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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. [ABSTRACT FROM AUTHOR]

Pythium aphanidermatum is known to cause diseases like damping-off, root rot, stem rot and fruit rot in a wide range of plants. Eventhough many chemical methods have been demonstrated to have the potential to manage these diseases, their benefits are being offset equally by the negative side effects. Therefore, the control of Pythium spp. using natural antifungal agents is of immense significance due to its environmental safety. Here, the plant associated microorganisms with antifungal metabolites have significant promises to be explored both as sustainable biocontrol agents and also as active constituents of antifungal materials. Antimicrobial packaging films prepared using such components can have significant applications to meet the requirements to prevent postharvest loss of agricultural produce by inhibiting the fungal growth. Eventhough there are reports on the development of antimicrobial packaging films for such applications, the use of bacterial extracts with antifungal activity for the same is least investigated. Hence, the present study demonstrates the development of biocomposite films prepared using polyvinyl alcohol (PVA) incorporated with the extracts prepared from bacterial isolates (Serratia sp. NhPB1, Kocuria sp. NhPB49, and Pantoea dispersa NhPB54) previously isolated from the pitcher plant. Here, the individual films were prepared by incorporating 1 mL of bacterial extract in 40 mL of 3% PVA solution and the developed films were then subjected to antifungal activity screening against P. aphanidermatum. The antifungal activity analysis of the films prepared with the incorporation of extracts from Serratia sp. NhPB1, Kocuria sp. NhPB49, and Pantoea dispersa NhPB54 showed remarkable activity against the tested pathogen. The application of biocomposite films on Solanum lycopersicum and Capsicum annuum fruits for its protection from P. aphanidermatum by dip coating method further indicates the promises of developed biocomposite films for active packaging applications. [ABSTRACT FROM AUTHOR]

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]

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.

In February 2021, damping off and collar and root rot on coriander (Coriandrum sativum L.) became widespread in the municipality of Vitória da Conquista, Bahia, Brazil. An oomycete was isolated from root and collar segments of affected seedlings and caused the same symptoms in inoculated seedlings. Based on morphological features and DNA sequences from the ITS and cox2 region, the pathogen was identified as Pythium aphanidermatum. To the best of our knowledge, this is the first report of the occurrence of P. aphanidermatum on coriander plants in Brazil. [ABSTRACT FROM AUTHOR]

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.

In February 2023 in Japan, seedlings of wax gourd [Benincasa hispida (Thunb.) Cogn.] in seedling boxes developed water-soaked rot on hypocotyls typical of damping off and eventually died. A Pythium sp. was isolated from the hypocotyls and was identified as Pythium aphanidermatum based on morphological characteristics and DNA sequence data. The same symptoms developed after seedlings were inoculated with the isolated fungus, and the same fungus was reisolated from the seedlings. This is the first report of damping off in wax gourd seedlings caused by P. aphanidermatum in seedling boxes in Japan. [ABSTRACT FROM AUTHOR]

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]

Worldwide, thegrowers suffer serious losses from mycoses caused by Pythium, Rhizoctonia, and Fusarium. Due to the root rot disease, the whole plant dies, regardless of the phenophase at the moment of infection. The increase in Cannabis sativa acreage in Bulgaria and the accompanying problems associated with the severity and incidence of various diseases necessitated this study. The study aimed to survey the root rot symptoms on field and greenhouse plantations and monitoring the plant`s health status of cannabis-planted areas in Bulgaria during 2021-2022. The main problem was darkening at the base of the stem, yellowing, dieback, and wilting of whole plants from the seedling stage to flowering. Following the Koch's postulates and morphological characteristics by microscopic observation, all collected samples corresponded to genus Pythium. For complete identification, a molecular diagnostic was performed with primers ITS1 and ITS4 using four isolates from different regions of the country, which confirmed Pythium aphanidermatum as the causative agent. Based on the molecular analyses, this is the first report of root rot caused by Pythium aphanidermatum on cannabis in Bulgaria. [ABSTRACT FROM AUTHOR]

