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Pythium aphanidermatum is a common plant pathogen, reportedly capable of human infection. This study investigated whether P. aphanidermatum can infect domestic rabbits. Four rabbits were inoculated with P. aphanidermatum subcutaneously and evaluated for 30 days. Blood and tissue samples were collected from all animals. The animals developed palpable nodules 5-10 days after inoculation. Necropsy revealed caseous nodular lesions characterized histopathologically by pyogranulomatous inflammation containing hyphae in the necrotic areas. P. aphanidermatum was isolated from the caseous material and anti-P. aphanidermatum antibodies were detected by serological examination. This is the first report of experimental P. aphanidermatum infection in mammals. The results demonstrate that this oomycete can produce infection at the inoculation site and induce an immune response. The results suggest that P. aphanidermatum may be undergoing adaptation to vertebrate hosts.

Alternative materials with added-value functions, such as phytopathogen suppression and biostimulant and/or biofertilising activity, have been proposed as peat substitutes in growing media. The aim of this work was to evaluate the effect of 23 agro-industrial composts as components of growing media for baby-leaf lettuce transplant production and their activity against the plant pathogen Pythium irregulare. The composts were produced by mixing different starting feedstocks—tomato waste, leek waste, olive mill cake and vineyard pruning waste—with different additives (coffee, thyme, lavender and rockrose waste), which were incorporated at the beginning of the maturation phase. The results obtained indicated that the composts were mature enough to be used as growing media. The fresh weight of the lettuce plants grown with the different composts was significantly higher than in plants obtained with peat. Composts with the coffee additive produced higher lettuce fresh weight, while those with thyme yielded a lower fresh weight. Moreover, composts as components of growing media showed significantly higher P. irregulare suppressiveness than peat. The composts with additives produced lower lettuce fresh weight than composts without additives, but showed higher suppressiveness. Composts with additives showed opposite results depending on whether they were exposed to pathogens or not. Composts with additives showed opposite results according to pathogen pressure or not. Out of all the composts studied, the compost with tomato waste and leek waste as the initial feedstock, and lavender as an additive, showed the highest suppressive capacity. After lettuce harvesting, the growing media with composts showed significantly lower concentrations of P. irregulare than peat. Principal Component Analysis (PCA) revealed that the growing media with compost can be grouped together according to the additive type, This work has been supported by the Spanish Ministry of Economy and Competitiveness and by European Regional Development Funds (ERDF, ‘‘Una manera de hacer Europa”) in the framework of the project ‘‘Compost as biofertilizer, resistance inductor against plant pathogens and healthy property promoter under a crop intensive sustainable production. Compoleaf” (Project AGL2017- 84085-C3-1-R, C3-2-R and C3-3-R)

Oomycetes are water moulds in the kingdom Protista and are not considered true fungi due to the structural lack of chitin and ergosterol. Many oomycetes are pathogenic, such as Pythium spp., and many fish are prone to Saprolegnia spp. infections, particularly in stressful farming situations. A juvenile American alligator (Alligator mississippiensis) was presented for necropsy examination with white, gelatinous, raised lesions over ulcerated regions of skin on the limbs and tail. The alligator came from a hatchery with age-divided enclosures, and several of the animals within the same enclosure showed similar lesions. Numerous hyphae with non-parallel walls and sparse, non-dichotomous branching were observed histologically on Gomori's methenamine silver staining within the ulcers. Although no organisms were detectable via polymerase chain reaction testing of fresh or formalin-fixed tissues, the organism was cultured and sequenced as an Achlya sp., an infrequently identified oomycete. To the author's knowledge, this is the first description of an oomycete infection within the class Reptilia.

We investigated virus infection in the plant pathogenic oomycete Globisporangium splendens, formerly classified as Pythium splendens, in Japan. From 12 strains investigated, three strains contained virus-like double-stranded (dsRNA). Next-generation sequencing revealed that the G. splendens strain MAFF 425508 and MAFF 305867 contained a virus related to toti-like viruses, that we named Pythium splendens RNA virus 1 (PsRV1). PsRV1 has a ca. 5700 nt-length genome encoding two overlapping open reading frames (ORFs). The ORF2 encodes an RNA-dependent RNA polymerase (RdRp). Phylogenetic analysis with deduced RdRp amino acid sequences indicated that PsRV1 was closely related to Pythium polare RNA virus 1 (PpRV1) from G. polare infecting mosses in the Arctic. PsRV1 was vertically transmitted through the hyphal swellings, vegetative organs of G. splendens, in a temperature-dependent manner. Also, we showed that PsRV1 infected in a symptomless manner.

The tyrosine kinase-like (TKL) gene family is widely existed in most eukaryotes and participates in many biological processes, however, has been rarely studied in oomycetes. In this study we performed bioinformatic and experimental analyses to characterize TKLs in Pythium guiyangense, a promising mosquito biological control agent. Our results revealed that TKLs were widely distributed in all the detected oomycetes, but were largely expanded in P. guiyangense in a species-specific expansion manner. The expansion was mostly driven by whole-genome duplication and tandem duplication. Domain distributions and exon-intron structures were highly conserved in the same group while diverse in different groups, suggesting of functional divergence. Transcriptional analysis revealed that over one fourth of TKLs were differentially expressed after infection of mosquito larvae, implying that these genes might participate in the infection process. Furthermore, subgroup A TKLs were functionally investigated using genetic transformation silencing method. Our findings demonstrated that subgroup A TKLs were up-regulated at the early infection stages and silencing of subgroup A TKLs led to reduced mycelia growth, zoospore production and alteration of stress responses. Pathogenicity assays also revealed that silencing of subgroup A TKLs reduced P. guiyangense virulence to mosquito larvae. Taken together, this study provides a comprehensive overview of P. guiyangense TKL family and reveals their potential roles in growth, development, stress response, and especially virulence.

Pythium spp. are the causal agents of Pythium root rot and damping-off on microgreens. The objective of this project was to assess the efficacy of biofungicides on Pythium root rot and damping-off caused by Pythium aphanidermatum and Pythium dissotocum on microgreens in greenhouses. In the first experiment, arugula (Eruca sativa Mill.), kale (Brassica oleracea var. sabellica L.), radish (Raphanus raphanistrum subsp. sativus L.), and mustard (Brassica juncea L. Czern) microgreens were treated with Companion® (Bacillus subtilis GB03), Triathlon BA® (Bacillus amyloliquefaciens D747), or RootShield Plus® (Trichoderma harzianum KRL-AG2 and Trichoderma virens G-41) in a hydroponic nutrient film technique system. Two days after treatment, the plants were inoculated with 3 × 105 zoospores of Pythium spp. After seven days, we measured root necrosis, damping-off incidence and severity, and plant biomass. All plants infected with Pythium spp. were smaller by 28% or more compared with non-inoculated plants. Overall disease was low, but biomass was lower in all treatments inoculated with Pythium spp. Arugula infected with Pythium spp. and treated with Triathlon BA® resulted in 8% lower disease incidence compared with the positive control, yet Triathlon BA® resulted in the highest root necrosis. On a separate experiment, arugula and mustard were grown in propagation trays, irrigated manually, and treated with the biofungicides mentioned above or Cease® (Bacillus subtilis QST 713). Arugula and mustard plants inoculated with Pythium spp. had 74.4% reduction of shoot dry weight. Arugula and mustard treated with Cease®, with and without Pythium spp., resulted in ≥59% more biomass compared with the untreated inoculated control. In the tray experiment, all the infected plants treated with biofungicides had more biomass than plants with no biofungicides. Results from this experiment suggest that microbial biofungicides can be introduced in nutrient solutions in nutrient film technique or applied in the irrigation to prevent Pythium root rot and damping-off in brassica microgreens. However, biofungicides can reduce plant biomass and growers may need to extend production time to achieve target yields.

