Pythium Aphanidermatum Research Articles

Efficacy of Streptomyces murinus JKTJ-3 in Suppression of Pythium Damping-Off of Watermelon.

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.

Talaromyces omanensis and Aspergillus fumigatus endophytic fungi suppress Pythium aphanidermatum and its induced damping-off diseases of cucumber and radish

Damping-off diseases caused huge losses in crop production in numerous countries. Pythium aphanidermatum represents a major cause of these diseases. In the present investigation, two endophytic fungi Talaromyces omanensis and Aspergillus fumigatus isolated from a desert plant, Rhazya stricta, were investigated for their efficiency in suppressing P. aphanidermatum and its stimulated damping-off diseases in cucumber and radish. The results proved the ability of both endophytes to inhibit P. aphanidermatum growth in both solid and liquid forms, inhibit its oospore production, induce abnormal patterns in its hyphae and suppress its induced damping-off diseases. Moreover, T. omanensis produced an inhibition zone area against P. aphanidermatum and enhanced the fresh weight of cucumber and length, fresh weight and dry weight of radish. Further, A. fumigatus caused cellular leakage in P. aphanidermatum mycelium. The previous results were interpreted through the secretion of β-1,3-glucanase, cellulase and siderophore by both endophytic fungi.

Antagonistic potential of rhizobacterial isolates against fungal pathogens causing rhizome rot in turmeric.

The study aims to select potent bacterial antagonists to be used as biocontrol agents against rhizome rot disease in turmeric (Curcuma longa L.). A total of 48 bacterial isolates were isolated from the rhizosphere of turmeric. These isolates were screened for their in vitro antagonism against Fusarium solani FS-01 and Pythium aphanidermatum (ITCC 7908). Production of volatile organic compounds and chitinase activity were also performed. Among the tested isolates, two bacterial isolates (IJ2 and IJ10) showed the highest inhibitory activity against these fungal pathogens. GC/MS analysis of the crude extract produced by Pseudomonas sp. IJ2 and B. subtilis IJ10 was found to contain many bioactive compounds with antifungal and antimicrobial activities. The rhizome treatment with these isolates exhibited the lowest percent disease severity with high biocontrol efficacy against the tested pathogens. These isolates with promising antagonistic potential, therefore, can be used as biocontrol agents against rhizome rot in turmeric.

Differences in Pathogenesis-Related Protein Expression and Polyphenolic Compound Accumulation Reveal Insights into Tomato–Pythium aphanidermatum Interaction

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.

Testing the Effect of Some Materials to Control Pythium Aphanidermatum Isolated from Cucumber

he main objective of this study was to identify the effectiveness of household materials that are used to sterilize vegetables from the fungus Pythium aphanidermatum (P. aphanidermatum). Samples were taken from the damaged cucumber in the local markets of Babil Governorate, Iraq. These samples were kept in sterile cool containers until they reached the Microbiology lab. of the Department of Community Health, Technical Institute of Babylon. The samples were cultured laboratory in the Sabouraud Dextrose Agar (SDA), then a microscopic examination was carried out to identify the fungus using the lacto phenol cotton blue dye. Use in this study most common household materials to sterilize vegetables before keeping them in the refrigerator or before eating are Potassium Permanganate (KMnO4), Sodium Hypochloride (NaOCl) and table salt (NaCl). Five concentrations were used for each sterile material, and five replicates of culture dishes were used for each concentration (A mixture of sterile material with the SDA) after which the fungus was cultured. By using the minimum inhibitory concentration assay, the radial growth inhibition assay and the microscopic fungal examination, the efficacy of sterilizers was identified. The final results showed the presence of antifungal efficacy for all sterilizers used, with different concentrations. This study concluded that these materials can be used by housewives to sterilize vegetables before keeping them in the refrigerator or eating them. How to Cite: Ibtisam Mohammed Hussein, Abbas Razzaq Abed, 2023. "Testing the Effect of Some Materials to Control Pythium Aphanidermatum Isolated from Cucumber." Journal of Agriculture and Crops, vol. 9, pp. 266-272.

Brinjal leaf diseases detection based on discrete Shearlet transform and Deep Convolutional Neural Network.

