Journal articles: 'Pythium oligandrum'

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Mohamed, N., J. Lherminier, M. J. Farmer, J. Fromentin, N. Béno, V. Houot, M. L. Milat, and J. P. Blein. "Defense Responses in Grapevine Leaves Against Botrytis cinerea Induced by Application of a Pythium oligandrum Strain or Its Elicitin, Oligandrin, to Roots." Phytopathology® 97, no. 5 (May 2007): 611–20. http://dx.doi.org/10.1094/phyto-97-5-0611.

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Pythium oligandrum is known to display antagonistic activities against several species of pathogenic fungi. It also produces an elicitor of plant defense named oligandrin, which belongs to the elicitin family (10-kDa proteins synthesized by Phytophthora and Pythium species). Here, the potential of P. oligandrum or its purified elicitin to limit the progression of B. cinerea on grapevine leaf and the resulting plant-microorganism interactions are described. P. oligandrum or oligandrin were applied to roots, and changes in the ultrastructure and at the molecular level were examined. When B. cinerea was applied to leaves of pretreated plants, leaf invasion was limited and the protection level reached about 75%. On leaf tissues surrounding B. cinerea inoculation, modifications of cuticle thickness, accumulation of phenolic compounds, and cell wall apposition were observed, indicating that grapevine can be considered reactive to elicitins. No macroscopic hypersensitive reaction associated with the elicitation treatment was observed. At the molecular level, the expression of three defense-related genes (LTP-1, β-1,3-glucanase, and stilbene synthase) was studied. RNAs isolated from B. cinerea-infected leaves of grapevine challenged or not with P. oligandrum or oligandrin were analyzed by real-time reverse transcription-polymerase chain reaction. In grapevine leaves, LTP-1 gene expression was enhanced in response to oligandrin, and RNA transcript levels of β-1,3-glucanase and stilbene synthase increased in response to all treatments with different magnitude. Taken together, these results open new discussion on the concept of plant reactivity to elicitins, which has until now, been mainly based on plant hypersensitive responses.

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Al-Rawahi, A. K., and J. G. Hancock. "Rhizosphere Competence of Pythium oligandrum." Phytopathology® 87, no. 9 (September 1997): 951–59. http://dx.doi.org/10.1094/phyto.1997.87.9.951.

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The associations of Pythium oligandrum with the root cortex, rhizoplane, and rhizosphere were measured with 11 crop species. This work was expedited by the use of a semiselective technique for isolation of P. oligandrum from soil and plant material. Cortical colonization of roots by P. oligandrum was not detected, and the rhizoplanes of the roots of most crops were free of the fungus. However, P. oligandrum was detected in large quantities with every crop tested when roots with adhering soil (rhizosphere soil) were assayed. Different crop species and cultivars of cantaloupe, cauliflower, and tomato varied in rhizosphere densities of P. oligandrum, but rhizosphere population densities of the fungus were consistently higher than in nonrhizosphere soils with plants grown in P. oligandrum-infested sterilized potting mix or an unsterilized mineral soil. After transplanting tomatoes into potting mix infested with P. oligandrum, increases in CFU occurred over time in the rhizosphere but not in the nonrhizosphere soil. In trials on delivery methods of inoculum of P. oligandrum, the rhizosphere populations of tomato plants grown in potting mix were about sixfold higher compared to seed-coat treatments when ground, alginate pelleted oospores were applied to seedlings growing in plug containers prior to transplanting or to pots containing potting mix before direct seeding.

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Vallance, Jessica, Gaétan Le Floch, Franck Déniel, Georges Barbier, C. André Lévesque, and Patrice Rey. "Influence of Pythium oligandrum Biocontrol on Fungal and Oomycete Population Dynamics in the Rhizosphere." Applied and Environmental Microbiology 75, no. 14 (May 15, 2009): 4790–800. http://dx.doi.org/10.1128/aem.02643-08.

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ABSTRACT Fungal and oomycete populations and their dynamics were investigated following the introduction of the biocontrol agent Pythium oligandrum into the rhizosphere of tomato plants grown in soilless culture. Three strains of P. oligandrum were selected on the basis of their ability to form oospores (resting structures) and to produce tryptamine (an auxin-like compound) and oligandrin (a glycoprotein elicitor). Real-time PCR and plate counting demonstrated the persistence of large amounts of the antagonistic oomycete in the rhizosphere throughout the cropping season (April to September). Inter-simple-sequence-repeat analysis of the P. oligandrum strains collected from root samples at the end of the cropping season showed that among the three strains used for inoculation, the one producing the smallest amount of oospores was detected at 90%. Single-strand conformational polymorphism analysis revealed increases in the number of members and the complexity of the fungal community over time. There were no significant differences between the microbial ecosystems inoculated with P. oligandrum and those that were not treated, except for a reduction of Pythium dissotocum (ubiquitous tomato root minor pathogen) populations in inoculated systems during the last 3 months of culture. These findings raise interesting issues concerning the use of P. oligandrum strains producing elicitor and auxin molecules for plant protection and the development of biocontrol.

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Sayed, Shaban R. M., Shaimaa A. M. Abdelmohsen, Hani M. A. Abdelzaher, Mohammed A. Elnaghy, Ashraf A. Mostafa, Fatemah F. Al-Harbi, and Ashraf M. M. Abdelbacki. "Myco-Suppression Analysis of Soybean (Glycine max) Damping-Off Caused by Pythium aphanidermatum." Plants 10, no. 4 (April 16, 2021): 788. http://dx.doi.org/10.3390/plants10040788.

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The role of Pythium oligandrum as a biocontrol agent against Pythium aphanidermatum was investigated to avoid the harmful impacts of fungicides. Three isolates of P. oligandrum (MS15, MS19, and MS31) were assessed facing the plant pathogenic P. aphanidermatum the causal agent of Glycine max damping-off. The tested Pythium species were recognized according to their cultural and microscopic characterizations. The identification was confirmed through sequencing of rDNA-ITS regions including the 5.8 S rDNA. The biocontrol agent, P. oligandrum, isolates decreased the mycelial growth of the pathogenic P. aphanidermatum with 71.3%, 67.1%, and 68.7% through mycoparasitism on CMA plates. While the half-strength millipore sterilized filtrates of P. oligandrum isolates degrade the pathogenic mycelial linear growth by 34.1%, 32.5%, and 31.7%, and reduce the mycelial dry weight of the pathogenic P. aphanidermatum by 40.1%, 37.4%, and 36.8%, respectively. Scanning electron microscopy (SEM) of the most effective antagonistic P. oligandrum isolate (MS15) interaction showed coiling, haustorial parts of P. oligandrum to P. aphanidermatum hyphae. Furthermore, P. oligandrum isolates were proven to enhance the germination of Glycine max seedling to 93.3% in damping-off infection using agar pots and promote germination of up to 80% during soil pot assay. On the other hand, P. oligandrum isolates increase the shoot, root lengths, and the number of lateral roots.