Koehler, A.M. and Shew, H.D. 2018. Effects of fungicide applications on root-infecting microorganisms and overwintering survival of perennial stevia. Crop Protection 117:000–000. Stevia (Stevia rebaudiana) is a perennial species emerging as a new crop in the southeastern United States. In previous studies, application of quinone outside inhibitor (QoI) fungicides enhanced overwintering survival of stevia. Greenhouse and field trials were conducted to assess the effect of multiple fungicides on plant growth, root associated microorganisms, and overwintering survival. In greenhouse trials in the absence of soilborne pathogens, no differences in plant height, shoot weight, or root system ratings were observed among treatments. In two field trials screening seven combination fungicides and one biological control, significant increases in overwintering survival of plants treated with QoI fungicides were observed. Plants were dug from the fields monthly to destructively sample root crowns and species of Fusarium, Ceratobasidium, Pythium, and Macrophomina phaseolina were consistently isolated. Abundant microsclerotia from M. phaseolina were observed on stems of plants that did not survive winter. In seven sample months at each of the two field trials, non-fungicide treated plants had the lowest root weights. This study is one of the first to evaluate interactions between fungicide use and root associated fungi in a perennial crop and provides a framework to further investigate the role of root-associated fungi in overwintering survival.

Biochar is thought to have great potential as a supplemental amendment in nursery growing media. The knowledge of how to optimize the use of biochar in the nursery setting during the most vulnerable pre-emergence and early seedling stages of the plant, however, is underdeveloped. The current study involves pre-emergence trials in the Pythium aphanidermatum-cucumber pathosystem using a commercial nursery potting mixture amended with up to 3% w:w wood-derived biochar. The major questions were: (i) is pre-conditioning required to elicit suppression of pre-emergence damping-off disease in the Pythium-cucumber system; (ii) what are the changes in bacterial community composition and diversity due to pre-conditioning of the biochar-amended potting medium; and (iii) can the pre-conditioning stage be shortened from 45 days and still provide disease suppression. Pre-conditioning, consisting of pre-planting fertigation of the nursery medium, was found to be needed to achieve suppression of damping-off disease by biochar, with a reduction in pre-emergence damping-off caused by P. aphanidermatum by up to 71%. Illumina sequencing of 16s bacterial gene revealed a significant enrichment in the abundance of bacteria in general and potentially beneficial microorganisms in particular, as well as shifts in microbial community structure as a result of biochar addition. These changes may play an important role in the overall effects of biochar on disease suppression in young seedlings. A pre-conditioning period of only 14 days was found to be effective for disease suppression, which can substantially improve its practical utility for nurseries.

Background Pythium insidiosum has been mainly reported to cause morbidity and mortality in thalassemia patients. P. insidiosum zoospores can germinate to be hyphae within a few hours; therefore, it is difficult to study the initial immune response that P. insidiosum zoospores induce. The present study aims to compare immune responses against P. insidiosum zoospore infection by comparing monocytes/macrophages from thalassemia patients with those from non-thalassemia controls. Methods In order to keepP. insidiosum in the zoospore stage in vitro for inoculation, the P. insidiosum zoospores were preserved without germination by treatment with inorganic hypochlorite solution. CD14+ cells were isolated from peripheral blood mononuclear cells of thalassemia and non-thalassemia donors and then left to transition to macrophages. Monocytes/macrophage culture was infected with P. insidiosum zoospores and culture supernatants were subjected to Th1/Th2 multiplex cytokine detection. Results Our study of cytokine production revealed that the basal level of GM-CSF produced by thalassemia monocytes/macrophages was lower than that observed in monocytes/macrophages of non-thalassemia individuals. Higher GM-CSF and IFN-γ response was also found when cells from non-thalassemia people were stimulated with P. insidiosum zoospores compared to thalassemia cells. It was also found that TNF-α, GM-CSF and IFN-γ productions from monocytes/macrophages of thalassemia patients who received iron chelator treatment were significantly higher than those produced from thalassemia patients without iron chelator treatment. Conclusion For the first time, the present study demonstrates defective immune responses in monocytes/macrophages derived from thalassemia patients in response toP. insidiosum zoospore infection. The results also show an inverse correlation between iron overload and cytokine production in monocytes/macrophages of thalassemia patients. This finding could explain why thalassemia patients are susceptible to P. insidiosum infection.

Pectin is a major component of the primary cell wall of higher plants. Some galacturonyl residues in pectin are often O-acetylated. Pectin acetylesterases (PAEs) involved in enzymatic deacetylation of pectin are widespread in the plant pathogenic oomycetes and show sequence and transcriptional polymorphism. Peronophythora litchii is the most destructive pathogens known on lychee (Litchi chinensis Sonn). Out of the 38 PAEs predicted from sequence analysis of P. litchii, Phytophthora species and Pythium species, five P. litchii PAE genes were selected for further study. Of these, P. litchii PAE4 and PAE5, named PlPAE4 and PlPAE5, were knocked out using CRISPR/Cas9 technique. The plpae5 mutants were less capable of host invasion than the wild-type P. litchii strain SHS3, as tested by lychee plant inoculation. Heterologous expression of PlPAE5 in Nicotiana benthamiana could promote the infection by Phytophthora capsici. These results demonstrate that PlPAE5 plays an important role in oomycete pathogenicity.

Soybean (Glycine max (L.) Merr.) has been a commercial oilseed crop in Canada since the 1920s. The production of soybean rapidly increased from 2004 to 2016 in Alberta and Manitoba. Root rot disease caused by the oomycete genus Pythium was observed from 105 fields in 2015 and 2016 in southern Alberta and Manitoba. In the present study, a total of 97 isolates of Pythium were recovered from the root tissues of soybean seedling collected from those fields. Identification of the Pythium species was achieved by examining their morphological features and sequences analysis of internal transcribed spacers (ITS) and cytochrome oxidase subunit 2 gene (Cox II). Nine species of Pythium were identified, with Pythium violae as the predominant species (27 out of 97, 27.8%), followed by P. intermedium (21), P. irregulare (16), P. sylvaticum (12), P. recalcitrans (8), P. ultimum (8), P. heterothallicum (3), P. conidiophorum (1) and P. macrosporum (1). This is the first report of P. conidiophorum, P. recalcitrans and P. violae on soybean in Canada. All the Pythium isolates except three isolates (S2d of P. violae, S29a and S29b of P. heterothallicum) were highly virulent on soybean, causing root rot disease symptoms.

Cyclic lipopeptides (CLiPs) are secondary metabolites produced by a variety of bacteria. These compounds show a broad range of antimicrobial activities; therefore, they are studied for their potential applications in agriculture and medicine. It is generally assumed that the primary target of the CLiPs is the cellular membrane, where they can permeabilize the lipid bilayer. Model membrane systems are commonly used to investigate the effect of lipid composition on the permeabilizing activity of CLiPs, but these systems do not represent the full complexity of true biological membranes. Here, we introduce a novel method that uses sterol-auxotrophic oomycetes to investigate how the activity of membrane-active compounds is influenced by alterations in membrane sterol composition. More specifically, we investigated how ergosterol, cholesterol, beta-sitosterol and stigmasterol affect the activity of the structurally related Pseudomonas-derived CLiPs tolaasin and sessilin against the oomycete Pythium myriotylum. Both compounds were effective against oomycetes, although tolaasin was considerably more active. Interestingly, tolaasin and sessilin effects were similarly reduced by the presence of sterols, with cholesterol showing the highest reduction of activity.

The “Indian saffron” Turmeric is taxonomically called as curcuma longa. It mainly grows in the regions of tropical and sub-tropical areas of the earth. Turmeric cultivation is mainly affected by the diseases attacking the plant. Among the various diseases reported it is unquestionable that rhizome rot causes a huge impact on the yield and economy of the farmers. Nearly 80% of crop loss has been reported due to rhizome rot. Pythium the causal agent of rhizome rot harms the root of turmeric under the soil which is unrecognizable by the farmers at the earlier stage. The paper mainly reviews and covers various aspect of turmeric plant such as geographical distribution, major diseases affecting the plant, disease control and recent detection methods and applications of turmeric in real time.