Plant-associated bacteria exhibit diverse chemical means to protect plants from the pathogens. The present study has been conducted to evaluate the volatile-mediated antifungal activity of Serratia sp. NhPB1 isolated from the pitcher plant against the notorious pathogen Pythium aphanidermatum. The study has also evaluated the protective effect of NhPB1 on Solanum lycopersicum and Capsicum annuum leaves and fruits against P. aphanidermatum. From the results, NhPB1 was found to have remarkable activity against the tested pathogen. The isolate was also found to impart disease protection in selected plants as evidenced by the morphological changes. Here, the leaves and fruits of S. lycopersicum and C. annuum control which were treated with the uninoculated LB and distilled water were found to have the presence of P. aphanidermatum growth with lesions and decaying of tissues. However, the NhPB1-treated plants did not show any symptoms of fungal infection. This could further be confirmed by the microscopical examination of tissues by propidium iodide staining. Here, the normal architecture of leaf and fruit tissues could be observed in the NhPB1-treated group, but the tissue invasion by P. aphanidermatum was observed in the control group which further confirms the promises of selected bacteria for biocontrol applications. [ABSTRACT FROM AUTHOR]

Curcuma longa L. (Turmeric) a perennial herb belongs to Zingiberaceae. It's highly grown for its remarkable medicinal uses. Apart from medicinal properties and importance, Turmeric has not been emphasized much with respect to agricultural view. Sustainable agriculture is need of hour and hence it must be brought in practice on large scale. Arbuscular Mycorrhizal (AM) fungi has mutually beneficial relationship with the roots and support plants during biotic and abiotic stress. The function of AM fungi in different morphological parameters when Turmeric under biotic stress shows scanty records so far. Existing research studies are intended to evaluate an influence of AM fungi on Turmeric plant during biotic stress. During this investigation Turmeric plants were assessed for Growth and Vigour Index, relative mycorrhizal dependency, some biochemical contents and fresh weight of the rhizome. Statistical analysis of the results obtained showed strongly significant results. [ABSTRACT FROM AUTHOR]

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]

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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]

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]

In the study, the bacterial isolate NhPB54 purified from the pitcher of Nepenthes plant was observed to have activity against Pythium aphanidermatum by dual culture and well diffusion. Hence, it was subjected to 16S rDNA sequencing and BLAST analysis, where the NhPB54 was found to have 100% identity to Pantoea dispersa. Upon screening for the plant beneficial properties, Pantoea dispersa NhPB54 was found to be positive for phosphate, potassium and zinc solubilization, nitrogen fixation, indole-3-acetic acid, ammonia, 1-aminocyclopropane-1-carboxylate deaminase, biofilm and biosurfactant production. Further to this, Solanum lycopersicum seedlings primed with P. dispersa NhPB54 were studied for the improved plant growth and disease protection. Here, the seedlings pre-treated with the NhPB54 culture supernatant were found to have enhanced plant growth and protection from damping off and fruit rot caused by P. aphanidermatum. From the LC-QTOF-MS/MS and GC MS analysis, P. dispersa NhPB54 was found to produce a blend of chemicals including 1-hydroxyphenazine, surfactin, and other bioactive metabolites with the likely basis of its observed antifungal and plant growth–promoting properties. From the results of the study, plants with unique adaptations can expect to harbor microbial candidates with beneficial applications. [ABSTRACT FROM AUTHOR]

In order to conduct green prevention and control of tobacco damp off, the sensitivity of Pythium aphanidermatum to different con- centrations of wood vinegar were determined by growth rate method, and the field control effect experiment was carried out. The results showed that the toxicity of wood vinegar was the highest in the indoor toxicity test with the inhibition rate of 100%, had significant difference with rea- gent controls; the secondly was 50-fold dilution with the inhibition rate of 70.54%.In the field efficacy test, the efficacy of wood vinegar solution and 50-fold dilution were 84.00% and 76.07%, and had significant difference with reagent controls, but the tobacco seeds soaked with it did not germinate. In production, the raw solution of wood vinegar and 50-fold dilution could be used to prevent and control tobacco damp off, but the seed soaking method was cautious. [ABSTRACT FROM AUTHOR]

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 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

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 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.