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Al-Rawahi, A. K., and J. G. Hancock. "Parasitism and Biological Control of Verticillium dahliae by Pythium oligandrum." Plant Disease 82, no. 10 (October 1998): 1100–1106. http://dx.doi.org/10.1094/pdis.1998.82.10.1100.

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Pythium oligandrum was a parasite of Verticillium dahliae in dual culture, impeding the latter's ability to grow and form microsclerotia. Variation occurred among isolates of P. oligandrum in their parasitism toward isolates of V. dahliae, and isolates of V. dahliae expressed a range of susceptibilities to parasitism by P. oligandrum. Temperature and matric potential significantly affected interactions between these fungi. Populations of P. oligandrum in the rhizosphere of pepper (Capsicum annuum) were similar in a potting soil infested and noninfested with V. dahliae, but the populations of V. dahliae in combined samples of rhizosphere and nonrhizosphere soil of pepper were significantly lower in the presence of P. oligandrum than in its absence. In greenhouse experiments with pepper grown in soil infested with V. dahliae, shoot and fruit weights were significantly higher in the presence of P. oligandrum than in its absence. However, when soil was infested only with P. oligandrum, fresh weights of shoots and fruits were 40 to 50% higher than when plants were grown in its absence, evidence that this fungus significantly promoted growth of this crop. Therefore, processes responsible for improved plant health associated with soil treatment with P. oligandrum could be the result of complex interactions between pathogen, host, and mycoparasite.

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Bělonožníková, Kateřina, Kateřina Vaverová, Tomáš Vaněk, Miroslav Kolařík, Veronika Hýsková, Radomíra Vaňková, Petre Dobrev, et al. "Novel Insights into the Effect of Pythium Strains on Rapeseed Metabolism." Microorganisms 8, no. 10 (September 25, 2020): 1472. http://dx.doi.org/10.3390/microorganisms8101472.

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Pythium oligandrum is a unique biological control agent. This soil oomycete not only acts as a mycoparasite, but also interacts with plant roots and stimulates plant defense response via specific elicitors. In addition, P. oligandrum can synthetize auxin precursors and stimulate plant growth. We analyzed the secretomes and biochemical properties of eleven Pythium isolates to find a novel and effective strain with advantageous features for plants. Our results showed that even closely related P. oligandrum isolates significantly differ in the content of compounds secreted into the medium, and that all strains secrete proteins, amino acids, tryptamine, phenolics, and hydrolytic enzymes capable of degrading cell walls (endo-β-1,3-glucanase, chitinase, and cellulase), exoglycosidases (especially β-glucosidase), proteases, and phosphatases. The most different strain was identified as a not yet described Pythium species. The changes in metabolism of Brassica napus plants grown from seeds coated with the tested Pythium spp. were characterized. Enhanced levels of jasmonates, ethylene precursor, and salicylic acid may indicate better resistance to a wide variety of pathogens. Glucosinolates, as defense compounds against insects and herbivores, were enhanced in young plants. Altogether, P. oligandrum strains varied in their life strategies, and either they could perform equally as plant growth promoters and mycoparasites or they had developed one of these strategies better.

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Načeradská, Martina, Michaela Fridrichová, Dita Kellnerová, Soňa Peková, and Petr Lány. "Antifungal effects of the biological agent Pythium oligandrum observed in vitro." Journal of Feline Medicine and Surgery 19, no. 8 (July 1, 2016): 817–23. http://dx.doi.org/10.1177/1098612x16658690.

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Objectives Dermatophytosis, commonly known as ringworm, is a superficial fungal skin disease and zoonosis. Pythium oligandrum is a micromycete with mycoparasitic properties that is used in agriculture to control fungal infections on plants. Formulations containing P oligandrum were also developed for the treatment of dermatophytoses, but only a small number of case studies have been published. In order to document the process in simplified conditions in vitro, we investigated the effectiveness of P oligandrum against three pathogenic dermatophytes common in domestic animals. Methods Cultures of the pathogens grown on nutrient media and experimentally infected cat hair were treated with P oligandrum preparations in therapeutic concentration and the changes were documented by microscopic videos and scanning electron microscopy. Results There was strong mycoparasitic activity of P oligandrum against Microsporum canis, Microsporum gypseum and Trichophyton mentagrophytes. Conclusions and relevance P oligandrum was demonstrated to be effective against three common causes of dermatophytosis in vitro.

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Faure, Charlène, Marine Veyssière, Betty Boëlle, Hélène San Clemente, Olivier Bouchez, Céline Lopez-Roques, Adeline Chaubet, et al. "Long-Read Genome Sequence of the Sugar Beet Rhizosphere Mycoparasite Pythium oligandrum." G3: Genes|Genomes|Genetics 10, no. 2 (December 2, 2019): 431–36. http://dx.doi.org/10.1534/g3.119.400746.

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Pythium oligandrum is a soil born free living oomycete able to parasitize fungi and oomycetes prey, including important plant and animals pathogens. Pythium oligandrum can colonize endophytically the root tissues of diverse plants where it induces plant defenses. Here we report the first long-read genome sequencing of a P. oligandrum strain sequenced by PacBio technology. Sequencing of genomic DNA loaded onto six SMRT cells permitted the acquisition of 913,728 total reads resulting in 112X genome coverage. The assembly and polishing of the genome sequence yielded180 contigs (N50 = 1.3 Mb; L50 = 12). The size of the genome assembly is 41.9 Mb with a longest contig of 2.7 Mb and 15,007 predicted protein-coding genes among which 95.25% were supported by RNAseq data, thus constituting a new Pythium genome reference. This data will facilitate genomic comparisons of Pythium species that are commensal, beneficial or pathogenic on plant, or parasitic on fungi and oomycete to identify key genetic determinants underpinning their diverse lifestyles. In addition comparison with plant pathogenic or zoopathogenic species will illuminate genomic adaptations for pathogenesis toward widely diverse hosts.

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Brožová, J. "Exploitation of the mycoparasitic fungus Pythium oligandrum in plant protection – A review." Plant Protection Science 38, No. 1 (January 29, 2012): 294–35. http://dx.doi.org/10.17221/4818-pps.

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Pythium oligandrum Drechs. belongs to the order Oomycetes. It is parasitic on many fungi from the same or other orders. The antagonism of P. oligandrum is a multifaceted process dependent on the target species involved. P. oligandrum is nonpathogenic on 12 species of crops from six families. It does not attack their tissue but occurs on the root surface, predominantly in the regions of hypocotyl – taproot, together with plant pathogenic fungi. It utilises the root exudates and fungus hyphae on the root surface, including those of the plant pathogens, for its own support. A growth stimulation of plants was observed. P. oligandrum can be utilised for biological control on a wide spectrum of crop plants. Different methods of application have been developed. The effect of a mycoparasite preparation is more preventive.

