetic variance was low, we did find changes in genotype presence and frequency at the site level. These genotypic differences allowed us to...
C. Robin; D. Piou; N. Feau; G. Douzon; N. Schenck; E. M. Hansen
Phytophthora lateralis has been isolated from root and collar lesions in Port-Orford Cedar (POC) trees (Chamaecyparis lawsoniana) in north-western France (Brittany). These trees, planted in hedgerows, displayed symptoms similar to the typical symptoms of POC root disease. Until now, the disease has been found outside of the...
N.J. Grünwald; E.M. Goss; K. Ivors; M. Garbelotto; F.N. Martin; S. Prospero; E. Hansen; P.J.M. Bonants; R.C. Hamelin; G. Chastagner; S. Werres; D.M. Rizzo; G. Abad; P. Beales; G.J. Bilodeau; C.L. Blomquist; C. Brasier; S.C. Brière; A. Chandelier; J.M. Davidson; S. Denman; M. Elliott; S.J. Frankel; E.M. Goheen; H. de Gruyter; K. Heungens; D. James; A. Kanaskie; M.G. McWilliams; W. Man in ' t Veld; E. Moralejo; N.K. Osterbauer; M.E. Palm; J.L. Parke; A.M. Perez Sierra; S.F. Shamoun; N. Shishkoff; P.W. Tooley; A.M. Vettraino; J. Webber; T.L. Widmer
Phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages which can only be distinguished by performing molecular marker-based analyses. However, in the recent literature there exists no consensus on naming of these lineages. Here we propose a system for naming clonal lineages of P. ramorum based...
Steven Swain; Matteo Garbelotto
The survival rate of Phytophthora ramorum was assessed when introduced at high rates into composts of varying provenance and curing time, produced by both "turned windrow" and "forced air static pile" techniques. Survival in some compost media was high and statistically indistinguishable from positive controls (P
Bonants, P.; Hagenaar-de Weerdt, M.; Gent-Pelzer, van M.; Lacourt, I.; Cooke, D.; Duncan, J.
Phytophthora fragariae Hickman, which causes strawberry red stele and raspberry root rot, is a quarantine organism for which specific and sensitive detection methods are required to test the health of planting material. Sequences of the internal transcribed spacer regions of the ribosomal gene
Richard S. Dodd; Daniel Hüberli; Tamar Y. Harnik; Brenda O' Dell; Matteo Garbelotto
We developed a branch cutting inoculation method to provide a controlled system for studying variation in response to inoculation of coast live oak (Quercus agrifolia) with Phytophthora ramorum. This method has advantages over inoculations of trees in the field, in containing the inoculum and in allowing high levels of replication...
S. Lucas; J. Parke; Y. Valachovic
Coast redwood (Sequoia sempervirens) is a host for Phytophthora ramorum but it is unclear if the pathogen represents a significant disease risk to this tree species. In an on-going field experiment, we are examining the prevalence of infection and the development of symptoms on coast redwood seedlings in naturally infested...
B.A. McPherson; D.L. Wood; S.R. Mori; A. Conrad; P. Bonello
Despite the presence of Phytophthora ramorum in northern and central California forests since at least 1994, asymptomatic coast live oaks (Quercus agrifolia NÃ©e) still remain in heavily infested stands. Coast live oak infection and mortality rates of 5 percent y-1 and 3 percent y-1, respectively, observed in long-term...
David M. Rizzo
The ultimate goal of Phytophthora ramorum research is to develop disease management strategies. To date, studies have been focused at three management levels: the individual tree, the landscape (or forest stand), and the regional to international scale (Garbelotto and others 2003, Rizzo and Garbelotto 2003, Rizzo and others 2005). I will focus my...
Rick G. Kelsey; Maia M. Beh; David C. Shaw; Daniel K. Manter
Ethanol in sapwood was analyzed along vertical transects, through small spot cankers and larger basal cankers, of Phytophthora ramorum-infected stems of Quercus agrifolia at three sites in California. Trees with large basal cankers, known to attract scolytid beetles, had a 4.3 times higher ethanol level than trees with spot cankers...
Rick G. Kelsey; Maia Beh; Dave Shaw; Daniel K. Manter
Successful infection of coast live oak (Quercus agrifolia NÃ©e) stems by Phytophthora ramorum results in the formation of a canker visible initially at the bark surface by the release of a dark red to black colored exudate referred to as "bleeding." Bark and ambrosia beetles are often attracted to diseased trees within...
Alan Kanaskie; Ellen Goheen; Nancy Osterbauer; Mike McWilliams; Everett Hansen; Wendy Sutton
Sudden oak death (SOD), caused by Phytophthora ramorum, was first discovered in Oregon forests in July 2001. Since then an interagency team has been working with landowners to eradicate the pathogen by cutting and burning all infected and nearby host plants. During the first two years of the eradication effort, all host vegetation within 15 to 30 m...
Erica M. Goss; Meg Larsen; Gary A. Chastagner; Donald R. Givens; Niklaus J. Grünwald; Barbara Jane Howlett
Recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. However, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. Phytophthora ramorum is the exotic pathogen, discovered in...
Kurt Heungens; Bjorn Gehesqui& egrave; re; Kris Van Poucke; Annelies Vercauteren; Martine. Maes
European phytosanitary measures as applied to nurseries require that potential host plants within a radius of 2 m of a Phytophthora ramorum-infected plant must be destroyed and that remaining host plants within a radius of 10 m cannot be traded until they are inspected and found to be pest free at further specific inspections. Despite the wide...
M.V. DiLeo; R.M. Bostock; D.M. Rizzo
Bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.) is the primary reservoir host of Phytophthora ramorum Werres, De Cock & Man n?t Veld in coastal California woodlands. Non-lethal foliar lesions on bay laurel trees support the majority of pathogen sporulation during the winter et season and appear to provide the...
E. Fichtner; D. Rizzo; S. Lynch; D. Rizzo; G. Buckles; J. Parke
Sudden oak death manifests as non-lethal foliar lesions on bay laurel (Umbellularia californica), which support sporulation and survival of Phytophthora ramorum in forest ecosystems. The pathogen survives the dry summers in a proportion of attached bay leaves, but the propagules responsible for survival are...
Steven F. Johnston; Michael F. Cohen; Tamas Torok; Ross K. Meentemeyer; Nathan E. Rank
Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to
Ji, Pingsheng; Koné, Daouda; Yin, Jingfang; Jackson, Kimberly L; Csinos, Alexander S
Phytophthora blight induced by Phytophthora capsici is responsible for serious yield loss in vegetable production in the United States and other countries. This study was conducted to evaluate the efficacy of Brassica cover crops used as soil amendments for managing Phytophthora blight of squash. In greenhouse studies, disease incidence on squash plants was significantly reduced by soil amendment with mustard shoots or roots used at 1 and 2.5% (plant tissue/soil, w/w). The shoots of canola used at 1 or 2.5% also suppressed disease, while the roots of canola or other crops did not reduce disease significantly. In field studies, soil amendments with mustard and canola provided the greatest disease reduction and increased squash yield significantly compared with the non-treated control. Mustard and canola did not appear to be susceptible to P. capsici. The results indicated that some Brassica crops, particularly mustard and canola, had the potential to significantly reduce Phytophthora blight on squash when used as soil amendments. As P. capsici has a remarkable ability to develop resistance to chemical fungicides, use of effective Brassica cover crops could be a biorational alternative to fungicides and a valuable component in developing integrated disease management programs. Copyright © 2011 Society of Chemical Industry.
Weg, van de W.E.; Henken, B.; Haymes, K.M.; Nijs, den A.P.M.
A gene-for-gene model is presented which explains interactions between cultivars of strawberry and races of Phytophthora fragariae var. fragariae, the causal agent of red core (red stele) root rot. The model allows the constitution of a universal differential set of strawberry genotypes and the
Eikemo, H.; Klemsdal, S.S.; Riisberg, I.; Bonants, P.J.M.; Stensvand, A.; Tronsmo, A.M.
Analysis of 44 isolates of Phytophthora cactorum, isolated from strawberry and other hosts, by AFLP showed that the crown rot pathotype is different from leather rot isolates and from P. cactorum isolated from other hosts. 16 of 23 crown rot isolates, including isolates from Europe, Japan,
Bradley R. Collins; Jennifer L. Parke; Barb Lachenbruch; Everett M. Hansen
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 inât 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...
Sonja Horatzek; Stephan König; Stefan Wagner; Sabine Werres; Lydia Schwenkbier; Karina Weber; Jörg. Weber
For Phytophthora spp. that are quarantine or regulated organisms, highly specific and sensitive diagnostic tools are recommended for surveys and monitoring. Furthermore, these diagnostic techniques should give results within a short time and should be not be too expensive. The techniques currently used for routine diagnosis of ...
Kelvin Hughes; Jenny Tomlinson; Neil Boonham; Kelly Ivors; Matteo Garbelotto; Ian Barker
Currently, diagnosis of Phytophthora ramorum involves sending samples to a laboratory for traditional isolation and morphological characterisation, and/or PCR analysis. This can take as long as 2 weeks from sampling to final diagnosis. However, the Plant Health Group, Central Science Laboratory, has produced on-site DNA extraction and real-time PCR (...
This experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC. The soil was Yonges loamy fine sand. This study was undertaken to determine the performance of seeded and seedless commercial watermelon varieties for tolerance to powdery mildew (PM) and Phytophthora fruit rot as...
The experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC. The soil was Yonges loamy fine sand. For the past 6 years, the field has been infested with Phytophthora capsici. The experimental design was a randomized complete block with four replications. Five-week-old seedli...
Margaret R. Metz; J. Morgan Varner; Kerri M. Frangioso; Ross K. Meentemeyer; David M. Rizzo
Invading species can alter ecosystems by impacting the frequency, severity, and consequences of endemic disturbance regimes (Mack and D'Antonio 1998). Phytophthora ramorum, the causal agent of the emergent disease sudden oak death (SOD), is an invasive pathogen causing widespread tree mortality in coastal forests of California and Oregon. In...
A. Vercauteren; I. De Dobbelaere; N. J. Grünwald; P. Bonants; E. Van Bockstaele; M. Maes; K. Heungens
Co-existence of both mating types A1 and A2 within the EU1 lineage of Phytophthora ramorum has only been observed in Belgium, which begs the question whether sexual reproduction is occurring. A collection of 411 Belgian P. ramorum isolates was established during a 7-year survey. Our main objectives were genetic characterization of this population to test for sexual...
Kelly Ivors; Matteo Garbelotto; Ineke De Vries; Peter Bonants
Investigating the population genetics of Phytophthora ramorum, the causal agent of sudden oak death (SOD), is critical to understanding the biology and epidemiology of this important phytopathogen. Raw sequence data (445,000 reads) of P. ramorum was provided by the Joint Genome Institute. Our objective was to develop and utilize...
Bij een inventarisatie onder telers met uitval bij kalachoë werden de bodemschimmels Pythium, Phytophthora, Rhizoctonia en Chalara elegans gevonden. Ook Botrytis en Rhizopus werden gevonden maar hiervan is het de vraag in hoeverre dit bodemschimmels zijn. In pathogeniteitsproeven werden planten
Dunn, Amara R; Smart, Christine D
Using host resistance is an important strategy for managing pepper root and crown rot caused by Phytophthora capsici. An isolate of P. capsici constitutively expressing a gene for green fluorescent protein was used to investigate pathogen interactions with roots, crowns, and stems of Phytophthora-susceptible bell pepper 'Red Knight', Phytophthora-resistant bell pepper 'Paladin', and Phytophthora-resistant landrace Criollos de Morelos 334 (CM-334). In this study, the same number of zoospores attached to and germinated on roots of all cultivars 30 and 120 min postinoculation (pi), respectively. At 3 days pi, significantly more secondary roots had necrotic lesions on Red Knight than on Paladin and CM-334 plants. By 4 days pi, necrotic lesions had formed on the taproot of Red Knight but not Paladin or CM-334 plants. Although hyphae were visible in the crowns and stems of all Red Knight plants observed at 4 days pi, hyphae were observed in crowns of only a few Paladin and in no CM-334 plants, and never in stems of either resistant cultivar at 4 days pi. These results improve our understanding of how P. capsici infects plants and may contribute to the use of resistant pepper cultivars for disease management and the development of new cultivars.
Rachel A. Stong; Eli Kolodny; Rick G. Kelsey; M.P. Gonzalez-Hernandez; Jorge M. Vivanco; Daniel K. Manter
Elicitin-mediated acquisition of plant sterols is required for growth and sporulation of Phytophthora spp. This study examined the interactions between elicitins, sterols, and tannins. Ground leaf tissue, sterols, and tannin-enriched extracts were obtained from three different plant species (California bay laurel, California black oak, and Oregon...
Elizabeth Stamm; Jennifer Parke
Tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, C.H. Cannon & S. H. Oh) is highly susceptible to Phytophthora ramorum. Symptoms include stem cankers, shoot dieback, and foliar blight. The mechanism by which P. ramorum kills the trees is not known, however. In this study we aimed to...
Justin P. Shaffer; Jennifer L. Parke
Phytophthora ramorum characteristically produces large amounts of chlamydospores in vitro, but the role of these propagules in the disease cycle remains unclear. Germination is difficult to observe and quantify if chlamydospores are not free of mycelium, and the low frequency of germination commonly reported suggests that...
It is assumed that resistance of wild Solanum species to Phytophthora infestans is multigenic on the basis of the exposure of such species to a wide range of pathogenic races of the oomycete. In order to quantify some enzymatic reactions in the host plants to the attack of the pathogen, three resist...
M. Elliot; T.R. Meagher; C. Harris; K. Searle; B.V. Purse; A. Schlenzig
This study looked at the factors that facilitated the spread of Phytophthora ramorum andP. kernoviae at two locations in the west of Scotland. Spore traps, river baiting, bait plants, and soil sampling were used to both confirm the presence of, and measure the amount of, inoculum in the environment in order...
S. Mascheretti; P.J.P. Croucher; M. Kozanitas; L. Baker; M. Garbelotto
A total of 669 isolates of Phytophthora ramorum, the pathogen responsible for Sudden Oak Death, were collected from 34 Californian forests and from the ornamental plant-trade. Seven microsatellite markers revealed 82 multilocus genotypes (MGs) of which only three were abundant (>10%). Iteratively collapsing based upon minimum Î¦ST, yielded five meta-samples and five...
