587 results on '"PYTHIUM aphanidermatum"'
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2. Pythium aphanidermatum as a Novel Oomycete Pathogen Causing Leak on Potato (Solanum tuberosum) in Korea.
- Author
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Kim, Yu Jin, Chung, Eui-Hwan, and Kim, Ki Deok
- Subjects
- *
CYTOCHROME oxidase , *FOOD crops , *TUBERS , *REPORTING of diseases , *MITOCHONDRIAL DNA , *POTATOES - Abstract
Potato (Solanum tuberosum L.) is one of the most important food crops in Korea. In July 2021 and 2022, dark black-rot symptoms with pink tinges were observed on field-grown potato tubers in Hongsung and Chuncheon, Korea, respectively. We obtained four isolates (HSv05 and HSv10 from Hongsung, and CCp03 and CCp05 from Chuncheon) from diseased tubers and identified these isolates as Pythium aphanidermatum by analyzing the sequences of internal transcribed spacer rDNA region and mitochondrial cytochrome c oxidase subunit II (COX2) mtDNA gene. Additionally, we compared the cultural and morphological characteristics of these four isolates with those of the reference isolate KACC 48066 of P. aphanidermatum and the literature. Further, we tested the pathogenicity of all these isolates against potato tubers. The cultural and morphological characteristics of the four test isolates were similar to those of the reference isolate and the literature; all four test isolates proved pathogenic to potato tubers. Therefore, we concluded that P. aphanidermatum is the causal agent of potato leak and this is the first report of the disease on potato in Korea. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
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3. Pythium aphanidermatum as a Novel Oomycete Pathogen Causing Leak on Potato (Solanum tuberosum) in Korea
- Author
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Yu Jin Kim, Eui-Hwan Chung, and Ki Deok Kim
- Subjects
Leak ,oomycetes ,potato ,Pythium aphanidermatum ,Solanum tuberosum ,coverslip culture technique ,Botany ,QK1-989 - Abstract
Potato (Solanum tuberosum L.) is one of the most important food crops in Korea. In July 2021 and 2022, dark black-rot symptoms with pink tinges were observed on field-grown potato tubers in Hongsung and Chuncheon, Korea, respectively. We obtained four isolates (HSv05 and HSv10 from Hongsung, and CCp03 and CCp05 from Chuncheon) from diseased tubers and identified these isolates as Pythium aphanidermatum by analyzing the sequences of internal transcribed spacer rDNA region and mitochondrial cytochrome c oxidase subunit II (COX2) mtDNA gene. Additionally, we compared the cultural and morphological characteristics of these four isolates with those of the reference isolate KACC 48066 of P. aphanidermatum and the literature. Further, we tested the pathogenicity of all these isolates against potato tubers. The cultural and morphological characteristics of the four test isolates were similar to those of the reference isolate and the literature; all four test isolates proved pathogenic to potato tubers. Therefore, we concluded that P. aphanidermatum is the causal agent of potato leak and this is the first report of the disease on potato in Korea. more...
- Published
- 2024
- Full Text
- View/download PDF
4. Studying the Antifungal Effects of Ageratina adenophora (Sprengel) R. King and H. Robinson (=Eupatorium adenophorum Sprengel) as a Bio-Fumigant Plant Alone and in Combination with Biochar Against Pythium aphanidermatum (Edson) Fitz
- Author
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Shiva Parsiaaref, Aocheng Cao, Yuan Li, Asgar Ebadollahi, Ghasem Parmoon, Jalal Gholamnezhad, Qiuxia Wang, Dongdong Yan, Wensheng Fang, Zhaoxin Song, Xianli Wang, and Min Zhang
- Subjects
Ageratina adenophora ,Pythium aphanidermatum ,biochar ,antifungal ,main compounds ,Botany ,QK1-989 - Abstract
Pythium spp. are soil-borne pathogens that cause damping-off and root rot diseases in many plant species such as cucumber. In the current study, the effect of dried roots–stems and leaves of Ageratina adenophora (Sprengel) R. King and H. Robinson (=Eupatorium adenophorum Sprengel) alone and in combination with pyrogenic biomass biochar to control Pythium aphanidermatum (Edson) Fitz was assessed. In four treatments of leaves, roots–stems, leaves + biochar, and roots–stems + biochar, it was observed that the treatment with leaves at an Emax (maximal effective concentration on control fungi) of 79 g/kg of soil had the most antifungal effect on P. aphanidermatum. Also, the Cmax (the highest level of control) increased with time and reached 82.4% and 71% on days 30 and 60, respectively. The highest cucumber fresh fruit weight and the highest height of the stems in the greenhouse were observed in leaf treatment of A. adenophora. Biochar did not have any remarkable controlling effect on P. aphanidermatum, and its population increased. The main compounds extracted from the dried leaves and roots–stems of A. adenophora, including α-pinene, nonanone, hexahydronaphthalene, 3-undecanone, muurolene, and heneicosane, had antifungal properties. We concluded that the leaves of A. adenophora have the potential to be used as a bio-fumigant for P. aphanidermatum management. more...
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- 2024
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5. Bicontrol of Pythium aphanidermatum and Damping-off Disease of Papaya Seedlings (Carica papaya cv. Tainung No.2) by Different Smoke-water
- Author
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Chang-Lin Chen, Yan-Ting Chen, and Huey-Ling Lin
- Subjects
damping-off disease ,pythium aphanidermatum ,smoke-water ,Plant culture ,SB1-1110 - Abstract
Two key trends of sustainable agriculture are reducing the amount of inputs such as pesticides, fungicides, or fertilizer and finding ways to reduce or reuse agricultural waste. Leafy plant waste can be burned to produced smoke-water extracts that have effective antimicrobial and germination properties. Damping-off disease caused by Pythium spp. leads to significant losses at the papaya seedling stage and is usually managed with fungicides. Five smoke-water extracts derived from burning different plant residues—namely, rice straw smoke-water (R-SW), wheat straw smoke-water (W-SW), pangola grass smoke-water (P-SW), cornstalk smoke-water (C-SW), and bamboo leave smoke-water (B-SW)—were prepared. These were mixed into the V8 media used for culture of Pythium aphanidermatum. In vitro treatment with 5% P-SW, C-SW, or B-SW reduced mycelial growth rate significantly, whereas 5% B-SW inhibited mycelial growth completely. All 1% smoke-water preparations reduced zoospore production significantly, but the inhibition rate of 3% R-SW, 3% W-SW, 1% P-SW, 1% C-SW, and 1% B-SW reached 100%. For in vivo experiments, P. aphanidermatum was inoculated in 1 kg of potting soil and mixed with B-SW in concentrations of 1% to 5%. The papaya seedlings treated with 2% to 5% B-SW maintained the growth parameter without damping-off symptoms. more...
- Published
- 2023
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6. Plant-Disease-Suppressive and Growth-Promoting Activities of Endophytic and Rhizobacterial Isolates Associated with Citrullus colocynthis.
- Author
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Al-Shuaibi, Badriya Khalfan, Kazerooni, Elham Ahmed, Hussain, Shah, Velazhahan, Rethinasamy, and Al-Sadi, Abdullah Mohammed
- Subjects
WATERMELONS ,CUCUMBERS ,ENDOPHYTIC bacteria ,FUSARIUM solani ,BACILLUS (Bacteria) ,BACILLUS cereus ,SCANNING electron microscopy - Abstract
This study was conducted to investigate the antagonistic potential of endophytic and rhizospheric bacterial isolates obtained from Citrullus colocynthis in suppressing Fusarium solani and Pythium aphanidermatum and promoting the growth of cucumber. Molecular identification of bacterial strains associated with C. colocynthis confirmed that these strains belong to the Achromobacter, Pantoea, Pseudomonas, Rhizobium, Sphingobacterium, Bacillus, Sinorhizobium, Staphylococcus, Cupriavidus, and Exiguobacterium genera. A dual culture assay showed that nine of the bacterial strains exhibited antifungal activity, four of which were effective against both pathogens. Strains B27 (Pantoea dispersa) and B28 (Exiguobacterium indicum) caused the highest percentage of inhibition towards F. solani (48.5% and 48.1%, respectively). P. aphanidermatum growth was impeded by the B21 (Bacillus cereus, 44.7%) and B28 (Exiguobacterium indicum, 51.1%) strains. Scanning electron microscopy showed that the strains caused abnormality in phytopathogens' mycelia. All of the selected bacterial strains showed good IAA production (>500 ppm). A paper towel experiment demonstrated that these strains improved the seed germination, root/shoot growth, and vigor index of cucumber seedlings. Our findings suggest that the bacterial strains from C. colocynthis are suppressive to F. solani and P. aphanidermatum and can promote cucumber growth. This appears to be the first study to report the efficacy of these bacterial strains from C. colocynthis against F. solani and P. aphanidermatum. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
- Full Text
- View/download PDF
7. Efficacy of Streptomyces murinus JKTJ-3 in Suppression of Pythium Damping-Off of Watermelon.
- Author
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Ge, Mihong, Cai, Xiang, Wang, Dehuan, Liang, Huan, Zhu, Juhong, Li, Guoqing, and Shi, Xianfeng
- Subjects
WATERMELONS ,STREPTOMYCES ,PYTHIUM ,BIOLOGICAL pest control agents ,SEED treatment ,DACTINOMYCIN - Abstract
Damping-off caused by Pythium aphanidermatum (Pa) is one of the most destructive diseases for watermelon seedlings. Application of biological control agents against Pa has attracted the attention of many researchers for a long time. In this study, the actinomycetous isolate JKTJ-3 with strong and broad-spectrum antifungal activity was screened from 23 bacterial isolates. Based on the morphological, cultural, physiological, and biochemical characteristics as well as the feature of 16S rDNA sequence, isolate JKTJ-3 was identified as Streptomyces murinus. We investigated the biocontrol efficacy of isolate JKTJ-3 and its metabolites. The results revealed that seed and substrate treatments with JKTJ-3 cultures showed a significant inhibitory effect on watermelon damping-off disease. Seed treatment with the JKTJ-3 cultural filtrates (CF) displayed higher control efficacy compared to the fermentation cultures (FC). Treatment of the seeding substrate with the wheat grain cultures (WGC) of JKTJ-3 exhibited better control efficacy than that of the seeding substrate with the JKTJ-3 CF. Moreover, the JKTJ-3 WGC showed the preventive effect on suppression of the disease, and the efficacy increased with increase in the inoculation interval between the WGC and Pa. Production of the antifungal metabolite actinomycin D by isolate JKTJ-3 and cell-wall-degrading enzymes such as β-1,3-glucanase and chitosanase were probably the mechanisms for effective control of watermelon damping-off. It was shown for the first time that S. murinus can produce anti-oomycete substances including chitinase and actinomycin D. This is the first report about S. murinus used as biocontrol agent against watermelon damping-off caused by Pa. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
- Full Text
- View/download PDF
8. INVESTIGATION AND MOLECULAR IDENTIFICATION OF CUCUMBER DAMPING-OFF FUNGI UNDER GREENHOUSE CONDITION .
- Author
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Muhammed, Sh. H. and Mohamed, R. Y.