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Picard, Karine, Yves Tirilly, and Nicole Benhamou. "Cytological Effects of Cellulases in the Parasitism of Phytophthora parasitica by Pythium oligandrum." Applied and Environmental Microbiology 66, no. 10 (October 1, 2000): 4305–14. http://dx.doi.org/10.1128/aem.66.10.4305-4314.2000.

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ABSTRACT The ubiquitous oomycete Pythium oligandrum is a potential biocontrol agent for use against a wide range of pathogenic fungi and an inducer of plant disease resistance. The ability ofP. oligandrum to compete with root pathogens for saprophytic colonization of substrates may be critical for pathogen increase in soil, but other mechanisms, including antibiosis and enzyme production, also may play a role in the antagonistic process. We used transmission electron microscopy and gold cytochemistry to analyze the intercellular interaction between P. oligandrum andPhytophthora parasitica. Growth of P. oligandrum towards Phytophthora cells correlated with changes in the host, including retraction of the plasma membrane and cytoplasmic disorganization. These changes were associated with the deposition onto the inner host cell surface of a cellulose-enriched material. P. oligandrum hyphae could penetrate the thickened host cell wall and the cellulose-enriched material, suggesting that large amounts of cellulolytic enzymes were produced. Labeling of cellulose with gold-complexed exoglucanase showed that the integrity of the cellulose was greatly affected both along the channel of fungal penetration and also at a distance from it. We measured cellulolytic activity of P. oligandrum in substrate-free liquid medium. The enzymes present were almost as effective as those from Trichoderma viride in degrading both carboxymethyl cellulose and Phytophthora wall-bound cellulose. P. oligandrum and its cellulolytic enzymes may be useful for biological control of oomycete pathogens, includingPhytophthora and Pythium spp., which are frequently encountered in field and greenhouse production.

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Luca, Iasmina, Mirela Imre, Marius Stelian Ilie, Ion Oprescu, and Gheorghe Dărăbuş. "The biological potential of a product containing Pythium oligandrum against Uncinaria stenocephala (Railliet, 1884) larvae." Journal of the Hellenic Veterinary Medical Society 73, no. 1 (April 29, 2022): 3651–56. http://dx.doi.org/10.12681/jhvms.25380.

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Pythium oligandrum is an oomycete commonly used in the biological control of plant and vegetable pests. In veterinary medicine is used to treat dermatophytosis produced by Microsporum canis. It acts as an antagonist, negatively influencing the development of other fungi. Through hydrolytic enzymes, such as kinase and cellulase, it destroys the cell wall and the internal cytoplasmic content. Many fungi are considered nematophagous. This potential has not been exploited for Pythium oligandrum, which is why in this study the potential larvicidal action against Uncinaria stenocephala larvae was investigated.Ecosin® product, which contains P. oligandrum and other excipients, was used. A solution was prepared according to manufacturer. The Uncinaria stenocephala larvae were exposed to this substance and the action was investigated after 7 days. The results obtained showed 37.23% larval reduction.Being an eco-friendly product, further studies are needed to improve the protocol for its use in cleaning spaces and surfaces in veterinary clinics, where various parasitic forms (larvae or eggs) are found.

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Juhásová, G., and S. Bernadovičová. "Efficacy of biofungicides Supresivit and Polyversum against Phytophthora root pathogens on European chestnut (Castanea sativa Mill.)." Horticultural Science 31, No. 3 (November 25, 2011): 109–14. http://dx.doi.org/10.17221/3802-hortsci.

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The effect of two commercially produced biopreparations on the originators of chestnut ink disease in Slovakia – soil fungi Phytophthora cambivora and Phytophthora cinnamomi was tested in laboratory conditions. Investigations of interrelations between Trichoderma harzianum (Pythium oligandrum) and isolates of Phytophthora sp. obtained from infected tissues of Castanea sativa Mill. proved more important inhibitive effects for Pythium oligandrum (biopreparation Polyversum) efficiency 25.3% (Ph. cambivora) and 26.2% (Ph. cinnamomi). Biopreparation Supresivit (Trichoderma harzianum) reached the efficiency 9.1% for Ph. cambivora isolates and 9.2% for Ph. cinnamomi isolates. Significant effect of the used bioformulas for inhibition of mycelial growth of both Phytophthora sp. and significant difference in the efficacy of two different bioformulas were confirmed statistically.  

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Benhamou, Nicole, Gaêtan le Floch, Jessica Vallance, Jonathan Gerbore, Damien Grizard, and Patrice Rey. "Pythium oligandrum: an example of opportunistic success." Microbiology 158, no. 11 (November 1, 2012): 2679–94. http://dx.doi.org/10.1099/mic.0.061457-0.

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Haghi, Zeinab, Reza Mostowfizadeh-Ghalamfarsa, and Véronique Edel-Hermann. "Genetic diversity of Pythium oligandrum in Iran." Journal of Plant Pathology 102, no. 4 (July 27, 2020): 1197–204. http://dx.doi.org/10.1007/s42161-020-00613-3.

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Luca, Iasmina, Marius Stelian Ilie, Tiana Florea, Adrian Olariu-Jurca, Adrian Stancu, and Gheorghe Dărăbuş. "The Use of Pythium oligandrum in the Biological Control of Roundworm Infection in Dogs and Cats." Pathogens 11, no. 3 (March 17, 2022): 367. http://dx.doi.org/10.3390/pathogens11030367.

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Pythium oligandrum is an oomycete used in veterinary medicine to treat dermatophytosis in animals. The ovicidal potential against various types of parasite eggs has not been investigated. Ascarids are very common in young animals and the resistance of eggs in the external environment is very high. A commercial product containing P. oligandrum was used in the present study. Its ovicidal action against Toxocara spp. eggs was investigated. Thus, two categories of media (soil and sandstone) were used, on which the ascarid eggs were dispersed. The commercial product was prepared as a solution and was applied according to the manufacturer. The treatment scheme indicated in case of animals with dermatophytosis was used. Thus, the external natural conditions were recreated in the laboratory, in order to establish whether there is any applicability for this oomycete in the biological control of some parasitic diseases. The results indicated an ovicidal action of Pythium oligandrum, supporting the prospects of its use in the decontamination methods of various surfaces or environments where ascarid eggs from carnivores are found.

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Yang, Kun, Xiaohua Dong, Jialu Li, Yi Wang, Yang Cheng, Ying Zhai, Xiaobo Li, Lihui Wei, Maofeng Jing, and Daolong Dou. "Type 2 Nep1-Like Proteins from the Biocontrol Oomycete Pythium oligandrum Suppress Phytophthora capsici Infection in Solanaceous Plants." Journal of Fungi 7, no. 7 (June 22, 2021): 496. http://dx.doi.org/10.3390/jof7070496.

