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Minimum evolution tree of Phytopythium and Pythium species based on internal transcribed spacer rDNA sequences. Achlya aquatica and A. sparrowii are used as outgroup. The isolates collected in Korea are shown in bold. Bootstrapping values (minimum evolution BP/maximum likelihood BP) higher than 70% are given above or below the branches (1000 replicate). The scale bar equals the number of nucleotide substitutions per site.
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Oomycetes are widely distributed in various environments, including desert and polar regions. Depending upon different habits and hosts, they have evolved with both saprophytic and pathogenic nutritional modes. Freshwater ecosystem is one of the most important habitats for members of oomycetes. Most studies on oomycete diversity, however, have been...
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... relationships between the Korean oomycete isolates and previously published authentic isolates were inferred using ML and ME analyses of the ITS rDNA, cox2, and cox1 mtDNA sequences. As topologies constructed by the two analyses were congruent, only the ME tree was shown for each locus (ITS in Figure 1, cox2 in Figure 2, and cox1 in Figure 3). Eight oomycete species isolated in the present study were placed in two major groups, representing two different genera, Phytopythium and Pythium; six isolates, W595, W630, W672, W707, W708, and W714, grouped in Phytopythium, whereas nine isolates, W254, W257, W631, W633, W637, W652, W654, W704, and W710, grouped in Pythium (Figures 1-3). ...
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... topologies constructed by the two analyses were congruent, only the ME tree was shown for each locus (ITS in Figure 1, cox2 in Figure 2, and cox1 in Figure 3). Eight oomycete species isolated in the present study were placed in two major groups, representing two different genera, Phytopythium and Pythium; six isolates, W595, W630, W672, W707, W708, and W714, grouped in Phytopythium, whereas nine isolates, W254, W257, W631, W633, W637, W652, W654, W704, and W710, grouped in Pythium (Figures 1-3). ...
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Up-to-date information is presented based on an intensive search of literature records on the identity, occurrence, nomenclature, substratum, host ranges, geographical distribution and literature references of the genus Pythium from India. All Pythium species published until 2020 are included in this list. The survey result of all forms of analyses...
Citations
... Phytopythium genusunun ortaya çıkışını özetlemek gerekirse, Pythium genusundan ayrılan ve ona göre taksonomik olarak daha genç bir genus olduğu söylenebilir (Bala ve ark., 2010;Rai ve ark., 2020;Tkaczyk, 2020). Bu genus, birçok Pythium ve Phytophthora türünün de yaşam koşullarını sürdürdüğü ortam koşullarıyla güçlü bir şekilde ilişkilidir (Nam & Choi, 2019). Phytopythium genusunda yaklaşık 20 tür bulunmakta ve bu organizmaların tarımsal üretimde önemli zararlar oluşturduğu son yıllarda yapılan çalışmalarla ortaya konmaktadır (Baten ve ark., 2014). ...
Phytopythium genusu önceleri Pythium cinsi altında yer alan, taksonomik çalışmaların devam etmesiyle birlikte Pythium genusundan ayrılan, günümüzde ise Pythium genusuna göre daha farklı özellikleri ortaya konmuş ve daha yeni anlaşılmaya başlamış toprak kaynaklı bir patojen grubudur. Phytopythium cinsi içinde yer alan toprak kaynaklı organizmalar Phytophthora ve Pythium türleri ile yakından ilişkili, benzer morfolojik yapı ve biyolojiye sahip organizmalardır. Phytopythium genusunda yaklaşık olarak 20 tür bulunmakta ve çoğu tür konukçu bitkilerde saprofitik olarak yaşamını devam ettirmektedir. Patojen olan türler ise konukçu bitkiler için oldukça tehlikeli ve potansiyel tehdit oluşturmaktadırlar. Bu türler içinde özellikle Phytopythium vexans dikkat çekmektedir. Yapılan çalışmalar incelendiğinde Pp. vexans’ın kültür bitkilerinin yanı sıra odunsu bitkilerde ve süs bitkilerinde de ciddi zararlar meydana getirdiği görülmektedir. Bu çalışmanın amacı Phytopythium genusunun genel özelliklerini tanıtabilmek, Phytophthora ve Pythium genusundan farklılaşan ve benzeşen özelliklerini ortaya koyabilmek, özellikle bitkilerde patojenik tür olan ve Türkiyede de son yıllarda çeşitli bitkilerde patojen olduğu saptanan ve önemi vurgulanan Pp. vexans hakkında ayrıntılı bilgi vermektir. Bu derlemede Phytopythium genusu hakkında genel bilgilendirmenin yanı sıra Pp. vexans’ın morfolojik özellikleri, konukçu bitkilerde meydana getirdiği hastalık belirtileri, tanılanmasında kullanılan yöntemler, dünyada ve Türkiye’de yürütülen çalışmalar ve savaşımına yönelik stratejilere yer verilecektir. Böylece toprak kaynaklı olan bu patojen grubunun tarımsal üretimde meydana getirdiği potansiyel tehdit hakkında fikir sahibi olunacaktır.