- Subjects
MOLECULES ,CUCUMBER industry ,GREENHOUSE gas mitigation ,PYTHIUM aphanidermatum ,FUSARIUM solani - Abstract
Copyright of Anbar Journal of Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...
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- 2023
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9. Differences in Pathogenesis-Related Protein Expression and Polyphenolic Compound Accumulation Reveal Insights into Tomato– Pythium aphanidermatum Interaction.
- Author
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Soliman, Seham A., Al-Askar, Abdulaziz A., Sobhy, Sherien, Samy, Marwa A., Hamdy, Esraa, Sharaf, Omaima A., Su, Yiming, Behiry, Said I., and Abdelkhalek, Ahmed
- Abstract
Plant diseases significantly reduce crop yields, threatening food security and agricultural sustainability. Fungi are the most destructive type of phytopathogen, and they are responsible for major yield losses in some of the most crucial crops grown across the world. In this study, a fungus isolate was detected from infected tomato plants and molecularly identified as Pythium aphanidermatum (GenBank accession number MW725032). This fungus caused damping-off disease and was shown to be pathogenic. Moreover, the expression of five pathogenesis-related genes, namely PR-1, PR-2, PR-3, PR-4, and PR-5, was quantitatively evaluated under the inoculation of tomato with P. aphanidermatum. The quantitative polymerase chain reaction (qPCR) showed that the expression levels of PR-1, PR-2, and PR-5 genes went up significantly at 5 days post-inoculation (dpi). The expression of the PR-1 gene also increased the variably, which reached its highest value at 20 dpi, with a reported relative expression level 6.34-fold higher than that of the control. At 15 dpi, PR-2 and PR-5 increased the most, while PR-1, PR-3, and PR-5 also increased noticeably at 20 dpi. On the contrary, PR-4 gene expression significantly decreased after inoculation, at all time intervals. Regarding PR-5 gene expression, the data showed a variable change in PR-5 gene expression at a different sample collection period. Still, it was highly expressed at 15 dpi and reached 3.99-fold, followed by 20 dpi, where the increasing percentage reached 3.70-fold, relative to the untreated control. The HPLC analysis indicated that the total concentration of all detected polyphenolic compounds was 3858 µg/g and 3202.2 µg/g in control and infected plant leaves, respectively. Moreover, the HPLC results concluded that Pythium infection decreased phenolic acids, such as chlorogenic and ellagic acids, which correlated with the infection–plant complex process. Based on the results, P. aphanidermatum could be a biotic stress pathogen that causes the expression of pathogen-related genes and stops the regulation of defensin phenolic compounds. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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10. Sensitivity of Different Isolates of Pythium aphanidermatum to Old and Novel Fungicides.
- Author
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Shah, Ghulam Sarwar, Rustamani, Maqsood Anwar, Khuhro, Rab Dino, Syed, Rehana Naz, and Lodhi, Abdul Mubeen
- Subjects
- *
FUNGICIDES , *ROOT rots , *PYTHIUM , *GLOBAL warming , *PROPICONAZOLE , *COPPER - Abstract
Pythium aphanidermatum is one of the most devastating soil-borne pathogens in the warmer climates of the world. It is more damaging in vegetables by causing seedling rots, root rot, pre- and postemergence damping-off, cottony-leak, cottony blight, and stalk rot diseases. An advantageous combination of various factors makes the control of Pythium aphanidermatum difficult. However, synthetic fungicides provide quick and effective control. Therefore, we checked the sensitivity of different isolates of P. aphanidermatum to 17-old and novel fungicides. Against all isolates, the fungicides’ main effect, concentration’s main effect, and fungicides’ × concentration’s effect are highly significant. Generally, based on their effectiveness, all tested fungicides were divided into three groups i.e., highly effective, moderately effective, and completely ineffective. All isolates of P. aphanidermatum were grown at par with the control when exposed to different concentrations of mandipropamid and fluoxastrobin. Both fungicides completely failed to cause any negative effects on in vitro growth of all isolates. On the other hand, all isolates appeared extremely sensitive to 10 fungicides including azoxystrobin, copper oxychloride, difenoconazole, propiconazole, azoxystrobin+difenoconazole, trifloxystrobin+tebuconazole, hexaconazole, mancozeb+mefenoxam, myclobutanil, and flutolanil. All isolates except Pa 12 (which grew only at 250 ppm of azoxystrobin) failed to tolerate 250-8000 ppm concentrations of these fungicides and produced no growth under in vitro conditions. To some extent, the tested isolates showed variable responses to fosetyl aluminium, iprovalicarb+propineb, thiophanate-methyl, cymoxanil+mancozeb, and propineb. The isolates grew well at lower concentrations, gradually inhibited, and failed to grow at higher concentrations. The findings of the present research will help to design an effective control strategy against P. aphanidermatum with effective fungicides under field conditions. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
- Full Text
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11. Impact of Spent Mushroom Substrate Enriched with Trichoderma harzianum on Damping off Disease in Chilli and Tomato.
- Author
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Kumar, Satish and Chugh, Rakesh Kumar
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- *
MUSHROOMS , *TRICHODERMA , *PEPPER diseases & pests , *TOMATO diseases & pests , *PYTHIUM aphanidermatum - Published
- 2022
- Full Text
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12. Plant-Disease-Suppressive and Growth-Promoting Activities of Endophytic and Rhizobacterial Isolates Associated with Citrullus colocynthis
- Author
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Badriya Khalfan Al-Shuaibi, Elham Ahmed Kazerooni, Shah Hussain, Rethinasamy Velazhahan, and Abdullah Mohammed Al-Sadi
- Subjects
antagonistic bacteria ,biological control ,damping-off ,Fusarium solani ,plant growth promotion ,Pythium aphanidermatum ,Medicine - Abstract
This study was conducted to investigate the antagonistic potential of endophytic and rhizospheric bacterial isolates obtained from Citrullus colocynthis in suppressing Fusarium solani and Pythium aphanidermatum and promoting the growth of cucumber. Molecular identification of bacterial strains associated with C. colocynthis confirmed that these strains belong to the Achromobacter, Pantoea, Pseudomonas, Rhizobium, Sphingobacterium, Bacillus, Sinorhizobium, Staphylococcus, Cupriavidus, and Exiguobacterium genera. A dual culture assay showed that nine of the bacterial strains exhibited antifungal activity, four of which were effective against both pathogens. Strains B27 (Pantoea dispersa) and B28 (Exiguobacterium indicum) caused the highest percentage of inhibition towards F. solani (48.5% and 48.1%, respectively). P. aphanidermatum growth was impeded by the B21 (Bacillus cereus, 44.7%) and B28 (Exiguobacterium indicum, 51.1%) strains. Scanning electron microscopy showed that the strains caused abnormality in phytopathogens’ mycelia. All of the selected bacterial strains showed good IAA production (>500 ppm). A paper towel experiment demonstrated that these strains improved the seed germination, root/shoot growth, and vigor index of cucumber seedlings. Our findings suggest that the bacterial strains from C. colocynthis are suppressive to F. solani and P. aphanidermatum and can promote cucumber growth. This appears to be the first study to report the efficacy of these bacterial strains from C. colocynthis against F. solani and P. aphanidermatum. more...
- Published
- 2023
- Full Text
- View/download PDF
13. A study of fungicidal and anti-phenol oxidase activity of some α-amino phosphonate derivatives
- Author
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Mohsen Abbod, Naser Safaie, Khodayar Gholivand, Mohammad Mehrabadi, Mahyar Bonsaii, and Ali Asghar Ebrahimi Valmoozi
- Subjects
Organophosphorus ,Phenol oxidase ,DFT ,Macrophomina phaseolina ,Pythium aphanidermatum ,Agriculture - Abstract
Abstract Background Developing new pesticides with multi-function may be a suitable strategy to save time and cost and reduce the emergence of resistant strains of pests and pathogens. The organophosphorus derivatives have not been widely used in agriculture as fungicides. In this work, a series of six α-amino phosphonate derivatives were prepared and tested for their fungicidal and anti-phenol oxidase activities. Results The prepared compounds revealed a promising anti-fungal activity against Macrophomina phaseolina and Pythium aphanidermatum, especially M4, with MIC of 62 mg/L for M. phaseolina. M4 did not affect the fungus permeability rate of the cell membrane; however, it displayed a significant efficiency on mycelial soluble protein content. M4 and M3 with a hydroxyl group on the aniline moiety exhibited an observed anti-phenol oxidase activity. M4 inhibited the enzyme at 1 mg/mL. The DFT theoretical study revealed a significant correlation between the substituents of aniline moiety and the bioactivity of the studied compounds. The negative charge conspicuously influenced the anti-phenol oxidase activity. Conclusions Our findings suggest the studied compounds as bases to design more effective α-amino phosphonate fungicides with additional anti-phenol oxidase activity. Graphic abstract more...