In Oregon, efforts to eradicate Phytophthora ramorum from forested areas have included use of herbicides to kill infected plants. Use of herbicides on disease-infected plants leads to various outcomes, from decreased spread of disease to greater spread of disease, depending on the plant-pathogen system being examined. In this study, viburnum (
A. Vercauteren; M. Riedel; M. Maes; S. Werres; K. Heungens
This study assesses the survival of Phytophthora ramorum in the root ball of Rhododendron container plants as well as in different rootless forest substrates and a horticultural potting medium. Following inoculation of the root balls, the aboveground plant parts stayed symptomless, whilst the pathogen could be recovered with a...
Qiao, Yongli; Shi, Jinxia; Zhai, Yi; Hou, Yingnan; Ma, Wenbo
A broad range of parasites rely on the functions of effector proteins to subvert host immune response and facilitate disease development. The notorious Phytophthora pathogens evolved effectors with RNA silencing suppression activity to promote infection in plant hosts. Here we report that the Phytophthora Suppressor of RNA Silencing 1 (PSR1) can bind to an evolutionarily conserved nuclear protein containing the aspartate-glutamate-alanine-histidine-box RNA helicase domain in plants. This protein, designated PSR1-Interacting Protein 1 (PINP1), regulates the accumulation of both microRNAs and endogenous small interfering RNAs in Arabidopsis. A null mutation of PINP1 causes embryonic lethality, and silencing of PINP1 leads to developmental defects and hypersusceptibility to Phytophthora infection. These phenotypes are reminiscent of transgenic plants expressing PSR1, supporting PINP1 as a direct virulence target of PSR1. We further demonstrate that the localization of the Dicer-like 1 protein complex is impaired in the nucleus of PINP1-silenced or PSR1-expressing cells, indicating that PINP1 may facilitate small RNA processing by affecting the assembly of dicing complexes. A similar function of PINP1 homologous genes in development and immunity was also observed in Nicotiana benthamiana. These findings highlight PINP1 as a previously unidentified component of RNA silencing that regulates distinct classes of small RNAs in plants. Importantly, Phytophthora has evolved effectors to target PINP1 in order to promote infection.
Lourdes de la Mata Saez
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.
Govers, Laura L; Man In 't Veld, Willem A; Meffert, Johan P; Bouma, Tjeerd J; van Rijswick, Patricia C J; Heusinkveld, Jannes H T; Orth, Robert J; van Katwijk, Marieke M; van der Heide, Tjisse
Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp. Zostera, P. gemini, or both, strongly affected sexual reproduction by reducing seed germination sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts. © 2016 The Author(s).
This study was conducted as part of the IR-4 Ornamental Horticulture program to evaluate fungicides and biopesticides for management of leaf spot of Rhododendron caused by Phytophthora plurivora. The experiment was conducted by treating two-year old Rhododendron plants with fungicides on September 2...
Sims, Laura Lee; Sutton, Wendy; Reeser, Paul; Hansen, Everett M
Phytophthora species were systematically sampled, isolated, identified and compared for presence in streams, soil and roots of alder (Alnus species) dominated riparian ecosystems in western Oregon. We describe the species assemblage and evaluate Phytophthora diversity associated with alder. We recovered 1250 isolates of 20 Phytophthora species. Only three species were recovered from all substrates (streams, soil, alder roots): P. gonapodyides, the informally described "P. taxon Pgchlamydo", and P. siskiyouensis. P. alni ssp. uniformis along with five other species not previously recovered in Oregon forests are included in the assemblage: P.citricola s.l., P. gregata, P. gallica, P. nicotianae and P. parsiana. Phytophthora species diversity was greatest in downstream riparian locations. There was no significant difference in species diversity comparing soil and unwashed roots (the rhizosphere) to stream water. There was a difference between the predominating species from the rhizosphere compared to stream water. The most numerous species was the informally described "P. taxon Oaksoil", which was mainly recovered from, and most predominant in, stream water. The most common species from riparian forest soils and alder root systems was P. gonapodyides. © 2015 by The Mycological Society of America.
Root rot, caused by Phytophthora cinnamomi and P. plurivora in containerized Rhododendron, can cause significant losses in the nursery industry. Studies commonly use a 48 h flooding event to stimulate root infection. While flooding rarely occurs in container nurseries, plants may sit in a shallow pu...
Phytophthora kernoviae has been reported to cause bleeding stem lesions and foliar necrosis on a wide range of species, with little knowledge of the optimal conditions for infection. Detached Rhododendron ponticum leaves were inoculated with six different isolates of P. kernoviae sporangia and set ...
Papper, C.S.; Chaudhri, M.A.
In order to study the effect of the disease due to Phytophthora Cinnamomi on the vegetation in Wilson's Promontory, the mineral compositions of tolerant and susceptible plants in both healthy and diseased areas have been compared, using proton-induced x-ray emission analysis
Skottrup, Peter; Nicolaisen, Mogens; Justesen, Annemarie Fejer
Phytophthora infestans is the cause of late blight disease in potato and is an economically important pathogen worldwide. Early disease detection is important to implement disease control measures. In this study a surface plasmon resonance (SPR) immunosensor for detection of P. infestans sporangia...
Lehtinen, A; Andersson, B; Le, V H
Potato fields in Denmark, Finland, Norway and Sweden were sampled for single-lesion isolates of Phytophthora infestans. The aggressiveness of the isolates was determined on detached leaflets of potato cvs Bintje (susceptible) and Matilda (moderately resistant). The aggressiveness tests were carried...
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 t...
Phytophthora cinnamomi causes root rot of highbush blueberry and decreases plant growth, yield, and profitability for growers. Fungicides can suppress root rot, but cannot be used in certified organic production systems and fungicide resistance may develop. Alternative, non-chemical, cultural manag...
Phytophthora nicotianae is the principal causal agent of root and crown rot disease of pepper plants in Extremadura (western Spain), a spring-summer crop in this region. Preplant soil treatment by anaerobic soil disinfestation (ASD) may effectively control plant pathogens in many crop production sys...
Fang, Yufeng; Cui, Linkai; Gu, Biao; Arredondo, Felipe; Tyler, Brett M
Phytophthora is a filamentous fungus-like microorganism, but belongs to the oomycetes, in the kingdom Stramenopila. Phytophthora species are notorious as plant destroyers, causing multibillion-dollar damage to agriculture and natural ecosystems worldwide annually. For a long time, genome editing has been unattainable in oomycetes, because of their extremely low rate of homologous recombination. The recent implementation of the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated) system in the soybean pathogen Phytophthora sojae, an experimental model for oomycetes, has opened up a powerful new research capability for the oomycete community. Here, we describe a detailed protocol for CRISPR/Cas9-mediated genome editing in P. sojae, including single guide RNA (sgRNA) design and construction, efficient gene replacement, and mutant-screening strategies. This protocol should be generally applicable for most culturable oomycetes. We also describe an optimized transformation method that is useful for other Phytophthora spp. including P. capsici and P. parasitica. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.
Black shank caused by Phytophthora nicotianae occurs worldwide and is responsible for significant yield loss in tobacco production in Georgia. Management of the disease has primarily relied on utilization of tobacco cultivars with resistance to race 0 of the pathogen and application of the fungicide...
Abreha, K.B.; Alexandersson, Erik; Vossen, J.H.; Anderson, Peter; Andreasson, Erik
Pathogen attack and the plant's response to this attack affect herbivore oviposition preference and larval performance. Introduction of major resistance genes against Phytophthora infestans (Rpi-genes), the cause of the devastating late blight disease, from wild Solanum species into potato
Yana Valachovic; Chris Lee; Brendan Twieg; David Rizzo; Richard Cobb; Radoslaw Glebocki
In 2006, three forested sites infested with Phytophthora ramorum in Humboldt County, California were subjected to different combinations of treatments designed to reduce inoculum and control spread. One treatment, consisting of removal of all California bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.) and tanoak...
Potato ( Solanum tuberosum L.) is one of the most important crops in the world. The oomycete Phytophthora infestans (Mont. de Bary) is the causal agent of late blight which is the most devastating disease of the cultivated potato. It causes economic losses of several billion US dollars in crop
John Shelly; Ramnik Singh; Christine Langford; Tad Mason
Removing trees inflicted with the sudden oak death (SOD) disease is often necessary because of hazard issues or homeowner/landowner desires. An alternative to disposal of this material is to find acceptable uses for this diseased material. A series of studies is being conducted to help understand the risk of spreading the Phytophthora ramorum...
Leaves with lesions caused by Phytophthora ramorum Werres, de Cock & Man in?t Veld often drop off infected plants. Because fallen leaves might serve as sources of inoculum both for the above-ground tissues of host plants and for their roots, this study quantified the inoculum produced by such leaves on the surface of pots when exposed to...
E.M. Goss; M. Larsen; A. Vercauteren; S. Werres; K. Heungens; N.J. Grünwald
Phytophthora ramorum, the cause of sudden oak death on oak and ramorum blight on woody ornamentals, has been reported in ornamental nurseries on the West Coast of North America from British Columbia to California. Long-distance migration of P. ramorum has occurred via the nursery trade, and shipments of host plants are known to...
Man in 't Veld, W.A.; Govers, F.; Meijer, H.J.G.
A correct interpretation of isozyme patterns can be seriously hampered by the lack of supporting genetic data. The availability of the complete genome sequence of Phytophthora ramorum, enabled us to correlate isozyme profiles with the gene models predicted for these enzymes. Thirty-nine P. ramorum
Full Text Available The study aims to identify the pathogenicity of Phytophthora. capsici isolates in major pepper-producingareas in Korea and the inherit genetic pattern of phytophthora blight resistance by inocula. With five kinds oftesting materials including ‘Kataguma (Sakata Korea’ peppers, a disease-susceptible material, ‘#308’, aphytophthora blight resistance material, ‘CM334’, and their F1 and F2, respective isolates of P. capsiciobtained from Icheon, Eumseong, Buan, Imsil and Yeongyang regions together with six kinds of peppers’inoculum including PA-159 (KACC No.40482 received from Korean Agricultural Culture Collection wereused for inoculation. The disease-susceptible material ‘#308’, the resistant material ‘CM334’ and the nonsegregatinggeneration of F1 represented 4.94−5.00, 1.00−1.07, and 1.01−1.08 phytophthora blight incidencerespectively in the group comparison by isolate. This result means that the phytophthora blight resistancewas clearly distinguished among testing materials in the group comparison by P. capsici isolate. Moreover, F2segregating generation showed 1.79−2.31 phytophthora blight incidence which turned out to be identical inthe group comparison by the six isolates of P. capsici isolate and with similarity between both the resistant andsusceptible materials. Thus, the result proved that using the six isolates of P. capsici tested as inocula wassuitable to investigate the phytophthora blight resistance. When it comes to group comparison of F2segregation generation, however, isolates were divided with PA-159 isolate being the center: a groupconsisting of isolates from Icheon, Buan, and Imsil and a group consisting of Yeongyang and Eumseongisolates with higher pathogenicity. The expected segregation ratio of the phytophthora blight resistance in F2generation by isolate was analyzed. PA-159 isolate showed 3:1 or 9:3:3:1, indicating that one to two geneswere involved. On the other hand, results also proved that
McLeod, Adele; Smart, Christine D.; Fry, William E.
We have investigated the core promoter structure of the oomycete Phytophthora infestans. The transcriptional start sites (TSS) of three previously characterized P. infestans genes, Piexo1, Piexo3, and Piendo1, were determined by primer extension analyses. The TSS regions were homologous to a previously identified 16-nucleotide (nt) core sequence that overlaps the TSS in most oomycete genes. The core promoter regions of Piexo1 and Piendo1 were investigated by using a transient protoplast expression assay and the reporter gene β-glucuronidase. Mutational analyses of the promoters of Piexo1 and Piendo1 showed that there is a putative core promoter element encompassing the TSS (−2 to + 5) that has high sequence and functional homology to a known core promoter element present in other eukaryotes, the initiator element (Inr). Downstream and flanking the Inr is a highly conserved oomycete promoter region (+7 to + 15), hereafter referred to as FPR (flanking promoter region), which is also important for promoter function. The importance of the 19-nt core promoter region (Inr and FPR) in Piexo1 and Piendo1 was further investigated through electrophoretic mobility shift assays (EMSA). The EMSA studies showed that (i) both core promoters were able to specifically bind a protein or protein complex in a P. infestans whole-cell protein extract and (ii) the same mutations that reduced binding of the EMSA complex also reduced β-glucuronidase (GUS) levels in transient expression assays. The consistency of results obtained using two different assays (GUS transient assays [in vivo] and EMSA studies [in vitro]) supports a convergence of inference about the relative importance of specific nucleotides within the 19-nt core promoter region. PMID:14871940
Cárdenas, Martha; Grajales, Alejandro; Sierra, Roberto; Rojas, Alejandro; González-Almario, Adriana; Vargas, Angela; Marín, Mauricio; Fermín, Gustavo; Lagos, Luz E; Grünwald, Niklaus J; Bernal, Adriana; Salazar, Camilo; Restrepo, Silvia
Phytophthora infestans (Mont.) de Bary, the causal agent of potato late blight, is responsible for tremendous crop losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato, and more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana) and tree tomato (Solanum betaceum), all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly understood in Colombia and Venezuela. To understand the P. infestans population structure in the Northern part of the Andes, four nuclear regions (ITS, Ras, β-tubulin and Avr3a) and one mitochondrial (Cox1) region were analyzed in isolates of P. infestans sampled from different hosts in Colombia and Venezuela. Low genetic diversity was found within this sample of P. infestans isolates from crops within several regions of Colombia and Venezuela, revealing the presence of clonal populations of the pathogen in this region. We detected low frequency heterozygotes, and their distribution patterns might be a consequence of a high migration rate among populations with poor effective gene flow. Consistent genetic differentiation exists among isolates from different regions. The results here suggest that in the Northern Andean region P. infestans is a clonal population with some within-clone variation. P. infestans populations in Venezuela reflect historic isolation that is being reinforced by a recent self-sufficiency of potato seeds. In summary, the P. infestans population is mainly shaped by migration and probably by the appearance of variants of key effectors such as Avr3a.