... This isolate grouped most closely to P. inflatum; however, it formed a distinct branch from this taxon. P. inflatum has been implicated as a pathogen of a number of crop plants, including strawberry, corn, and soybean, and it has been isolated from soil and water samples in Africa and Korea [57][58][59][60]; however, a description of it as an invertebrate or mosquito larval pathogen has not been reported. ...
Only a handful of microbial mosquito larval pathogens have been described to date. Sampling several natural enzootic infections of mosquito larvae in southwestern Florida indicated the presence of microbial pathogens capable of extensive larval mortality. A microscopic analysis of one sample site revealed extensive apparent growth of a Pythium-like microbe on mosquito larvae, with the highest degree of infection observed in the siphon and head regions. Structures consistent with sporangia were seen on infected insects after lactophenol blue staining, and higher-resolution scanning electron microscopy (SEM) micrographs showed sporangia and encysted zoospores targeting the head and siphon regions. The isolate was single-colony purified, and molecular identification targeting the ITS and COX1 loci coupled to phylogenetic reconstruction indicated that the isolate belonged to the Pythium genus but was distinct from its closest characterized species, P. inflatum. Morphological features were characterized, with the isolate showing rapid growth on all mycological media tested and relatively high thermotolerance, capable of robust growth at 37 °C; hence, it was designated P. thermoculicivorax. Sampling from a second series of natural infections of mosquito larvae resulted in the molecular identification of three Trichoderma isolates, one with high similarity to T. strigosum and the other two clustering closely with T. asperellum. These data highlight the occurrence of natural enzootic infections of mosquito larvae, potentially as a resource for the identification of new mosquito pathogens.
... This isolate grouped most closely to P. inflatum, however, it formed a distinct branch from this taxon. P. inflatum has been implicated as a pathogen of a number of crop plants including strawberry, corn, and soybean, and has been isolated from soil and water samples in Africa and Korea [57][58][59][60], however, its description as an invertebrate or mosquito larval pathogen has not been reported. ...
Only a handful of microbial mosquito larval pathogens have been described to date. Sampling of several natural enzootic infections of mosquito larvae in southwestern Florida indicated the presence of microbial pathogens capable of extensive larval mortality. Microscopic analysis of one sample site revealed extensive apparent growth of a Pythium-like microbe on mosquito lar-vae, with highest infection observed on the siphon and head regions. Structures consistent with sporangia were seen on infected insects after lactophenol blue staining, and higher resolution scanning electron micrographs (SEM) showed sporangia and encysted zoospores targeting the head and siphon regions. The isolate was single colony purified and molecular identification targeting the ITS and COX1 loci coupled to phylogenetic reconstruction indicated that the isolate belonged to the Pythium genus, but was distinct from its closest characterized species, P. angusta-tum. Morphological features were characterized, with the isolate showing rapid growth on all mycological media tested and relatively high thermotolerance, capable of robust growth at 37oC, and hence was designated, P. thermoculicivorax. Sampling from a second series of natural infec-tions of mosquito larvae resulted in the molecular identification of three Trichoderma isolates, one with high similarity to T. strigosum, and the other two clustering with, but distinct from, T. asperellum. These data highlight the occurrence of natural enzootic infections of mosquito larvae, potentially as a resource for the identification of new mosquito pathogens.