The loss of fresh produces owing to the microbial infestation is a major challenge to the global food industry. The drastic food loss caused mainly by the fungal attack demands the need for development of active packaging materials with antimicrobial properties. Many studies have already been reported on the applications of polymers like polyvinyl alcohol (PVA) engineered with antimicrobial components as active antifungal packaging materials. In the current study, material properties of PVA alone, PVA incorporated with chitosan nanoparticles (PCS), clove oil (PCO), and their combination (PCSCO) have been studied for its microbial barrier and antifungal properties. All the developed films were characterised by the XRD and FTIR analysis, which confirmed the molecular interactions among the individual components of the nanocomposite. At the same time, the bionanocomposite PCSCO was found to have low moisture content and film solubility indicating its suitability for the modified atmosphere packaging applications. In addition, the presence of chitosan nanoparticles and clove oil was found to provide the microbial barrier properties to the PCS, PCO, and PCSCO films. The PCSCO film was further demonstrated to have superior antifungal activity against the selected Pythium aphanidermatum. The results of the study indicate the potential application of developed nanocomposite film as a promising antifungal packaging material. [ABSTRACT FROM AUTHOR]

Chemical fungicides used in plant disease management may have deteriorative effects on humans, animals, and the environment. The use of native strains of Trichoderma spp. against plant diseases may help to reduce the dependence on chemical fungicides. In this study, eleven novel isolates of Trichoderma spp. from virgin forest soils of different agro-climatic zones of Kerala were characterized and evaluated for their efficacy against damping off disease of tomato caused by Pythium aphanidermatum under in vitro and in vivo; and also, against wilt pathogen, Fusarium oxysporum under in vitro conditions. Dual culture assay showed that all the Trichoderma isolates were found to inhibit the growth of P. aphanidermatum and F. oxysporum under in vitro conditions with multiple modes of action. The mycelial colour, texture, and conidial characters varied among all the isolates. The volatile metabolites by isolates of Trichoderma spp. also showed in vitro inhibition of the pathogens. Seed treatment (20 g kg-1) and potting medium addition @ 2 % (w/w) of isolates TRMW-2, TRKR-2, TRPN-3, TRPN-11 and TRPN-17 could effectively reduce pre- and post-emergence damping off of tomato. Among them, isolates TRMW-2, TRKR-2, and TRPN-11 were the most effective ones in reducing pre- and post-emergence damping off to about 72 and 90 percent respectively. Molecular identification of the isolates of Trichoderma spp. using ITS universal primers revealed similarity with certain reference strains of the NCBI Genbank database. [ABSTRACT FROM AUTHOR]

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.

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

The experiment was designed to investigate the effects of Ocimum gratissimum extracts in the control of Pythium aphanidermatum in cowpea. This was conducted in Crop Science and Biotechnology laboratory, Imo State University, Owerri between May to August 2018 using completely randomized design (C.R.D). There were 8 treatments replicated 4 times. Powder and Liquid extracts of the leaves of Ocimum gratissimum were applied at different concentrations (0, 5, 10, 15) g and (0, 5, 10, 15) mls respectively, inoculated on the media, Potato Dextrose Agar (PDA) in petri dishes to check the incidence and spread of the disease. Extracts of Ocimum gratissimum were effective against Pythium aphanidermatum in all the parameters tested. On inoculation of PDA media, different forms of Pythium aphanidermatum (ring or circular and dotted) in all treatments were observed, except the control. Quantitative analyses and Infrared spectroscopy of Ocimum gratissimum leaf extracts revealed the presence of active phytochemicals (alkaloids 3.6, tannins 15.4, flavonoids, oxalate 5.8, saponins 3.1) ug/g and infrared compounds (alkenes (3201.2), alcohol (3344.5), carboxylic acid (2995.5), aldehyde (2719.5), and isocyanate (2804.4) absorbed at different wave lengths in cm-1 were identified. Different fungal growths were cleared using different levels of extracts, (15>10>5>0) mls than powder extracts respectively. The ability of the extracts to exert fungicidal effects was due to the presence of active phytochemicals and infrared compounds present in the extracts. [ABSTRACT FROM AUTHOR]