Grünwald Niklaus J
Full Text Available Abstract Background Phytophthora infestans (Mont. de Bary, the causal agent of potato late blight, is responsible for tremendous crop losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato, and more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana and tree tomato (Solanum betaceum, all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly understood in Colombia and Venezuela. To understand the P. infestans population structure in the Northern part of the Andes, four nuclear regions (ITS, Ras, β-tubulin and Avr3a and one mitochondrial (Cox1 region were analyzed in isolates of P. infestans sampled from different hosts in Colombia and Venezuela. Results Low genetic diversity was found within this sample of P. infestans isolates from crops within several regions of Colombia and Venezuela, revealing the presence of clonal populations of the pathogen in this region. We detected low frequency heterozygotes, and their distribution patterns might be a consequence of a high migration rate among populations with poor effective gene flow. Consistent genetic differentiation exists among isolates from different regions. Conclusions The results here suggest that in the Northern Andean region P. infestans is a clonal population with some within-clone variation. P. infestans populations in Venezuela reflect historic isolation that is being reinforced by a recent self-sufficiency of potato seeds. In summary, the P. infestans population is mainly shaped by migration and probably by the appearance of variants of key effectors such as Avr3a.
Jennifer Parke; Eunsung Oh; Steve Voelker; Everett Hansen; Gerri Buckles; Barb Lachenbruch
Culture, detection with diagnostic PCR, and microscopy demonstrated the presence of Phytophthora ramorum in the sapwood of mature, naturally infected tanoak (Lithocarpus densiflorus) trees in Curry County, Oregon. The pathogen was strongly associated with discolored sapwood (P
S. Rooney-Latham; C. L. Blomquist; T. Swiecki; E. Bernhardt; S.J. Frankel
Phytophthora tentaculata Kröber & Marwitz, has been detected in several native plant nurseries in 4 California counties and in restoration sites on orange sticky monkey flower (Diplacus aurantiacus subsp. aurantiacus (W. Curtis) Jeps. [Scrophulariaceae]), toyon (Heteromeles...
Joanne Mudge on "Phytophthora capsici - Loss of Heterozygosity (LOH): A Widespread Mechanism for Rapid Mutation" at the 2012 Sequencing, Finishing, Analysis in the Future Meeting held June 5-7, 2012 in Santa Fe, New Mexico.
Nagy, Zoltán A; Bakonyi, József; Ersek, Tibor
A new Phytophthora disease of common alder (Alnus glutinosa) similar to that previously reported in several countries in Europe has been observed in Hungary. Based on these earlier studies, the alder Phytophthora was considered likely to be a hybrid between P cambivora and a P fragariae-like species: across Europe a range of new alder Phytophthora is spreading that comprise a range of heteroploid hybrids including a 'standard' hybrid type and several other hybrid types termed 'variants'. Phenotypic and molecular features of the pathogen in Hungary were characterised and compared with isolates from elsewhere. The morphologies of five isolates from one region (Hévíz) resembled the common, 'standard' type, whereas the three isolates from another region (Hanság) exhibited traits similar to those of one of the 'variant' types, ie the Swedish 'variant'. Molecular markers of these two groups of Hungarian isolates also represented a good fit to those of the standard type and the Swedish variant, respectively. Isozyme patterns and profiles of restriction fragments of the entire internal transcribed spacer (ITS) region or mitochondrial DNAs and of RAPD-PCR products did not differ within a group, but distinct polymorphisms were exhibited between the two groups of isolates. Southern analysis of random amplified polymorphic DNA (RAPD) revealed the homologous nature of co-migrating bands of P cambivora and the isolates of alder Phytophthora. Furthermore, restriction fragment profiles of the ITS region of ribosomal DNAs and the mtDNAs were consistent with reported biparental origin of alder Phytophthora. The hybrid status of these continuously evolving pathogens raises many issues and challenges concerning efficient control measures.
Miles, Timothy D; Martin, Frank N; Coffey, Michael D
Several isothermal amplification techniques recently have been developed that are tolerant of inhibitors present in many plant extracts, which can reduce the need for obtaining purified DNA for running diagnostic assays. One such commercially available technique that has similarities with real-time polymerase chain reaction (PCR) for designing primers and a labeled probe is recombinase polymerase amplification (RPA). This technology was used to develop two simple and rapid approaches for detection of Phytophthora spp.: one genus-specific assay multiplexed with a plant internal control and the other species-specific assays for Phytophthora ramorum and P. kernoviae. All assays were tested for sensitivity (ranging from 3 ng to 1 fg of DNA) and specificity using DNA extracted from more than 136 Phytophthora taxa, 21 Pythium spp., 1 Phytopythium sp., and a wide range of plant species. The lower limit of linear detection using purified DNA was 200 to 300 fg of DNA in all pathogen RPA assays. Six different extraction buffers were tested for use during plant tissue maceration and the assays were validated in the field by collecting 222 symptomatic plant samples from over 50 different hosts. Only 56 samples were culture positive for Phytophthora spp. whereas 91 were positive using the Phytophthora genus-specific RPA test and a TaqMan real-time PCR assay. A technique for the generation of sequencing templates from positive RPA amplifications to confirm species identification was also developed. These RPA assays have added benefits over traditional technologies because they are rapid (results can be obtained in as little as 15 min), do not require DNA extraction or extensive training to complete, use less expensive portable equipment than PCR-based assays, and are significantly more specific than current immunologically based methods. This should provide a rapid, field-deployable capability for pathogen detection that will facilitate point-of-sample collection processing
Cepeda Pena, William Enrique
The article tries on the wrong use of the artificial light, of the main problems of the light contamination, dispersion of the light, noxious effects of the light contamination, ecological effects, effects on the man's biological rhythm, economic effects and effects about the civic and vial security, among other topics
Lipscomb, I P; Pinchin, H E; Collin, R; Harris, K; Keevil, C W
Regulations recommend the routine application of biochemical tests, such as the Ninhydrin or Biuret tests, to confirm the efficacy of hospital sterile service department (SSD) washer-disinfector cycles in removing proteinaceous material, particularly with respect to prions. The effectiveness of these methods relies on both the effective sampling of the instruments and the sensitivity of the tests employed. Two commercially available contamination assessment tests were evaluated for their sensitivity to ME7 brain homogenate on surgical-grade stainless steel surfaces. Controls were visualized by the application of episcopic differential interference contrast/Epi-fluorecence microscopy (EDIC/EF) combined with the sensitive fluorescent reagent, SYPRO Ruby, which has been shown previously to rapidly visualize and assess low levels of contamination on medical devices. The Ninhydrin test displayed a minimum level of detection observed by 75% of volunteers (MLD(75)) of 9.25 microg [95% confidence interval (95% CI) 8.6-10.0 microg]. The Biuret test provided better sensitivity, with a MLD(75) of 6.7 microg (95% CI 5.4-8.2 microg). However, much lower concentrations of proteinaceous soiling (pg) were visualized using the EDIC/EF microscopy method. From these findings, it is clear that these approved colorimetric tests of cleaning are relatively insensitive. This investigation demonstrates how large amounts (up to 6.5 microg) of proteinaceous brain contamination could remain undetected and the instruments deemed clean using such methods. The application of more sensitive cleanliness evaluation methods should be applied to reduce the risk of iatrogenic transmission of prion disease in 'high-risk' instruments such as neurosurgical devices.
Milenković, Slobodan; Sretenović, Dušica
Phytophthora fragariae was first detected in the Republic of Serbia in 2002, and it has been included in A2 quarantine list of damaging organisms since 2003. The project titled ‘Monitoring of soft fruit mother plantings aimed at the control of Phytophthora fragariae, causal agent of root rot’ was realized over 2004 – 2005 aiming at determination of population rate of the pathogen and the control of raspberry planting material. Over that period, the total 388 samples were tested. Collected sam...
Zhu, Yun J; Agbayani, Ricelle; Moore, Paul H
Phytophthora spp., some of the more important casual agents of plant diseases, are responsible for heavy economic losses worldwide. Plant defensins have been introduced as transgenes into a range of species to increase host resistance to pathogens to which they were originally susceptible. However, the effectiveness and mechanism of interaction of the defensins with Phytophthora spp. have not been clearly characterized in planta. In this study, we expressed the Dahlia merckii defensin, DmAMP1, in papaya (Carica papaya L.), a plant highly susceptible to a root, stem, and fruit rot disease caused by Phytophthora palmivora. Extracts of total leaf proteins from transformed plants inhibited growth of Phytophthora in vitro and discs cut from the leaves of transformed plants inhibited growth of Phytophthora in a bioassay. Results from our greenhouse inoculation experiments demonstrate that expressing the DmAMP1 gene in papaya plants increased resistance against P. palmivora and that this increased resistance was associated with reduced hyphae growth of P. palmivora at the infection sites. The inhibitory effects of DmAMP1 expression in papaya suggest this approach has good potential to impart transgenic resistance against Phytophthora in papaya.
Ye, Wenwu; Wang, Yang; Shen, Danyu; Li, Delong; Pu, Tianhuizi; Jiang, Zide; Zhang, Zhengguang; Zheng, Xiaobo; Tyler, Brett M; Wang, Yuanchao
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.
Reeksting, B J; Olivier, N A; van den Berg, N
Avocado (Persea americana Mill.) is a commercially important fruit crop worldwide. A major limitation to production is the oomycete Phytophthora cinnamomi, which causes root rot leading to branch-dieback and tree death. The decline of orchards infected with P. cinnamomi occurs much faster when exposed to flooding, even if flooding is only transient. Flooding is a multifactorial stress compromised of several individual stresses, making breeding and selection for tolerant varieties challenging. With more plantations occurring in marginal areas, with imperfect irrigation and drainage, understanding the response of avocado to these stresses will be important for the industry. Maintenance of energy production was found to be central in the response to flooding, as seen by up-regulation of transcripts related to glycolysis and induction of transcripts related to ethanolic fermentation. Energy-intensive processes were generally down-regulated, as evidenced by repression of transcripts related to processes such as secondary cell-wall biosynthesis as well as defence-related transcripts. Aquaporins were found to be down-regulated in avocado roots exposed to flooding, indicating reduced water-uptake under these conditions. The transcriptomic response of avocado to flooding and P. cinnamomi was investigated utilizing microarray analysis. Differences in the transcriptome caused by the presence of the pathogen were minor compared to transcriptomic perturbations caused by flooding. The transcriptomic response of avocado to flooding reveals a response to flooding that is conserved in several species. This data could provide key information that could be used to improve selection of stress tolerant rootstocks in the avocado industry.
Döring, G; Ulrich, M; Müller, W; Bitzer, J; Schmidt-Koenig, L; Münst, L; Grupp, H; Wolz, C; Stern, M; Botzenhart, K
Pseudomonas aeruginosa was isolated from sinks of washing basins, showers, toilets and bathtubs, from the personnel and patients of a mixed infectious disease ward in a German children's hospital during a prospective 4-week epidemiological study. 81% of all sinks were contaminated with P. aeruginosa strains. Upon entering the hospital, all personnel hand cultures were P. aeruginosa-negative. However, during duty, 42.5% of the personnel members carried different P. aeruginosa strains on their hands. Detection of P. aeruginosa strains in sinks preceding the isolation of identical genotypes from personnel hands suggested a transmission route from sinks to hands. Opening of water taps generated aerosols containing P. aeruginosa sink organisms which contaminated hands during hand washing. Survival times of various P. aeruginosa strains in aerosols was dependent on strain characteristics, light and humidity, and t 1/2 differed between 3-76 min. Heating of washing basin sinks to 70 degrees C with a new, safe and inexpensive device inhibited bacterial growth in sinks, generation of P. aeruginosa aerosols, and resulted in hand cultures negative for P. aeruginosa after washing.
Zhao, Wei; Wang, Tao; Liu, Shusen; Chen, Qingqing; Qi, Rende
In eukaryotic organisms, histone acetyltransferase complexes are coactivators that are important for transcriptional activation by modifying chromatin. In this study, a gene (PsGcn5) from Phytophthora sojae encoding a histone acetyltransferase was identified as a homolog of one component of the histone acetyltransferase complex from yeasts to mammals. PsGcn5 was constitutively expressed in each stage tested, but had a slightly higher expression in sporulating hyphae and 3 h after infection. PsGcn5-silenced mutants were generated using polyethylene glycol-mediated protoplast stable transformation. These mutants had normal development, but compared to wild type strains they had higher sensitivity to hydrogen peroxide (H2O2) and significantly reduced virulence in soybean. Diaminobenzidine staining revealed an accumulation of H2O2 around the infection sites of PsGcn5-silenced mutants but not for wild type strains. Inhibition of the plant NADPH oxidase by diphenyleneiodonium prevented host-derived H2O2 accumulation in soybean cells and restored infectious hyphal growth of the mutants. Thus, we concluded that PsGcn5 is important for growth under conditions of oxidative stress and contributes to the full virulence of P. sojae by suppressing the host-derived reactive oxygen species. Copyright © 2015 Elsevier Ltd. All rights reserved.
Kim, Yu Seung; Zelenay, Piotr; Johnston, Christina
An electrochemical cell assembly that is expected to prevent or at least minimize electrode contamination includes one or more getters that trap a component or components leached from a first electrode and prevents or at least minimizes them from contaminating a second electrode.
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Comparing a combination of penicillin G and gentamicin to a combination of clindamycin and amikacin as prophylactic antibiotic regimens in prevention of clean contaminated wound infections in cancer surgery
El-Mahallawy, H.A.; Hassan, S.Sh.; Khalifa, H.I.; Safa, M.M.E.; Khafagy, M.M.