Hard red spring wheat is an important crop in the Pacific Northwest and is a component of a 3-year crop rotation involving soft white winter wheat; cool season pulse crops such as pea, lentil and chickpea; and canola. Pythium root rot and damping-off have long been observed as an annual problem, particularly in spring planted crops. As such, a seed treatment that includes metalaxyl is very common. Recently, an increase in the incidence of Pythium damping-off highlighted that there is an emerging population of Pythium spp. that are resistant to traditional seed treatments containing metalaxyl. The use of alternative chemistries to manage Pythium root rot and damping-off has gained regional interest to increase crop health and improve yields. The effectiveness of ethaboxam was evaluated along with two other seed treatment cocktails in controlling metalaxyl-resistant Pythium in replicated field experiments of spring wheat over three growing seasons in northern Idaho. Emergence, seedling characteristics, plant height, yield and test weight were assessed. The addition of ethaboxam to metalaxyl-containing seed treatment blends consistently increased emergence and yield of spring wheat compared to seed treatment blends containing metalaxyl only. First leaf length, an indirect measure of early season Pythium damage, was longest in seed treatments containing ethaboxam and the average number of tillers was lower, likely due to increased emergence, than non-treated seed. These results indicate that ethaboxam can improve disease control in spring wheat production when applied as a seed treatment in combination with metalaxyl, specifically in the presence of metalaxyl-resistant Pythium spp.

Pythium is a genus of parasitic oomycetes which target plants and both nonvertebrate and vertebrate animals, including fish and mammalian species. However, several Pythium spp., such as P. oligandrum, function as mycoparasites of pathogenic fungi, bacteria, and oomycetes in soil and thus as advantageous biocontrol agents. This review primarily focuses on biochemical processes underlying their positive effects. For example, P. oligandrum degrades host cell wall polysaccharides using chitinases, cellulases, endo-β-1,3-glucanases, and various exoglycosidases. Proteases from various classes also participate in the cell wall hydrolysis. All these processes can modify cell surface structures and help Pythium spp. compete for space and nutrition. Accordingly, enzyme secretion most likely plays a key role in plant root colonisation. Plant-P. oligandrum interactions, nevertheless, do not involve tissue injury but instead activate plant defence mechanisms, thereby strengthening future plant responses to pathogen attacks. Priming induces the phenylpropanoid and terpenoid pathways and thus synthesis of secondary metabolites, including lignin, for cell wall fortification and other metabolic adjustments. Such metabolic changes are mediated by elicitins, cell wall glycoproteins and oligandrins produced by P. oligandrum. As homologous proteins of β-cinnamomin from Phytophthora cinnamomi with similar essential amino acids for sterol binding, oligandrins stand out for their structure, which they share with cell wall glycoproteins, albeit without the Ser-Thr-rich O-glycosylated domain for cell wall attachment. P. oligandrum also provides plant with tryptamine used for auxin synthesis, promoting plant growth. Overall, in addition to discussing plant metabolic and phytohormonal changes after P. oligandrum inoculation, we review data on P. oligandrum applications as researchers increasingly search for effective and environmentally friendly ways to protect crops. In this context, P. oligandrum emerges as a highly suitable biotechnological solution.

Novel bio-based nanocomposites were developed as carriers for loading and sustained-release of vanillin (Van.) and cinnamaldehyde (Cinn.) antioxidants. The composites were obtained by intercalation of chitosan (CS) into sodium montmorillonite (CS/Mt), incorporation of chitosan with polyaniline (CS/PANI) and chitosan/polyaniline/exfoliated montmorillonite (CS/PANI/Mt). The structure and morphology of composites were characterized by FTIR, XRD, SEM and TEM. The release data of Van. and Cinn. from CS and CS/Mt obeyed well zero-order equation. However, Higuchi and Korsmeyer-Peppas models fitted well the release data from CS/PANI and CS/Mt composites. Their antifungal activity was examined towards Fusarium oxysporum and Pythium debaryanum. In vitro assay, CS, Cinn., Van., CS/PANI and CS/PANI/Cinn., have a strong inhibitory effect on the linear growth of the target pathogens, even at lower concentrations. Greenhouse assay indicated that seedling treatment by the loaded CS/PANI/Cinn and CS/Mt/Cinn. reduced both disease index and disease incidence parameters of both pathogens and possessed seedlings growth promoting potential of tomato compared to untreated-infected controls.

Objective: Pythiosis is a life-threatening infectious disease caused by the oomycete Pythium insidiosum. The disease has been increasingly reported worldwide. Most patients with pythiosis undergo surgical removal of an infected organ. Early diagnosis contributes to better prognosis of pythiosis patients. Here, we assessed the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification and biotyping of P. insidiosum. Methods: A comprehensive set of mass spectra of P. insidiosum was generated to evaluate MALDI-TOF MS for identification and biotyping of P. insidiosum. Results: MALDI-TOF MS accurately identified all 13 P. insidiosum strains tested, at the species level. Mass spectra of P. insidiosum did not match any other microorganisms, including fungi (i.e., Aspergillus species, Fusarium species, and fungal species of the class Zygomycetes), which have similar microscopic morphologies with this oomycete. MALDI-TOF MS- and rDNA sequence-based biotyping methods consistently classified P. insidiosum into three groups: Clade-I (American strains), II (Asian and Australian strains), and III (mostly Thai strains). Conclusions: MALDI-TOF MS has been successfully used for identification and biotyping of P. insidiosum. The obtained mass spectral database allows clinical microbiology laboratories, well-equipped with a MALDI-TOF mass spectrometer, to conveniently identify P. insidiosum, without requiring any pathogen-specific reagents (i.e., antigen, antibody or primers). Keywords: Pythium insidiosum, Pythiosis, MALDI-TOF MS, Mass spectrum, Identification, Biotyping

A study aiming at investigating biological control agents for protecting strawberry during the post-transplant period was performed. For this purpose, a series of fertile soils, rich in organic matter, which had been subjected to intensive strawberry cultivation, were selected. Soil samples taken from those soils were subjected to thermal treatment (up to 80 °C) for a short time to induce microbial changes aiming at improving soil suppressiveness. A greenhouse growth assay with treated and original soils was carried out in pot using frigo-plants. Plants were grown for two months, up to the end of the first production cycle; productive parameters were measured during this period, whilst plant vigour was estimated at the end of the trial as dry matter of the above ground part of the plants. At the end of the trial, root colonizing fungi were evaluated with culture base methods, whilst rhizosphere fungi and bacteria were quantified in terms of DNA amplicons using specific primers. Soil thermal treatments gave an overall increase of both vegetative and productive parameters of strawberry plants, even though the highest plant growth improvements were observed in soil samples originating from the fields showing most severe yield decline amongst the four contemplated in this study. Such an increase in soil health, besides the expected reduction of root infection by the fungal pathogens responsible for root rot in strawberry (mainly Pythium spp. and Dactylonectria torresensis), was related to qualitative and quantitative microbial changes in root and rhizosphere. Root-colonising fungal communities shifted towards Aspergillus, Penicillium along with a series of other non-pathogenic fungal saprophytes. A dramatic reduction of total soil fungi was observed in rhizosphere, whilst total bacteria increased in heat treated soil. Notably, actinomycetes and, to a lesser extent, Pseudomonas were associated with plant growth improvement, while Bacillus did not. Findings suggest that microbiome disturbance of agricultural soils that are rich in organic matter and maintain a good diversity degree, can be effective when searching for beneficial microbial populations with a higher specialisation towards the main crop, as well as for investigating on new biocontrol strategies to reduce post-transplant issues in strawberry crops.

Series of 1,2,4-triazole Schiff bases (2a-2d, 2f-2h and 3a-3h) have been designed and synthesized. The structure of title compounds was confirmed on the basis of their spectral data and elemental analysis. All the target compounds were screened for their in vitro antifungal activity and antibacterial activity. Two of the tested compounds (2a and 2b) exhibited significant antifungal activity against most fungi, especially compound 2a showed better antifungal activity than triadimefon. Meanwhile, the antibacterial activity assay also indicated compound 2a exhibited excellent antibacterial activities comparable to chloramphenicol. The SAR manifested no substitution at position 5 of the triazole ring caused an increase in activity, and 3-phenoxy phenyl group introduced in 1,2,4-triazole scaffold can enhance the antibacterial activity. The DFT calculation indicated triazole ring, S atom and benzene ring in both of the 2a and 3a make a major contribution to the activity.