- Published
- 2021
- Full Text
- View/download PDF
14. Efficacy of Streptomyces murinus JKTJ-3 in Suppression of Pythium Damping-Off of Watermelon
- Author
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Mihong Ge, Xiang Cai, Dehuan Wang, Huan Liang, Juhong Zhu, Guoqing Li, and Xianfeng Shi
- Subjects
watermelon ,damping-off ,Pythium aphanidermatum ,Streptomyces murinus ,biocontrol ,Biology (General) ,QH301-705.5 - Abstract
Damping-off caused by Pythium aphanidermatum (Pa) is one of the most destructive diseases for watermelon seedlings. Application of biological control agents against Pa has attracted the attention of many researchers for a long time. In this study, the actinomycetous isolate JKTJ-3 with strong and broad-spectrum antifungal activity was screened from 23 bacterial isolates. Based on the morphological, cultural, physiological, and biochemical characteristics as well as the feature of 16S rDNA sequence, isolate JKTJ-3 was identified as Streptomyces murinus. We investigated the biocontrol efficacy of isolate JKTJ-3 and its metabolites. The results revealed that seed and substrate treatments with JKTJ-3 cultures showed a significant inhibitory effect on watermelon damping-off disease. Seed treatment with the JKTJ-3 cultural filtrates (CF) displayed higher control efficacy compared to the fermentation cultures (FC). Treatment of the seeding substrate with the wheat grain cultures (WGC) of JKTJ-3 exhibited better control efficacy than that of the seeding substrate with the JKTJ-3 CF. Moreover, the JKTJ-3 WGC showed the preventive effect on suppression of the disease, and the efficacy increased with increase in the inoculation interval between the WGC and Pa. Production of the antifungal metabolite actinomycin D by isolate JKTJ-3 and cell-wall-degrading enzymes such as β-1,3-glucanase and chitosanase were probably the mechanisms for effective control of watermelon damping-off. It was shown for the first time that S. murinus can produce anti-oomycete substances including chitinase and actinomycin D. This is the first report about S. murinus used as biocontrol agent against watermelon damping-off caused by Pa. more...
- Published
- 2023
- Full Text
- View/download PDF
15. Vascular pythiosis caused by Pythium aphanidermatum: the first case report in Asia
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Pannaporn Thongsuk, Rongpong Plongla, Arsa Thammahong, Jaruwan Tiewsurin, Navaporn Worasilchai, Ariya Chindamporn, and Chusana Suankratay
- Subjects
Pythiosis ,Pythium ,Pythium insidiosum ,Pythium aphanidermatum ,Case report ,Asia ,Medicine - Abstract
Abstract Background Pythium, soil-borne plant pathogens, are in the class Oomycetes. They are not true fungi, but are related to diatom and algae. There are two human pathogens including P. insidiosum and P. aphanidermatum. To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia. Case presentation A 47-year-old Thai woman, living in North Thailand, with ß thalassemia/hemoglobin E presented with acute recurrent arterial insufficiency of both legs. Emergent embolectomy with clot removal was performed. The pathology of the clot exhibited noncaseous granulomatous inflammation with many fungal hyphal elements. PCR identified P. aphanidermatum with 100% identity. Final diagnosis is vascular pythiosis. Unfortunately, the patient eventually expired after treatment with itraconazole, terbinafine, azithromycin, and doxycycline. Conclusions To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia. more...
- Published
- 2021
- Full Text
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16. Allelopathy Effect of Trichoderma spp. and Some Plant Extracts against Pythium aphanidermatum (In-vitro)
- Author
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Al-Taie, Azher H., Al-Zubaidi, Noor K., and Al-Shammary, Musa K.
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- 2020
- Full Text
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17. Antifungal activity and GC-MS detection of leaves and roots parts of Chenopodium album extract against some phytopathogenic fungi
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Alkooranee, Jawadayn Talib, Al-khshemawee, Hasan Hadi, Al-badri, Mutaz Abdul Kadhim, Al-srai, Maha Shaker, and Daweri, Hadeel Hamazah
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- 2020
- Full Text
- View/download PDF
18. Fruit rot disease in butternut squash caused by Pythium aphanidermatum in Trincomalee district, Sri Lanka
- Author
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P. Sevvel, D. Kugathasan, and C. J. Emmanuel
- Subjects
fruit rot ,butternut squash ,pythium aphanidermatum ,Science - Abstract
Fruit rot disease is a serious, emerging problem in butternut squash (Cucurbita moschata) cultivation in Northern and Eastern Provinces of Sri Lanka. Aim of the present study was to identify the causative agent of the fruit rot in the Trincomalee District and find a suitable fungicide to control the disease. Diseased fruit samples were collected randomly from four fields in Nilaveli, Morawewa, Kinniya and Thambalagamam. Fruit rots appeared brown colour, sunken and water-soaked spots which later turned black, enlarged rots with moldy appearance. The pathogen was isolated on Potato Dextrose Agar (PDA) medium. Cultural and morphological characteristics were studied. On PDA, cultures initially appeared white, cottony with heavy aerial mycelium which later became flat. Younger hyphae had swollen tips, while matured hyphae were hyaline, aseptate and dichotomously branched. Aplerotic oospores were surrounded by terminal oogonia. Zoospores arose from globose sporangia. There was no morphological variation among isolates, collected from the four different villages in the Trincomalee district. Internal transcribed spacer (ITS) region of the genome was PCR amplified. PCR products were subjected to DNA sequencing. Based on morphological features and analysis of ITS region of the genome, the pathogen was identified as Pythium aphanidermatum. Koch’s postulates confirmed the pathogenicity of P. aphanidermatum. Four concentrations (10, 100, 1,000 and 10,000 ppm) of commercial fungicides (Captan 50 WP, Mancozeb 80 WP, Homai 80 WP and Topsin 70 WP) were tested against the isolate in vitro. Fungicides, namely Homai or Captan (>1000 mg l-1), can be used to reduce the pathogen growth. more...
- Published
- 2020
- Full Text
- View/download PDF
19. A study of fungicidal and anti-phenol oxidase activity of some α-amino phosphonate derivatives.
- Author
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Abbod, Mohsen, Safaie, Naser, Gholivand, Khodayar, Mehrabadi, Mohammad, Bonsaii, Mahyar, and Valmoozi, Ali Asghar Ebrahimi
- Subjects
PHOSPHONATE derivatives ,PHOSPHONATES ,MACROPHOMINA phaseolina ,HYDROXYL group ,PHENOL oxidase ,FUNGICIDES - Abstract
Background: Developing new pesticides with multi-function may be a suitable strategy to save time and cost and reduce the emergence of resistant strains of pests and pathogens. The organophosphorus derivatives have not been widely used in agriculture as fungicides. In this work, a series of six α-amino phosphonate derivatives were prepared and tested for their fungicidal and anti-phenol oxidase activities. Results: The prepared compounds revealed a promising anti-fungal activity against Macrophomina phaseolina and Pythium aphanidermatum, especially M4, with MIC of 62 mg/L for M. phaseolina. M4 did not affect the fungus permeability rate of the cell membrane; however, it displayed a significant efficiency on mycelial soluble protein content. M4 and M3 with a hydroxyl group on the aniline moiety exhibited an observed anti-phenol oxidase activity. M4 inhibited the enzyme at 1 mg/mL. The DFT theoretical study revealed a significant correlation between the substituents of aniline moiety and the bioactivity of the studied compounds. The negative charge conspicuously influenced the anti-phenol oxidase activity. Conclusions: Our findings suggest the studied compounds as bases to design more effective α-amino phosphonate fungicides with additional anti-phenol oxidase activity. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
- View/download PDF
20. Damping-off caused by Pythium aphanidermatum on sugar beet in Egypt.
- Author
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Mahmoud, Mohamed Abdellatif A., Omar, Ayman Faisal, Mohamed, Ayman A. A., Gouda, Moustafa I., and Emeran, Amero A.
- Subjects
DAMPING-off diseases ,FUNGAL diseases of plants ,PYTHIUM aphanidermatum ,SUGAR beets - Abstract
Damping-off, root rot and necrotic lesions were observed on sugar beet (Beta vulgaris) seedlings in the Kafrelsheikh Governorate, in the northern part of the Nile River delta, Egypt. Pythium aphanidermatum was identified as the causal agent using the morphology of the asexual and sexual morphs and molecular studies. This is the first record of P. aphanidermatum on sugar beet in Egypt. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
- View/download PDF
21. Influence of Pythium oligandrum on Mycelia and Production of Zoo-and Oo-spores of Two Phytopathogenic Pythium spp.
- Author
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Shaima Mohamed Nabil Moustafa
- Subjects
cultural filtrate of p. oligandrum ,oospores ,pythium aphanidermatum ,pythium diclinum ,zoospores. ,Microbiology ,QR1-502 - Abstract
Pythium oligandrum is one of the best known fungi in biological control of many fungal plant diseases. The objective of this study was conducted to highlight the possibility of using cultural filtrate of this fungus in inhibiting the growth of reproducting units of the pathogenic Pythium aphanidermatum and P. diclinum. Two isolates of each fungus were studied. Ability of P. oligandrum to grow and develop on V-8 liquid medium was tested in order to study its effect on mycelium growth, zoospore and oospore production of each of the pathogenic pythia of P. aphanidermatum and P. diclinum. Cultural filtrate of P. oligandrum (quarter and half concentration) significantly inhibited mycelial growth and the production of zoospores and oospores of the pathogenic tested fungi. The rate of inhibition in all treatments reached more than 90% in case of the use of half concentration of the cultural filtrate of P. oligandrum. The study will provide information for the use of cultural filtrate of potential selected isolates of P. oligandrum in biological control of some fungal diseases especially in aquaculture. The outcomes of this research can be easily applied in aquatic farming but need further work on different types of pathogenic fungi. more...