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]

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]

Chili peppers (Capsicum annuum L.) are popular globally as a vegetable and condiment and are particularly popular in Guizhou, China. Root rot, the most prevalent soil-borne disease affecting chili peppers, is widespread in Guizhou. In 2023, it was observed in 10–20% of six fields, leading to significant economic losses. Eight strains were isolated from rotten roots of 'Huaxi' chili samples to support the need for appropriate pathogen control. Four strains were identified as Pythium aphanidermatum (strains: HSLJ-2, HSLJ-4) and Pythium myriotylum (strains: LDLJY-1, LDLJJ-3) through morphological analysis of sporangia, oospores, antheridia, and oogonia; multi-locus phylogenetic analysis of the internal transcribed spacer and mitochondrial cytochrome c oxidase subunit 1 gene regions; followed by pathogenicity testing using inoculated autoclaved wheat seeds. The two Pythium species were thus identified as novel causal agents of chili pepper root rot in Guizhou, China. • Root rot is a widespread soil-borne disease of chili pepper (Capsicum annuum L.) in Guizhou, China. • In 2023, root rot affected 10–20% of six fields in Huishui and Luodian prefectures, resulting in significant economic losses. • Four strains, isolated from rotten roots, were identified as Pythium aphanidermatum and Pythium myriotylum. • These two Pythium species were found to be the novel causal agents of chili pepper root rot in Guizhou. [ABSTRACT FROM AUTHOR]

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.

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 first information regarding biocontrol activity of a biosurfactant produced by the rhizobacterium B. altitudinis VS7 against P. aphanidermatum. [ABSTRACT FROM AUTHOR]

The present study has been designed to improve the activity of endophytic Bacillus amyloliquefaciens BmB1 against Pythium aphanidermatum through the culture supplementation with carbon sources, nitrogen sources and zinc oxide nanoparticles (ZnONPs). From the results of the study, supplementation with glucose (45 g/L), yeast extract (7.5 g/L) and ZnONPs (5 mg/L) were found to enhance the antifungal activity of B. amyloliquefaciens BmB1. This was also confirmed by comparative statistical analysis with experimental control. Further LC-Q-TOF-MS analysis of extracts of B. amyloliquefaciens BmB1 cultured with supplements showed a remarkable modulation of its lipopeptide profile. The blend of lipopeptides enhanced during the culture supplementation of B. amyloliquefaciens BmB1 as evidenced by the mass spectrometric analysis can consider to be the basis of its increased activity against P. aphanidermatum. As Bacillus spp. are well known for their biocontrol activities, the results of the study offer ways to improve its agricultural applications. [ABSTRACT FROM AUTHOR]

BACKGROUND Lipopeptides from the Bacillus spp. possess an excellent spectrum of antimicrobial properties which make them suitable candidates to be explored for the food, agricultural, pharmaceutical and biotechnological applications. As the low yield of the lipopeptides limits their applications, methods to enhance their production are highly significant. RESULTS: In this study, extracts prepared from endophytic Bacillus sp. Fcl1 cultured in the presence of various supplements were screened for antifungal activity against Pythium aphanidermatum. From the results, the supplementation of carbon sources and zinc oxide nanoparticles (ZnONPs) was found to have an enhancement effect on the antifungal activity of Bacillus sp. Fcl1. Among these, the highest antifungal activity (73.2%) could be observed for the Fcl1 sample cultured with 5 mg L−1 of ZnONP supplementation. The growth of Fcl1 in the presence of ZnONPs also indicated its compatibility with the nano‐supplement in the concentration range used. By liquid chromatography quadrupole time‐of‐flight mass spectrometry (LC‐Q‐TOF‐MS) analysis, the synthesis of increased numbers of lipopeptide surfactin derivatives could be identified from the extracts of Fcl1 prepared from the carbon sources and ZnONP‐supplemented cultures. In addition to the surfactin derivatives, the presence of another lipopeptide iturin was also detected from the extracts of Fcl1 cultured with ZnONPs. CONCLUSION: ZnONP supplementation was found to enhance antifungal activity and lipopeptide production in the Bacillus sp. Fcl1. The use of nanoparticles to enhance the antifungal mechanisms of Fcl1 as observed in the study provides novel insights to explore its applications for sustainable agricultural productivity. [ABSTRACT FROM AUTHOR]

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.