Pythium insidiosum is a straminopilan pathogen causing life threatening infections in mammals inhabiting temperate, tropical and subtropical areas of the world. The concept that P. insidiosum could also infect mosquitoes was mentioned earlier by investigators conducting phylogenetic analysis on available P. insidiosum isolates deposited at different culture collections. However, an official report and details on its pathological features in mosquitoes are not available. We are reporting the isolation of P. insidiosum from infected mosquito larvae during a survey conducted in central Brazil. At least three oomycotan isolates were recovered during the survey. Due to their ability to infect mosquito larvae the isolates were deposited in the U.S. Department of Agriculture, Agricultural Research Service Collection of Entomopathogenic Fungi (ARSEF; Ithaca, New York) as putative Lagenidium species. The investigated isolates developed very well at 37 °C, produced typical Pythium-like vesicles containing numerous biflagellate zoospores, hydrolyzed sucrose, and their cultured extracted proteins were recognized in serological analysis by anti-P. insidiosum antibodies. Phylogenetic analyses using ITS and partial COXII DNA sequences identified the isolates as P. insidiosum within the American Cluster I. This is the first official report of P. insidiosum recovered from infected mosquito larvae, indicating that this mammalian pathogen, in addition to plants, it could also use mosquito larvae to complete its life cycle in nature.

We investigated virus infection in the oomycete Pythium polare from the Arctic. From 39 isolates investigated, 14 contained virus-like double-stranded RNA (dsRNA). Next generation sequencing revealed that the P. polare isolate OPU1176 contained three different virus-like sequences. We determined the full-length genome sequence of one of them. The 5397 nt-length genome had two overlapped open reading frames (ORFs) consistent with a toti and toti-like viruses, that we named Pythium polare RNA virus 1 (PpRV1). The ORF2 encoded an RNA-dependent RNA polymerase (RdRp). The shifty heptamer motif and RNA pseudoknot were predicted near the stop codon of ORF1, implying that the RdRp could be translated as a fusion protein with the ORF1 protein. Phylogenetic analysis with deduced RdRp amino acid sequences indicated that oomycete virus PpRV1 was closely related to the unclassified arthropod toti-like viruses. The comparison of PpRV1-free and -infected lines suggested that PpRV1 infected in a symptomless manner.

Objectives Vascular pythiosis is a life-threatening infection caused by the oomycete Pythium insidiosum . This article reports the clinical presentation, serodiagnosis, pathology, and outcomes seen at the authors' institution. Methods The cases of patients with proven vascular pythiosis at Ramathibodi Hospital, Mahidol University, Bangkok, Thailand from January 2006 to December 2016 were analyzed retrospectively. Results Thirteen patients were analyzed, eight of whom had underlying thalassemias. Of the remaining five patients, one had aplastic anemia, one had myelodysplasia, one had acute leukemia, one had cirrhosis, and one had alcoholism. Neutropenic patients showed a rapid clinical deterioration. Atypical presentations including carotid arteritis, aneurysm, brain abscess, and stroke occurred in the non-thalassemic patients. Serology yielded positive results in all cases, with a rapid turnaround time. Serology has the advantage of providing a presurgical diagnosis, which allows prompt surgery and clinical cure to be achieved. Pathology revealed a neutrophilic response in the acute phase and a later shift to granuloma. Immunotherapy in combination with itraconazole and terbinafine was given. The amputation rate was 77%, and disease-free surgical margins were achieved in five cases (38%). The mortality rate was 31%. Conclusions This study highlights new aspects of pythiosis, such as the unusual host, clinical presentation, serology as a marker for rapid diagnosis, histopathology, and outcomes. Early recognition of the disease with prompt multimodality treatment may improve survival.

Crop decline is a progressive soil health reduction commonly associated to the specialized cultivations. As a series of biotic factors are involved in this phenomenon, it can be controlled with essentially agronomic methods, the impact of winter cover crops on early growth at subsequent vegetable crops was investigated in a two-year field study. Barley and hairy vetch were incorporated into the soil following two mechanical terminations of cover crops (green manure and green mulching). Immediately after, tomato and zucchini seedlings were transplanted and grown for 28 days. The above-ground biomass of the vegetables was taken as indicator of crop response to pre-plant treatments, whilst root colonizing fungi and rhizosphere bacteria were the two analyzed soil microbial components. Root-colonizing fungi were evaluated using culture-based methods, bacteria were analyzed by amplification of rhizosphere soil DNA with 16S rDNA, then processed with PCR-DGGE. Tomato and zucchini growth response after vetch was always significantly higher than after barley regardless of mechanical termination. Rhizosphere bacterial communities differed significantly between cover crops and this differences was maintained also in the subsequent vegetable crops. Root-colonizing fungi differed between barley and vetch, although they shared most species (70%) such as Pythium spp., binucleate Rhizoctonia AG-A and several Fusarium spp. The latter three fungal groups were also found most abundant in tomato and zucchini roots. Pathogenicity test showed that tomato was more susceptible than zucchini to Pythium, Rhizoctonia solani, Fusarium oxysporum and Fusarium spp. and that their relationship with vegetable plants varied from pathogenic to neutral, up to mutualistic in the case of Rhizoctonia AG-A. These findings indicate difficulty to identify specific biotic agents responsible of crop decline. Tomato and zucchini showed an undoubted growth improvement after legume; however, a certain specificity of Cylindrocarpon-like fungi and Phoma spp. to hairy vetch suggests that, when exploiting benefit of this cover crop for mitigating yield decline of vegetable crops, legume should alternate cereal and other botanically distant genera in rotation.

Rhizome rot of turmeric caused by Pythium aphanidermatum is a major threat to turmeric-cultivating areas of India. This study intends to evaluate the performance of fluorescent pseudomonads against Rhizome rot disease and understand the resistance mechanism in Turmeric plants. Fluorescent pseudomonads were screened against Pythium aphanidermatum using dual culture. Selected strains were evaluated for the performance of growth promoting attributes and the presence of antibiotic genes through PCR analysis. Strain FP7 recorded the maximum percent inhibition of P. aphanidermatum under in vitro conditions. Strains FP7 and TPF54 both increased plant growth in turmeric plants in vitro. Strain FP7 alone contained all the evaluated antibiotic biosynthetic genes. Talc and liquid-based formulations were prepared with effective strain and tested for its biocontrol activities under both glasshouse and field conditions. Enzymatic activities of the induced defense enzymes such as PO, PPO, PAL, CAT and SOD were estimated and subjected to spectrophotometric analysis. A combination of rhizome dip and soil drench of FP7 liquid formulation treatment remarkably recorded the minimum disease incidence, higher defense enzymes, maximum plant growth and yield under glasshouse and field conditions. Application of strain FP7 increased the defense molecules, plant growth and yield in turmeric plants thereby reducing the incidence of rhizome rot disease. Moreover, this study has a potential to be adopted for sustainable and eco-friendly turmeric production.

Pythiosis in sheep is an important disease in Brazil, which could cause rhinitis, dermatitis and alimentary tract inflammation. It is caused by the aquatic oomycete, Pythium insidiosum. The rhinofacial pythiosis causes facial deformity and upper respiratory tract clinical signs associated with necroproliferative masses occupying the rostral nasal cavity and hard palate. Little is known regarding the therapy, prophylaxis and pathogenesis of this disease.During the 6-year study, we examined 13 sheep presenting rhinofacial pythiosis. The diagnosis was performed through biopsy of the rhinofacial lesions followed by histopathology and immunohistochemistry using specific antibodies against P insidiosum, polymerase chain reaction and an indirect enzyme-linked immunosorbent assay.This study presents the clinical findings of a potassium iodide treatment of rhinofacial pythiosis in sheep. All sheep were treated with 10 ml of 10% potassium iodide solution, administered orally every day during 63-120 (mean 85) days. Among treated sheep, 84.6% demonstrated complete recovery.Potassium iodide therapy may treat rhinofacial pythiosis in sheep.