- Published
- 2019
- Full Text
- View/download PDF
22. First report of Pythium aphanidermatum infecting tomato in Egypt and controlling it using biogenic silver nanoparticles
- Author
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Ibrahim Elshahawy, Hesham Mohamed Abouelnasr, Sirag Mohamed Lashin, and Osama Mohamed Darwesh
- Subjects
biogenic synthesis ,Pythium aphanidermatum ,silver nanoparticles (AgNps) ,tomato ,Plant culture ,SB1-1110 - Abstract
In August 2016, tomato plants grown during a hot, wet summer with heavy soil flooding, displaying symptoms of wilting, dead plant, root rot with crown and stem rot, at Beni Suef and Fayoum governorates were examined. A number of 16 fungal isolates were isolated from tomato plants displaying the above symptoms. These isolates were classified as belonging to six species, namely: Alternaria solani, Chaetomium globosum, Fusarium solani, Fusarium oxysporum, Pythium spp. and Rhizoctonia solani. Isolates of Pythium spp. were prevalent and were found to be more pathogenic than the other fungal isolates. This species causes damping-off, root rot, sudden death, stem rot and fruit rot. The pathogen was identified as Pythium aphanidermatum based on morphological, cultural, and molecular characteristics. Biogenic silver nanoparticles (AgNPs) were produced using the F. oxysporum strain and characterized by transmission electron microscopy (TEM). The size of these spherical particles ranged from 10 to 30 nm. In vitro, biogenic AgNPs showed antifungal activity against P. aphanidermatum. In greenhouse and field experiments, AgNPs treatment significantly reduced the incidence of dead tomato plants due to root rot caused by P. aphanidermatum compared to the control. All of the investigated treatments were effective and the treatment of root dipping plus soil drenching was the most effective. To the best of our knowledge, this study describes P. aphanidermatum on tomato in Egypt for the first time. Also, biogenic AgNPs could be used for controlling root rot disease caused by this pathogen. more...
- Published
- 2018
- Full Text
- View/download PDF
23. Microbial Origin of Aquaponic Water Suppressiveness against Pythium aphanidermatum Lettuce Root Rot Disease.
- Author
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Stouvenakers, Gilles, Massart, Sébastien, Depireux, Pierre, and Jijakli, M. Haïssam
- Abstract
Aquaponic systems are an integrated way to produce fish and plants together with mutual benefits. Fish provide nutrients to plants on the one side, and plant nutrients uptake allow water reuse for fish on the other side. In this kind of system, the use of phytosanitary treatments to control plant pathogens is sensitive because of the risk of toxicity for fish present in the same water loop, especially coupled aquaponics. Among plant pathogens, Pythium aphanidermatum is a most problematic microorganism due to the Oomycete’s capacity to produce mobile form of dispersion (zoospores) in the recirculated water. Therefore, this study aimed at elucidating the potential antagonistic capacity of aquaponic water against P. aphanidermatum diseases. It was shown that aquaponic water presented an inhibitory effect on P. aphanidermatum mycelial growth in in vitro conditions. The same result was observed when lettuce plants growing in aquaponic water were inoculated by the same plant pathogen. Aquaponic lettuce was then compared to lettuce grown in hydroponic water or complemented aquaponic water (aquaponic water plus mineral nutrients). The disease was suppressed in the presence of aquaponic water, contrary to lettuce grown in hydroponic water or complemented aquaponic water. Root microbiota were analyzed by 16S rDNA and ITS Illumina sequencing to determine the cause of this aquaponic suppressive action. It was determined that the diversity and the composition of the root microbiota were significantly correlated with the suppressive effect of aquaponic water. Several taxa identified by metabarcoding were suspected to be involved in this effect. Moreover, few of these microorganisms, at the genus level, are known to have an antagonistic effect against P. aphanidermatum. These innovative results indicate that aquaponic water could be an interesting and novel source of antagonistic agents adapted to control P. aphanidermatum diseases in soilless culture. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
- View/download PDF
24. Damping off on soybean (Glycine max) caused by Pythium aphanidermatum in Buenos Aires Province (Argentina).
- Author
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Grijalba, Pablo E., del C. Ridao, Azucena, and Steciow, Mónica
- Subjects
- *
SOYBEAN , *PYTHIUM aphanidermatum , *DAMPING-off diseases , *TEMPERATURE , *OOMYCETES , *MICROBIAL virulence , *GROWTH rate - Abstract
Pythium aphanidermatum has a cosmopolitan distribution in the warmer parts of the world. The aim of this study was to identify the causal agent of damping off in soybean seedlings on late planting dates under hot conditions, from different locations in Buenos Aires province. The isolates induced different levels of plant and seedling death and growth rate at different incubation temperatures (15, 25 and 35°C). In accordance with morphological, cultural and molecular characteristics, the pathogen was identified as P. aphanidermatum, and this is the first report of this oomycete causing soybean root and stem rot in Buenos Aires province, Argentina. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
25. Vascular pythiosis caused by Pythium aphanidermatum: the first case report in Asia.
- Author
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Thongsuk, Pannaporn, Plongla, Rongpong, Thammahong, Arsa, Tiewsurin, Jaruwan, Worasilchai, Navaporn, Chindamporn, Ariya, and Suankratay, Chusana
- Subjects
PYTHIUM ,SOILBORNE plant pathogens ,BACTERIAL wilt diseases ,TERBINAFINE - Abstract
Background: Pythium, soil-borne plant pathogens, are in the class Oomycetes. They are not true fungi, but are related to diatom and algae. There are two human pathogens including P. insidiosum and P. aphanidermatum. To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia. Case presentation: A 47-year-old Thai woman, living in North Thailand, with ß thalassemia/hemoglobin E presented with acute recurrent arterial insufficiency of both legs. Emergent embolectomy with clot removal was performed. The pathology of the clot exhibited noncaseous granulomatous inflammation with many fungal hyphal elements. PCR identified P. aphanidermatum with 100% identity. Final diagnosis is vascular pythiosis. Unfortunately, the patient eventually expired after treatment with itraconazole, terbinafine, azithromycin, and doxycycline. Conclusions: To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
- View/download PDF
26. Development and evaluation of polyclonal antibodies for detection of Pythium aphanidermatum and Fusarium oxysporum in ginger
- Author
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Monalisa Ray, Swagatika Dash, K. Gopinath Achary, Sanghamitra Nayak, and Shikha Singh
- Subjects
ginger ,rhizome rot ,pythium aphanidermatum ,fusarium oxysporum ,polyclonal antibodies ,sds-page ,elisa ,western blot ,Agriculture (General) ,S1-972 ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Polyclonal antibodies against Pythium aphanidermatum and Fusarium oxysporum proteins were developed for the detection of rhizome rot in ginger using serological assays. Under optimal experimental conditions, the detection limit of P. aphanidermatum by indirect ELISA was 10 µg/ml with a linear working range from 5 to 100 µg/ml (R2 = 0.994). In case of F. oxysporum, the linear working range was 5–100 µg/ml (R2 = 0.991) and the limit of detection was 25 µg/ml. The developed antibodies showed the highest titer in ELISA at 1:2000 dilutions. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis identified proteins ranging from molecular weights 15–97 kDa and 14–116 kDa of P. aphanidermatum and F. oxysporum isolates, respectively. In Western blot analysis, the developed antisera gave positive reactions against the isolated antigens of the fungi. The antibodies revealed immune-reactive bands of molecular weights 59 and 65 kDa in P. aphanidermatum and 44 and 75 kDa in F. oxysporum. The results suggest that the developed antibodies could be successfully applied for the specific immunodetection of P. aphanidermatum and F. oxysporum at an early stage of rhizome rot disease. more...
- Published
- 2018
- Full Text
- View/download PDF
27. Mycogenic Nano-Complex for Plant Growth Promotion and Bio-Control of Pythium aphanidermatum
- Author
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Shaima M.N. Moustafa and Rania H. Taha
- Subjects
Zn-Nanocomplex ,Trichoderma longibrachiatum ,Pythium aphanidermatum ,antifungal activity ,Botany ,QK1-989 - Abstract
(1) Background: biological way is one of the most ecofriendly and safe strategies for nanomaterials synthesis. So, biosynthesis-green method was used for the preparation of Zn(II) complex (in the Nano scale) from the reaction of the schiff base ligand 2,2′-((1E,1′E)-(1,2-phenylenebis (azanylylidene)), bis(methanylylidene))bis(4-bromophenol), and Zn(II)sulphate. The biogenic ZnNP-T was characterized by different methods. Our purpose was to evaluate the ability of biosynthesis-green method for the preparation of Zn(II) complex as an antifungal agent against diseases from fungal species. (2) Methods: in this work, isolates of Pythium aphanidermatum and Trichderma longibrachiatum were obtained, and Trichderma longibrachiatum was used to prepare nano metal complex. We tested the pathogenicity of nano metal complex against seedling and germination of seeds, and we evaluated the effectiveness of ZnNP-T for growth promotion of Vicia feba in early stage and inhibitory activity against Pythium aphanidermatum. (3) Results: antagonistic activity of ZnNP-T was tested in vitro against Pythium aphanidermatum, and then the growth rates of Vicia faba were determined. The obtained data revealed that mycelial growth of pathogenic fungus was inhibited about 73.8% at 20 ppm. In addition, improved the total biomass of Vicia faba in the presence of P. aphanidermatum. All concentration of ZnNP-T positively affected root weight of Vicia faba seedlings, and positively affected shoot weight. Root and shoot lengths were affected by using 20 ppm of ZnNP-T with up to 180 and 96.5 mm of shoot and root length compared to that of the control, while germination percentage was significantly enhanced with up to 100% increase after 72 h of germination. (4) Conclusion: one of the modern challenges in vegetable or fruit production is to enhance seed germination and to grow healthy plants with strong root system. In future, there should be a focus on using of biogenic Zinc nano-complex as plant growth promoter agents. more...