Background and aim: Appropriate antibiotic selection and timing of administration for prophylaxis are crucial to reduce the likelihood of surgical site infection (SSI) after a clean contaminated cancer surgery. Our aim is to compare the use of two prophylactic antibiotic (PA) regimens as regards efficacy, timing, and cost. Patients and methods: Two hundred patients with gastric, bladder, or colorectal cancer were randomized to receive preoperative PA, group A received penicillin G sodium and gentamicin and group B received clindamycin and amikacin intravenously. The demographic data of patients were collected, and they were observed for wound infections. Results: Infected wounds occurred in 19 patients with a rate of 9.5%. Highest incidence of SSI was among bladder cancer patients (14.2%); p = 0.044. The rate of SSI was 11 % in group A, and 8% in group B, p = 0.469. The cost of PA administered in group A was significantly less than that of group B (21.96 ± 3.22 LE versus 117.05 ± 12.74 LE, respectively; p < 0.001). SSI tended to be higher among those who had longer time for antibiotic and incision (≥ 30 min) than those who had shorter time interval (<30 min), (13% vs. 6.5%, respectively). Conclusion: Both penicillin + gentamicin and clindamycin + amikacin are safe and effective for the prevention of SSI in clean contaminated operative procedures. In a resource limited hospital, a regimen including penicillin + gentamicin is a cost-effective alternative for the more expensive and broader coverage of clindamycin + amikacin. Timing of PA is effective in preventing SSIs when administered 30 min before the start of surgery
Ali, Shahin S.; Shao, Jonathan; Lary, David J.; Kronmiller, Brent A.; Shen, Danyu; Strem, Mary D.; Amoako-Attah, Ishmael; Akrofi, Andrew Yaw; Begoude, B.A. Didier; ten Hoopen, G. Martijn; Coulibaly, Klotioloma; Kebe, Boubacar Ismaël; Melnick, Rachel L.; Guiltinan, Mark J.; Tyler, Brett M.; Meinhardt, Lyndel W.
Phytophthora megakarya (Pmeg) and Phytophthora palmivora (Ppal) are closely related species causing cacao black pod rot. Although Ppal is a cosmopolitan pathogen, cacao is the only known host of economic importance for Pmeg. Pmeg is more virulent on cacao than Ppal. We sequenced and compared the Pmeg and Ppal genomes and identified virulence-related putative gene models (PGeneM) that may be responsible for their differences in host specificities and virulence. Pmeg and Ppal have estimated genome sizes of 126.88 and 151.23 Mb and PGeneM numbers of 42,036 and 44,327, respectively. The evolutionary histories of Pmeg and Ppal appear quite different. Postspeciation, Ppal underwent whole-genome duplication whereas Pmeg has undergone selective increases in PGeneM numbers, likely through accelerated transposable element-driven duplications. Many PGeneMs in both species failed to match transcripts and may represent pseudogenes or cryptic genetic reservoirs. Pmeg appears to have amplified specific gene families, some of which are virulence-related. Analysis of mycelium, zoospore, and in planta transcriptome expression profiles using neural network self-organizing map analysis generated 24 multivariate and nonlinear self-organizing map classes. Many members of the RxLR, necrosis-inducing phytophthora protein, and pectinase genes families were specifically induced in planta. Pmeg displays a diverse virulence-related gene complement similar in size to and potentially of greater diversity than Ppal but it remains likely that the specific functions of the genes determine each species’ unique characteristics as pathogens. PMID:28186564
Eikemo, H.; Klemsdal, S.S.; Riisberg, I.; Bonants, P.J.M.; Stensvand, A.; Tronsmo, A.M.
Analysis of 44 isolates of Phytophthora cactorum, isolated from strawberry and other hosts, by AFLP showed that the crown rot pathotype is different from leather rot isolates and from P. cactorum isolated from other hosts. 16 of 23 crown rot isolates, including isolates from Europe, Japan, Australia, and New Zealand, were identical in an analysis based on 96 polymorphic bands from seven primer combinations. Leather rot isolates of strawberry could not be distinguished from isolates from other...
Diana Elizabeth Toapanta-Gallegos; Luis Eduardo Morillo-Velastegui; William Fernando Viera-Arroyo
One of the most damaging diseases in cultivation of avocado (Persea americana Mill.) is root rot associated with Phytophthora cinnamomi Rands. This disease causes progressive wilt and even death of the tree. The objective of this study was to identify the presence of P. cinnamomi in two productive areas of avocado in Ecuador using the molecular technique PCR-RFLP. Tree root samples were obtained with root rot symptoms in the production areas,...
Brurberg, May Bente; Elameen, Abdelhameed; Le, Ving Hong
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...... types (60 % A1) support the hypothesis that sexual reproduction is contributing notably to the genetic variation of P. infestans in the Nordic countries....
Sixty-one isolates of Phytophthora nicotianae were tested for pathogenicity to tobacco and tomato. All the isolates but one from tobacco were pathogenic to tobacco but none of the isolates from tobacco were pathogenic to tomato. Of the 53 isolates from non tobacco hosts, 19 proved pathogenic to tomato. Seven isolates from different non tobacco hosts colonized the tobacco stem and produced necrosis but not black shank. Five isolates colonized the tomato stem without causing disease...
Gao, Ruifang; Cheng, Yinghui; Wang, Ying; Wang, Ying; Guo, Liyun; Zhang, Guiming
Phytophthora fragariae var. fragariae is a serious plant-pathogenic fungus causing red core disease in strawberries, resulting in a larger number of fruit produced, and the fungus has been regulated as a quarantine pest of many countries and regions. Here, we announce the genome sequence of P.?fragariae var. fragariae, and this information might provide insight into the mechanism of pathogenicity and host specificity of this pathogen, as well as help us further identify targets for fungicides.
Weg, van de, W.E.; Henken, B.; Haymes, K.M.; Nijs, den, A.P.M.
A gene-for-gene model is presented which explains interactions between cultivars of strawberry and races of Phytophthora fragariae var. fragariae, the causal agent of red core (red stele) root rot. The model allows the constitution of a universal differential set of strawberry genotypes and the characterizing of fungal isolates into races, the genotyping of strawberry cultivars and selections in a breeding programme, and facilitates the search for linked molecular markers for more efficient s...
Chibucos, M. Constantine; Morris, Paul F.
Polyamines are ubiquitous biologically active aliphatic cations that are at least transiently available in the soil from decaying organic matter. Our objectives in this study were to characterize polyamine uptake kinetics in Phytophthora sojae zoospores and to quantify endogenous polyamines in hyphae, zoospores, and soybean roots. Zoospores contained 10 times more free putrescine than spermidine, while hyphae contained only 4 times as much free putrescine as spermidine. Zoospores contained no...
Le Grand-Pernot, Francoise; Pellegrin, F.
Up to now, neither cytological nor genetical studies have clearly demonstrated the 'ploidy' degree of somatic nuclei in different species of Phytophthora. Two complementary studies, using biological effect of γ rays upon zoospores, and microspectrophotometric techniques measuring relative amount of DNA by nucleus in zoospores or in hyphae, allowed to demonstrate diploid nature of the vegetative phase in P. palmivora (BUTLER) BUTLER and P. parasitica DASTUR cycles [fr
Wong, James; Gao, Lei; Yang, Yang; Zhai, Jixian; Arikit, Siwaret; Yu, Yu; Duan, Shuyi; Chan, Vicky; Xiong, Qin; Yan, Jun; Li, Shengben; Liu, Renyi; Wang, Yuanchao; Tang, Guiliang; Meyers, Blake C; Chen, Xuemei; Ma, Wenbo
The genus Phytophthora consists of many notorious pathogens of crops and forestry trees. At present, battling Phytophthora diseases is challenging due to a lack of understanding of their pathogenesis. We investigated the role of small RNAs in regulating soybean defense in response to infection by Phytophthora sojae, the second most destructive pathogen of soybean. Small RNAs, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), are universal regulators that repress target gene expression in eukaryotes. We identified known and novel small RNAs that differentially accumulated during P. sojae infection in soybean roots. Among them, miR393 and miR166 were induced by heat-inactivated P. sojae hyphae, indicating that they may be involved in soybean basal defense. Indeed, knocking down the level of mature miR393 led to enhanced susceptibility of soybean to P. sojae; furthermore, the expression of isoflavonoid biosynthetic genes was drastically reduced in miR393 knockdown roots. These data suggest that miR393 promotes soybean defense against P. sojae. In addition to miRNAs, P. sojae infection also resulted in increased accumulation of phased siRNAs (phasiRNAs) that are predominantly generated from canonical resistance genes encoding nucleotide binding-leucine rich repeat proteins and genes encoding pentatricopeptide repeat-containing proteins. This work identifies specific miRNAs and phasiRNAs that regulate defense-associated genes in soybean during Phytophthora infection. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.
Zhang, Li; Yajima, Arata; Ojika, Makoto
The crop destroyer Phytophthora uses mating hormones α1 and α2 to commence its sexual reproduction. The α1-induced sexual reproduction of the A2 mating type was unexpectedly found to be interfered with by the counterhormone α2 that the A2 type itself produces to induce the sexual reproduction of the A1 type. A plausible mechanism is proposed based on structure-activity relationships.
31 oct. 2013 ... diamètre 90 mm. Le transfert des isolats s'est fait par prélèvement sur le front de croissance d'un fragment de gélose, contenant de très fins filaments mycéliens. Clonage des isolats de Phytophthora spp par isolements monozoospores : Les isolats issus de cultures en masses ont été clonés par isolement.
Phytophthora root rot of soybean (Glycine max Merr.) is caused by the oomycete Phytophthora sojae (Kaufm. and Gerd.). P. sojae has a narrow host range, consisting primarily of soybean, and it is a serious pathogen worldwide. It exists in root and stem tissues as mycelium, wherein it can form oospo...
Yana Valachovic; Dave Rizzo; Brendan Twieg
We are working to evaluate risks associated with human spread of the sudden oak death (SOD) pathogen, Phytophthora ramorum, to currently uninfested areas in California. Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl.) root disease (POC RD), caused by Phytophthora lateralis, has brought...
Català, Santiago; Pérez-Sierra, Ana; Abad-Campos, Paloma
Phytophthora is one of the most important and aggressive plant pathogenic genera in agriculture and forestry. Early detection and identification of its pathways of infection and spread are of high importance to minimize the threat they pose to natural ecosystems. eDNA was extracted from soil and water from forests and plantations in the north of Spain. Phytophthora-specific primers were adapted for use in high-throughput Sequencing (HTS). Primers were tested in a control reaction containing eight Phytophthora species and applied to water and soil eDNA samples from northern Spain. Different score coverage threshold values were tested for optimal Phytophthora species separation in a custom-curated database and in the control reaction. Clustering at 99% was the optimal criteria to separate most of the Phytophthora species. Multiple Molecular Operational Taxonomic Units (MOTUs) corresponding to 36 distinct Phytophthora species were amplified in the environmental samples. Pyrosequencing of amplicons from soil samples revealed low Phytophthora diversity (13 species) in comparison with the 35 species detected in water samples. Thirteen of the MOTUs detected in rivers and streams showed no close match to sequences in international sequence databases, revealing that eDNA pyrosequencing is a useful strategy to assess Phytophthora species diversity in natural ecosystems.
Phytophthora megakarya (Pmeg) and Phytophthora palmivora (Ppal) cause black pod rot of Theobroma cacao. Of these two clade 4 species; Pmeg is more virulent and is displacing Ppal on cacao in many cacao production areas in Africa. To understand the advantages Pmeg has over Ppal, we compared symptom...
R.G. Linderman; E.A. Davis
The recent incidence of Ramorum blight, caused by Phytophthora ramorum, on many nursery crops has focused attention on improving management strategies against Phytophthora diseases in nurseries. We evaluated several chemical agents that target Oomycete pathogens for their capacity to inhibit infection of rhododendron or lilac...
... Health Matters Information on Specific Types of Emergencies Contamination vs. exposure Recommend on Facebook Tweet Share Compartir ... contaminate their surroundings and personal property. Types of Contamination Internal Contamination Internal contamination occurs when people swallow ...
Brunner, Frédéric; Rosahl, Sabine; Lee, Justin; Rudd, Jason J; Geiler, Carola; Kauppinen, Sakari; Rasmussen, Grethe; Scheel, Dierk; Nürnberger, Thorsten
Innate immunity, an ancient form of defense against microbial infection, is well described for animals and is also suggested to be important for plants. Discrimination from self is achieved through receptors that recognize pathogen-associated molecular patterns (PAMPs) not found in the host. PAMPs are evolutionarily conserved structures which are functionally important and, thus, not subject to frequent mutation. Here we report that the previously described peptide elicitor of defense responses in parsley, Pep-13, constitutes a surface-exposed fragment within a novel calcium-dependent cell wall transglutaminase (TGase) from Phytophthora sojae. TGase transcripts and TGase activity are detectable in all Phytophthora species analyzed, among which are some of the most destructive plant pathogens. Mutational analysis within Pep-13 identified the same amino acids indispensable for both TGase and defense-eliciting activity. Pep-13, conserved among Phytophthora TGases, activates defense in parsley and potato, suggesting its function as a genus-specific recognition determinant for the activation of plant defense in host and non-host plants. In summary, plants may recognize PAMPs with characteristics resembling those known to trigger innate immune responses in animals.
Silvar, C; Díaz, J; Merino, F
ABSTRACT Reliable and sensitive quantification of Phytophthora capsici in pepper plants is of crucial importance in managing the multiple syndromes caused by this pathogen. A real-time polymerase chain reaction (PCR) assay was developed for the determination of P. capsici in pepper tissues. DNA levels of a highly virulent and a less virulent isolate were measured in different pepper genotypes with varying degrees of resistance. Using SYBR Green and specific primers for P. capsici, the minimal amount of pathogen DNA quantified was 10 pg. Pathogen DNA was recorded as early as 8 h postinoculation. Thereafter, the increase was rapid in susceptible cultivars and slower in resistant ones. The amount of pathogen DNA quantified in each pepper genotype correlated with susceptibility to Phytophthora root rot. Likewise, there was a relationship between the virulence of the pathogen and the degree of colonization. Differences also were found in oomycete amount among pepper tissues, with maximal pathogen biomass occurring in stems. The real-time PCR technique developed in this study was sensitive and robust enough to assess both pathogen development and resistance to Phytophthora root rot in different pepper genotypes.
Reeves, Gregory; Monroy-Barbosa, Ariadna; Bosland, Paul W
A novel disease resistance inhibitor gene (inhibitor of P. capsici resistance [Ipcr]), found in the chile pepper (Capsicum annuum) variety 'New Mexico Capsicum Accession 10399' (NMCA10399), inhibits resistance to Phytophthora capsici but not to other species of Phytophthora. When a highly P. capsici-resistant variety was hybridized with NMCA10399, the resultant F1 populations, when screened, were completely susceptible to P. capsici for root rot and foliar blight disease syndromes, despite the dominance inheritance of P. capsici resistance in chile pepper. The F2 population displayed a 3:13 resistant-to-susceptible (R:S) ratio. The testcross population displayed a 1:1 R:S ratio, and a backcross population to NMCA10399 displayed complete susceptibility. These results demonstrate the presence of a single dominant inhibitor gene affecting P. capsici resistance in chile pepper. Moreover, when lines carrying the Ipcr gene were challenged against six Phytophthora spp., the nonhost resistance was not overcome. Therefore, the Ipcr gene is interfering with host-specific resistance but not the pathogen- or microbe-associated molecular pattern nonhost responses.