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As a non-pathogenic oomycete, the biocontrol agent Pythium oligandrum is able to control plant diseases through direct mycoparasite activity and boosting plant immune responses. Several P. oligandrum elicitors have been found to activate plant immunity as microbe-associated molecular patterns (MAMPs). Necrosis- and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs) are a group of MAMPs widely distributed in eukaryotic and prokaryotic plant pathogens. However, little is known about their distribution and functions in P. oligandrum and its sister species Pythium periplocum. Here, we identified a total of 25 NLPs from P. oligandrum (PyolNLPs) and P. periplocum (PypeNLPs). Meanwhile, we found that PyolNLPs/PypeNLPs genes cluster in two chromosomal segments, and our analysis suggests that they expand by duplication and share a common origin totally different from that of pathogenic oomycetes. Nine PyolNLPs/PypeNLPs induced necrosis in Nicotiana benthamiana by agroinfiltration. Eight partially purified PyolNLPs/PypeNLPs were tested for their potential biocontrol activity. PyolNLP5 and PyolNLP7 showed necrosis-inducing activity in N. benthamiana via direct protein infiltration. At sufficient concentrations, they both significantly reduced disease severity and suppressed the in planta growth of Phytophthora capsici in solanaceous plants including N. benthamiana (tobacco), Solanum lycopersicum (tomato) and Capsicum annuum (pepper). Our assays suggest that the Phytophthora suppression effect of PyolNLP5 and PyolNLP7 is irrelevant to reactive oxygen species (ROS) accumulation. Instead, they induce the expression of antimicrobial plant defensin genes, and the induction depends on their conserved nlp24-like peptide pattern. This work demonstrates the biocontrol role of two P. oligandrum NLPs for solanaceous plants, which uncovers a novel approach of utilizing NLPs to develop bioactive formulae for oomycete pathogen control with no ROS-caused injury to plants.

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Takenaka, Shigehito. "Studies on biological control mechanisms of Pythium oligandrum." Journal of General Plant Pathology 81, no. 6 (September 11, 2015): 466–69. http://dx.doi.org/10.1007/s10327-015-0620-0.

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Takenaka, Shigehito, Hiroyuki Sekiguchi, Kazuhiro Nakaho, Motoaki Tojo, Akira Masunaka, and Hideki Takahashi. "Colonization of Pythium oligandrum in the Tomato Rhizosphere for Biological Control of Bacterial Wilt Disease Analyzed by Real-Time PCR and Confocal Laser-Scanning Microscopy." Phytopathology® 98, no. 2 (February 2008): 187–95. http://dx.doi.org/10.1094/phyto-98-2-0187.

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It recently has been reported that the non-plant-pathogenic oomycete Pythium oligandrum suppresses bacterial wilt caused by Ralstonia solanacearum in tomato. As one approach to determine disease-suppressive mechanisms of action, we analyzed the colonization of P. oligandrum in rhizospheres of tomato using real-time polymerase chain reaction (PCR) and confocal laser-scanning microscopy. The real-time PCR specifically quantified P. oligandrum in the tomato rhizosphere that is reliable over a range of 0.1 pg to 1 ng of P. oligandrum DNA from 25 mg dry weight of soil. Rhizosphere populations of P. oligandrum from tomato grown for 3 weeks in both unsterilized and sterilized field soils similarly increased with the initial application of at least 5 × 105 oospores per plant. Confocal microscopic observation also showed that hyphal development was frequent on the root surface and some hyphae penetrated into root epidermis. However, rhizosphere population dynamics after transplanting into sterilized soil showed that the P. oligandrum population decreased with time after transplanting, particularly at the root tips, indicating that this biocontrol fungus is rhizosphere competent but does not actively spread along roots. Protection over the long term from root-infecting pathogens does not seem to involve direct competition. However, sparse rhizosphere colonization of P. oligandrum reduced the bacterial wilt as well as more extensive colonization, which did not reduce the rhizosphere population of R. solanacearum. These results suggest that competition for infection sites and nutrients in rhizosphere is not the primary biocontrol mechanism of bacterial wilt by P. oligandrum.

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Orlikowski, L. B., and A. Jaworska-Marosz. "Influence of Pythium oligandrum on population of Fusarium oxysporum f.sp. dianthi and development of Fusarium wilt of carnation." Plant Protection Science 38, SI 1 - 6th Conf EFPP 2002 (January 1, 2002): 209–11. http://dx.doi.org/10.17221/10357-pps.

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Relationship between initial oospore number of Pythium oligandrum, mode of the mycoparasite application and population<br />dynamics of Fusarium oxysporum f.sp. dianthi and development of Fusarium wilt of carnation was studied. Mixing of<br />oospores with peat 10 days before carnation planting resulted in strong inhibition of the pathogen development. Number<br />of colony forming units of the pathogen decreased at least 3 times. Application of P. oligandrum resulted in suppression<br />of Fusarium wilt development, especially when the mycoparasite was applied at dose 100 oospore/g of peat.

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Yacoub, Amira, Noel Magnin, Jonathan Gerbore, Rana Haidar, Emilie Bruez, Stéphane Compant, Rémy Guyoneaud, and Patrice Rey. "The Biocontrol Root-Oomycete, Pythium Oligandrum, Triggers Grapevine Resistance and Shifts in the Transcriptome of the Trunk Pathogenic Fungus, Phaeomoniella Chlamydospora." International Journal of Molecular Sciences 21, no. 18 (September 19, 2020): 6876. http://dx.doi.org/10.3390/ijms21186876.

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The worldwide increase in grapevine trunk diseases, mainly esca, represents a major threat for vineyard sustainability. Biocontrol of a pioneer fungus of esca, Phaeomoniella chlamydospora, was investigated here by deciphering the tripartite interaction between this trunk-esca pathogen, grapevine and the biocontrol-oomycete, Pythium oligandrum. When P. oligandrum colonizes grapevine roots, it was observed that the wood necroses caused by P. chlamydospora were significantly reduced. Transcriptomic analyses of plant and fungus responses were performed to determine the molecular events occurring, with the aim to relate P.chlamydospora degradation of wood to gene expression modulation. Following P. oligandrum-root colonization, major transcriptomic changes occurred both, in the grapevine-defense system and in the P. chlamydospore-virulence factors. Grapevine-defense was enhanced in response to P. chlamydospora attacks, with P. oligandrum acting as a plant-systemic resistance inducer, promoting jasmonic/ethylene signaling pathways and grapevine priming. P. chlamydospora pathogenicity genes, such as those related to secondary metabolite biosynthesis, carbohydrate-active enzymes and transcription regulators, were also affected in their expression. Shifts in grapevine responses and key-fungal functions were associated with the reduction of P. chlamydospora wood necroses. This study provides evidence of wood fungal pathogen transcriptional changes induced by a root biocontrol agent, P. oligandrum, in which there is no contact between the two microorganisms.