Different diseases are observed in vegetables, fruits, cereals, and commercial crops by farmers and agricultural experts. Nonetheless, this evaluation process is time-consuming, and initial symptoms are primarily visible at microscopic levels, limiting the possibility of an accurate diagnosis. This paper proposes an innovative method for identifying and classifying infected brinjal leaves using Deep Convolutional Neural Networks (DCNN) and Radial Basis Feed Forward Neural Networks (RBFNN). We collected 1100 images of brinjal leaf disease that were caused by five different species (Pseudomonas solanacearum, Cercospora solani, Alternaria melongenea, Pythium aphanidermatum, and Tobacco Mosaic Virus) and 400 images of healthy leaves from India's agricultural form. First, the original plant leaf is preprocessed by a Gaussian filter to reduce the noise and improve the quality of the image through image enhancement. A segmentation method based on expectation and maximization (EM) is then utilized to segment the leaf's-diseased regions. Next, the discrete Shearlet transform is used to extract the main features of the images such as texture, color, and structure, which are then merged to produce vectors. Lastly, DCNN and RBFNN are used to classify brinjal leaves based on their disease types. The DCNN achieved a mean accuracy of 93.30% (with fusion) and 76.70% (without fusion) compared to the RBFNN (82%-without fusion, 87%-with fusion) in classifying leaf diseases.

Thyme essential oil fostering the efficacy of aqueous extract of licorice against fungal phytopathogens of Capsicum annuum L.

Capsicum annuum L. production is impeded by various biotic factors, including fungal diseases caused by Colletotrichum capsici, Pythium aphanidermatum, and Fusarium oxysporum. Various plant extracts and essential oils are increasingly used to control different plant diseases. In this study, licorice (Glycyrrhiza glabra) cold water extract (LAE) and thyme (Thymus vulgaris) essential oil (TO) were found to be highly effective against the C.annuum pathogens. LAE at 200mgml-1 demonstrated the maximum antifungal activity of 89.9% against P.aphanidermatum, whereas TO at 0.25mgml-1 showed 100% inhibition of C.capsici. However, when used in combination, much lower doses of these plant protectants (100mgml-1 LAE and 0.125mgml-1 TO) exhibited a synergistic effect in controlling the fungal pathogens. Metabolite profiling using gas chromatography-mass spectrometry and high resolution-liquid chromatography-mass spectrophotometry analysis showed the presence of several bioactive compounds. Enhanced cellular components leakage revealed damage to the fungal cell wall and membrane due to and LAE treatment, which can be attributed to the TO lipophilicity and triterpenoid saponins of LAE. TO and LAE treatments also caused a reduction in ergosterol biosynthesis might be due to the presence of thymol and sterol components in the botanicals. Although the aqueous extracts have a low preparation cost, their uses are limited by modest shelf life and lacklustre antifungal effect. We have shown that these limitations can be bypassed by combining oil (TO) with the aqueous extract (LAE). This study further opens the avenues for utilizing these botanicals against other fungal phytopathogens.

Encapsulation of Nepeta hormozganica and Nepeta dschuprensis essential oils in shrimp chitosan NPs: Enhanced antifungal activity

This study investigated the encapsulation of Nepeta hormozganica (NHEO) and Nepeta Dschuprensis (NDEO) essential oils into chitosan nanoparticles (CSN) via a simple ionic gelation method with tripolyphosphate (TPP). Chitosan (CS) is prepared by demineralizing, deproteinizing, and deacetylating shrimp shells waste in high yield (70.2 %). SEM, TEM, FT-IR, TGA, and XRD techniques were employed to characterize the encapsulated essential oils ((NHEO-CSN) and (NDEO-CSN)). The prepared EOs-CSN and CSN are found with particle sizes of 100–150 nm and 400–500 nm, respectively, and regular distribution. The encapsulation efficiency of encapsulated Nepeta hormozganica and Dschuprensis essential oils were found to be 73.64 % and 75.91 %, respectively. The synthesized nanocapsules were evaluated for antifungal activity against Fusarium oxysporium, Sclerotinia sclerotiorum, Pythium aphanidermatum, Alternaria alternata, Rhizactonia Solani, and Botrytis cinerea. Antifungal studies show that encapsulated essential oils increased antifungal efficiency by up to 100 %.

Semi-VOCs of Wood Vinegar Display Strong Antifungal Activities against Oomycete Species Globisporangium ultimum and Pythium aphanidermatum