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]

Kitchen garden crops, especially cucumbers, play a substantial role in people's life both nutritionally and economically. In recent years, mass production of cucumbers in greenhouse cultures has become an important factor in farmers' earnings at vegetable markets. Therefore, it is particularly important to pay attention to this plant in the country. Due to favorable greenhouse conditions for the development of various microorganisms, this plant is constantly exposed to pathogens including the fungus causing the seedling damping-off disease Pythium aphanidermatum. The disease is prevalent in hot regions with heavy soils, and is very widespread in the fields and greenhouses of Tehran province (Varamin) and Isfahan. Chemical control by the use of fungicides has been effective in reducing the disease, but it is also necessary to examine the efficacy of new fungicides in controlling the disease due to the resistance of disease agents to conventional fungicides. This study was conducted in a randomized complete block design with nine treatments and four replications in three different areas of Tehran, Varamin, and Isfahan. Treatments were healthy control, infected control, redoxil (2g/L), ridomex (2g/L), mancolaxil (1.5g/L), mancolaxil (1.75g/L), manocloxil fungicide(2g/L), previcur energy (3ml/L), and Downy-G (2g/L). The disease was evaluated by determining the percentage of disease incidence through calculating the number of healthy seedlings and the efficacy of fungicides used in disease control at the four-six leaf stage. Data obtained from the three different regions were statistically analyzed based on composite analysis through the MS TAT C software. If the effect of treatment × place was significant, analysis of variance of results was done separately for each region and mean values of studied traits (seedling damping-off or efficacy percentage) were grouped based on Duncan's multiple range test. In case of non-significant effect of treatment × place, mean values of traits were grouped using Duncan's multiple range test based on composite analysis. According to the composite analysis, the effect of treatment × place was significant for the percentage of seedling damping-off incidence. In the three studied regions, percentage of seedling damping-off incidence decreased significantly in all the fungicide treatments compared to infected control. The composite analysis also revealed that the effect of treatment × place was not significant for the percentage level of efficacy. Besides, no significant differences were observed between the different fungicidal treatments in terms of grouping mean percentages of efficacy based on composite analysis. The efficacy ranged from the lowest (75%) for mancolaxil with the lowest dose used (1.5g/L) to the highest level (88%) for ridomex and previcur energy fungicides. [ABSTRACT FROM AUTHOR]

Damping-off disease in seeds and young seedlings in agricultural crops is a major fungal disease that limits the agriculture production. Frequent use of synthetic fungicides against damping-off diseases is known to hamper the environmental balance. Thus, an alternative approach needs to be explored for the management of such economically important fungal diseases. In the present study, simple, economically feasible chitosan-coupled copper nanoparticles (Ch-CuNPs) were synthesized and demonstrated antifungal activity against damping-off disease causing phytopathogens, Rhizoctonia solani and Pythium aphanidermatum. Physico-chemical studies confirmed the size, shape, surface charge, element confirmation and mono-dispersed nature of Ch-CuNPs. In vitro efficacy studies revealed up to 98% mycelial growth inhibition at 0.1% Ch-CuNPs. An extracellular conductivity study of the mycelium showed cellular content leakage within 12 h of treatment. Further, plant toxicity study against chili, cowpea and tomato plants; showed that ≤0.2% NPs were safe under greenhouse conditions. NPs also exhibited growth-promoting activity with chili seeds, by overcoming the limited germination rate of susceptible seeds. Overall, the present study emphasizes the benefits of synthesized Ch-CuNPs on agricultural crops as fungicide and growth-promoter, as well as a safe alternative to pesticides in order to avoid hazardous effect on the environment. [ABSTRACT FROM AUTHOR]