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.
Ma, Zhenchuan; Zhu, Lin; Song, Tianqiao; Wang, Yang; Zhang, Qi; Xia, Yeqiang; Qiu, Min; Lin, Yachun; Li, Haiyang; Kong, Liang; Fang, Yufeng; Ye, Wenwu; Wang, Yan; Dong, Suomeng; Zheng, Xiaobo; Tyler, Brett M; Wang, Yuanchao
The extracellular space (apoplast) of plant tissue represents a critical battleground between plants and attacking microbes. Here we show that a pathogen-secreted apoplastic xyloglucan-specific endoglucanase, PsXEG1, is a focus of this struggle in the Phytophthora sojae -soybean interaction. We show that soybean produces an apoplastic glucanase inhibitor protein, GmGIP1, that binds to PsXEG1 to block its contribution to virulence. P. sojae , however, secretes a paralogous PsXEG1-like protein, PsXLP1, that has lost enzyme activity but binds to GmGIP1 more tightly than does PsXEG1, thus freeing PsXEG1 to support P. sojae infection. The gene pair encoding PsXEG1 and PsXLP1 is conserved in many Phytophthora species, and the P. parasitica orthologs PpXEG1 and PpXLP1 have similar functions. Thus, this apoplastic decoy strategy may be widely used in Phytophthora pathosystems. Copyright © 2017, American Association for the Advancement of Science.
Savidor, Alon [ORNL; Donahoo, Ryan S [ORNL; Hurtado-Gonzales, Oscar [University of Tennessee, Knoxville (UTK); Land, Miriam L [ORNL; Shah, Manesh B [ORNL; Lamour, Kurt H [ORNL; McDonald, W Hayes [ORNL
Phytophthora ramorum and Phytophthora sojae are destructive plant pathogens. Phytophthora sojae has a narrow host range whereas P. ramorum has a wide host range. A global proteomic comparison of the vegetative (mycelium) and infective (germinating-cyst) life-stages of P. sojae and P. ramorum was conducted to identify candidate proteins involved in host range, early infection and vegetative growth. Sixty-two candidates for early infection, 26 candidates for vegetative growth, and numerous proteins that may be involved in defining host specificity were identified. In addition, common life stage proteomic trends between the organisms were observed. In mycelia, proteins involved in transport and metabolism of amino acids, carbohydrates and other small molecules were up-regulated. In the germinating cysts, up-regulated proteins associated with lipid transport and metabolism, cytoskeleton and protein synthesis were observed. It appears that the germinating cyst catabolizes lipid reserves through the -oxidation pathway to drive the extensive protein synthesis necessary to produce the germ tube and initiate infection. Once inside the host, the pathogen switches to vegetative growth, where energy is derived from glycolysis and utilized for synthesis of amino acids and other molecules that assist survival in the plant tissue.
Daniel D. Rosa
Full Text Available Due to the economic importance of gummosis disease for the citriculture, studies on P. parasitica-Citrus interaction comprise a significant part in the Brazilian Citrus genome data bank (CitEST. Among them, two cDNA libraries constructed from two different growth conditions of the P. parasitica pathogen are included which has generated the PP/CitEST database (CitEST - Center APTA Citros Sylvio Moreira/IAC- Millennium Institute. Through this genomic approach and clustering analyses the following has been observed: out of a total of 13,285 available in the Phytophthora parasitica database, a group of 4,567 clusters was formed, comprising 2,649 singlets and 1,918 contigs. Out of a total of 4,567 possible genes, only 2,651 clusters were categorized; among them, only 4.3% shared sequence similarities with pathogenicity factors and defense. Some of these possible genes (103 corresponding to 421 ESTs, were characterized by phylogenetic analysis and discussed. A comparison made with the COGEME database has shown homology which may be part of an evolutionary pathogenicity pathway present in Phytophthora and also in other fungi. Many of the genes which were identified here, which may encode proteins associated to mechanisms of citrus gummosis pathogenicity, represent only one facet of the pathogen-host Phytophthora - Citrus interaction.
Full Text Available The paper presents the results of the study performed with aims to determine the presence and diversity of Phytophthora species on maple trees in Serbia. Due to high aggressiveness and their multicyclic nature, presence of these pathogens is posing significant threat to forestry and biodiversity. In total, 29 samples of water, soil and tissues were taken from 10 different localities, and six different maple hosts were tested. After the isolation tests, 17 samples from five different maple hosts were positive for the presence of Phytophthora spp., and 31 isolates were obtained. After the detailed morphological and physiological classification, four distinct groups of isolates were separated. DNA was extracted from selected representative isolates and molecular identification with sequencing of ITS region was performed. Used ITS4 and ITS6 primers successfully amplified the genomic DNA of chosen isolates and morphological identification of obtained isolates was confirmed after the sequencing. Four different Phytophthora species were detected, including P. cactorum, P. gonapodyides, P. plurivora and P. lacustris. The most common isolated species was homothallic, and with very variable and semipapillate sporangia, P. plurivora with 22 obtained isolates. This is the first report of P. plurivora and P. gonapodyides on A. campestre, P. plurivora and P. lacustris on Acer heldreichii and first report of P. lacustris on A. pseudoplatanus and A. tataricum in Serbia. [Projekat Ministarstva nauke Republike Srbije, br. TR 37008
Wang, Yong; Sun, Yang; Zhang, Ying; Zhang, Xing; Feng, Juntao
Phytophthora blight of pepper caused by Phytophthora capsici Leonian is a destructive disease throughout the world. Cuminic acid, extracted from the seed of Cuminum cyminum L., belongs to the benzoic acid chemical class. In this study, the sensitivity and biochemical response of P. capsici to cuminic acid was determined. The mean EC50 (50% effective concentration) values for cuminic acid in inhibiting mycelial growth and zoospore germination of the 54 studied P. capsici isolates were 14.54 ± 5.23 μg/mL and 6.97 ± 2.82 μg/mL, respectively. After treatment with cuminic acid, mycelial morphology, sporangium formation and mycelial respiration were significantly influenced; cell membrane permeability and DNA content increased markedly, but pyruvic acid content, adenosine triphosphate (ATP) content, and ATPase activity decreased compared with the untreated control. In pot experiments, cuminic acid exhibited both protective and curative activity. Importantly, POD and PAL activity of the pepper leaves increased after being treated with cuminic acid. These indicated that cuminic acid not only showed antifungal activity, but also could improve the defense capacity of the plants. All the results suggested that cuminic acid exhibits the potential to be developed as a new phytochemical fungicide, and this information increases our understanding of the mechanism of action of cuminic acid against Phytophthora capsici.
Wu, Dongliang; Navet, Natasha; Liu, Yingchao; Uchida, Janice; Tian, Miaoying
As an agriculturally important oomycete genus, Phytophthora contains a large number of destructive plant pathogens that severely threaten agricultural production and natural ecosystems. Among them is the broad host range pathogen P. palmivora, which infects many economically important plant species. An essential way to dissect their pathogenesis mechanisms is genetic modification of candidate genes, which requires effective transformation systems. Four methods were developed for transformation of Phytophthora spp., including PEG(polyethylene glycol)/CaCl2 mediated protoplast transformation, electroporation of zoospores, microprojectile bombardment and Agrobacterium-mediated transformation (AMT). Among them, AMT has many advantages over the other methods such as easy handling and mainly generating single-copy integration in the genome. An AMT method previously reported for P. infestans and P. palmivora has barely been used in oomycete research due to low success and low reproducibility. In this study, we report a simple and efficient AMT system for P. palmivora. Using this system, we were able to reproducibly generate over 40 transformants using zoospores collected from culture grown in a single 100 mm-diameter petri dish. The generated GFP transformants constitutively expressed GFP readily detectable using a fluorescence microscope. All of the transformants tested using Southern blot analysis contained a single-copy T-DNA insertion. This system is highly effective and reproducible for transformation of P. palmivora and expected to be adaptable for transformation of additional Phytophthora spp. and other oomycetes. Its establishment will greatly accelerate their functional genomic studies.
Lassiter, Erica S; Russ, Carsten; Nusbaum, Chad; Zeng, Qiandong; Saville, Amanda C; Olarte, Rodrigo A; Carbone, Ignazio; Hu, Chia-Hui; Seguin-Orlando, Andaine; Samaniego, Jose A; Thorne, Jeffrey L; Ristaino, Jean B
Phytophthora infestans is one of the most destructive plant pathogens of potato and tomato globally. The pathogen is closely related to four other Phytophthora species in the 1c clade including P. phaseoli, P. ipomoeae, P. mirabilis and P. andina that are important pathogens of other wild and domesticated hosts. P. andina is an interspecific hybrid between P. infestans and an unknown Phytophthora species. We have sequenced mitochondrial genomes of the sister species of P. infestans and examined the evolutionary relationships within the clade. Phylogenetic analysis indicates that the P. phaseoli mitochondrial lineage is basal within the clade. P. mirabilis and P. ipomoeae are sister lineages and share a common ancestor with the Ic mitochondrial lineage of P. andina. These lineages in turn are sister to the P. infestans and P. andina Ia mitochondrial lineages. The P. andina Ic lineage diverged much earlier than the P. andina Ia mitochondrial lineage and P. infestans. The presence of two mitochondrial lineages in P. andina supports the hybrid nature of this species. The ancestral state of the P. andina Ic lineage in the tree and its occurrence only in the Andean regions of Ecuador, Colombia and Peru suggests that the origin of this species hybrid in nature may occur there.
Kunadiya, Manisha; White, Diane; Dunstan, William A; Hardy, Giles E St J; Andjic, Vera; Burgess, Treena I
Phytophthora cinnamomi is one of the world's most invasive plant pathogens affecting ornamental plants, horticultural crops and natural ecosystems. Accurate diagnosis is very important to determine the presence or absence of this pathogen in diseased and asymptomatic plants. In previous studies, P. cinnamomi species-specific primers were designed and tested using various polymerase chain reaction (PCR) techniques including conventional PCR, nested PCR and quantitative real-time PCR. In all cases, the primers were stated to be highly specific and sensitive to P. cinnamomi. However, few of these studies tested their primers against closely related Phytophthora species (Phytophthora clade 7). In this study, we tested these purported P. cinnamomi-specific primer sets against 11 other species from clade 7 and determined their specificity; of the eight tested primer sets only three were specific to P. cinnamomi. This study demonstrated the importance of testing primers against closely related species within the same clade, and not just other species within the same genus. The findings of this study are relevant to all species-specific microbial diagnosis. © FEMS 2017. All rights reserved. For permissions, please e-mail: email@example.com.
Black pod rot disease, caused by Phytophthora palmivora, is an important disease of cacao (Theobroma cacao L.) in Nigeria and other cacao producing countries of West Africa and Latin America. A naturally occurring source of genetic resistance to the disease has not been found. This paper completes the report, the first part of which was published in Induced Mutations in Vegetatively Propagated Plants, IAEA, Vienna (1973). The survivors of the irradiated seedlings reported on in this publication were transplanted to the field along with their controls. When the Phytophthora pod disease season began in 1973, all experimental plants along with the controls were sprayed with active and freshly prepared dense sporangial suspension of P. palmivora. Observations on Phytophthora infection were recorded at two-weekly intervals for three months. Results were pooled for each set of experimental plants, after having confirmed that no marked difference appeared among individual plants of each group. Contrary to the observations recorded at the nursery stage, all experimental plants that showed no infection indicated disease infection levels normally characteristic of the F 3 Amazon cultivar of Cacao in Nigeria. Although the nursery and the field data are difficult to reconcile and interpret, it is suggested that probably temporary disease tolerance/resistance, which some irradiated plants showed at the nursery (seedling) stage, was lost as the plants matured, thus suggesting different resistance factor systems for juvenile and mature cacao trees. (author)
Dick, Margaret A; Dobbie, Kiryn; Cooke, David E L; Brasier, Clive M
A locally severe crown disease of exotic plantation Eucalyptus trees has been recorded periodically in New Zealand since 1986. Symptoms include leaf spots, petiole infection and twig and small branch lesions. Outbreaks of disease are episodic and individual trees may show marked variation in crown symptoms ranging from unaffected to total defoliation. Two previously unknown species of Phytophthora are associated with the disease. These are described and formally designated here as P. captiosa, from Eucalyptus botryoides and E. saligna; and P. fallax, from E. delegatensis, E. fastigata, E. nitens and E. regnans. Both P. captiosa and P. fallax have non-papillate, non-caducous sporangia and both are self-fertile. Phylogenetic analysis on the basis of ITS rDNA sequence data indicates they are closely related to each other but evolutionarily distant from the majority of described Phytophthora taxa. They share a common ancestor with another assemblage of Phytophthora lineages that includes P. insolita, P. macrochlamydospora and P. richardiae. Sporulation of P. captiosa and P. fallax has not been observed in the field. The mode of infection and spread of these non-caducous Phytophthora species in the eucalypt tree canopy remains unknown. This issue, and the possible geographic origins of these two Phytophthora species are discussed.
Hulvey, Jon; Gobena, Daniel; Finley, Ledare; Lamour, Kurt
In 2008 statewide surveys of symptomatic foliage of nursery plants from Tennessee resulted in isolation of 43 isolates of Phytophthora spp. This sample set includes four described species (P. citrophthora, P. citricola, P. nicotianae, P. syringae), and a provisional species of Phytophthora ('P. hydropathica'). At the same time a stream-baiting survey was initiated to recover Phytophthora from eight watersheds in eastern Tennessee, some of which are near plant nurseries. Baiting was accomplished by submerging healthy Rhododendron leaves approximately 1 wk and isolation onto selective media. Six baiting periods were completed, and in total 98 Phytophthora isolates and 45 isolates of Pythium spp. were recovered. Three described species (P. citrophthora, P. citricola and P. irrigata) and the provisional species 'P. hydropathica' were obtained as well as three undescribed Phytophthora taxa and Pythium litorale. Isolates from both surveys were identified to species with morphology and the internal transcribed spacer (ITS) sequence. Isolates from species co-occurring in streams and nurseries (P. citricola, P. citrophthora and 'P. hydropathica') were characterized further with amplified fragment length polymorphism (AFLP) analyses and mefenoxam tolerance assays. Isolates representing a putative clonal genotype of P. citricola were obtained from both environmental and nursery sample sets.