... Over 400 Phytophthora and Pythium and allied species have now been identified. Only a relatively small proportion of these are readily isolated and regularly seen in water samples (65+ including species of Phytophthora, Pythium, Phytopythium, and Halophytophora: Hwang et al., 2008;Reeser et al., 2011;Hüberli et al., 2013;Huai et al., 2013;Nagel et al., 2013;Zappia et al., 2014;Choudhary et al., 2016;Stamler et al., 2016;Nam and Choi, 2019;Redekar et al., 2019;Riolo et al., 2020). However, it seems likely that many more species are in fact able to spread in bodies of water. ...
Monitoring oomycete populations and communities in bodies of water is vital in developing our understanding of this important group of fungus-like protists that contains many serious pathogens of both crops and wild plants. The methodologies involved in monitoring oomycetes are often presented as a developmental hierarchy, progressing from ‘traditional’ culture-based techniques through immunological techniques and basic PCR to qPCR and metagenomics. Here, techniques are assessed according to the roles they can perform in relation to four stages of the monitoring process: capture, detection and identification, viability determination, and quantification. Possible synergies are then considered for the combined use of different techniques in addressing the various needs relating to different questions asked of monitoring, with an emphasis on the continuing value of cultural and immunodiagnostic procedures. Additionally, the exciting future presented by the ongoing development and improvement of metabarcoding and the use of high throughput sequencing techniques in the measurement and monitoring of oomycete inoculum to determine and mitigate plant disease risks is addressed.
... Oomycetes are also called "water molds," and most of the species in this group are found in aquatic habitats (Li et al. 2014;Link et al. 2002). These two species of Phytopythium are abundantly found in greenhouse irrigation water tanks (Choudhary et al. 2016;Parke et al. 2019), hydroponic systems (Gonçalves et al. 2016;Kanjanamaneesathian et al. 2013;Teixeira et al. 2006), ebb and flow irrigation systems , and natural rivers and reservoirs used as a source of agricultural irrigation (Hon-Hing et al. 2012;Nam and Choi 2019). ...
Phytopythium vexans and Phytopythium helicoides are important waterborne plant pathogens causing root and crown rot disease in plants from different families ( P. vexans = 19 and P. helicoides = 18) worldwide. The main objective of this diagnostic guide is to provide detailed information about symptoms and signs of root and crown rot disease, host range, geographic distribution, pathogen isolation, conventional and molecular identification, storage, and pathogenicity testing, and present a reliable zoospore production procedure for these pathogens. This guide is aimed at facilitating the detection and identification of these pathogens in the field and laboratory, and the zoospore production procedure is anticipated to help in further investigations and development of different management strategies.
[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
... Pythium insidiosum is an oomycete residing in aquatic bodies, with a higher prevalence in tropical and subtropical regions of the world. 1 It belongs to the kingdom Straminipila, class Oomycete, phylum Oomycota and family Pythiaceae. 2 It causes sight-threatening keratitis and the clinical picture closely mimics fungal keratitis. Hence, it is also called a "parafungus". ...