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Benhamou, Nicole, Patrice Rey, Mohamed Chérif, John Hockenhull, and Yves Tirilly. "Treatment with the Mycoparasite Pythium oligandrum Triggers Induction of Defense-Related Reactions in Tomato Roots When Challenged with Fusarium oxysporum f. sp. radicis-lycopersici." Phytopathology® 87, no. 1 (January 1997): 108–22. http://dx.doi.org/10.1094/phyto.1997.87.1.108.

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The influence exerted by the mycoparasite Pythium oligandrum in triggering plant defense reactions was investigated using an experimental system in which tomato plants were infected with the crown and root rot pathogen Fusarium oxysporum f. sp. radicis-lycopersici. To assess the antagonistic potential of P. oligandrum against F. oxysporum f. sp. radicis-lycopersici, the interaction between the two fungi was studied by scanning and transmission electron microscopy (SEM and TEM, respectively). SEM investigations of the interaction region between the fungi demonstrated that collapse and loss of turgor of F. oxysporum f. sp. radicis-lycopersici hyphae began soon after close contact was established with P. oligandrum. Ultrastructural observations confirmed that intimate contact between hyphae of P. oligandrum and cells of the pathogen resulted in a series of disturbances, including generalized disorganization of the host cytoplasm, retraction of the plasmalemma, and, finally, complete loss of the protoplasm. Cytochemical labeling of chitin with wheat germ agglutinin (WGA)/ovomucoid-gold complex showed that, except in the area of hyphal penetration, the chitin component of the host cell walls was structurally preserved at a time when the host cytoplasm had undergone complete disorganization. Interestingly, the same antagonistic process was observed in planta. The specific labeling patterns obtained with the exoglucanase-gold and WGA-ovomucoid-gold complexes confirmed that P. oligandrum successfully penetrated invading cells of the pathogen without causing substantial cell wall alterations, shown by the intense labeling of chitin. Cytological investigations of samples from P. oligandrum-inoculated tomato roots revealed that the fungus was able to colonize root tissues without inducing extensive cell damage. However, there was a novel finding concerning the structural alteration of the invading hyphae, evidenced by the frequent occurrence of empty fungal shells in root tissues. Pythium ingress in root tissues was associated with host metabolic changes, culminating in the elaboration of structural barriers at sites of potential fungal penetration. Striking differences in the extent of F. oxysporum f. sp. radicis-lycopersici colonization were observed between P. oligandrum-inoculated and control tomato plants. In control roots, the pathogen multiplied abundantly through much of the tissues, whereas in P. oligandrum-colonized roots pathogen growth was restricted to the outermost root tissues. This restricted pattern of pathogen colonization was accompanied by deposition of newly formed barriers beyond the infection sites. These host reactions appeared to be amplified compared to those seen in nonchallenged P. oligandrum-infected plants. Most hyphae of the pathogen that penetrated the epidermis exhibited considerable changes. Wall appositions contained large amounts of callose, in addition to be infiltrated with phenolic compounds. The labeling pattern obtained with gold-complexed laccase showed that phenolics were widely distributed in Fusarium-challenged P. oligandrum-inoculated tomato roots. Such compounds accumulated in the host cell walls and intercellular spaces. The wall-bound chitin component in Fusarium hyphae colonizing P. oligandrum-inoculated roots was preserved at a time when hyphae had undergone substantial degradation. These observations provide the first convincing evidence that P. oligandrum has the potential to induce plant defense reactions in addition to acting as a mycoparasite.

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Bělonožníková, Kateřina, Veronika Hýsková, Marie Vašková, Tomáš Křížek, Kateřina Čokrtová, Tomáš Vaněk, Lucie Halířová, Michal Chudý, Antoniana Žufić, and Helena Ryšlavá. "Seed Protection of Solanum lycopersicum with Pythium oligandrum against Alternaria brassicicola and Verticillium albo-atrum." Microorganisms 10, no. 7 (July 4, 2022): 1348. http://dx.doi.org/10.3390/microorganisms10071348.

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Pythium oligandrum, strain M1, is a soil oomycete successfully used as a biological control agent (BCA), protecting plants against fungal, yeast, and oomycete pathogens through mycoparasitism and elicitor-dependent plant priming. The not yet described Pythium strains, X42 and 00X48, have shown potential as BCAs given the high activity of their secreted proteases, endoglycosidases, and tryptamine. Here, Solanum lycopersicum L. cv. Micro-Tom seeds were coated with Pythium strains, and seedlings were exposed to fungal pathogens, either Alternaria brassicicola or Verticillium albo-atrum. The effects of both infection and seed-coating on plant metabolism were assessed by determining the activity and isoforms of antioxidant enzymes and endoglycosidases and the content of tryptamine, amino acids, and heat shock proteins. Dual culture competition testing and microscopy analysis confirmed mycoparasitism in all three Pythium strains. In turn, seed treatment significantly increased the total free amino acid content, changing their abundance in both non-infected and infected plants. In response to pathogens, plant Hsp70 and Hsp90 isoform levels also varied among Pythium strains, most likely as a strategy for priming the plant against infection. Overall, our results show in vitro mycoparasitism between Pythium strains and fungal pathogens and in planta involvement of heat shock proteins in priming.

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Walther, D., and D. Gindrat. "Biological Control of Phoma and Pythium Damping-Off of Sugar-Beet with Pythium oligandrum." Journal of Phytopathology 119, no. 2 (June 1987): 167–74. http://dx.doi.org/10.1111/j.1439-0434.1987.tb00479.x.

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Takenaka, Shigehito, Zenta Nishio, and Yumi Nakamura. "Induction of Defense Reactions in Sugar Beet and Wheat by Treatment with Cell Wall Protein Fractions from the Mycoparasite Pythium oligandrum." Phytopathology® 93, no. 10 (October 2003): 1228–32. http://dx.doi.org/10.1094/phyto.2003.93.10.1228.

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To detect molecules with elicitor properties from Pythium oligandrum, cell wall protein fractions (CWPs) were extracted from 10 P. oligandrum isolates and examined for elicitor activity in sugar beet and wheat. P. oligandrum isolates were divided into two groups based on the number of major proteins in CWP: isolates with two major proteins (D-type) and isolates with one major protein (S-type). Sugar beet seedlings treated with both types of CWP through their roots showed enhanced activities of phenylalanine ammonia lyase and chitinase, and D-type-treated seedlings also showed significantly higher cell wall-bound phenolic compounds, mainly ferulic acid, compared with the distilled-water-treatment control. Damping-off severity was significantly reduced on seedlings treated with both types of CWP compared with the control, following challenge with Rhizoctonia solani AG2-2. Both types of CWP significantly reduced the number of infected spikelets developed from the injected spikelet compared with the control, following challenge with Fusarium graminearum. Neither type of CWP resulted in any reduction in pathogen growth rate in plate tests. These results demonstrate that CWPs of P. oligandrum have elicitor properties in sugar beet and wheat.