Safaiefarahani, Banafsheh; Mostowfizadeh-Ghalamfarsa, Reza; Hardy, Giles E St J; Burgess, Treena I
During a study on the phylogenetic relationships between species in the Phytophthora cryptogea complex and related species, Phytophthora erythroseptica and Phytophthora sansomeana, 19 hybrid isolates with multiple polymorphisms in the nuclear sequences were observed. Molecular characterization of hybrids was achieved by sequencing three nuclear (internal transcribed spacers, β-tubulin (TUB), heat shock protein 90) and two mitochondrial (cytochrome c oxidase subunit I (coxI), NADH dehydrogenase subunit I (NADH)) gene regions and cloning of the single-copy nuclear gene, TUB. Based on the molecular studies the hybrid isolates belonged to six distinct groups between P. cryptogea, P. erythroseptica, Phytophthora pseudocryptogea, P. sansomeana, and Phytophthora sp. kelmania. In all cases, only a single coxI and NADH allele was detected and nuclear genes were biparentally inherited, suggesting that the hybrids arose from sexual recombination events. Colony morphology, growth rate, cardinal temperatures, breeding system, and morphology of sporangia, oogonia, oospores, and antheridia were also determined. Some morphological differences between the hybrids and the parental species were noted; however, they were not sufficient to reliably distinguish the taxa and DNA markers from nuclear and mitochondrial genes will to be necessary for their identification. The parental species are all important pathogens of agricultural fields that have been transported globally. With the apparent ease of hybridization within this group there is ample opportunity for virulent hybrids to form, perhaps with extended host ranges. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.
Vettraino, A M; Bonants, P; Tomassini, A; Bruni, N; Vannini, A
To evaluate the accuracy of pyrosequencing for the description of Phytophthora communities in terms of taxa identification and risk of assignment for false Molecular Operational Taxonomic Units (MOTUs). Pyrosequencing of Internal Transcribed Spacer 1 (ITS1) amplicons was used to describe the structure of a DNA mixture comprising eight Phytophthora spp. and Pythium vexans. Pyrosequencing resulted in 16 965 reads, detecting all species in the template DNA mixture. Reducing the ITS1 sequence identity threshold resulted in a decrease in numbers of unmatched reads but a concomitant increase in the numbers of false MOTUs. The total error rate was 0·63% and comprised mainly mismatches (0·25%) Pyrosequencing of ITS1 region is an efficient and accurate technique for the detection and identification of Phytophthora spp. in environmental samples. However, the risk of allocating false MOTUs, even when demonstrated to be low, may require additional validation with alternative detection methods. Phytophthora spp. are considered among the most destructive groups of invasive plant pathogens, affecting thousands of cultivated and wild plants worldwide. Simultaneous early detection of Phytophthora complexes in environmental samples offers an unique opportunity for the interception of known and unknown species along pathways of introduction, along with the identification of these organisms in invaded environments. © 2012 The Authors Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.
Yamada, Y.; Fukutsu, K.; Yuuki, M.; Akashi, M.
After radiological emergencies, patients contaminated with radioactivity are taken to radiation emergency hospitals for treatment. Numerical simulations using the computer software 'Flow Designer R were made in order to evaluate indoor air contamination caused by the breathing out of contaminated air. The National Inst. of Radiological Sciences facility was used for the numerical evaluation. Results indicate that the dispersion of contaminated air depends on the characteristics of the contaminants, and that the dispersion range was limited and localised. Only medical staff standing in a special position near the patient was exposed to almost un-diluted contaminated air. Highly contaminated air was evacuated with a local exhaust pump system. Room air quality was monitored using a continuous air sampling system, but it was found that the sampling point was not representative for the purpose of radiation protection. From the air-flow analysis, some problems that affect radiological safety were revealed and valuable information and measures for preventing secondary contamination were determined. (authors)
Scott, P M; Burgess, T I; Barber, P A; Shearer, B L; Stukely, M J C; Hardy, G E St J; Jung, T
A new Phytophthora species, isolated from rhizosphere soil of declining or dead trees of Eucalyptus gomphocephala, E. marginata, Agonis flexuosa, and another 13 plant species, and from fine roots of E. marginata and collar lesions of Banksia attenuata in Western Australia, is described as Phytophthora multivora sp. nov. It is homothallic and produces semipapillate sporangia, smooth-walled oogonia containing thick-walled oospores, and paragynous antheridia. Although morphologically similar to P. citricola, phylogenetic analyses of the ITS and cox1 gene regions demonstrate that P. multivora is unique. Phytophthora multivora is pathogenic to bark and cambium of E. gomphocephala and E. marginata and is believed to be involved in the decline syndrome of both eucalypt species within the tuart woodland in south-west Western Australia.
Brasier, Clive M; Kirk, Susan A; Delcan, Jose; Cooke, David E L; Jung, Thomas; Man in't Veld, Willem A
In 1993 a destructive new Phytophthora pathogen of riparian Alnus trees was discovered in the UK and subsequently shown to be present in other parts of Europe. The new Phytophthora comprised a group of emergent heteroploid hybrids, probably between P. cambivora and a species related to P. fragariae. These included a common, near tetraploid standard hybrid, the presumptive allopolyploid; and four scarcer major variant types with chromosome numbers intermediate between diploid and tetraploid, named the Swedish, Dutch, German and UK variants. The standard hybrid type is formally designated here as Phytophthora alni subsp. alni. The Swedish variant is designated as P. alni subsp. uniformis; and the Dutch, German and UK variants collectively as P. alni subsp. multiformis. The properties of the Dutch, German and UK variants within subsp. multiformis are informally described. The problems of designating emergent species hybrids under the International Code of Botanical Nomenclature and the reasons for the taxonomic choices made are discussed.
Iwai, Rika; Han, Chunguang; Govindam, Sudhakar V S; Ojika, Makoto
Vegetable juices, typical culture media for the plant pathogen Phytophthora, effectively induce its asexual reproduction (zoosporangia formation). However, some chromatographic fractions from a vegetable juice were found to inhibit asexual reproduction. Bioassay-guided chromatographic steps led to the isolation of four novel compounds, named lycosides A-D, 1-4, that could be metabolic products from a carotenoid. They showed 50% inhibitory activity against the asexual reproduction of P. capsici at 2.1-7.6 μM. The structure-activity relationship and the universality of the inhibitory activity within the Phytophthora genus were also investigated. In addition, the quantitative analysis of lycosides in fresh vegetables and vegetable juices revealed that tomato is the source of these active substances. These food-derived chemicals could help provide safe agents to control the outbreak of the agricultural pest Phytophthora in fields.
Larroque, Mathieu; Belmas, Elodie; Martinez, Thomas; Vergnes, Sophie; Ladouce, Nathalie; Lafitte, Claude; Gaulin, Elodie; Dumas, Bernard
The cellulose binding elicitor lectin (CBEL) of the genus Phytophthora induces necrosis and immune responses in several plant species, including Arabidopsis thaliana. However, the role of CBEL-induced responses in the outcome of the interaction is still unclear. This study shows that some of CBEL-induced defence responses, but not necrosis, required the receptor-like kinase BAK1, a general regulator of basal immunity in Arabidopsis, and the production of a reactive oxygen burst mediated by respiratory burst oxidases homologues (RBOH). Screening of a core collection of 48 Arabidopsis ecotypes using CBEL uncovered a large variability in CBEL-induced necrotic responses. Analysis of non-responsive CBEL lines Ws-4, Oy-0, and Bla-1 revealed that Ws-4 and Oy-0 were also impaired in the production of the oxidative burst and expression of defence genes, whereas Bla-1 was partially affected in these responses. Infection tests using two Phytophthora parasitica strains, Pp310 and Ppn0, virulent and avirulent, respectively, on the Col-0 line showed that BAK1 and RBOH mutants were susceptible to Ppn0, suggesting that some immune responses controlled by these genes, but not CBEL-induced cell death, are required for Phytophthora parasitica resistance. However, Ws-4, Oy-0, and Bla-1 lines were not affected in Ppn0 resistance, showing that natural variability in CBEL responsiveness is not correlated to Phytophthora susceptibility. Overall, the results uncover a BAK1- and RBOH-dependent CBEL-triggered immunity essential for Phytophthora resistance and suggest that natural quantitative variation of basal immunity triggered by conserved general elicitors such as CBEL does not correlate to Phytophthora susceptibility.
Baker, R.; Candresse, T.; Dormannsné Simon, E.
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....... The many other remaining uncertainties (fitness of progeny, hybridisation with other Phytophthora species, host range and epidemiological role of new hosts, early detection of new outbreaks, understanding of long-range dispersal, structure of plant trade networks, origin of the pathogen) call for further...
Mateus, Maria C; Neves, Dina; Dacunha, Bruno; Laczko, Endre; Maia, Cristiana; Teixeira, Rúben; Cravador, Alfredo
To investigate bioactive compounds potentially involved in the biotic interactions exhibited by Phlomis purpurea (Lamiaceae) in rhizospheres infested with Phytophthora cinnamomi, the plant rhizome was chemically analysed. The nortriterpenoid (17S)-2α,3α,11α,23,24-pentahydroxy-19(18 → 17)-abeo-28-norolean-12-en-18-one, was isolated and its structure was elucidated by comprehensive spectroscopic analysis, chiefly using 2D NMR experiments, and X-ray analysis. It was shown to be exuded by roots and to exhibit anti-Phytophthora and antitumor activities. Copyright © 2016. Published by Elsevier Ltd.
Gyetvai, Gabor; Sønderkær, Mads; Göbel, Ulrike
Late blight, caused by the oomycete Phytophthora infestans, is the most important disease of potato (Solanum tuberosum). Understanding the molecular basis of resistance and susceptibility to late blight is therefore highly relevant for developing resistant cultivars, either by marker-assissted s......Late blight, caused by the oomycete Phytophthora infestans, is the most important disease of potato (Solanum tuberosum). Understanding the molecular basis of resistance and susceptibility to late blight is therefore highly relevant for developing resistant cultivars, either by marker...
Montes, Melanie Sarah; Nielsen, B. J.; Schmidt, S. G.
Control of the potato late blight pathogen Phytophthora infestans relies heavily on chemicals. The fungicide metalaxyl-M (Mefenoxam) has played an important role in controlling the disease, but insensitivity to the fungicide in certain isolates is now of major concern. A genetic basis for resista......Control of the potato late blight pathogen Phytophthora infestans relies heavily on chemicals. The fungicide metalaxyl-M (Mefenoxam) has played an important role in controlling the disease, but insensitivity to the fungicide in certain isolates is now of major concern. A genetic basis...
Full Text Available Evaluation of the Resistance of some Varieties of Biological Potato to the Mildew Phytophthora infestans. To control the mildew, in particular in biological productions, the varietal resistance of potato could be an advantage to associate with other cultural measurements. For this purpose, sixteen varieties potentially interesting in conventional and biological production were tested with regard to the mildew. Eleven varieties were subscribed in the list A (Alaska, Arinda, Baraka, Fabula, Liseta, Mondial, Platina, Safrane, Santana, Spunta and Timate and five are in the process of evaluation (Carréra, Cicéro, Derby, Vivaldi, and Voyager. It seemed that the mildew affected all the tested varieties. However, some of them appeared more tolerant than others. Indeed, the Derby and Voyager varieties revealed to be able to delay the starting of the disease of one month. Cicéro, Vivaldi and Timate could delay the development of mildew disease of twelve days, relatively to its appearance on susceptible varieties. Furthermore, the foliar level of destruction remained very limited compared to that on susceptible varieties and not exceed 10% for Timate. The varieties Fabula, Liséta, Carréra, Mondial, Spunta, Platina, Safrane, Arinda, Santana and Baraka showed an early and fast starting of the epidemy. In addition, the tolerance or varietal resistance could not resolve the problem when tubers are affected, since a relatively weak rate of leaves contamination is enough to cause a very important economic loss on the tubers.
Khrustaleva, V.V.; Shcherbakov, V.K.
Information on the production of currant tomato mutants is contained in a previous report. Evaluation of fruit resistance against Phytophthora infestans (Mont.) de Bary was carried out with pathotypes T 0 and T 1 . For artificial infection we used mainly a culture of T 1 (isolate 275), supplied by the Byelorussian Scientific Research Institute of Potato, Fruit and Vegetable Growing at Samokhvalovich. As inoculum for T 0 , a local population of the potato pathotype from the village of Shebantsevo, Moscow province was used. The standard variety 'Gruntovyj gribovskij 1180' was used as the control. Green fruits were taken from the first or second raceme of 20 plants. They were inoculated by spraying in plastic cuvettes with moist filter paper. The cuvettes were covered with glass and maintained at temperature of 18-20 deg. C. The results were checked 5, 9 and 12 days after inoculation. Under natural conditions, each of the 20 plants was also evaluated. As result, three lines with increased resistance to Phytophthora were selected from the original wild-type of currant tomato. Induced mutant forms were tested in the same way for resistance to Phytophthora. Data is presented from 4 years study. Of 26 mutant lines studied, we identified seven whose fruit displayed a stable and enhanced resistance to Phytophthora under both laboratory and field conditions. With regard to leaf infection of these lines, positive results were not obtained. There appears to be no direct relationship between resistance to Phytophthora of the fruit and the leaves. The mutant lines are of determinate type with early and medium ripening time. The average fruit weight is 5-33 g; in the case of the original specimen, it is only 0.9-1.7 g. The fruits have a pleasant sour-sweet taste and a thick skin. It is noteworthy that the mutant lines selected on the basis of their suitability for cultivation not only showed the resistance selected from the wild-type, but in a number of cases even turned out to
MigdaŁ, Wojciech; Orlikowski, Leszek B.; Ptaszek, Magdalena; Gryczka, Urszula
Very extensive production procedure, especially in plants growing under covering, require methods, which would allow quick elimination or substantial reduction of populations of specific pathogens without affecting the growth and development of the cultivated plants. Among soil-borne pathogens, the Phytophthora species are especially dangerous for horticultural plants. In this study, irradiation with electron beam was applied to control Phytophthora cinnamomi. The influence of irradiation dose on the reduction of in vitro growth and the population density of the pathogen in treated peat and its mixture with composted pine bark (1:1), as well as the health of Chamaecyparis lawsoniana and Lavandula angustifolia plants were evaluated. Application of irradiation at a dose of 1.5 kGy completely inhibited the in vitro development of P. cinnamomi. This irradiation effect was connected with the disintegration of the hyphae and spores of the species. Irradiation of peat and its mixture with composted pine bark with 10 kGy resulted in the inhibition of stem base rot development in Ch. lawsoniana. Symptoms of the disease were not observed when the substrates were treated with 15 kGy. In the case of L. angustifolia, stem root rot was not observed on cuttings transplanted to infected peat irradiated at a dose of 10 kGy. Irradiation of the horticultural substrates did not affect plant growth. - Highlights: ► Electron beam irradiation is effective against soil-borne pathogens. ► Application of irradiation at dose 1.5 kGy completely inhibited in vitro development of Phytophthora cinnamomi. ► Irradiation of horticultural substrata did not influence the growth of plants.