Pythium insidiosum is an oomycete belonging to the phylum Straminipila and family Pythiaceae. It causes rapidly progressive vision-threatening keratitis. Clinically, microbiologically and morphologically, it closely resembles fungal keratitis; hence it is also labelled as a “parafungus”. The clinical features mimicking fungus are subepithelial and stromal infiltrate, endo-exudates, corneal melt and hypopyon. The hallmark features of Pythium are tentacular projections, reticular dot-like infiltrate, peripheral furrowing and thinning, and rapid limbal spread. Microbiological corneal smearing on KOH and Gram stain reveal septate or aseptate, obtuse to perpendicular hyphae which mimic fungal hyphae. Culture on any nutritional agar reveals cream, cottonwool-like, fluffy colonies, and diagnosis is confirmed by zoospore formation by the leaf incarnation method. Medical management with antifungals and antibacterials still presents a dilemma. Early therapeutic keratoplasty has been the proposed treatment in most cases. We hypothesize that the prognosis of Pythium keratitis is governed by regional geographical variations, ulcer size and density on presentation, and initial treatment strategy. The available literature supporting the proposed hypothesis is also discussed, along with the hallmark features of Pythium and how it masquerades as other microorganisms causing keratitis. We also aim to propose a novel diagnostic and treatment algorithm for managing this vision-threatening keratitis.
... In fact, other oomycetes could be also as abundant as Saprolegniales but we misinterpret the current knowledge. For instance, Halophytophthora, Nothophytophthora and Phytopythium are non-Saprolegniales members of oomycetes which are recently found in various freshwater ecosystems (Caballol et al., 2021;O'Hanlon et al., 2021;Nam and Choi, 2019). However, since isolating each taxon requires different methodologies, it would be impossible to understand the composition of different taxa in the environment. ...
Research on the order of Saprolegniales (Oomycota) has been an ongoing quest for more than a century. The best studied genera are Saprolegnia and Aphanomyces, known for their pathogenicity on freshwater animals. In this study, we reviewed 1073 papers and 2803 ITS sequences of Saprolegniales to investigate its taxonomy, diversity and potential roles in mainly freshwater ecology. We found that generally, our knowledge on diversity and ecology of Saprolegniales in freshwater ecosystems is limited. Neither classic taxonomy nor available molecular techniques have been sufficient to resolve several genera and species. Also, we currently lack a comprehensive understanding of their involvement in carbon turnover and food web dynamics. Finally, due to lack of high-throughput sequencing techniques, it is not clear how and to what extent communities of Saprolegniales might differ in freshwater econiches. Therefore, give a historical perspective on the establishment of Saprolegniales, explain improvements, highlight deficiencies, and finally propose new research avenues for more systematic studies on this order. We conclude that challenges in studying Saprolegniales can be removed by increasing the practicality of classic taxonomy and applying available molecular toolboxes (multi-gene phylogeny and high-throughput sequencing). Additionally, inclusion of Saprolegnialesin freshwater carbon cycling should be addressed for their better ecological resolution..
... To determine the effect of direct predation of Trichoderma spp. on the viability of P. infestans, mycelial plugs were transferred from both control and confrontation plates into new V8 agar medium amended with the antifungal nystatin at 50 μg/ml. It was previously reported that, whereas genus Trichoderma is sensitive to this reagent, P. infestans is insensitive to its growth inhibitory effect (Nam and Choi 2019;Sato and Kato 1993). We observed that, al- Fig. 1. ...
Potato growers worldwide are embattled in a war since more than 150-years with an enemy whose lifecycle, genome size and architecture, and economic impacts are the epitome of a plant pathogen. Phytophthora infestans (Mont.) de Bary is an oomycete that causes the notorious late blight infection in potato and tomato. In this study we explored the benefits of the multi-talented plant symbiotic fungi Trichoderma spp. and of their metabolites as potential biopesticides against P. infestans. Eleven strains of Trichoderma spp. were obtained from soil and tree barks and were identified using DNA sequence analysis. The antagonistic potential of the strains against P. infestans was first evaluated in vitro. In dual culture assays, P. infestans growth was significantly inhibited (53-95%) by different Trichoderma spp. through direct mycoparasitism, competition for space and nutrients, and/or antibiosis. The cell-free filtrates (CFF) of different Trichoderma strains were obtained, characterized for anti-Phytophthora activities as well as biochemical stability. The results indicated that Trichoderma CFF were chemically stable and strongly decreased P. infestans’ mycelial growth as well as zoospore motility and viability. Similarly, Trichoderma CFF showed significant protection against P. infestans infection in leaf disk assays. Ultra-performance liquid chromatography analysis revealed the presence of harzianic (HA), iso harzianic (iso-HA) acid and 6-Pentyl-2H-pyran-2-one (6PP) as major compounds in different Trichoderma CFF. Furthermore, selected Trichoderma strains significantly protected potato plants against soil-mediated late blight infection. Finally, Trichoderma spp. showed high compatibility with a copper-based fungicide, suggesting that both protective agents could be combined in integrated pest management program.