Plant disease outbreaks are increasingly exacerbated by climate change and the conditions of stress combinations. They are negatively affecting crop yield and driving threats to food security in many areas of the world. Although synthetic pesticides offer relative success in the control of pests and plant diseases, they are often overused, and this method faces numerous drawbacks, including environmental toxicity, soil degradation, and adverse effects on human health. Therefore, alternatives are being developed and examined, including the biocontrol of pests and pathogens and biomass pyrolysis leading to wood vinegar that has shown great promise in agriculture and organic farming. However, while wood vinegar use is expanding and allows the control of numerous pests and bacterial and fungal diseases, its application to control oomycete diseases is limited. This study aimed to test wood vinegar for the control of oomycete plant pathogens from which six wood vinegars of pistachio, pomegranate, almond, pine, cypress, and walnut were produced. The inhibitory effects of volatile metabolites (semi-VOCs) of different wood vinegars concentrations (100%, 50%, 25%, 12.5%, and 6.25%) were examined against the hyphal growth of Globisporangium ultimum and Pythium aphanidermatum isolates. An in vitro analysis unambiguously demonstrated that for Globisporangium ultimum, the wood vinegar semi-VOCs of almond, pistachio (C 100% and 50%), and walnut (C 100%) totally inhibited mycelial growth. On the other hand, Pythium aphanidermatum, pistachio (C 100%, 50%, and 25%), and cypress (C 100%) expressed their abilities to completely inhibit the mycelial growth. Other treatments, including relevant concentrations of pine and pomegranate significantly inhibited the growth of mycelia of both species compared to the control (p ≤ 0.05). Therefore, wood vinegar could be considered a natural and organic product to use in agriculture to cope not only against pests, bacterial and fungal pests but also against emerging oomycete plant diseases.

Biological Control Efficacy of Indigenous Antagonistic Bacteria Isolated from the Rhizosphere of Cabbage Grown in Biofumigated Soil against Pythium aphanidermatum Damping-Off of Cucumber

Soil biofumigation is a widely used farming practice for soil-borne disease management in vegetable crops. Soil biofumigation is the practice of the incorporation of fresh plant materials from the members of the Brassicaceae family into the soil which release antimicrobial volatile organic compounds (VOCs), namely glucosinolates and their hydrolysis products. However, the VOCs may affect non-target beneficial soil biota including microbial biocontrol agents (MBAs) due to their broad-spectrum toxicity. In this study, native antagonistic rhizobacteria were isolated from cabbage plants grown in biofumigated fields and their potential in the management of Pythium aphanidermatum cucumber damping-off was evaluated with and also without biofumigation using cabbage leaf residue. A total of 20 morphologically distinct, culturable bacterial strains were recovered from the rhizosphere soil of cabbage cultivated in a biofumigated field, with the largest fraction of the isolates belonging to the genus Bacillus. The other bacterial genera isolated were Pseudomonas, Serratia, Stenotrophomonas, Microbacterium and Priestia. Of the 20 bacterial isolates, Pseudomonas aeruginosa B1-SQU, Pseudomonas indica B2-SQU, Serratia marcescens B3-SQU and Pseudomonas brenneri B4-SQU exhibited inhibitory activity against P. aphanidermatum in a co-culture assay. The deformation and shrinkage of P. aphanidermatum hyphae due to diffusible antimicrobial compounds from these bacterial strains were witnessed through scanning electron microscopy. A biofilm was formed by these bacterial strains in vitro and they exhibited compatibility with each other; however, they had no significant plant growth promotion effect on cucumber. These bacterial strains significantly reduced damping-off in cucumber under greenhouse conditions when applied to soil singly, but failed to show a significant effect when combined with biofumigation treatment, though the bacterial population in the soil was maintained at higher levels. Soil biofumigation alone was also not effective in suppressing the damping-off of cucumber. Gas chromatography–mass spectrometry analysis revealed that 1-butanol, n-butyl butyrate and butyl acetate were the predominant VOCs in the soil amended with cabbage leaf residue. The results suggest that soil biofumigation with cabbage leaf residue has no significant effect on P. aphanidermatum under high inoculum levels; furthermore, it affects the efficiency of the bacterial antagonists in controlling damping-off in cucumber.

9-Tricosene Containing Blend of Volatiles Produced by Serratia sp. NhPB1 Isolated from the Pitcher Plant Provide Plant Protection Against Pythium aphanidermatum.

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 selectedbacteria for biocontrol applications.

Comparative genomics of Bacillus cereus sensu lato spp. biocontrol strains in correlation to in-vitro phenotypes and plant pathogen antagonistic capacity.