Full Text Available Avocado (Persea americana – a major fruit crop worldwide – is threatened by root rot caused by Phytophthora cinnamomi. This pathogen is known to infect the plant via the feeder roots leading to branch dieback, and eventually tree mortality. While it is known that different avocado rootstocks have varying degrees of susceptibility to Phytophthora root rot, little research has been done on the avocado–Phytophthora interaction. In this study, transcript abundance levels of defence-related genes coding for phenylalanine ammonia-lyase, lipoxygenase, pathogenesis-related protein 5, endochitinase, gluthathionine S-transferase and metallothionein were characterised and compared among five rootstocks with varying susceptibility to root rot, after exposure to P. cinnamomi. Root samples were collected at 0 h, 3 h, 6 h, 12 h, 24 h, 48 h and 72 h post-infection and transcript abundance of the defence-related genes was determined using quantitative real-time reverse transcription PCR. The results indicated the involvement of PR-5 and endochitinase in the defence response of all avocado rootstocks to P. cinnamomi but these genes could not be directly linked to the observed phenotypic resistance. PR-5 and endochitinase were highly upregulated at 72 h post-infection. Differences in transcript abundance of phenylalanine ammonia-lyase and lipoxygenase genes were seen when comparing tolerant and less tolerant rootstocks, which may suggest that transcripts of these genes contribute to resistance. These data provide important insights into plant defence and into how different avocado rootstocks may exhibit increased resistance to infection by P. cinnamomi.
Richter, Brantlee Spakes; Ivors, Kelly; Shi, Wei; Benson, D M
Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml(-1) or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml(-1) significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml(-1). In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml(-1) with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml(-1) 2 weeks before planting yielded activity of 20.08 μmol glucose equivalents per gram of soil water (GE g(-1) aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 μmol GE g(-1) aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.
Hansen, Everett M; Reeser, Paul W; Sutton, Wendy
Phytophthora species are widespread and diverse in forest ecosystems, but little is known about their ecology. We explore ecological attributes of the closely related clade 3 species that occur sympatrically in western North American forests. We address the population structure, pathology, and epidemiology of P. ilicis, P. nemorosa, P. pluvialis, P. pseudosyringae, and P. psychrophila. Phytophthora species were isolated from plant tissues, rainwater falling through the forest canopy, streams, and soils in forests in western Oregon. Species identifications were based on morphology in culture with molecular confirmation using COX spacer and internal transcribed spacer (ITS) sequences. All five clade 3 Phytophthora species are present in western Oregon forests, although P. ilicis (only 1 forest isolate) and P. psychrophila (only 12 isolates) are apparently rare. P. ilicis is known only from holly in horticultural situations and once from a naturalized seedling in an urban forest. The known distribution of P. nemorosa in forest settings coincides with the ranges of its principle hosts, tanoak and myrtlewood, in Oregon and California. Although it is regularly identified from streams within the tanoak range, it has not been recovered from streams beyond that range. P. pluvialis is primarily associated with Douglas-fir canopies. It was identified from scattered locations throughout western Oregon in rain traps beneath Douglas-fir plantations and from diseased needles. P. pseudosyringae is also isolated from tanoak and myrtlewood in southwest Oregon and California, but its distribution, in streams at least, extends throughout much of western Oregon. P. psychrophila in Oregon is known only from rain traps beneath tanoak trees. Little intraspecific variation was detected in the nuclear rDNA ITS of clade 3 species. Variation in the mitochondrial COX spacer region was more frequent, with 2 to 10 haplotypes identified in the clade 3 species, for which we had multiple isolates.
Full Text Available In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. Each species produces two distinct populations of small RNAs that are predominantly 21- or 25-nucleotides long. The 25-nucleotide small RNAs were primarily derived from loci encoding transposable elements and we propose that these small RNAs define a pathway of short-interfering RNAs that silence repetitive genetic elements. The 21-nucleotide small RNAs were primarily derived from inverted repeats, including a novel microRNA family that is conserved among the three species, and several gene families, including Crinkler effectors and type III fibronectins. The Phytophthora microRNA is predicted to target a family of amino acid/auxin permeases, and we propose that 21-nucleotide small RNAs function at the post-transcriptional level. The functional significance of microRNA-guided regulation of amino acid/auxin permeases and the association of 21-nucleotide small RNAs with Crinkler effectors remains unclear, but this work provides a framework for testing the role of small RNAs in Phytophthora biology and pathogenesis in future work.
Fahlgren, Noah; Bollmann, Stephanie R; Kasschau, Kristin D; Cuperus, Josh T; Press, Caroline M; Sullivan, Christopher M; Chapman, Elisabeth J; Hoyer, J Steen; Gilbert, Kerrigan B; Grünwald, Niklaus J; Carrington, James C
In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. Each species produces two distinct populations of small RNAs that are predominantly 21- or 25-nucleotides long. The 25-nucleotide small RNAs were primarily derived from loci encoding transposable elements and we propose that these small RNAs define a pathway of short-interfering RNAs that silence repetitive genetic elements. The 21-nucleotide small RNAs were primarily derived from inverted repeats, including a novel microRNA family that is conserved among the three species, and several gene families, including Crinkler effectors and type III fibronectins. The Phytophthora microRNA is predicted to target a family of amino acid/auxin permeases, and we propose that 21-nucleotide small RNAs function at the post-transcriptional level. The functional significance of microRNA-guided regulation of amino acid/auxin permeases and the association of 21-nucleotide small RNAs with Crinkler effectors remains unclear, but this work provides a framework for testing the role of small RNAs in Phytophthora biology and pathogenesis in future work.
Park, C N; Lee, D; Kim, W; Hong, Y; Ahn, J S; Kim, B S
The antifungal activities of novel salicylic acid derivatives, salaceyin A, 6-(9-methyldecyl) salicylic acid, and salaceyin B, 6-(9-methylundecyl) salicylic acid were evaluated against plant pathogenic fungi. Salaceyin A showed antifungal activity against Cladosporium cucumerinum, Colletotrichum orbiculare and Phytophthora capsici at 64 microg ml(-1) while salaceyin B was less effective. In vitro antifungal activities of the compounds were influenced by the experimental pH value of the MIC test medium wherein their antifungal activities were enhanced by increasingly acidic conditions. Salaceyin A showed potent in vivo control efficacy against Phytophthora blight in pepper plants. The disease was effectively suppressed at 500 microg ml(-1), which was comparable to the commercial fungicide, metalaxyl. Salaceyin A suppressed anthracnose development on cucumber leaves in a concentration dependent manner. The control efficacy of salaceyin A against C. orbiculare infection was similar to chlorothalonil when applied prior to pathogen inoculation. Since the salaceyins are derivatives of salicylic acid, a known important signal molecule critical to plant defenses against pathogen invasion, we investigated the possibility that exogenous application of the salaceyin A would activate a systemic acquired resistance against P. capsici infection and C. orbiculare development on pepper and cucumber plants respectively. The addition of 500 microg ml(-1) of salaceyin A to the plant root systems did not significantly decrease disease development in the hosts. We are led to conclude that the disease control efficacy of salaceyin A against the Phytophthora blight and anthracnose diseases, mainly originates from the direct interaction of the agent with the pathogens.
Husson, C; Aguayo, J; Revellin, C; Frey, P; Ioos, R; Marçais, B
Alder decline has been a problem along European watercourses since the early 1990s. Hybridization was identified as the main cause of this emerging disease. Indeed, the causal agent, a soil-borne pathogen named Phytophthora alni subsp. alni (Paa) is the result of interspecific hybridization between two taxa, Phytophthora alni subsp. multiformis (Pam) and Phytophthora alni subsp. uniformis (Pau), initially identified as subspecies of Paa. The aim of this work was to characterize the ploidy level within the P. alni complex that is presently poorly understood. For that, we used two complementary approaches for a set of 31 isolates of Paa, Pam and Pau: (i) quantification of allele copy number of three single-copy nuclear genes using allele-specific real-time PCR and (ii) comparison of the genome size estimated by flow cytometry. Relative quantification of alleles of the three single-copy genes showed that the copy number of a given allele in Paa was systematically half that of its parents Pau or Pam. Moreover, DNA content estimated by flow cytometry in Paa was equal to half the sum of those in Pam and Pau. Our results therefore suggest that the hybrid Paa is an allotriploid species, containing half of the genome of each of its parents Pam and Pau, which in turn are considered to be allotetraploid and diploid, respectively. Paa thus results from a homoploid speciation process. Based on published data and on results from this study, a new formal taxonomic name is proposed for the three taxa Paa, Pam and Pau which are raised to species status and renamed P. ×alni, P. ×multiformis and P. uniformis, respectively. Copyright © 2015 Elsevier Inc. All rights reserved.
Fahlgren, Noah; Bollmann, Stephanie R.; Kasschau, Kristin D.; Cuperus, Josh T.; Press, Caroline M.; Sullivan, Christopher M.; Chapman, Elisabeth J.; Hoyer, J. Steen; Gilbert, Kerrigan B.; Grünwald, Niklaus J.; Carrington, James C.
In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. Each species produces two distinct populations of small RNAs that are predominantly 21- or 25-nucleotides long. The 25-nucleotide small RNAs were primarily derived from loci encoding transposable elements and we propose that these small RNAs define a pathway of short-interfering RNAs that silence repetitive genetic elements. The 21-nucleotide small RNAs were primarily derived from inverted repeats, including a novel microRNA family that is conserved among the three species, and several gene families, including Crinkler effectors and type III fibronectins. The Phytophthora microRNA is predicted to target a family of amino acid/auxin permeases, and we propose that 21-nucleotide small RNAs function at the post-transcriptional level. The functional significance of microRNA-guided regulation of amino acid/auxin permeases and the association of 21-nucleotide small RNAs with Crinkler effectors remains unclear, but this work provides a framework for testing the role of small RNAs in Phytophthora biology and pathogenesis in future work. PMID:24204767
Lu, Shan; Chen, Linlin; Tao, Kai; Sun, Nannan; Wu, Yuren; Lu, Xiaoxue; Wang, Yuanchao; Dou, Daolong
RxLR effectors produced by Phytophthora pathogens have been proposed to bind to phosphatidylinositol 3-phosphate (PtdIns(3)P) to mediate their translocation into host cells and/or to increase their stability in planta. Since the levels of PtdIns(3)P in plants are low, we examined whether Phytophthora species may produce PtdIns(3)P to promote infection. We observed that PtdIns(3)P-specific GFP biosensors could bind to P. parasitica and P. sojae hyphae during infection of Nicotiana benthamiana leaves transiently secreting the biosensors, suggesting that the hyphae exposed PtdIns(3)P on their plasma membrane and/or secreted PtdIns(3)P. Silencing of the phosphatidylinositol 3-kinases (PI3K) genes, treatment with LY294002, or expression of PtdIns(3)P-binding proteins by P. sojae reduced the virulence of the pathogen on soybean, indicating that pathogen-synthesized PtdIns(3)P was required for full virulence. Secretion of PtdIns(3)P-binding proteins or of a PI3P-5-kinase by N. benthamiana leaves significantly increased the level of resistance to infection by P. parasitica and P. capsici. Together, our results support the hypothesis that Phytophthora species produce external PtdIns(3)P to aid in infection, such as to promote entry of RxLR effectors into host cells. Our results derived from P. sojae RxLR effector Avr1b confirm that both the N-terminus and the C-terminus of this effector can bind PtdIns(3)P.
Wulff, Ednar Gadelha; Pérez, W.; Nelson, R.J.
Abstract: In this study, genotype by environment (G x E) interactions and phenotypic stability of resistance to Phytophthora infestans, the cause of late blight, were analysed in Peru lot 13 potato genotypes, using additive main effects and multiplicative interaction (AMMI) analysis and Huehn's non......-parametric test. The potato genotypes were tested in seven experiments over two years in the vicinity of Comas, Peru, an area used by the International potato Center to screen for resistance to late blight. Results of the two analyses generally correlated and indicated that quantitative resistance to P. infestans...
Gao, Ruifang; Cheng, Yinghui; Wang, Ying; Wang, Ying; Guo, Liyun; Zhang, Guiming
Phytophthora fragariae var. fragariae is a serious plant-pathogenic fungus causing red core disease in strawberries, resulting in a larger number of fruit produced, and the fungus has been regulated as a quarantine pest of many countries and regions. Here, we announce the genome sequence of P. fragariae var. fragariae, and this information might provide insight into the mechanism of pathogenicity and host specificity of this pathogen, as well as help us further identify targets for fungicides. Copyright © 2015 Gao et al.
Leszek B. Orlikowski
Full Text Available Phytophthora cinnamomi was isolated from rotted root and stem parts of lavender as well as from soil taken from containers with diseased plants. Additionally Botrytis cinerea, Fusarium spp. and Sclerotinia sclerotiorum were often isolated from diseased tissues. P. cinnamomi colonised leaves and stem parts of 4 lavender species in laboratory trials and caused stem rot of plants in greenhouse experiments. Cardinal temperature for in vitro growth were about 7,5 and 32°C with optimum 25-27,5°C. The species colonised stem tissues at temperature ranged from 10° to 32°C.
Chaudhri, M.A.; Lee, M.M.; Rouse, J.L.; Weste, G.