- Published
- 2021
- Full Text
- View/download PDF
28. Evaluation of different native Streptomyces spp. for effective management of rhizome rot of turmeric.
- Author
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Nithya, Muthusamy, Ponmurugan, Ponnusamy, Gnanamangai, Balasubramanian Mythili, Robinson, Jayachandran Philip, Mathivanan, Narayanasamy, and Senthilkumar, Jeyaraj
- Abstract
The efficacy of talc based bioformulations containing various biocontrol agents against rhizome rot disease caused by Pythium aphanidermatum in turmeric plants was evaluated under field condition. Indigenous biocontrol agents such as Streptomyces lydicus, Streptomyces griseus and Streptomyces sannanensis belonging to actinomycetes group, Pseudomonas fuorescens (bacterial) and Trichoderma atroviride (fungal) were selected for the biological control of rhizome rot of turmeric. The results indicated a signifiicantly stronger reduction in disease severity in trial plots treated with Bacillus subtilis based commercial fungicide ‘Companion’ when compared to plants treated with indigenous biocontrol agents. However, it was reverse in trial plots in terms of turmeric rhizome yield potential, yield attributes, physiological components, biochemical constituents and quality characteristics of rhizomes. Among 17 treatments, a dual mixture of S. griseus and T. atroviride achieved the best disease control as well as plant growth improvement when compared to single and triple combinations of biocontrol agents. The present study confirms that exploration of microbial formulations containing Streptomyces spp. as soil inoculant to turmeric plants exhibited some benefits to turmeric plant growth as well as controlling rhizome rot disease, which ultimately enhance the overall quality characteristics of rhizomes. Further, our results suggest that a dual combination of biocontrol agents represent a promising method for effective management of rhizome rot of turmeric. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
- View/download PDF
29. Influence of Pythium oligandrum on Mycelia and Production of Zoo-and Oo-spores of Two Phytopathogenic Pythium spp.
- Author
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Nabil Moustafa, Shaima Mohamed
- Subjects
- *
PYTHIUM diseases , *PHYTOPATHOGENIC microorganisms , *MYCOSES , *PATHOGENIC fungi , *PHYSIOLOGICAL control systems - Abstract
Pythium oligandrum is one of the best known fungi in biological control of many fungal plant diseases. The objective of this study was conducted to highlight the possibility of using cultural filtrate of this fungus in inhibiting the growth of reproducting units of the pathogenic Pythium aphanidermatum and P. diclinum. Two isolates of each fungus were studied. Ability of P. oligandrum to grow and develop on V-8 liquid medium was tested in order to study its effect on mycelium growth, zoospore and oospore production of each of the pathogenic pythia of P. aphanidermatum and P. diclinum. Cultural filtrate of P. oligandrum (quarter and half concentration) significantly inhibited mycelial growth and the production of zoospores and oospores of the pathogenic tested fungi. The rate of inhibition in all treatments reached more than 90% in case of the use of half concentration of the cultural filtrate of P. oligandrum. The study will provide information for the use of cultural filtrate of potential selected isolates of P. oligandrum in biological control of some fungal diseases especially in aquaculture. The outcomes of this research can be easily applied in aquatic farming but need further work on different types of pathogenic fungi. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
30. Biological Control of Pythium aphanidermatum, the Causal Agent of Tomato Root Rot by Two Streptomyces Root Symbionts
- Author
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Mohadeseh Hassanisaadi, Gholam Hosein Shahidi Bonjar, Akbar Hosseinipour, Roohollah Abdolshahi, Essaid Ait Barka, and Ismail Saadoun
- Subjects
Streptomyces ,Pythium aphanidermatum ,biocontrol ,root symbionts ,PGPR ,16S rRNA ,Agriculture - Abstract
Damping-off caused by Pythium aphanidermatum, as one of the most infamous plant diseases, is considered as a significant disease that causes severe damages in greenhouse and field crops in a vast range of hosts especially vegetables. The application of chemical fungicides as a common method to control this disease poses negative side effects on humans and the environmental components. Actinobacteria, especially members of the genus Streptomyces, are fascinating biocontrol agents and plant growth-promoting rhizobacteria, which exhibit safer alternative managements to control this disease. The present study aims to explore for bioactives soil Streptomyces isolates that are able to control P. aphanidermatum, which is the causal agent of damping-off in tomato. Out of a total of 116 actinobacteria isolates collected from the soil, 53 have showed an antagonistic activity against P. aphanidermatum, as deduced through in vitro dual cultures. Based on in vitro Petri plate seedling-bioassays (IPSB), from the 53 tested isolates in dual cultures, two isolates coded as H2 and H3, considered as the most bioactive agents, were selected to assess their biocontrol performances against P. aphanidermatum in the Sandwich bed-mix technique in greenhouse experiments. In vivo greenhouse statistical studies were performed to compare seven treatments using completely randomized design experiments. Metalaxyl fungicide was applied as the chemical-control treatment. To evaluate biocontrol efficiencies of the two Streptomyces symbionts, disease incidence recorded throughout the course of experiment and criteria of number of leaves, length of the plants, plant fresh and dry weights, were measured at the end of experiment and analyzed statistically. The resulted disease incidences for all treatments indicated that the two Streptomyces strains had PGPR activity, and they were effective in decreasing disease incidence and improving plant performances regarding number of leaves, height, and plant fresh and dry weights. Based on the phylogenetic analysis of the partial sequences of the 16S rRNA gene, the strain H2 revealed a close relation to six Streptomyces species, namely S. badius, S. caviscabies, S. globisporus, S. parvus, S. sindenensis, and S. griseoplanus, with 99.9% similarity. The strain H3 also indicated a close relation of the same similarity to two species, namely S. flavogriseus and S. pratensis. In overall, collected data dictated that the two bioactive root symbiont Streptomyces strains effectively controlled the damping-off disease caused by P. aphanidermatum. more...
- Published
- 2021
- Full Text
- View/download PDF
31. The Effect of Chitosan on the Induction Systemic Resistance against Pythium aphanidermatum in Cucumber
- Author
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seyed kazem sabbagh, Ebrahim sabbaghh, javad Abkho, and Farva sadat Mostafavi
- Subjects
Chitosan ,Cupi4 ,Gene expression ,Lypoxigenase ,Pythium aphanidermatum ,Systemic acuired resistance ,Agriculture (General) ,S1-972 - Abstract
Introduction: Land use change, deforestation, grazing, intentional and unintentional fire and invasive pests and diseases are all the major cause of damage to the Zagros forest ecosystem. The green oak leaf roller (Tortrix viridana L.) is one of the important pests of Zagros forests. Larvae of the pest significantly damage the oak forests with feeding on leaves and buds of different species of oaks each year. Larvae enter 2'd instar after eating the internal contents of oak buds, then the third and 4th instars larvae consume whole buds and even oak leaves. After development to the 5th larval instar, they roll the leaves and enter the pupal stage. The attacked trees revitalize by creating new leaves from early May onwards. New leaves, pale green and are smaller than normal leaves. Continuation of the pest activity on Quercus species causes gradual weakness the trees and readiness to accept a variety of secondary pests and diseases in later years. Based on the status of Zagros forests and their importance in the conservation of soil and water sources, the nutritional indices of Tortrix viridana larvae of two species of Oak i.e. Quercus infectoria and Q. libani were determined to get a better understanding of this pest. Materials and Methods: Since early April, with regular visits, last instar larvae (5th instar) of T. viridana in oak forests in Perdanan areas (around the village Ghabr Hossein) were collected and transferred to the laboratory chamber. The larvae were fed on the two oak species. The leaves of these species were collected and transported to the laboratory in a room at a temperature of 25°C and suitable photoperiod conditions. The larvae were fed individually or in a group. In a grouping method, 10 larvae in two replicates and in individually method 40 larvae (one larva per replicate) for each host were considered. Larval weight, amount of consumed food and weight of feces were estimated by using a sensitive digital Carriage scale (0.001 gr). Relative consumption rate (RCR), relative growth rate (RGR), the efficiency of conversion of ingested food (ECI), the efficiency of conversion of digested food (ECD) and approximate digestibility (AD) were also calculated. For statistical analysis t-test and SPSS17 software were used to compare the mean of the data. Results and Discussion: Results of t-test (α=5%) indicated that the larval biomass, RGR, ECI, and AD were significantly different among the hosts in both methods of grouping and individually rearing of the larvae. In this study, Q. libani showed the lowest rate of digestibility. The larvae fed on Q. infectoria have the higher rate of AD than Q. libani because of high RCR, RGR, ECD and ECI. Also, the results related to the comparison of two methods (grouping and individually rearing of the larvae), on nutritional indices were significantly different and in both host trees, the rate of RGR, ECI and ECD in grouping method was more than individually rearing method. RCR is the indication of the insect's exploitation speed of food. In the other words, it shows feeding rate regarding insect's weight at the specific point of time depending on the amount of water and other nutrition physicochemical characteristics in insects. The result showed that this index rate in group rearing method on two host species is equal, but in individual rearing method on Q. infectoria, it is more than Q. libani. The possible reasons are more feeding of larvae in individual rearing method due to the lack of competition stress, the more likelihood of the desirability of Q. infectoria compared to Q. libani, the probability of the existence of antixenosis in Q. libani. The similar study investigating individual and group rearing methods in one insect species is not available. This result confirms that T. viridana larvae’s has a tendency toward social life and in the group situation, they eat effectively. In fact, although larvae in individual form feed more because of lack of competition stress, but in the group they make use of that little food in the best way. Conclusion: In this study, Q. libani had low food quality. As a result, its relative consumption rate, relative growth rate, the efficiency of conversion of ingested food and efficiency of conversion of digested food was less than Q. infectoria. According to the results, Q. infectoria is an appropriate host for this pest. Also, it shows that the larvae were more considering the rate of larval biomass, RCR, RGR, ECI and ECD in grouping method than the single method. more...