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25

Cliquet, Sophie, and Yves Tirilly. "Development of a Defined Medium for Pythium oligandrum Oospore Production." Biocontrol Science and Technology 12, no. 4 (August 2002): 455–67. http://dx.doi.org/10.1080/09583150220146031.

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26

Foley, M. F., and J. W. Deacon. "Isolation of Pythium oligandrum and other necrotrophic mycoparasites from soil." Transactions of the British Mycological Society 85, no. 4 (December 1985): 631–39. http://dx.doi.org/10.1016/s0007-1536(85)80257-6.

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27

Takenaka, S. "Studies on biological control mechanisms of Pythium oligandrum." Japanese Journal of Phytopathology 81, no. 3 (2015): 176–79. http://dx.doi.org/10.3186/jjphytopath.81.176.

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28

Laing, S. A. K., and J. W. Deacon. "Video microscopical comparison of mycoparasitism by Pythium oligandrum, P. nunn and an unnamed Pythium species." Mycological Research 95, no. 4 (April 1991): 469–79. http://dx.doi.org/10.1016/s0953-7562(09)80848-4.

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29

Benhamou, Nicole, Patrice Rey, Karine Picard, and Yves Tirilly. "Ultrastructural and Cytochemical Aspects of the Interaction Between the Mycoparasite Pythium oligandrum and Soilborne Plant Pathogens." Phytopathology® 89, no. 6 (June 1999): 506–17. http://dx.doi.org/10.1094/phyto.1999.89.6.506.

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The interaction between the oomycete Pythium oligandrum and various soilborne oomycete and fungal plant pathogens (P. ultimum, P. aphanidermatum, Fusarium oxysporum f. sp. radicis-lycopersici, Verticillium albo-atrum, Rhizoctonia solani, and Phytophthora megasperma) was studied by light and electron microscopy in order to assess the relative contribution of mycoparasitism and antibiosis in the antagonistic process. Scanning electron microscope investigations of the interaction regions showed that structural alterations of all pathogenic fungi and oomycetes (except for Phytophthora megasperma) occurred soon after contact with the antagonist. Light and transmission electron microscope studies of the interaction region between the antagonist and P. ultimum revealed that intimate contact between both partners preceded a sequence of degradation events including aggregation of host cytoplasm and penetration of altered host hyphae. Localization of the host wall cellulose component showed that cellulose was altered at potential penetration sites. A similar scheme of events was observed during the interaction between P. oligandrum and F. oxysporum f. sp. radicis-lycopersici, with the exception that complete loss of host protoplasm was associated with antagonist invasion. The interaction between P. oligandrum and R. solani resulted in an abnormal deposition of a wall-like material at potential penetration sites for the antagonist. However, the antagonist displayed the ability to circumvent this barrier and penetrate host hyphae by locally altering the chitin component of the host hyphal wall. Interestingly, antagonist cells also showed extensive alteration as evidenced by the frequent occurrence of empty hyphal shells. In the case of Phytophthora megasperma, hyphal interactions did not occur, but hyphae of the plant pathogen were damaged severely. At least two distinct mechanisms appear to be involved in the process of oomycete and fungal attack by P. oligandrum: (i) mycoparasitism, mediated by intimate hyphal interactions, and (ii) antibiosis, with alteration of the host hyphae prior to contact with the antagonist. However, the possibility that the antagonistic process may rely on the dual action of antibiotics and hydrolytic enzymes is discussed.

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Moustafa, Shaima Mohamed Nabil. "Influence of Pythium oligandrum on Mycelia and Production of Zoo-and Oo-spores of Two Phytopathogenic Pythium spp." Journal of Pure and Applied Microbiology 13, no. 1 (March 31, 2019): 233–40. http://dx.doi.org/10.22207/jpam.13.1.24.

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31

Vallance, J., F. Déniel, G. Barbier, L. Guerin-Dubrana, N. Benhamou, and P. Rey. "Influence of Pythium oligandrum on the bacterial communities that colonize the nutrient solutions and the rhizosphere of tomato plants." Canadian Journal of Microbiology 58, no. 9 (September 2012): 1124–34. http://dx.doi.org/10.1139/w2012-092.

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The influence exerted by the biocontrol oomycete Pythium oligandrum on the bacterial populations proliferating in the rhizosphere of tomato plants grown in a hydroponic system and in the circulating solutions is studied in the present experiment. Quantitative PCR and single-strand conformation polymorphism were used to investigate the genetic structure and dynamics of the bacterial communities colonizing the root systems and the various circulating solutions. Quantitative PCR assays showed that bacteria heavily colonized the rhizosphere of tomato plants with, however, no significant density changes throughout the cultural season (April–September). Single strand conformation polymorphism fingerprints revealed the occurrence of transient perturbations in the rhizospheric indigenous bacterial communities following P. oligandrum introduction in the root system of plants. This effect was, however, transient and did not persist until the end of the cropping season. Interestingly, the genetic structure of the bacterial microflora colonizing either the roots or the nutrient solutions evolved throughout the cropping season. This temporal evolution occurred whatever the presence and persistence of P. oligandrum in the rhizosphere. Evidence is also provided that bacterial microflora that colonize the root system are different from the ones colonizing the circulating solutions. The relationships between these 2 microflora (at the root and solution levels) are discussed.

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32

McQuilken, M. P., J. M. Whipps, and R. C. Cooke. "Use of Oospore Formulations of Pythium oligandrum for Biological Control of Pythium Damping-off in Cress." Journal of Phytopathology 135, no. 2 (June 1992): 125–34. http://dx.doi.org/10.1111/j.1439-0434.1992.tb01259.x.

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33

Kinoshita, Tomio, Takio Ichitani, and Taeko Okumura. "Materials for Pythium Flora of Japan VIII of Pythium: Two species P. pyrilobum and P. oligandrum." Mycoscience 35, no. 2 (July 1994): 191–98. http://dx.doi.org/10.1007/bf02318500.

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34

Mulligan, Deborah F. C., E. Eirian Jones, and J. W. Deacon. "Monitoring and manipulation of populations of Pythium oligandrum, Pythium mycoparasiticum and a Papulaspora species in soil." Soil Biology and Biochemistry 27, no. 10 (October 1995): 1333–43. http://dx.doi.org/10.1016/0038-0717(95)00049-k.

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35

Witkowicz, Robert, Wioletta Biel, Joanna Chłopicka, Agnieszka Galanty, Katarzyna Gleń-Karolczyk, Edyta Skrzypek, and Mateusz Krupa. "Biostimulants and Microorganisms Boost the Nutritional Composition of Buckwheat (Fagopyrum esculentum Moench) Sprouts." Agronomy 9, no. 8 (August 20, 2019): 469. http://dx.doi.org/10.3390/agronomy9080469.