Pythiosis is a life-threatening disease caused by the fungus-like microorganism Pythium insidiosum that can lead to death if not treated. Since P. insidiosum has particular cell wall characteristics, pythiosis is difficult to treat, as it does not respond well to traditional antifungal drugs. In our study, we investigated a new immunotherapeutic approach with potential use in treatment and in the acquisition of immunity against pythiosis. Dendritic cells from both human and mouse, pulsed with P. insidiosum heat-inactivated zoospore, (1,3)(1,6)-β-glucan and the immunotherapeutic PitiumVac® efficiently induced naive T cell differentiation in a Th1 phenotype by the activation of specific Th1 cytokine production in vitro. Heat-inactivated zoospores showed the greatest Th1 response among the tested groups, with a significant increase in IL-6 and IFN-γ production in human cells. In mice cells, we also observed a Th17 pathway induction, with an increase on the IL-17A levels in lymphocytes cultured with β-glucan pulsed DCs. These results suggest a potential use of DCs pulsed with P. insidiosum antigens as a new therapeutic strategy in the treatment and acquisition of immunity against pythiosis.

Ten fungal strains; namely, Penicillium melinii, Petriella setifera, Aspergillus pseudo-niger, Alternaria chlamydospora, Pythium nayoroense, Phoma glomerata, Mucor ramosissimus, Mucor racemosus, Fusarium chlamydosporum and Rhizopus azygosporus were isolated from soil. The extra- and intra-cellular extracts of the fungal strains grown on malt extract and yeast-extract sucrose media were screened for their anticandidal activity against different clinically-isolated Candida species. Most of the fungal extracts showed activity against different Candida species. However, the fungal strains grew on malt extract showed greater activities than those grew on yeast extract sucrose media. The activity of the intracellular was higher than the extracellular metabolites. All fungal extracts (extra and intra) were similar in chemical constituent; they contained carbohydrates and/or glycosides, unsaturated sterols and/or triterpens, tannins and traces of coumarins. Alkaloids, flavonoids, saponins, anthraquinones and cardenolides were no detected. The intra-cellular extracts contained more compounds than the extra-cellular extracts.

Perennial strawberries affected with black root rot generally decline in runner production, yield, and overall plant vigor over time. Several plant pathogens have been implicated in black root rot, including plant-parasitic nematodes, Pythium and Rhizoctonia spp. Pre-plant treatments such as a 3- to 5-year crop rotation or chemical fumigation are the main means of disease management. During 2007 and 2008, five post-plant treatments were evaluated for mitigation of strawberry black root rot in a naturally declining site in Ottawa County in Michigan. Fungicides and nutritional amendments were applied as drenches or foliar sprays. Most treatments increased runner establishment, yield, and overall plant vigor, particularly azoxystrobin and azoxystrobin + potassium phosphite. Root necrosis and incidence of root infection by binucleate Rhizoctonia spp. were reduced. Results were more apparent and significant in 2008 than in 2007, indicating cumulative effects over the 2 years of the trial. During 2008 and 2009, a large-scale demonstration trial was conducted with these treatments in a strawberry field with a history of black root rot in Leelanau County, MI. Improvements in bed fill and average plant weight and reductions in root necrosis and Rhizoctonia isolations were noted. This research represents the first post-plant chemical management strategy capable of slowing or even reversing the decline due to black root rot in established strawberry fields.

A greenhouse equipped with two flooded floors with separate reservoirs was used to determine if partial saturation versus more complete saturation of the root medium, with and without silicon addition, could suppress Pythium root rot of poinsettias. The partial saturation floor was designed to deliver and drain water quickly. The control floor operated with longer watering to achieve close to full saturation. The partial saturation floor used approximately 25% less water than the control floor over the life of a crop. Rooted poinsettias were grown on each floor in 2010, 2011, and 2014. A K2SiO3 solution was added to the root medium several times in each season. Controls received K2CO3. In 2010 and 2011, fifteen plants were artificially inoculated with Pythium aphanidermatum and placed randomly on each floor. In 2014, one half of the plants were artificially inoculated with Pythium aphanidermatum. Disease was monitored by evaluating plant weights, uptake, and retention of silicon, and by rating the root systems for percent root rot. In 2010 and 2014, disease was significantly reduced under partial saturation compared to control watering. There were some effects of silicon, but it never halted the onset of symptoms or reduced the damaging effect of disease on plant growth. There were no interactions of effects of watering and silicon on progress of disease. Plants were smaller and more compact under partial saturation than under control watering. These findings should encourage growers to adopt partial saturation on their flooded floors in order to reduce damage from disease after inoculum has been accidentally introduced.

Field experiments were conducted to evaluate the effects of soil solarization or cover crop on bell pepper (Capsicum annuum) and lima bean (Phaseolus lunatus) rhizosphere microorganisms. In Experiment I, flat surface solarization (FSS), raised bed solarization (RBS), cowpea (Vigna unguiculata) cover crop alone (CP), and the combination of cowpea cover crop followed by raised bed soil solarization (CP + RBS) were compared with methyl bromide fumigation (MB) and an untreated control (UTC) for effects on rhizosphere bacteria and fungi on bell pepper. In Experiment II, effects of cover crop on rhizosphere microorganisms were examined on lima bean in a 3 × 3 split-plot experiment with three summer cover crop treatments: sunn hemp (SH) (Crotalaria juncea), cowpea (CP), and fallow (F) as main plots, and three organic amendments: sunn hemp hay (SHH), cowpea hay (CPH), and no hay (NH) as subplots. Rhizosphere bacteria including siderophore producers, gram-positive spore-formers, and fluorescent pseudomonads were assessed, as well as two fungi, Fusarium oxysporum and Rhizoctonia solani. In year 1 of Experiment I, CP + RBS reduced F. oxysporum and R. solani in the rhizosphere, resulting in levels similar to those in MB fumigation. This was not observed in year 2. Heavy rainfall in year 2 resulted in a severe outbreak of Pythium on bell pepper, which was most destructive in MB fumigated plots. Effects of solarization and cover crop on rhizosphere bacteria also differed between years. Fluorescent pseudomonads were abundant across treatments in year 1, but were greatly reduced in year 2, when the Pythium outbreak occurred. In Experiment II, populations of rhizobacteria on lima bean were not affected by cover crop in either year. At the end of year 1, isolation of R. solani from lima bean roots increased in SHH plots. SH cover crop reduced gram-positive spore forming bacteria and fluorescent pseudomonads. In year 2, CP followed by CPH had higher levels of fungi and bacteria than CP followed by either NH or SHH. Overall, cover crop amendments did not result in consistent enhancement of rhizobacteria, and some treatments resulted in increased abundance of pathogenic fungi. The most consistent treatment for reducing rhizosphere fungal populations was MB.

Pythium insidiosum causes a life-threatening infectious disease, called pythiosis, in humans and animals worldwide. Diagnosis of pythiosis is difficult and often delayed. Surgical removal of infected tissue is the main treatment option. Disabilities and death are common outcomes for pythiosis patients. Reports of Py. insidiosum infections are rising. While it would be useful for clinical, epidemiological, and microbiological studies, information on genetic variation in Py. insidiosum strains is limited. This limitation is, at least in part, due to the cost and time-requirements of DNA sequencing procedures. rDNA-sequence-based phylogenetic analyses categorize Py. insidiosum into three groups, in relation to geographic distribution: Clade-I (American strains), Clade-II (American, Asian, and Australian strains), and Clade-III (Thai and American strains). In rDNA sequence analyses, we observed single nucleotide polymorphisms (SNP) that were associated with the phylogenetic clades of Py. insidiosum . In this study, we aim to develop a multiplex PCR assay, targeting the identified SNPs, for rapid genotyping of Py. insidiosum . We also aim to assess diagnostic efficiency of the assay for identification of Py. insidiosum . Fifty-three isolates of Py. insidiosum from humans ( n = 35), animals ( n = 14), and the environment ( n = 4), and 22 negative-control fungi were recruited for assay evaluation. Based on the pattern of amplicons, the multiplex PCR correctly assigned phylogenetic clades in 98% of the Py. insidiosum isolates tested. The assay exhibited 100% sensitivity and specificity for identification of Py. insidiosum . The assay successfully identified and genotyped the first proven isolate of Py. insidiosum from an animal with pythiosis in Thailand. In conclusion, the multiplex PCR provided accurate, sensitive and specific results for identifying and genotyping Py. insidiosum . Thus, this multiplex-PCR assay could be a simple, rapid, and cost-effective alternative to DNA sequencing for the identification and genotyping of Py. insidiosum .