- Published
- 2016
- Full Text
- View/download PDF
32. First report of Pythium aphanidermatum infecting tomato in Egypt and its control using biogenic silver nanoparticles
- Author
-
S. M. Lashin, Hesham Mohamed Abouelnasr, Osama M. Darwesh, and Ibrahim Elshahawy
- Subjects
0106 biological sciences ,Pythium aphanidermatum ,silver nanoparticles (AgNps) ,Soil Science ,Plant Science ,tomato ,01 natural sciences ,Silver nanoparticle ,SB1-1110 ,Biogenic substance ,010608 biotechnology ,Botany ,Soil treatment ,Fungal morphology ,biogenic synthesis ,biology ,business.industry ,Pest control ,food and beverages ,Plant culture ,biology.organism_classification ,Plant disease ,business ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
In August 2016, tomato plants grown during a hot, wet summer with heavy soil flooding, displaying symptoms of wilting, dead plant, root rot with crown and stem rot, at Beni Suef and Fayoum governorates were examined. A number of 16 fungal isolates were isolated from tomato plants displaying the above symptoms. These isolates were classified as belonging to six species, namely: Alternaria solani, Chaetomium globosum, Fusarium solani, Fusarium oxysporum, Pythium spp. and Rhizoctonia solani. Isolates of Pythium spp. were prevalent and were found to be more pathogenic than the other fungal isolates. This species causes damping-off, root rot, sudden death, stem rot and fruit rot. The pathogen was identified as Pythium aphanidermatum based on morphological, cultural, and molecular characteristics. Biogenic silver nanoparticles (AgNPs) were produced using the F. oxysporum strain and characterized by transmission electron microscopy (TEM). The size of these spherical particles ranged from 10 to 30 nm. In vitro, biogenic AgNPs showed antifungal activity against P. aphanidermatum. In greenhouse and field experiments, AgNPs treatment significantly reduced the incidence of dead tomato plants due to root rot caused by P. aphanidermatum compared to the control. All of the investigated treatments were effective and the treatment of root dipping plus soil drenching was the most effective. To the best of our knowledge, this study describes P. aphanidermatum on tomato in Egypt for the first time. Also, biogenic AgNPs could be used for controlling root rot disease caused by this pathogen. more...
- Published
- 2023
- Full Text
- View/download PDF
33. Microbial Origin of Aquaponic Water Suppressiveness against Pythium aphanidermatum Lettuce Root Rot Disease
- Author
-
Gilles Stouvenakers, Sébastien Massart, Pierre Depireux, and M. Haïssam Jijakli
- Subjects
aquaponic ,disease suppressive ,Pythium aphanidermatum ,lettuce ,high-throughput sequencing ,microorganism ,Biology (General) ,QH301-705.5 - Abstract
Aquaponic systems are an integrated way to produce fish and plants together with mutual benefits. Fish provide nutrients to plants on the one side, and plant nutrients uptake allow water reuse for fish on the other side. In this kind of system, the use of phytosanitary treatments to control plant pathogens is sensitive because of the risk of toxicity for fish present in the same water loop, especially coupled aquaponics. Among plant pathogens, Pythium aphanidermatum is a most problematic microorganism due to the Oomycete’s capacity to produce mobile form of dispersion (zoospores) in the recirculated water. Therefore, this study aimed at elucidating the potential antagonistic capacity of aquaponic water against P. aphanidermatum diseases. It was shown that aquaponic water presented an inhibitory effect on P. aphanidermatum mycelial growth in in vitro conditions. The same result was observed when lettuce plants growing in aquaponic water were inoculated by the same plant pathogen. Aquaponic lettuce was then compared to lettuce grown in hydroponic water or complemented aquaponic water (aquaponic water plus mineral nutrients). The disease was suppressed in the presence of aquaponic water, contrary to lettuce grown in hydroponic water or complemented aquaponic water. Root microbiota were analyzed by 16S rDNA and ITS Illumina sequencing to determine the cause of this aquaponic suppressive action. It was determined that the diversity and the composition of the root microbiota were significantly correlated with the suppressive effect of aquaponic water. Several taxa identified by metabarcoding were suspected to be involved in this effect. Moreover, few of these microorganisms, at the genus level, are known to have an antagonistic effect against P. aphanidermatum. These innovative results indicate that aquaponic water could be an interesting and novel source of antagonistic agents adapted to control P. aphanidermatum diseases in soilless culture. more...
- Published
- 2020
- Full Text
- View/download PDF
34. Corrigendum: Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew
- Author
-
Eman M. Khalaf and Manish N. Raizada
- Subjects
seed endophytes ,cucurbit ,biocontrol ,Phytophthora capsici ,Pythium aphanidermatum ,Rhizoctonia solani ,Microbiology ,QR1-502 - Published
- 2018
- Full Text
- View/download PDF
35. Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew
- Author
-
Eman M. Khalaf and Manish N. Raizada
- Subjects
seed endophytes ,cucurbit ,biocontrol ,Phytophthora capsici ,Pythium aphanidermatum ,Rhizoctonia solani ,Microbiology ,QR1-502 - Abstract
The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens (Rhizoctonia solani, Fusarium graminearum, Phytophthora capsici, Pythium aphanidermatum). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea, the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus. All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro, respectively. These results show that seeds of cultivated cucurbits package microbes with significant disease-suppression potential. As seeds can act as vectors for genetic transmission of endophytes across host generations, it is interesting to hypothesize whether humans, when selecting seeds of healthy hosts, may have inadvertently selected for disease-suppressing seed endophytes. As the majority of pathogen-suppressing endophytes belong to Bacillus and Paenibacillus, and since Bacilli are widely used as commercial biocontrol agents of vegetables, we propose that these agents are mimicking the ecological niche established by their endophytic cousins. more...
- Published
- 2018
- Full Text
- View/download PDF
36. Aspergillus piperis A/5 from plum-distilling waste compost produces a complex of antifungal metabolites active against the phytopathogen Pythium aphanidermatum
- Author
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Jovičić-Petrović Jelena, Jeremić Sanja, Vučković Ivan, Vojnović Sandra, Bulajić Aleksandra, Raičević Vera, and Nikodinovic-Runic Jasmina
- Subjects
antifungal activity ,antifungal proteins ,Aspergillus piperis ,organic acids ,Pythium aphanidermatum ,compost ,Biology (General) ,QH301-705.5 - Abstract
Adding compost to soil can result in plant disease suppression through the mechanisms of antagonistic action of compost microflora against plant pathogens. The aim of the study was to select effective antagonists of Pythium aphanidermatum from compost, to assess the effect of its extracellular metabolites on the plant pathogen, and to characterize antifungal metabolites. The fungal isolate selected by a confrontation test was identified as Aspergillus piperis A/5 on the basis of morphological features and the internal transcribed spacer (ITS) region, β-tubulin and calmodulin partial sequences. Liquid chromatography-mass spectroscopy (LC-MS) analysis showed that gluconic and citric acid were the most abundant in the organic culture extract. However, the main antifungal activity was contained in the aqueous phase remaining after the organic solvent extraction. The presence of considerable amounts of proteins in both the crude culture extract as well as the aqueous phase remaining after solvent extraction was confirmed by SDS-PAGE. Isolated Aspergillus piperis A/5 exhibits strong antifungal activity against the phytopathogen Pythium aphanidermatum. It secretes a complex mixture of metabolites consisting of small molecules, including gluconic acid, citric acid and itaconic acid derivatives, but the most potent antifungal activity was associated with proteins resistant to heat and organic solvents. Our findings about the activity and characterization of antagonistic strain metabolites contribute to the understanding of the mechanism of interaction of antifungal metabolites as well as fungal-fungal interaction. The obtained results provide a basis for further application development in agriculture and food processing. [Projekat Ministarstva nauke Republike Srbije, br. TR31080 i br. ON173048, i EU Commission project AREA, br.316004] more...
- Published
- 2016
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37. Evaluation of antifungal activity of silver nanoparticles against some phytopathogenic fungi and Trichoderma harzianum
- Author
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Valiollah Mahdizadeh, Naser Safaie, and Fatemeh Khelghatibana
- Subjects
rhizoctonia solani ,sclerotinia sclerotiorum ,pythium aphanidermatum ,Agriculture - Abstract
In vitro antifungal activity of silver nanoparticles, at concentrations of 6, 8, 10, 12, 14 and 16 ppm, was studied on five phytopathogenic fungi, and a biocontrol agent. Then effect of silver nanoparticle at 6 ppm (optimum concentration) was evaluated on Macrophomina phaseolina in greenhouse. For in vitro experiment, the fungal isolates were grown on potato dextrose agar medium amended with silver nanoparticles. Radial fungal growth was recorded after 1, 2, 3, 5 and 10 days and mycelial growth inhibition rates were calculated. The most sensitive fungus to nanoparticles was Pythium aphanidermatum, since all tested concentrations showed 100% inhibition during the 10 days of observation.The second most sensitive fungus was Sclerotinia sclerotiorum, since it was able to grow only at concentration of 6 ppm and M. phaseolina was the third in sensitivity since its growth was inhibited in all concentrations after three days. In greenhouse experiments, five treatments including no nanosilver-no pathogen (Negative control), no nanosilver +pathogen (Positive control), 6 ppm nanosilver– no pathogen, 6 ppm nanosilver +pathogen, Carboxin-Thiram (0.15%) +pathogen were compared. Four characters viz shoot and root fresh and dry weights were measured. Based on the greenhouse experimental results, treatments with nanosilver and fungicide gave higher yields than the positive control. The chemical control treatment had the highest measured parameters, while 6 ppm nanosilver +pathogen treatment had the same parameters as negative control. It may therefore be suggested to use nanosilver as a safer alternative to chemical fungicides for control of M. phaseolina. more...
- Published
- 2015
38. Development and evaluation of polyclonal antibodies for detection of Pythium aphanidermatum and Fusarium oxysporum in ginger.