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This study investigated the influence of biological control agents and plant growth promoters on the chemical composition of the cultivars Panda and Kora buckwheat sprouts. Before sowing, seeds were soaked in solutions containing Bacillus subtilis bacteria, Pythium oligandrum oospores, Ecklonia maxima algae extract, and/or nitrophenols. The sprouts of the Panda displayed higher levels of protein, fat, and dietary fiber fractions than the Kora. Measurable effects of biological control agents (BCAs) and plant growth promoters (PGPs) on the chemical composition of sprouts were also confirmed. Soaking the seeds in a solution containing P. oligandrum oospores resulted in a decrease in the level of crude ash in sprouts, while the addition of nitrophenols increased the level of both crude ash and protein. We also found statistically significant effects of interactions between the cultivar and BCA and/or PGP for each of the examined components.

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36

Walther, D., and D. Gindrat. "Antagonism of Rhizoctonia spp. to Pythium oligandrum and Damping-Off Fungi." Journal of Phytopathology 119, no. 3 (July 1987): 248–54. http://dx.doi.org/10.1111/j.1439-0434.1987.tb04395.x.

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37

Godfrey, Scott A. C., Russell D. Mond, Duncan T. Lash, and John W. Marshall. "Identification of Pythium oligandrum using species-specific ITS rDNA PCR oligonucleotides." Mycological Research 107, no. 7 (July 2003): 790–96. http://dx.doi.org/10.1017/s0953756203008104.

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38

Bradshaw-Smith, R. P., W. M. Whalley, and G. D. Craig. "Interactions between Pythium oligandrum and the fungal footrot pathogens of peas." Mycological Research 95, no. 7 (July 1991): 861–65. http://dx.doi.org/10.1016/s0953-7562(09)80050-6.

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39

Ribeiro, Wilma R. C., and E. E. Butler. "Comparison of the mycoparasites Pythium periplocum, P. acanthicum and P. oligandrum." Mycological Research 99, no. 8 (August 1995): 963–68. http://dx.doi.org/10.1016/s0953-7562(09)80757-0.

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40

Postulkova, Michaela, Jan Rezanina, Jaromir Fiala, Marek C. Ruzicka, Pavel Dostalek, and Tomas Branyik. "Suppression of fungal contamination by Pythium oligandrum during malting of barley." Journal of the Institute of Brewing 124, no. 4 (September 14, 2018): 336–40. http://dx.doi.org/10.1002/jib.518.

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41

Al-Rawahi, A. K., and J. G. Hancock. "Temperature and Water Effects on the Viability of Alginate-Formulated Oospores of Pythrium Oligandrum." Journal of Agricultural and Marine Sciences [JAMS] 3, no. 2 (June 1, 1998): 27. http://dx.doi.org/10.24200/jams.vol3iss2pp27-33.

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The low germination rates of oospores hinder the use of Pythium oligandrum as a biocontrol agent of soilborne plant pathogens. To improve the reliability of oospore-inoculum of P. oligandrum for the biological control of root diseases, oospores were formulated in calcium alginate pellets (oospore-pellets). Oospore-pellets of five isolates of P. oligandrum stored at 4°C under dry conditions remained viable (more or equal than 99% germination for each time interval) over 12 months regardless of the culture medium used to produce the oospores. In contrast, oospore-pellets stored at 25°C under the same conditions maintained their viability for 3 months but declined to 50%, viability in the following 9 months. Germination of oospore-pellets was at the highest (98%) at solute potentials (y8) higher than -l.33 MPa or relative humidities (RH) higher than 97% at 25° and 33°C. Germination declined sharply as (y8), decreased from -1.33 to -2.59 MPa and RH decreased from 97 to 94% with no germination occurring at -3.59 MPa and 92% RH. Only 60% germination was found at 16°C in the top range of y, and RH, and germination declined sharply as y, and RH were decreased, with no germination occurring at - l .33 MPa and 95% RH. Mycelial growth exhibited similar ranges of tolerance under the same moisture conditions and temperatures. High degrees of survival during storage accompanied by high percentages of germination under relatively dry conditions suggest that the oospore-pellet inoculum of P. oligandrum can be used for the control of pathogens in soil or a potting mix at high temperatures during a warm season or under greenhouse conditions.

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42

McQuilken, M. P., J. M. Whipps, and R. C. Cooke. "Oospores of the biocontrol agent Pythium oligandrum bulk-produced in liquid culture." Mycological Research 94, no. 5 (July 1990): 613–16. http://dx.doi.org/10.1016/s0953-7562(09)80661-8.

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43

Martin, Frank N. "Linear mitochondrial molecules and intraspecific mitochondrial genome stability in a species of Pythium." Genome 34, no. 1 (February 1, 1991): 156–62. http://dx.doi.org/10.1139/g91-024.

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Restriction maps of the mitochondrial genomes of 11 isolates of Pythium oligandrum revealed sizes ranging from 69.8 to 72.7 kb. While most isolates had circular genomes, two isolates contained predominantly linear molecules with the position of the ends corresponding to the small unique region of the circular molecules. The termini of these molecules were resistant to Exo III and λ exonuclease digestion and had hairpin loop structures. Several isolates with circular genomes also appeared to contain what may be a small percentage of linear molecules. The inverted repeat and large unique region were 28.6 and 11.5 kb, respectively, and were equal in size among isolates. The small unique region was the most variable portion of the genome and ranged from 0.98 to 3.92 kb in size. Polymorphisms among isolates were due mainly to insertions–deletions in the small unique region, which not only contributed to size differences but also generated additional unique restriction sites. The only variation detected in the inverted repeat or the large unique region was the addition–loss of several restriction sites in four isolates. Less sequence divergence was observed in the inverted repeat than in the large unique region (maximum of 0.83 compared with 2.50%, respectively). Percent sequence divergence for the entire genome (excluding one arm of the inverted repeat) ranged from 0 to 1.00%. Excluding differences caused by insertions–deletions in the small unique region, 94% or greater of the restriction sites are conserved among all isolates.Key words: Pythium oligandrum, mtDNA, inverted repeat, intraspecific variation, linear genome.

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Kurzawińska, Halina, and Mazur Stanisław. "The effect of bio-preparations on the infestation of tubers by Streptomyces spp." Folia Horticulturae 20, no. 2 (December 1, 2008): 103–10. http://dx.doi.org/10.2478/fhort-2013-0119.