Bacillus cereus sensu lato (Bcsl) strains are widely explored due to their capacity to antagonize a broad range of plant pathogens. These include B. cereus sp. UW85, whose antagonistic capacity is attributed to the secondary metabolite Zwittermicin A (ZwA). We recently isolated four soil and root-associated Bcsl strains (MO2, S-10, S-25, LSTW-24) that displayed different growth profiles and in-vitro antagonistic effects against three soilborne plant pathogens models: Pythium aphanidermatum (oomycete) Rhizoctonia solani (basidiomycete), and Fusarium oxysporum (ascomycete). To identify genetic mechanisms potentially responsible for the differences in growth and antagonistic phenotypes of these Bcsl strains, we sequenced and compared their genomes, and that of strain UW85 using a hybrid sequencing pipeline. Despite similarities, specific Bcsl strains had unique secondary metabolite and chitinase-encoding genes that could potentially explain observed differences in in-vitro chitinolytic potential and anti-fungal activity. Strains UW85, S-10 and S-25 contained a (~500 Kbp) mega-plasmid that harbored the ZwA biosynthetic gene cluster. The UW85 mega-plasmid contained more ABC transporters than the other two strains, whereas the S-25 mega-plasmid carried a unique cluster containing cellulose and chitin degrading genes. Collectively, comparative genomics revealed several mechanisms that can potentially explain differences in in-vitro antagonism of Bcsl strains toward fungal plant pathogens.

Effectiveness of Endophytic and Rhizospheric Bacteria from Moringa spp. in Controlling Pythium aphanidermatum Damping-Off of Cabbage.

In this study, endophytic and rhizospheric bacteria were isolated from Moringa olifera and M. perigreina from Oman, and their in vitro antagonistic activity against Pythium aphanidermatum was tested using a dual culture assay. The promising strains were tested further for their compatibility and potential for plant growth promotion, biofilm formation, antifungal volatile organic compound (VOC) production, and the biological control of P. aphanidermatum damping-off of cabbage (Brassica oleracea L.) under greenhouse conditions. A total of 12 endophytic and 27 rhizospheric bacteria were isolated from Moringa spp. Among them, Bacillus pumilus MPE1 showed the maximum antagonistic activity against P. aphanidermatum in the dual culture assay, followed by Paenibacillus glucanolyticus MPE3 and Pseudomonas indica MOR3 and MOR8. These bacterial isolates induced abundant morphological abnormalities in the hyphae of P. aphanidermatum, as observed via scanning electron microscopy. The in vitro cross-streak assay showed that these bacterial isolates were compatible among themselves, except for P. indica MOR8 × P. glucanolyticus MPE3. These antagonists released VOCs that restricted the growth of P. aphanidermatum in an in vitro assay. These antagonistic bacteria released 2,4-dimethylheptane and 4-methyloctane as the predominant volatile compounds. Of the four antagonistic bacterial strains, P. indica MOR8 was capable of forming biofilm, which is considered a trait that improves the efficacy of rhizosphere inoculants. The results of the greenhouse experiments showed that the soil treatment with B. pumilus MPE1 showed the highest reduction (59%) in the incidence of P. aphanidermatum damping-off in cabbage, evidencing its potential as a biological control agent for the management of this disease. Further research is needed to characterize the antifungal traits and activities of B. pumilus MPE1 and to assert its potential use against other soil-borne plant pathogens.

Evaluation of different farming systems for management of rhizome rot disease of zinger (Zingiber officinale Rose) incited by Pythium aphanidermatum (Edson) Fitz

Evaluation of different farming systems for management of rhizome rot disease of zinger (Zingiber officinale Rose) incited by Pythium aphanidermatum (Edson) Fitz

Eggplant Fruit Periderm Firmness Correlated with Resistance to Phytophthora nicotianae

Worldwide, Phytophthora nicotianae and Pythium aphanidermatum are the Phytophthora and Pythium species most frequently reported on eggplant ( Solanum melongena). Both species were identified on the fruit of several eggplant cultivars grown in Charleston, South Carolina, in spring 2018. The objectives of this study were to determine whether seven cultivars, each representing a different fruit type, differed in susceptibility to Phytophthora nicotianae and whether periderm or flesh firmness or fruit density was associated with differences. Eggplant fruit were inoculated with colonized agar plugs and incubated for 4 days at high relative humidity. Japanese eggplant cultivar Millionaire had a greater incidence of fruit infection, wider lesion diameter, and greater percentage of lesion area with pathogen growth than the six other cultivars. Patio Baby, an Indian type, and Fairy Tale, a graffiti type, had the lowest incidence compared with the other five cultivars and no pathogen growth in lesions. Periderm firmness was negatively correlated with incidence, lesion diameter, and diameter of pathogen growth within lesions ( P ≤ 0.01). The significant correlations of lesion size with the size of pathogen growth suggest that the same characteristics that limit lesion expansion (e.g., some aspect of periderm firmness) could also limit mycelial growth and sporangial production. Growers might need to apply oomycete-specific fungicides registered on eggplant more frequently to Japanese cultivars than to cultivars that produce graffiti- or Indian-type fruit.