- Author
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Ray, Monalisa, Dash, Swagatika, Achary, K. Gopinath, Nayak, Sanghamitra, and Singh, Shikha
- Subjects
- *
PYTHIUM aphanidermatum , *FUSARIUM oxysporum , *GINGER , *ENZYME-linked immunosorbent assay , *SODIUM dodecyl sulfate , *POLYACRYLAMIDE gel electrophoresis - Abstract
Polyclonal antibodies against Pythium aphanidermatum and Fusarium oxysporum proteins were developed for the detection of rhizome rot in ginger using serological assays. Under optimal experimental conditions, the detection limit of P. aphanidermatum by indirect ELISA was 10 µg/ml with a linear working range from 5 to 100 µg/ml (R2 = 0.994). In case of F. oxysporum, the linear working range was 5-100 µg/ml (R2 = 0.991) and the limit of detection was 25 µg/ml. The developed antibodies showed the highest titer in ELISA at 1:2000 dilutions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis identified proteins ranging from molecular weights 15-97 kDa and 14-116 kDa of P. aphanidermatum and F. oxysporum isolates, respectively. In Western blot analysis, the developed antisera gave positive reactions against the isolated antigens of the fungi. The antibodies revealed immune-reactive bands of molecular weights 59 and 65 kDa in P. aphanidermatum and 44 and 75 kDa in F. oxysporum. The results suggest that the developed antibodies could be successfully applied for the specific immunodetection of P. aphanidermatum and F. oxysporum at an early stage of rhizome rot disease. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
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39. In vitro and In vivo Antifungal Activity of Selected Fungal Species against the Fusarium Wilt of Solanum lycopersicum.
- Author
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Zulqarnain and Iqbal, Zafar
- Subjects
- *
ANTIFUNGAL agents , *FUSARIUM wilt of tomato , *ALTERNARIA solani , *PYTHIUM aphanidermatum , *PENICILLIUM - Abstract
Fusarium wilt of tomato is a devastating fungal disease with several infectious strategies leading to the complete death of plant. None of the strategies in controlling the wilt have shown fruitful results. Dual culture assay was employed is this study to identify the fungal species with their potent antifungal activity against the Fusarium wilt of tomato. Six distinct fungal species including Penicillium sp., Aspergillus niger, Aspergillus flavus, Trichoderma harzianum, Alternaria solani and Pythium aphanidermatum showed growth inhibition (%) against the pathogen. Penicillium sp. showed maximum growth inhibition (63.85 ± 3.26 %) and its extract showed 9.20 ± 0.14 mm zone of inhibition at 1000 mg·L-1 against the Fusarium wilt. Based on its higher in vitro antifungal activity, in vivo screen house experiments were conducted. Plants given the treatment as Penicillium + Fusarium showed slight yellowing of the leaves after 60th days of cultivation. Present results may help in exploiting the Penicillium sp. extract for isolation and structural characterization of its antifungal compounds. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
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40. Fitness Attributes of Pythium aphanidermatum with Dual Resistance to Mefenoxam and Fenamidone.
- Author
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Lookabaugh, E. C., Kerns, J. P., Cubeta, M. A., and Shew, B. B.
- Subjects
- *
PYTHIUM aphanidermatum , *MEFENOXAM , *FUNGICIDES , *CYTOCHROME b , *MYCELIUM - Abstract
Pythium aphanidermatum is the predominant species causing Pythium root rot on commercially grown poinsettias in North Carolina. Resistance to mefenoxam is common in populations of P. aphanidermatum but resistance to fenamidone and other quinone outside inhibitor fungicides has only just been reported in greenhouse floriculture crops. The in vitro sensitivity to the label rate of mefenoxam (17.6 μl active ingredient [a.i.]/ml) and fenamidone (488 μl a.i./ml) was determined for 96 isolates of P. aphanidermatum. Isolates were assigned to four fungicide phenotypes: mefenoxam-sensitive/fenamidone-sensitive (MefS, FenS), mefenoxam-sensitive/fenamidone-insensitive (MefS, FenR), mefenoxam-insensitive/fenamidone-sensitive (MefR, FenS), and mefenoxam-insensitive/fenamidone-insensitive (MefR, FenR). In all, 58% of isolates were insensitive to one (MefR, FenS = 36% and MefS, FenR = 16%) or both fungicides (MefR, FenR = 6%). A single point mutation in the cytochrome b gene (G143A) was identified in fenamidone-insensitive isolates. Mycelial growth rate at three temperatures (20, 25, and 30°C), in vitro oospore production, and aggressiveness on poinsettia were evaluated to assess relative fitness of sensitive and insensitive isolates. Isolates with dual insensitivity to mefenoxam and fenamidone had reduced radial hyphal growth at 30°C and produced fewer oospores than isolates sensitive to one or both fungicides. Isolates sensitive to both fungicides produced greater numbers of oospores. Aggressiveness on poinsettia varied by isolate but fungicide phenotype was not a good predictor of aggressiveness. These results suggest that populations of P. aphanidermatum with dual resistance to mefenoxam and fenamidone may be less fit than sensitive populations under our imposed experimental conditions but populations of P. aphanidermatum should continue to be monitored in poinsettia production systems for mefenoxam and fenamidone insensitivity. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
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41. Use of LAMP Detection to Identify Potential Contamination Sources of Plant-Pathogenic Pythium Species in Hydroponic Culture Systems of Tomato and Eustoma.
- Author
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Wenzhuo Feng, Akira Nukaya, Mamoru Satou, Naoko Fukuta, Yasushi Ishiguro, Haruhisa Suga, and Koji Kageyama
- Subjects
- *
HORTICULTURE , *HYDROPONICS , *PYTHIUM aphanidermatum , *TOMATO diseases & pests , *GREENHOUSES - Abstract
Hydroponic culture systems are subject to high risks of diseases caused by zoosporic plant pathogens. Control is generally difficult because of the rapid spread of zoospores in the nutrient solutions. In Japan, tomato and eustoma, which are cultivated using the D-tray and nutrient film techniques, respectively, are susceptible to diseases caused by Pythium aphanidermatum and P. irregulare. We used loop-mediated isothermal amplification to identify potential contamination sources of these two pathogens by monitoring their presence in the water supply wells, seedling terraces, nutrient solutions, diseased plants, and ground soils of a tomato greenhouse complex and a eustoma greenhouse complex. The results indicated that the pathogens may enter the culture systems from the soils around the greenhouses. Entry most likely occurs when seedlings are moved from the seedling terraces to the greenhouses, and sterilization of the hydroponic systems may not be sufficient. Therefore, monitoring pathogens in the culture systems and ground soils is very important for the management and prevention of these diseases. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
42. Antibiotic-producing Pseudomonas fluorescens mediates rhizome rot disease resistance and promotes plant growth in turmeric plants.
- Author
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Prabhukarthikeyan, S.R., Keerthana, U., and Raguchander, T.
- Subjects
- *
TURMERIC , *PYTHIUM aphanidermatum , *PYTHIUM , *PHYSIOLOGICAL control systems , *CURCUMA - Abstract
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. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
43. First report of Pythium aphanidermatum infecting tomato in Egypt and its control using biogenic silver nanoparticles.
- Author
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Elshahawy, Ibrahim, Abouelnasr, Hesham Mohamed, Lashin, Sirag Mohamed, and Darwesh, Osama Mohamed
- Subjects
PYTHIUM aphanidermatum ,TOMATO disease & pest prevention ,SILVER nanoparticles ,TRANSMISSION electron microscopy ,PHYTOPATHOGENIC microorganisms - Abstract
In August 2016, tomato plants grown during a hot, wet summer with heavy soil flooding, displaying symptoms of wilting, dead plant, root rot with crown and stem rot, at Beni Suef and Fayoum governorates were examined. A number of 16 fungal isolates were isolated from tomato plants displaying the above symptoms. These isolates were classified as belonging to six species, namely: Alternaria solani, Chaetomium globosum, Fusarium solani, Fusarium oxysporum, Pythium spp. and Rhizoctonia solani. Isolates of Pythium spp. were prevalent and were found to be more pathogenic than the other fungal isolates. This species causes damping-off, root rot, sudden death, stem rot and fruit rot. The pathogen was identified as Pythium aphanidermatum based on morphological, cultural, and molecular characteristics. Biogenic silver nanoparticles (AgNPs) were produced using the F. oxysporum strain and characterized by transmission electron microscopy (TEM). The size of these spherical particles ranged from 10 to 30 nm. In vitro, biogenic AgNPs showed antifungal activity against P. aphanidermatum. In greenhouse and field experiments, AgNPs treatment significantly reduced the incidence of dead tomato plants due to root rot caused by P. aphanidermatum compared to the control. All of the investigated treatments were effective and the treatment of root dipping plus soil drenching was the most effective. To the best of our knowledge, this study describes P. aphanidermatum on tomato in Egypt for the first time. Also, biogenic AgNPs could be used for controlling root rot disease caused by this pathogen. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
44. Characterization of Foliar Web Blight of Spinach, Caused by Pythium aphanidermatum, in the Desert Southwest of the United States.
- Author
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Bo Liu, Chunda Feng, Correll, James C., and Matheron, Michael E.