... This variability was previously observed for Phytopythium species, such as P. vexans [21,28,29], P. helicoides [21,28,30,31], P. litorale, P. kandeliae [32], P. mercuriale and P. oedochilum [33]. Based on micro-and macro-morphology analyses, the selected strains confirmed the typical characteristics of species [25,[33][34][35][36]. ...
Since 2012, the kiwifruit vine decline syndrome (KVDS) has progressively compromised Italian kiwifruit orchards. Different abiotic and biotic factors have been associated with the establishment and development of KVDS. During monitoring of orchards affected by KVDS in north-western Italy during 2016–2019, 71 Phytopythium spp. were isolated. Based on maximum likelihood concatenated phylogeny on the ITS1-5.8S-ITS2 region of the rDNA, large subunit rDNA, and cytochrome oxidase I, isolates were identified as P. vexans (52), P. littorale (10), P. chamaehyphon (7) and P. helicoides (2). Phytopythium litorale and P. helicoides are reported for the first time as agents of KVDS in Italy. To demonstrate pathogenicity and fulfil Koch’s postulates, representative isolates of P. vexans, P. littorale, P. chamaehyphon and P. helicoides were inoculated in potted plants. In these trials, waterlogging was applied to stress plant with a temporary anoxia and to favour the production of infective zoospores by the oomycetes. In experiments in vitro, the four species showed the highest growth at 25–30 °C, depending on the media used. P. helicoides was able to grow also at 40 °C. The four species were able to grow in vitro at a pH ranging from 5.0 to 8.0, showing that pH had less effect on growth than temperature. The present study suggests a strong role of different species of Phytopythium in the establishment and development of KVDS. Phytopythium spp. could be favoured by the average increase in soil temperatures during summer, associated with global warming.
... Consequently, members of Achlyaceae [7], Peronosporaceae [42], and Pythiaceae [43] were recently revealed. In the present study, we analyzed the diversity and ecology of Saprolegniaceae, which accounted for 13% of the collection. ...
... The samples were distributed throughout thin layers of PDA and V8A agar plates. For plant debris, like leaves, stems, and twigs, the samples were washed three times with distilled water [43,44] and cut into 3-5 mm 2 sections before placing them on the two types of solid growth media. Bacterial and fungal growth were suppressed by adding 15 ppm rifampicin and 20 ppm nystatin to the medium. ...
The fungal-like family Saprolegniaceae (Oomycota), also called “water mold,” includes mostly aquatic saprophytes as well as notorious aquatic animal pathogens. Most studies on Saprolegniaceae have been biased toward pathogenic species that are important to aquaculture rather than saprotrophic species, despite the latter’s crucial roles in carbon cycling of freshwater ecosystems. Few attempts have been made to study the diversity and ecology of Saprolegniaceae; thus, their ecological role is not well-known. During a survey of oomycetes between 2016 and 2021, we investigated the diversity and distribution of culturable Saprolegniaceae species in freshwater ecosystems of Korea. In the present study, members of Saprolegniaceae were isolated and identified at species level based on their cultural, morphological, and molecular phylogenetic analyses. Furthermore, substrate preference and seasonal dynamics for each were examined. Most of the species were previously reported as animal pathogens; however, in the present study, they were often isolated from other freshwater substrates, such as plant debris, algae, water, and soil sediment. The relative abundance of Saprolegniaceae was higher in the cold to cool season than that in the warm to hot season of Korea. This study enhances our understanding of the diversity and ecological attributes of Saprolegniaceae in freshwater ecosystems.