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Abstract The effect of tuber dressing and plant spraying with Polyversum (B.A.S. Pythium oligandrum) and Biochikol 020 PC (B.A.S. chitosan) bio-preparations on the infestation of potatoe tubers by Streptomyces spp. was studied during the 2005-2007 years. The Vitavax 2000 FS (B.A.S. karboxin and thiuram) was used as a standard fungicide. The results received from field experiments indicate that, during all years of study these preparations significantly reduced tubers infestation by Streptomyces spp. The Polyversum bio-preparation, which was applied to tuber dressing and sprayed on plants four times during vegetation period, showed the best protective effect against Streptomyces spp.

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45

Zheng, Qun, Peiya Wang, Ying Zhu, Bin Ji, Ting Mao, Yanhao Fang, Xuqiang Zhang, Zhiye Wang, and Hui Yang. "A novel sensitized matrix Pythium oligandrum-derived carbon for enhancement photocatalytic hydrogen evolution." Materials Letters 284 (February 2021): 128939. http://dx.doi.org/10.1016/j.matlet.2020.128939.

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46

Ikeda, Sachiko, Ayano Shimizu, Motoshige Shimizu, Hideki Takahashi, and Shigehito Takenaka. "Biocontrol of black scurf on potato by seed tuber treatment with Pythium oligandrum." Biological Control 60, no. 3 (March 2012): 297–304. http://dx.doi.org/10.1016/j.biocontrol.2011.10.016.

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47

HASE, S., S. TAKENAKA, S. TAKAHASHI, K. NAKAHO, Y. KAWAMURA, and T. NAMAI. "Role of ^|^beta;-cyanoalanine in induced resistance mediated by Pythium oligandrum in tomato." Japanese Journal of Phytopathology 78, no. 4 (2012): 309–12. http://dx.doi.org/10.3186/jjphytopath.78.309.

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48

Gabrielová, Alena, Karel Mencl, Martin Suchánek, Radim Klimeš, Vít Hubka, and Miroslav Kolařík. "The Oomycete Pythium oligandrum Can Suppress and Kill the Causative Agents of Dermatophytoses." Mycopathologia 183, no. 5 (July 2, 2018): 751–64. http://dx.doi.org/10.1007/s11046-018-0277-2.

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49

محمد, نوارة علي, أسماء المبروك, and آمنة عقيلة المبروك. "دراسة معملية لتقييم تأثير بعض المواد الزراعية على نمو وتكاثر الفطريات الأحيائية Trichoderma harzianum وفطر Pythium oligandrum." Al-Mukhtar Journal of Sciences 32, no. 2 (December 31, 2017): 173–87. http://dx.doi.org/10.54172/mjsc.v32i2.189.

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أجريت هذه الدراسة بمعمل أمراض النبات التابع لقسم وقاية النبات، كلية الزراعة -جامعة عمر المختار، البيضاء، ليبيا، لمعرفة تأثير بعض المواد الزراعية الأكثر تداولاً والشائعة الاستخدام في المنطقة على فطريات معزولة من الترب المحلية فطرTrichoderma harzianum وفطر Pythium oligandrum، وشملت هذه المواد كلاًّ من المبيدات: السبيركل، الجول، البينومايل ودياثين م – 45، والأسمدة الكيميائية ( يوريا، نتروجين-فوسفات-بوتاسيوم (NPK)، فوسفات 18/46(P18/46) ،داى امونيوفوسفات) الهرمونات (إندول حمض الخليك، نفثالين، جبريلين، إندول حمض البيوتريك) والمضادات الحيوية (الفانكوميسين، الاستربتومايسين،كلورامفينكول، تتراسكلين) بعدة تراكيز بما فيها التركيز الموصى به. قيمَّ البحث تأثير هذه المواد على النمو الميسليومي، الوزن الجاف وتجرثم الفطر، وأظهرت النتائج أن هناك فروقاً معنوية بين المبيدات المختبرة عند التراكيز المستخدمة في تثبيط النمو الفطريات، وأن نسبة التثبيط للنمو الفطرى تزداد بزيادة تركيز المبيد، كان مبيد دياثين م – 45 الأعلى تثبيطاً للنمو الميسيليومي والوزن الجاف وتجرثم الفطريات، بينت النتائج أيضاً أن المعاملة بالأسمدة خفَّضت معنويا نمو الفطرين P.oligandrum وT.harzianum، وبشكل خاص سماد اليوريا الذي أعطى أعلى تأثير، حيث أدى إلى تناقص في الوزن الجاف بزيادة التركيز، ووصلت نسبة تأثير المعاملة إلى 41% و36.6% لكلا الفطرين على التوالي. من ناحية أخرى عند معاملة الفطريات بالهرمونات كان فطرT. harzianum أكثر تأثراً مقارنة بالفطر P. oligandrum ، وأعطى هرمون الجبريلين تثبيطاً عاليا للنمو والتجرثم، حيث أدى زيادة تركيز الهرمون إلى الانخفاض في الوزن الجاف. في حين سُجَّل تأثير عالٍ للمضاد الحيوى التتراسيكلين عند تركيز 0.012 مليجم/مل على نمو المسيليوم وإنتاج الجراثيم للفطريات المختبرة.

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Ai, Gan, Kun Yang, Wenwu Ye, Yuee Tian, Yaxin Du, Hai Zhu, Tianli Li, et al. "Prediction and Characterization of RXLR Effectors in Pythium Species." Molecular Plant-Microbe Interactions® 33, no. 8 (August 2020): 1046–58. http://dx.doi.org/10.1094/mpmi-01-20-0010-r.

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RXLR effectors, a class of secreted proteins that are transferred into host cells to manipulate host immunity, have been reported to widely exist in oomycetes, including those from genera Phytophthora, Hyaloperonospora, Albugo, and Saprolegnia. However, in Pythium species, no RXLR effector has yet been characterized, and the origin and evolution of such virulent effectors are still unknown. Here, we developed a modified regular expression method for de novo identification of RXLRs and characterized 359 putative RXLR effectors in nine Pythium species. Phylogenetic analysis revealed that all oomycetous RXLRs formed a single superfamily, suggesting that they might have a common ancestor. RXLR effectors from Pythium and Phytophthora species exhibited similar sequence features, protein structures, and genome locations. In particular, there were significantly more RXLR proteins in the mosquito biological control agent P. guiyangense than in the other eight Pythium species, and P. guiyangense RXLRs might be the result of gene duplication and genome rearrangement events, as indicated by synteny analysis. Expression pattern analysis of RXLR-encoding genes in the plant pathogen P. ultimum detected transcripts of the majority of the predicted RXLR genes, with some RXLR effectors induced in infection stages and one RXLR showing necrosis-inducing activity. Furthermore, all predicted RXLR genes were cloned from two biocontrol agents, P. oligandrum and P. periplocum, and three of the RXLR genes were found to induce a defense response in Nicotiana benthamiana. Taken together, our findings represent the first evidence of RXLR effectors in Pythium species, providing valuable information on their evolutionary patterns and the mechanisms of their interactions with diverse hosts.

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Journal articles on the topic 'Pythium oligandrum'

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