- Subjects
- *
BLIGHT diseases (Botany) , *SPINACH diseases & pests , *PYTHIUM aphanidermatum , *NUCLEOTIDE sequencing , *RIBOSOMAL DNA - Abstract
A unique foliar disease of spinach, determined to be caused by Pythium aphanidermatum, was observed on spinach in Yuma County, AZ and imperial County, CA desert spinach production areas in both 2015 and 2016. The foliar symptoms of the disease included water-soaked foliage, rapid collapse of young plants, and white, aerial, cottony mycelia. The disease was associated with hot (27 to 42°C) and wet conditions associated with overhead irrigation under high-density plantings (>8.0 million seeds/ha). Isolations were performed on symptomatic tissue, and DNA was recovered from pure culture of the isolates recovered and sequenced using the internal transcribed spacer (ITS) ribosomal DNA (rDNA) primers ITS1/ITS4 and gene cytochrome oxidase I (COXI) primers FM55 and FM59. BLAST searches in GenBank indicated that the isolates were P. aphanidermatum based on 99 to 100% homology of ITS rDNA. Moreover, the DNA sequences of the ITS and COXI were identical for the five representative isolates. The objective of this research was to determine whether P. aphanidermatum recovered from symptomatic spinach tissue was able to cause foliar web blight and damping-off of spinach and other crops. In addition to spinach, other hosts evaluated included cotton, soybean. pepper, tomato, cucumber, melon, squash, lettuce, corn, wheat, and rice in greenhouse trials. Inoculations were performed by either foliar inoculations or infesting the soil with plugs of potato dextrose agar colonized by the P. aphanidermatum. Web blight symptoms were severe on spinach and all other dicotyledonous hosts tested, except lettuce. No web blight symptoms were observed on corn or rice, and only minor symptoms were observed on 10-day-old seedlings of wheat. P. aphanidermatum caused severe preemergence damping-off of all dicotyledonous plant species tested but only caused limited seedling size reduction in corn and wheat. Mefenoxam treatment of spinach seed provided complete protection against preemergence damping-off of spinach at both low (0.15 g a.i./kg of seed) and high (0.70 g a.i./kg of seed) rates of application. and the high rate of the application resulted in complete protection against web blight of spinach for 10 to 20 days after planting. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
45. Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew.
- Author
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Khalaf, Eman M. and Raizada, Manish N.
- Subjects
ENDOPHYTES ,OOMYCETES ,POWDERY mildew diseases - Abstract
The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soilborne pathogens (Rhizoctonia solani, Fusarium graminearum, Phytophthora capsici, Pythium aphanideratum). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea, the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus. All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro, respectively. These results show that seeds of cultivated cucurbits package microbes with significant disease-suppression potential. As seeds can act as vectors for genetic transmission of endophytes across host generations, it is interesting to hypothesize whether humans, when selecting seeds of healthy hosts, may have inadvertently selected for disease-suppressing seed endophytes. As the majority of pathogen-suppressing endophytes belong to Bacillus and Paenibacillus, and since Bacilli are widely used as commercial biocontrol agents of vegetables, we propose that these agents are mimicking the ecological niche established by their endophytic cousins. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
46. Aspergillus terreus Inhibits Growth and Induces Morphological Abnormalities in Pythium aphanidermatum and Suppresses Pythium-Induced Damping-Off of Cucumber.
- Author
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Halo, Boshra A., Al-Yahyai, Rashid A., and Al-Sadi, Abdullah M.
- Subjects
ASPERGILLUS terreus ,PYTHIUM aphanidermatum ,CUCUMBERS - Abstract
The study investigated the efficacy of two isolates of Aspergillus terreus (65P and 9F) on the growth, morphology and pathogenicity of Pythium aphanidermatum on cucumber. In vitro tests showed that the two isolates inhibited the growth of P. aphanidermatum in culture. Investigating P. aphanidermatum hyphae close to the inhibition zone showed that the hyphae showed abnormal growth and loss of internal content. Treating P. aphanidermatum with the culture filtrate (CF) of A. terreus resulted in significant rise in cellular leakage of P. aphanidermatum mycelium. Testing glucanase enzyme activity by both A. terreus isolates showed a significant increase in glucanase activity. This suggests that the cell walls of Pythium, which consist of glucan, are affected by the glucanase enzyme produced by A. terreus. In addition, Aspergillus isolates produced siderephore, which is suggested to be involved in inhibition of Pythium growth. Also, the CFs of 65P and 9F isolates significantly reduced spore production by P. aphanidermatum compared to the control (P < 0.05). In bioassay tests, the two isolates of A. terreus increased the survival rate of cucumber seedlings from 10 to 20% in the control seedlings treated with P. aphanidermatum to 38-39% when the biocontrol agents were used. No disease symptoms were observed on cucumber seedlings only treated with the isolates 65P and 9F of A. terreus. In addition, the A. terreus isolates did not have any negative effects on the growth of cucumber seedlings. This study shows that isolates of A. terreus can help suppress Pythium-induced damping-off of cucumber, which is suggested to be through the effect of A. terreus and its glucanase enzyme on P. aphanidermatum mycelium. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
47. A study of fungicidal and anti-phenol oxidase activity of some α-amino phosphonate derivatives
- Author
-
Mohammad Mehrabadi, Naser Safaie, Mahyar Bonsaii, Mohsen Abbod, Khodayar Gholivand, and Ali Asghar Ebrahimi Valmoozi
- Subjects
chemistry.chemical_classification ,Oxidase test ,Chemistry ,Organophosphorus ,Pythium aphanidermatum ,Agriculture ,Biochemistry ,Phosphonate ,DFT ,Cell membrane ,Fungicide ,chemistry.chemical_compound ,medicine.anatomical_structure ,Aniline ,Enzyme ,Macrophomina phaseolina ,Phenol oxidase ,medicine ,Moiety ,Organic chemistry ,Agronomy and Crop Science ,Mycelium ,Food Science ,Biotechnology - Abstract
Background Developing new pesticides with multi-function may be a suitable strategy to save time and cost and reduce the emergence of resistant strains of pests and pathogens. The organophosphorus derivatives have not been widely used in agriculture as fungicides. In this work, a series of six α-amino phosphonate derivatives were prepared and tested for their fungicidal and anti-phenol oxidase activities. Results The prepared compounds revealed a promising anti-fungal activity against Macrophomina phaseolina and Pythium aphanidermatum, especially M4, with MIC of 62 mg/L for M. phaseolina. M4 did not affect the fungus permeability rate of the cell membrane; however, it displayed a significant efficiency on mycelial soluble protein content. M4 and M3 with a hydroxyl group on the aniline moiety exhibited an observed anti-phenol oxidase activity. M4 inhibited the enzyme at 1 mg/mL. The DFT theoretical study revealed a significant correlation between the substituents of aniline moiety and the bioactivity of the studied compounds. The negative charge conspicuously influenced the anti-phenol oxidase activity. Conclusions Our findings suggest the studied compounds as bases to design more effective α-amino phosphonate fungicides with additional anti-phenol oxidase activity. Graphic abstract more...
- Published
- 2021
48. Transcriptional and Antagonistic Responses of Biocontrol Strain Lysobacter enzymogenes OH11 to the Plant Pathogenic Oomycete Pythium aphanidermatum
- Author
-
Yangyang Zhao, Guoliang Qian, Yuan Chen, Liangcheng Du, and Fengquan Liu
- Subjects
Lysobacter enzymogenes ,Pythium aphanidermatum ,transcriptome ,interactions ,HSAF ,twitching motility ,Microbiology ,QR1-502 - Abstract
Lysobacter enzymogenes is a ubiquitous, beneficial, plant-associated bacterium emerging as a novel biological control agent. It has the potential to become a new source of antimicrobial secondary metabolites such as the Heat-Stable Antifungal Factor (HSAF), which is a broad-spectrum antimycotic with a novel mode of action. However, very little information about how L. enzymogenes detects and responds to fungi or oomycetes has been reported. An in vitro confrontation bioassay between the pathogenic oomycete Pythium aphanidermatum and the biocontrol bacterial strain L. enzymogenes OH11 was used to analyze the transcriptional changes in the bacteria that were induced by the oomycetes. Analysis was performed at three time points of the interaction, starting before inhibition zone formation until inhibition zone formation. A L. enzymogenes OH11 DNA microarray was constructed for the analysis. Microarray analysis indicated that a wide range of genes belonging to 14 diverse functions in L. enzymogenes were affected by P. aphanidermatum as critical antagonistic effects occurred. L. enzymogenes detected and responded to the presence of P. aphanidermatum early, but alteration of gene expression typically occurred after inhibition zone formation. The presence of P. aphanidermatum increased the twitching motility and HSAF production in L. enzymogenes. We also performed a contact interaction between L. enzymogenes and P. aphanidermatum, and found that HSAF played a critical role in the interaction. Our experiments demonstrated that L. enzymogenes displayed transcriptional and antagonistic responses to P. aphanidermatum in order to gain advantages in the competition with this oomycete. This study revealed new insights into the interactions between bacteria and oomycete. more...
- Published
- 2017
- Full Text
- View/download PDF
49. Biocontrol of Pythium aphanidermatum causing soft rot in ginger with biosurfactant produced by a rhizospheric Bacillus species
- Author
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D Goswami and M B Syiem
- Subjects
Bacillus species ,Horticulture ,biology ,Biological pest control ,food and beverages ,Pythium aphanidermatum ,biology.organism_classification - Abstract
Plant growth-promoting rhizobacteria benefit plants by producing phytohormones and acquiring vital nutrients from soil. They also form a shield against potential phytopathogens with the production of antimicrobial compounds such as bacteriocin, biosurfactants etc. In the present study, among various rhizobacteria isolated from ginger rhizosphere, the isolate identified as Bacillus altitudinis VS7 that showed a potent biosurfactant producing ability in the preliminary tests was selected for the further study. Compositional analyses indicated that the biosurfactant produced by VS7 was a surfactin like compound, a cyclic lipopeptide. In both microtitre plate and mycelium growth inhibition studies, the biosurfactant showed dose dependent antagonistic activities against Pythium aphanidermatum that causes soft rot in ginger. Although there are reports of biocontrol activity of various rhizobacteria against soft rot in ginger, this is the firstinformation regarding biocontrol activity of a biosurfactant produced by the rhizobacterium B. altitudinis VS7 against P. aphanidermatum. more...
- Published
- 2021
- Full Text
- View/download PDF
50. Efficacy of Bio - Agents and Lantana camara against Damping - Off (Pythium aphanidermatum) of Chilli (Capsicum annuum L.)
- Author
-
Gandham Grace Susanthi Sunil Zacharia
- Subjects
Horticulture ,Capsicum annuum ,biology ,Damping off ,Lantana camara ,Pythium aphanidermatum ,biology.organism_classification - Published
- 2021
- Full Text
- View/download PDF
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