The antifungal activity of the brown macroalga, Sargassum vulgare (C. Agardh, 1820), collected from different sites along Tunisian costs, was assessed against Pythium aphanidermatum causing Pythium leak disease in potato. Aqueous and organic extracts of this alga, used at different concentrations, were screened in vitro using the poisoned food technique and in vivo on potato tubers cv. Spunta for their ability to inhibit P. aphanidermatum mycelial growth and to suppress potato leak severity. All extracts tested showed antifungal activity toward the targeted pathogen depending on sampling sites, concentrations tested and organic solvent used for extraction. For aqueous extracts, the highest inhibition of pathogen radial growth, by 28%, was achieved using extracts from Tunis and Mahdia1 sites tested respectively at 40 and 50 g L −1 . Pythium leak severity was reduced by 34.33 and 31.67% using S. vulgare extracts from Tunis and Monastir, respectively, with these treatments being the most effective. Among S. vulgare organic extracts tested, the methanolic extract displayed the strongest antifungal potential either by inhibiting pathogen mycelial growth by almost 51%, or by reducing disease severity noted on potato tubers cv. Spunta by more than 82% over untreated controls. A total of 34 compounds were identified and quantified using HPLC-DAD chemical profiling in methanolic crude extracts of S. vulgare samples removed from Tunis and Monastir. Presence of phenolic acids and flavonoids may explain the strong antifungal activity displayed by S. vulgare against P. aphanidermatum . These results suggest that S. vulgare may be explored for the isolation of antifungal compounds for Pythium leak control.

We analyzed the transcriptome and the secretome of Pythium irregulare and Pythium iwayamai when they were infecting bentgrass or growing saprophytically. Proteases, glycosidases, and ABC transporters showed the largest numbers of differentially expressed transcripts, but proteases appear to be the main class of enzymes secreted to degrade plant cell walls. There was no correlation between transcript level and protein secretion, and a very low correlation between the presence of signal peptide sequences and the actual secreted proteins. These results point to the usefulness of the proteomics analysis to study the direct interaction of plant pathogens with their hosts.

The objective of the present study was to isolate and characterize effective lactic acid bacteria (LAB) with antifungal activities from some corn silages in Iran. The corn biomass was harvested from fields of three different regions, chopped, and ensiled in the lab silos. From 200 LABs isolates, 18 isolates with the highest acidic pH resistance (up to pH 3), salt resistance (up to 8%) and growth at 15–45 °C were selected for the next experiments. The highest (11.31 mg/ml) and the lowest (1.9 mg/ml) lactic acid production among the selected strains were belonged to the isolates E4 and G1, respectively. The antifungal properties of the selected strains were evaluated against some important plant pathogenic fungi, including Fusarium verticillioides , Penicillium sp. and Verticillium dahlia, and also against a parasitic oomycote “ Pythium aphani dematum ”. The in vitro experiments confirmed that the strains could inhibit from 0 to 40 mm of mycelial growth of different fungi. Based on amplification and sequencing of the16SrDNA gene, the strains were belonged to Lactobacillus fermentum (61.2%), L. plantarum (11.2%), L. paralimentaris (11.2%), L. pentosus (5.6%), L. buchneri (5.6%), and Sporolactobacillus (5.6%). The field experiments confirmed that different combinations of the selected strains could reduce disease index F. verticillioides up to 40%. This is the first report of antifungal activity of lactobacilli strains against F. verticillioides at lab and field levels. Finally, it could be concluded that the native LABs isolated form Iranian corn silages have high antifungal activities and via their biochemical activities may be used as silage additive to enhance quality and durability for ensiled corns.

The study into the outbreak of the blast disease in the oil palm plantation in Akamkpa local government of Cross River State was carried out with the aim of identifying the possible sources of contamination of the oil palm seedlings and also the physicochemical parameters of the soil samples. Fungi associated with the blast disease were isolated using the direct plating and bait methods while the physicochemical parameters of the soil were determined using standard methods. The symptoms of the blast disease in the palms begins with rotting of the tips of the roots and then further spreads into the media zone of the cortex resulting in the eventual death of the palm. Fungi isolated from different portion of the affected seedlings, water and soil samples include Pythium, Phytothora, Macrophomina, Aspergillus and Penicillium spp. The results of the soil physical properties of the soil samples showed the particle size analyses of the soils samples to range from 835 gkg1 to 840 gkg1 respectively. The soil texture was sandy loam with an acidic pH ranging from 5.3 to 5.8. The contents of organic matter ranged from 6.10g kg-1 to 14.25 g kg-1, total nitrogen 1.58 g kg-1 to 2.25 g kg-1, available phosphorus 5.08 mg kg-1 to 6.10mg kg-1 and potassium 1.16 cmol kg-1 to 2.18cmol kg-1. The result of this study has indicated that the source of water used for the watering of the oil palm nursery serve as the possible source of introduction of pathogenic pathogens to the oil palm seedlings.

Chytranthus macrobotrys and Radlkofera calodendron are two Sapindaceae characterized by a lack of phytochemical data. Both root barks from the two Sapindaceae species were processed by ethanol extraction followed by the isolation of their primary constituents by liquid chromatography. This process yielded four previously undescribed terpenoid glycosides together with eight known analogues. Extracts and isolated compounds from C. macrobotrys and R. calodendron were then screened for antimicrobial activity against fifteen phytopathogens. The biological screening also involved extracts and pure compounds from Blighia unijugata and Blighia welwitschii, two Sapindaceae previously studied by our group. Phytopathogens were chosen based on their economic impact on agriculture worldwide. The selection was composed primarily of fungal species including; Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Zymoseptoria tritici, Fusarium oxysporum, Botrytis cinerea, Pythium spp., Trichoderma spp. and Rhizoctonia solani. Furthermore, pure terpenoid glycosides were tested for the first time against wood-inhabiting phytopathogens such as; Phaeomoniella chlamydospora, Phaeoacremonium minimum, Fomitiporia mediterranea, Eutype lata and Xylella fastidiosa. Raw extracts exhibited different levels of activity dependent on the organism. Some pure compounds, including 3-O-α-L-arabinopyranosyl-(1 → 4)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (α-hederin), 3-O-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (macranthoside A) and 3-O-α-L-arabinopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (clemontanoside C), exhibited significant growth inhibitions on Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Fomitiporia mediterranea and Zymoseptoria tritici. Monodesmoside triterpene saponins, in particular, exhibited MIC (IC100) values as low as 25 μg/ml and IC50 values as low as 10 μg/ml against these phytopathogens. Structure-activity relationships, as well as plant-microbe interactions, were discussed.

This work highlights the ability of various cyanobacterial extracts from Anabaena spp., Tolypothrix spp., Nostoc or Trichormus, among others genera, to control the incidence of damping-off caused by Pythium ultimum in cucumber seedlings. Protocols applied aimed at the preliminary characterization of the cyanobacterial collection were very useful for predicting their phytotoxic, phytostimulating and biopesticidal capacity. First, the phytostimulatory or phytotoxic potential of a collection of 31 sonicated cyanobacterial extracts was analyzed by calculating the germination index in watercress seeds and the increase or loss of seedling weight. Likewise, the collection was characterized according to its ability to inhibit the growth of P. ultimum by dual culture bioassays and detached-leaf test. Finally, after selecting the most effective extracts, a preventive damping-off bioassay was performed based on cucumber seed biopriming. The strain SAB-M465 showed to be the most efficient strain against the in vitro growth of P. ultimum, while SAB-B912 was more discreet in this regard, but proved to be the most effective as a germination stimulator. Seed biopriming strategy with sonicated extracts of cyanobacteria revealed a remarkable promoter effect in the early stages of plant development, although only SAB-M465 was positioned as an effective control agent against damping-off caused by P. ultimum in cucumber seedbeds.