Screening and Characterization of Plant Growth Promoting Endophytic Microbes of Tomato (Solanum lycopersicum L.) combats Pythium aphanidermatum

About 45 bacteria, 9 fungi, 3 yeast, and 1 actinobacterium were isolated from plant tissues of tomato and screened for their plant growthpromoting traits and antagonistic activity against damping-off fungus Pythium aphanidermatum. The bacterial isolate, Bacillus pumilus TEB10 exhibited pathogen inhibition of about 55 and 79%, while yeast isolate Candida tropicalis TEY1 showed 30 and 68% in the dual plate and inverted plate assay, respectively. In addition, the Bacillus pumilus TB10 showed siderophore, HCN, cellulase, and phosphate solubilization activities. Similarly, yeast isolate Candida tropicalis TEY1 exhibited catalase, phosphate, and zinc solubilization activities. The sterol biosynthesis pathway end product ergosterol was profiled in secondary metabolites of P. aphanidermatum, suggesting the potentiality of this pathogenesis.

Sensitivity of Different Isolates of Pythium aphanidermatum to Old and Novel Fungicides

Sensitivity of Different Isolates of Pythium aphanidermatum to Old and Novel Fungicides

Impact of plant growth promoting rhizobacteria Serratia nematodiphila RGK and Pseudomonas plecoglossicida RGK on secondary metabolites of turmeric rhizome

Plant growth promoting rhizobacteria (PGPR) are diverse group of soil bacteria that live in the rhizosphere of plants. The current research focuses on the plant growth promoting potential of two strains, Serratia nematodiphila RGK and Pseudomonas plecoglossicida RGK isolated from the rhizospheric soil of the turmeric plant. Both of these bacterial strains found to have the capacity to solubilize phosphate, zinc and potassium as well as potential to produce indole acetic acid, siderophores, nitrogen fixation, ammonia, hydrogen cyanide (HCN) and exopolysaccharide synthesis. Further, they showed the salinity tolerance up to the 6–7% NaCl and antibiotic sensitivity to Gentamycin, Kanamycin, Streptomycin, Tobramycin, and Amikacin. The isolate Pseudomonas plecoglossicida RGK also has shown antifungal activity against fungal pathogen of turmeric Pythium aphanidermatum. Treatment of turmeric rhizomes with separate and by combination of both strains demonstrated remarkable increase growth parameters of turmeric as compared to control. They improved the growth metrics of the plant such as the number of leaves, shoot height, rhizome biomass as well as phenolic, flavonoid content, and free-radical (DPPH) scavenging ability. As compared to the untreated plants, PGPR treated rhizomes showed higher amounts of secondary metabolites, primarily curcumin and additional compounds such 4-Hydroxy-2-methylacetophenone, 2,4-Di-tertbutyl phenol, aR-Turmerone, and (Z) -gamma-Atlantone. The detection of a phenolic compound, 4-Hydroxy-2-methylacetophenone, in a consortium-treated turmeric plant, which has significant biological activity is reported for first time. The use of different microbial strains in a single formulation is a new and developing trend for sustainable agriculture.

Characterization of novel strains of <i>Trichoderma</i> spp. and their utilization in management of damping off disease in tomato

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.

In vitro Evaluation of Biocontrol Potential of Lactic Acid Bacteria Isolated from Natural Ecosystem against Plant Pathogenic Fungi

Lactic acid bacteria (LAB) are ubiquitous, Gram-positive, fermentative bacteria, which are regarded as safe for both humans and the environment. The present study aimed to evaluate the biocontrol efficiency of LAB isolated from different natural ecosystems against fungal pathogens. A total of 30 LAB was isolated from rhizosphere soil and phyllosphere sample of Solanaceous crop viz., Brinjal, Capsicum, Chilli, Tomato, whey, and sauerkraut out of them 14, 9, 4 and 3 lactic acid bacteria (LAB) were isolated from rhizosphere soil & phyllosphere sample of Solanaceous crops, whey and Sauerkraut respectively. The biocontrol ability of LAB isolates were tested against fungal plant pathogens such as Fusarium oxysporum, Pythium aphanidermatum, Sclerotium rolfsi, Rhizoctonia solani, Alternaria sp. agar well diffusion assay and mycelial growth inhibition in liquid culture. The results indicated that the isolates LAB 4, LAB 10, LAB 22, LAB 24 and LAB 29 were prominent in inhibiting the growth of most of the pathogens. Molecular characterization of selected LAB isolates revealed that LAB 4, LAB 10, LAB 22, LAB 24 belongs to Lactobacillus plantarum and LAB 29 belong to Leuconostoc mesentroides.