As part of a study of disease caused by Phytophthora cinnamomi in native vegetation, the mineral composition of diseased plants has been compared with those free from disease, but grown under the same conditions. Using proton activation it has been shown that a reduction of 70% in iron and 41% in titanium occurs for diseased Eucalytus obliqua compared with disease-free plants. The reduction in iron is associated with severe chlorosis which occurs as a primary symptom in most plants attacked by this pathogen. (author)
Aguayo, Jaime; Halkett, Fabien; Husson, Claude; Nagy, Zoltán Á; Szigethy, András; Bakonyi, József; Frey, Pascal; Marçais, Benoit
Assessing the process that gives rise to hybrid pathogens is central to understanding the evolution of emerging plant diseases. Phytophthora ×alni, a pathogen of alder, results from the homoploid hybridization of two related species, Phytophthora uniformis and Phytophthora ×multiformis Describing the genetic characteristics of P ×alni should help us understand how reproductive mechanisms and historical processes shaped the population structure of this emerging hybrid pathogen. The population genetic structure of P ×alni and the relationship with its parental species were investigated using 12 microsatellites and one mitochondrial DNA (mtDNA) marker on a European collection of 379 isolates. Populations of P ×alni were dominated by one multilocus genotype (MLG). The frequency of this dominant MLG increased after the disease emergence together with a decline in diversity, suggesting that it was favored by a genetic mechanism such as drift or selection. Combined microsatellite and mtDNA results confirmed that P ×alni originated from multiple hybridization events that involved different genotypes of the progenitors. Our detailed analyses point to a geographic structure that mirrors that observed for P. uniformis in Europe. The study provides more insights on the contribution of P. uniformis, an invasive species in Europe, to the emergence of Phytophthora-induced alder decline. Our study describes an original approach to assess the population genetics of polyploid organisms using microsatellite markers. By studying the parental subgenomes present in the interspecific hybrid P. ×alni, we were able to assess the geographical and temporal structure of European populations of the hybrid, shedding new light on the evolution of an emerging plant pathogen. In turn, the study of the parental subgenomes permitted us to assess some genetic characteristics of the parental species of P. ×alni, P. uniformis, and P ×multiformis, which are seldom sampled in nature. The
Chaudhri, M.A.; Melbourne Univ., Austin; Weste, G.; Papper, C.S.
The mineral composition of susceptible and resistant plants from native forests infected with Phytophthora cinnamomi was compared between themselves and with the same species from disease-free areas. Root and shoot samples from different plants were carefully ashed, compressed into pellets and analysed with the thick target PIXE technique. A number of elements, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr, Sn, and Pb, were detected. Many of the elements showed variations, sometimes large, between the composition of suspectible and resistant plants, and between the same species from infected and disease-free forests. (orig.)
Chaudhri, M. Anwar; Papper, C. S.; Weste, G.
The mineral composition of susceptible and resistant plants from native forests infected with Phytophthora cinnamomi was compared between themselves and with the same species from disease-free areas. Root and shoot samples from different plants were carefully ashed, compressed into pellets and analysed with the thick target PIXE technique. A number of elements, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr, Sn and Pb, were detected. Many of the elements showed variations, sometimes large, between the composition of susceptible and resistant plants, and between the same species from infected and disease-free forests.
Kivekaes, L. [Lohja Envirotec, Helsinki (Finland)
A versatile remediation centre for contaminated soils has operated at Virkkala close to Helsinki since 1998. It is the first regional soil remediation centre in Finland and serves a large area in south- western Finland. Contaminated soils are collected from tens of small and large sites each year and transported to Virkkala for a very high class and environmentally safe treatment under controlled conditions. The centre consists of a 2 ha large hall for storage and treatment of the soils, a 1 ha outside bio-remediation field and a service and truck washing hall. Three treatment technologies are available at the centre: Stabilization/solidification, washing and bio-remediation. With these methods all the most common types of contamination can be treated: Heavy metals, oils, PAHs, creosotes and chlorophenols. Special care has been taken with prevention of environmental emissions, because the centre is located close to a housing area and on a lake-front. All the storage and treatment areas are covered with a double or triple bottom liner system and all environmental emissions are being monitored constantly. EU's Life Environment -fund has supported the project. (orig.)
The fungus Phytophthora fragariae, is able to cause red stele root rot in the strawberry. Symptoms of the disease is discolouration of the stele of the roots, rotting away of the infected roots, dwarfism, wilting, and finally plant death. Chemical control of red stele
A. G. Greslebin; E. M. Hansen
Field observations, isolations and pathogenicity tests were performed on Austrocedrus chilensis (Cupressaceae) trees to determine the pathogenicity of Phytophthora austrocedrae and its role in the aetiology of the cypress disease mal del ciprés (MDC) in Argentina. It was found that P. austrocedrae...
Gun Woong Lee
Full Text Available Phytophthora blight and anthracnose disease caused by Phytophthora capsici and Collectotrichum gloeosporioides are the most important devastating diseases of red pepper plants, worldwide. Five different bacterial isolates were isolated from the red pepper rhizosphere and non-rhizosphere soil and subsequently tested for antagonistic activity against P. capsisi and C. gloeosporioides. The area of the inhibition zone was taken as a measure for antagonistic activity. Among the 5 isolates tested, S54 exhibited a maximum antagonistic activity under in vitro and in vivo conditions. In greenhouse studies the isolate has successfully reduced the disease symptom. Protect value was 80.8% (Phytophthora blight and 81.9% (Anthrancnose disease, whereas the infection rate of control plants was 21.3% and 23.2%. Based on the 16S rDNA sequence and API 50CHB Kit analysis the most effective isolate was identified as Bacillus subtilis. The results of the study indicate that the stratin S54 could be used as an potential biological control of Phytophthora blight and anthracnose disease of red pepper.
Tatiana Roubtsova; Richard Bostock
Of concern for disease management and certification programs in nursery ornamentals is that roots, when colonized by Phytophthora ramorum, may serve as a potential reservoir of inoculum. An additional complication is that the above ground portion of plants with root infections may be asymptomatic. Our central hypothesis is that mild abiotic...
Partial resistance to Phytophthora sojae in soybean is controlled by multiple quantitative trait loci (QTL). With traditional QTL mapping approaches, power to detect these QTL, frequently of small effect, can be limited by population size. Joint linkage QTL analysis of nested recombinant inbred li...
Scott, P.M.; Burgess, T.I.; Barber, P.A.; Shearer, B.L.; Stukely, M.J.C.; Hardy, G.E.St.J.; Jung, T.
A new Phytophthora species, isolated from rhizosphere soil of declining or dead trees of Eucalyptus gomphocephala, E. marginata, Agonis flexuosa, and another 13 plant species, and from fine roots of E. marginata and collar lesions of Banksia attenuata in Western Australia, is described as
Daniel K. Manter; Rick G. Kelsey; Joseph J. Karchesy
Previously, we demonstrated that wood chips, essential oil, and four individual compounds from Alaska yellow-cedar (Chamaecyparis nootkatensis [D. Don] Spach) heartwood strongly inhibit the germination f Phytophthora ramorum (Werres, de Cock, Man int Veld) zoospores or sporangia, and reduce hyphal growth in culture (Manter and...
Jennifer Yuzon; David M. Rizzo; Mathu Malar C; Sucheta Tripathy; Takao Kasuga
Phytophthora ramorum has spread and diversified throughout Californiaâs northwestern coast since its introduction in the 1990s. Tracking the spread of P. ramorum and the functional response of the pathogen to the environment is of particular interest to managing the epidemic. Using genetic tools such as microsatellite...
Catherine A. Eyre; Melina Kozanitas; Matteo Garbelotto
We present a study of the epidemiology of sudden oak death (SOD) in California within a watershed based on temporally and spatially replicated surveys of symptoms, viability of the pathogen from symptomatic leaves, and genetic analyses using polymorphic SSR markers.Phytophthora ramorum is sensitive to climate; its...
C.A. Eyre; M. Kozanitas; M. Garbelotto
Limited information is available on how soil and leaf populations of the sudden oak death pathogen, Phytophthora ramorum, may differ in their response to changing weather conditions, and their corresponding role in initiating the next disease cycle after unfavorable weather conditions. We sampled and cultured from 425 trees in six sites, three...
S. Prospero; E.M. Hansen; N.J. Grünwald; J. Britt; L.M. Winton.
Phytophthora ramorum is a devastating pathogen in native forests in California and southwestern Oregon and in nursery crops in California, Oregon and Washington. In this study we analyzed the population structure of P. ramorum in the west coast (CA, OR, and WA) of the United States by screening 579 isolates recovered...
Li, Y.; Lee, van der T.A.J.; Zhu, J.H.; Jin, G.H.; Lan, C.Z.; Zhu, S.X.; Zhang, R.F.; Liu, B.W.; Zhao, Z.J.; Kessel, G.J.T.; Huang, S.W.; Jacobsen, E.
The population structure of Phytophthora infestans in China was studied and three mitochondrial haplotypes (Ia, IIa, IIb) were observed. Genetic analysis with 10 highly informative SSR markers identified 68 different genotypes, including three dominant clonal lineages. In the Chinese P. infestans
Mark Spencer; Kevin O' Hara
Phytophthora ramorum attacks tanoak (Lithocarpus densiflorus) in California and Oregon. We present a stand-level study examining the presence of disease symptoms in individual stems. Working with data from four plots in redwood (Sequoia sempervirens)/tanoak forests in Marin County, and three plots in Mendocino...
F.N. Martin; M.D. Coffey; K. Zeller; R.C. Hamelin; P. Tooley; M. Garbelotto; K.J.D. Hughes; T. Kubisiak; G.J. Bilodeau; L. Levy; C. Blomquist; P.H. Berger
Given the importance of Phytophthora ramorum from a regulatory standpoint, it is imperative that molecular markers for pathogen detection are fully tested to evaluate their specificity in detection of the pathogen. In an effort to evaluate 11 reported diagnostic techniques, we assembled a standardized DNA library using accessions from the World...
Champouret, N.; Bouwmeester, K.; Rietman, H.; Lee, van der T.; Maliepaard, C.A.; Heupink, A.; Vondervoort, van de P.J.I.; Jacobsen, E.; Visser, R.G.F.; Vossen, van der E.A.G.; Govers, F.; Vleeshouwers, V.G.A.A.
A strategy to control the devastating late blight disease is providing potato cultivars with genes that are effective in resistance to a broad spectrum of Phytophthora infestans isolates. Thus far, most late blight resistance (R) genes that were introgressed in potato were quickly defeated. In
Isabelle De Dobbelaere; Kurt Heungens; Martine Maes
Although Rhododendron is the most important host of Phytophthora ramorum. in Europe, there is little scientific information about the susceptibility levels of different Rhododendron species and cultivars. Increasing this knowledge would help nurseries in the management of the disease and could be used by plant protection services to target their...
Niklaus J. Grunwald; E. Anne Davis; Robert G. Linderman
Phytophthora ramorum is a recently introduced plant pathogen causing a range of diseases including sudden oak death, Ramorum shoot dieback and Ramorum blight (Rizzo and others 2002, 2004; Werres and others 2001). P. ramorum also attacks several nursery crops including viburnum and rhododendron (Werres and others 2001). Since its...
Weg, van de W.E.
Red stele (red core) root rot is the major soil-borne disease of strawberries (Fragaria spp.) in many areas with cool, moist soil conditions. It is caused by the soil-borne fungus Phytophthora fragariae var. fragariae. Red stele
Weg, van de W.E.
A gene-for-gene model is postulated to explain the observed interactions between cultivars of strawberry and races of Phytophthora fragariae. Five interacting resistance (R1 · R5) and avirulence (Avr1 Avr5) factors explain all the available data involving 15 host genotypes, including the USA and
The cocoa tree, Theobroma cacao L., suffers large yield losses in Aceh Indonesia to the disease black pod rot, caused by Phytophthora spp. Despite having the largest area under cacao production in Sumatra, farmers in the Aceh region have low overall production because of losses to insect pests and b...
A. Trippe; E. Berghauer; N. Osterbauer
Phytophthora ramorum is a pathogen of regulatory concern in North America and Europe. In 2004, potentially infected plants were shipped from large, wholesale nurseries on the West Coast (California, Oregon, and Washington) throughout the U.S. This prompted a nationwide survey effort and the adoption of a federal order requiring mandatory inspection...
Marco Pautasso; Tom Harwood; Mike Shaw; Xiangming Xu; Mike Jeger
Since the first finding of Phytophthora ramorum in the U.K. (on Viburnum tinus, 2002), the pathogen has been reported throughout the country on a variety of susceptible species both in the horticultural sector and in woodlands and historic gardens. The nursery network may have properties which affect the epidemic threshold for...
R.G. Linderman; Patricia B. de Sá; E.A. Davis
Phytophthora ramorum, cause of sudden oak death of trees or ramorum blight of other plant species, has many hosts. Some geographic regions, such as the Appalachian range of the eastern United States, are considered high risk of becoming infested with the pathogen because known susceptible plants occur there and climatic characteristics appear...
Steve Tjosvold; David Chambers; Sylvia Mori
The objective of our research was to determine the environmental conditions and lesion age favorable for Phytophthora ramorum sporulation under field conditions. For 2 years, new camellia, rhododendron, and California bay laurel (Umbellaria californica (Hook. & Arn.) Nutt.) nursery stock were seasonally inoculated (every 3 months) on foliage....
A. Vercauteren; M. Larsen; E. Goss; N. Grunwald; M. Maes; K. Heungens
Phytophthora ramorum is a recently introduced pathogen in Europe and North America consisting of three clonal lineages. Due to the limited intralineage genetic variation, only a few polymorphic markers are available for use in studies involving the epidemiology and evolution of P. ramorum. A total of 159 primer pairs for...
Dou, D.; Kale, S.D.; Wang, X.; Chen, Y.; Wang, Q.; Jiang, R.H.Y.; Arredondo, F.D.; Anderson, R.G.; Thakur, P.B.; McDowell, J.M.; Wang, Y.; Tyler, B.M.
The sequenced genomes of oomycete plant pathogens contain large superfamilies of effector proteins containing the protein translocation motif RXLR-dEER. However, the contributions of these effectors to pathogenicity remain poorly understood. Here, we show that the Phytophthora sojae effector protein