Pythium insidiosum is an important oomycete due to its ability to infect humans and animals. It causes pythiosis, a disease of difficult treatment that occurs more frequently in humans in Thailand and in horses in Brazil. Since cell-wall components are frequently related to host shifts, we decided here to use sequences from the exo-1,3-β-glucanase gene (exo1), which encodes an immunodominant protein putatively involved in cell wall remodeling, to investigate the microevolutionary relationships of Brazilian and Thai isolates of P. insidiosum. After neutrality ratification, the phylogenetic analyses performed through Maximum parsimony (MP), Neighbor-joining (NJ), Maximum likelihood (ML), and Bayesian analysis (BA) strongly supported Thai isolates being paraphyletic in relation to those from Brazil. The structure recovered by these analyses, as well as by Spatial Analysis of Molecular Variance (SAMOVA), suggests the subdivision of P. insidiosum into three clades or population groups, which are able to explain almost 81% of the variation encountered for exo1. Moreover, the two identified Thai clades were almost as strongly differentiated between each other, as they were from the Brazilian clade, suggesting an ancient Asian subdivision. The derived positioning in the phylogenetic tree, linked to the lower diversity values and the recent expansion signs detected for the Brazilian clade, further support this clade as derived in relation to the Asian populations. Thus, although some patterns presented here are compatible with those recovered with different molecular markers, exo1 was revealed to be a good marker for studying evolution in Pythium, providing robust and strongly supported results with regard to the patterns of origin and diversification of P. insidiosum.

This study tries to identify the native population of phosphate solubilizing bacteria (PSB) in the rhizospheres of maize, rice, ginger and large cardamom grown in different regions of Sikkim (India). Out of 104 rhizospheric samples collected from three agroclimatic zones of the state, 42 number of PSBs were isolated. However, only 26 best performing PSB based upon their solubilization in solid media are reported in this paper. The highest number of PSB with greatest variants were found in the rhizosphere of rice.The population density of PSB varies between 2–36×10 6 cfu g −1 . Based upon the morphological and 16S rRNA sequencing, the isolates were clustered under the genera Bacillus , Pseudomonas , Micrococcus, Staphylococcus, Microbacterium and Delftia . Phosphate solubilization efficiency of these isolates varied between 46 to 160% in solid medium and in the liquid Pikovskaya's medium phosphate solubilization capacity varied between 30.2 to 203.7 mg L −1 . Though all of the isolates were able to solubilize aluminum and iron phosphate significantly however, they solubilized Ca 3 (PO 4 ) 2 to a greater extent than the other two with AlPO 4 exhibiting comparatively poor solubilization among the three phosphate sources. Further, the in vitro antagonistic effect of the PSB isolates were studied with seven locally available fungal pathogens and it revealed that the Bacillus amyloliquefaciens PSB isolates showed higher antifungal activity against soil and root borne pathogens ( Rhizoctonia sp., Pythium sp., Fusarium sp.) than the leaf pathogens.

Made available in DSpace on 2018-12-11T17:07:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-10-01. Added 1 bitstream(s) on 2021-07-15T15:21:45Z : No. of bitstreams: 1 S1517-83822016000400863.pdf: 1654059 bytes, checksum: 22a58776e8b3997586140bdb7304515f (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Propolis and geopropolis are resinous products of bees showing antimicrobial effects. There is no data concerning their action against Pythium insidiosum – the causative agent of pythiosis, a pyogranulomatous disease of the subcutaneous tissue that affects mostly horses, dogs and humans. Fragments of 15 isolates of P. insidiodum were incubated with propolis and geopropolis extracts and evaluated for up to seven days to detect the minimal fungicidal concentration (MFC). Propolis inhibited three isolates at 1.0 mg mL−1 after 24 h and all other isolates at 3.4 mg mL−1. Geopropolis led to more variable results, exerting predominantly a fungistatic action than a fungicidal one. Propolis was more efficient than geopropolis in inhibiting P. insidiosum since lower concentrations led to no growth after 24 h. This effect may be due to propolis chemical composition, which has more active compounds than geopropolis. Propolis seemed to be a good candidate for in vivo studies, since treatment with conventional antifungal compounds is difficult in most of the cases, requiring extensive surgical debridement. Unesp Univ Estadual Paulista Instituto de Biociências Departamento de Microbiologia e Imunologia Unesp Univ Estadual Paulista Instituto de Biociências Departamento de Microbiologia e Imunologia FAPESP: 2010/01028-8 FAPESP: 2010/50064-7

Peanut pod rot, which can be caused by Pythium spp. and Rhizoctonia solani , is difficult to manage with fungicides. The objective of this study was to compare the effects of a calendar-based (CB) versus threshold-based (INC) fungicide application timings on pod rot incidence, yield, value of the crop, and returns minus fungicide cost. Large plot replicated trials were conducted in five fields with a history of pod rot. Pod rot was assessed weekly throughout the season following development of pods. Disease incidence was reduced by the preventative CB compared with INC or the non-fungicide treated control (NONE) in three of five sites. Disease was very low in the remaining two sites. Yield was not affected by treatment at individual sites, but in a combined analysis, INC at 1–2% incidence had higher yields than CB treated with mefenoxam or NONE. Occurrence of segregation 2 kernels, which results in a substantial reduction in price, was more frequent with INC and NONE than with CB at two sites. CB and INC had a higher value/ha than NONE, but there were no differences in return minus fungicide costs. CB had less pod rot during the season and a lower risk of segregation 2 kernels at harvest than INC. These results suggest that preventative CB applications made at early pegging should be used to manage pod rot. This recommendation is based on the reduction of risk to segregation 2 kernels, not because of a higher value/ha of the crop.

Vascular pythiosis, caused by Pythium insidiosum, is associated with a high mortality rate. We reviewed the outcomes and established the factors predicting prognosis of patients treated in our institution with surgery, antifungal therapy, or immunotherapy.We undertook a retrospective record review of patients with vascular pythiosis treated in Siriraj Hospital, Bangkok, Thailand, between January 2005 and January 2015. Patient characteristics, type of surgery, adjunctive antifungal treatment, adjunctive immunotherapy, and disease status of surgical arterial and surrounding soft tissue margins were recorded. We calculated the mortality rate and established factors predicting prognosis.The records of 11 patients were reviewed. All patients had thalassemia. Nine patients (81.8%) had a history of contact with contaminated water. The clinical presentations were chronic ulcers (45.5%), toe gangrene (27.3%), pulsatile mass (27.3%), and acute limb ischemia (27.3%). Above-knee amputation was required in 10 patients (90.9%). The mortality rate was 36.4%. Independent variables between survivors and nonsurvivors were lack of an arterial disease-free surgical margin (P = .003), lack of a surrounding soft tissue disease-free surgical margin (P .05), a suprainguinal lesion (P .05) and duration of symptoms (P .05). Adjuvant itraconazole, terbinafine, and Pythium vaccine have a role to play in patients with a disease-free arterial surgical margin but in whom infected surrounding soft tissue could not be completely excised.Achieving adequate disease-free surgical margins-especially the arterial margin-at amputation or débridement is the most important prognostic factor in patients with vascular pythiosis. Early detection combined with a multidisciplinary approach to treatment, including surgery, antifungal agents, and immunotherapy, allows the best possible outcome to be obtained.

Preplant soil fumigation is commonly used to control soilborne pathogens and weeds in forest seedling nurseries of Oregon and Washington. However, lower chemical inputs are desired to meet state and federal application regulations, to minimize buffer zone size requirements, and to help protect the environment. Therefore, the objectives of this research were to evaluate the efficacy of three reduced rate soil fumigants under totally impermeable film (TIF) in managing soilborne diseases and weeds, and to determine if combined applications of up to four biocontrol agents improved soilborne disease control. Reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene, all applied in combination with chloropicrin, were effective in decreasing soil populations of Pythium and Fusarium as well as the presence of Pythium in root debris from the previous crop. The roots of Douglas-fir (Pseudotsuga menziesii) seedlings transplanted into each fumigant treatment were also colonized less by Pythium and Fusarium than those transplanted into nonfumigated control plots. However, biocontrol treatments were not effective against either pathogen. Weed biomass and weeding times were also significantly reduced by fumigation. Application costs were similar for all three fumigant treatments, but seedling size was largest from the methyl bromide and metam sodium treatments followed by the 1,3-dichloropropene treatment. Based on the results of this study, reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene show promise in managing soilborne diseases and weeds in forest nurseries.

Background Recent molecular phylogenetic analysis of Lagenidium strains recovered from subcutaneous lesions in cats, dogs, and a human with lagenidiosis resolved into four clades; one of them was Lagenidium giganteum, but three others were novel. Aims Due to the recent increase in L. giganteum infections from mammals, we studied 21 Lagenidium strains isolated from dogs and a human available in our collection. Methods Molecular phylogenetic studies and phenotypic characteristics were used to characterize the strains. Results We report the finding of three novel species, herein designated as Lagenidium ajelloi, sp. nov., Lagenidium albertoi sp. nov, and Lagenidium vilelae sp. nov. Their morphological and growth features are also presented. Conclusions Our study revealed the presence of three novel Lagenidium species infecting mammals.

Biotic and abiotic constraints jeopardize the expansion of common bean (Phaseolus vulgaris L.) cultivation to the Cameroon warmer lowlands. The crop is traditionally perceived as a cooler region crop unsuited for the humid tropical areas. We surveyed 78 farmer's fields during the 2015 and 2016 growing seasons, across 7 sub-divisions in the lowland agro-ecological zone of the Centre Region of Cameroon, to document the occurrence of the common bean root rot (BRR) epidemic, the identification of causal pathogens, as well as related agro-ecological variables. We found that BRR occurred in all the surveyed farmer's fields, with disease incidence ranging from 7.4% to 92.4% and disease severity from 3.7 to 9 (On the 1–9 disease rating scale). The disease distribution was closely related to tillage, cropping systems, plant age and variety and physiological status in both seasons. The simple linear regression model and the Pearson correlation revealed significantly negative correlations between the soil pH and phosphorus content, and the disease incidence and severity. Five causative fungal genera were identifies, with varying occurrence: Fusarium spp. (65.4%), Pythium spp. (4.2%), Sclerotium spp. (5.1%), and Macrophomina spp. (8.2%), with Fusarium being the most represented and widespread pathogen irrespective of sampling field and season. Fusarium occurred singly, or in complex with the other pathogenic fungal genera. This study provides clear evidence of high prevalence of BRR disease in the humid lowlands of Cameroon, and suggests deep ploughing and phosphoric fertilizer amendment with basic soil for managing BRR in lowland agro-ecosystems.

The epidemiological, clinical and anatomopathological aspects of pythiosis in cats in northeastern Brazil are described. From January 2000 to December 2018 the Laboratory of Animal Pathology of the Federal University of Campina Grande received 1928 tissue samples of cats, three of which were diagnosed as pythiosis. Grossly, the cats showed a multinodular mass in the oral cavity associated with facial deformity (case 1), a large multinodular mass thickening the jejunum wall (case 2), and an ulcerated nodule in the skin at the base of the tail (case 3). Histologically, pyogranulomatous inflammation and necrosis, with intralesional predominantly negatively stained hyphae, were observed in all cases. Immunohistochemistry for Pythium insidiosum revealed strong immunolabelling of the hyphae. The diagnosis of pythiosis was based on the epidemiological, clinical and anatomopathological findings, and was confirmed by immunohistochemistry. Although uncommon in cats, pythiosis should be readily considered as a differential diagnosis of chronic pyogranulomatous infections of the gastrointestinal tract and skin, especially in endemic areas, where the disease is often diagnosed in other animal species.

Although oomycete species can contribute to significant losses in soybean plant density, root mass and yield, they are often underrepresented in high-throughput sequencing studies. In this study, soybean oomycete rhizosphere communities were characterized over two years from locations with and without historical disease pressure. The goals of this research were to examine the effect of location, soybean genotype, and seed treatment on oomycete communities. Soybean oomycete rhizosphere communities were dominated by Pythium, but community composition differed depending on the location and year. Pythium ultimum var. ultimum was the most abundant oomycete OTU accounting on average for >30% relative abundance in high disease pressure sites. However, sites without historical disease pressure were not devoid of oomycete plant pathogens indicating that historical disease pressure may be due to an imbalance of species, rather than simply the presence or absence of highly pathogenic species. High-disease pressure sites contained more oomycete taxa and were less even. There was no substantial evidence of seed treatment or soybean genotype impacting oomycete community composition or diversity, however, plant density and root biomass increased with the addition of neonicotinoid insecticides. Overall, this study represents an improvement of our understanding of oomycete communities in soybean rhizosphere and the impacts of agronomic factors on oomycete diversity.

This study examined the effect of minocycline alone and in combination with immunotherapy against pythiosis. Twenty rabbits, aged three months old and subcutaneously inoculated with Pythium insidiosum zoospores were divided into four groups (n = 5): treated with minocycline (10 mg/kg/day twice daily), treated with immunotherapy (34 mg subcutaneously every 14 days), treated with minocycline plus immunotherapy, and untreated (control group). The treatments were started 30 days after inoculation and continued for 70 days. The subcutaneous nodular injury areas in infected groups were measured every seven days after the beginning of treatment. Only the rabbits that developed lesions were selected for this study. When compared with the control group over 70 days, the minocycline and minocycline plus immunotherapy groups of rabbits with pythiosis showed significantly reduced injuries. The histopathology showed the presence of inflammation, macrophages and eosinophils. Grocott's staining revealed irregular hyphae-like structures that were ramified and occasionally septate. Our results suggest that minocycline has fungistatic activity and that the combination of minocycline and immunotherapy is more effective than the individual therapies tested.

From 2009 to 2012, a spatial study was conducted on soybean fields undergoing rice and soybean rotations to determine the distribution and importance of Rhizoctonia spp. Fields were sampled for soil populations by toothpick-baiting and plants were collected at growth stage V3 from GPS sampling points placed on either side of the rice levee system from the previous rice cropping year. Anastomosis group 11 (AG11) of Rhizoctonia solani, a group not recognized as causing any plant diseases on rice or soybean, was the most prevalent Rhizoctonia spp. recovered from soil and soybeans in fields assayed from 2009 to 2012. The mean recovery from the soil was 7.1 (0–94.4) and 12.2 (0–79.7) propagules/kg from fields with 48 and >96 GPS points, respectively, while the mean number of plants colonized by the fungus was 114.3 (24%) for fields with 48 GPS points and 153.8 (16%) for fields with >96 points. In 2012, all three fields assayed indicated aggregation of the soil inoculum potential of the fungus and two of the three fields indicated aggregation from the plants colonized by R. solani AG11. In all years, semi-variogram models indicated 15 measured major ranges exceeded 50 m and 11 exceeded 100 m with most of the nugget values (error) less than 5 m indicating that there is a contiguous population across space with little microstructure below the measured major range at these distances. For the three fields examined in 2012, recovery of AG11 from plants was negatively correlated with soil volumetric water content suggesting dryer areas of the field favored infection of plants. Plant stands from soil obtained for GPS locations grown under a controlled environment found a positive correlation for two of the three locations between plant stand and colonization by AG11. These studies suggest that R. solani AG11 is the dominate Rhizoctonia group in rice soybean rotations in Arkansas in the United States. R. solani AG11 opportunistically colonizes soybean and is associated with greater plant stands across fields suggesting a positive rather than a negative pathogenic role for this fungus and the host plant.