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Isolation and Characterization of Native Entomopathogenic Fungi and Their Pathogenicity Against Cowpea aphid
2024
Alyaa Elsawy | mohamed elzemaity | Yosra Ahmed | Walaa Abdelghany
The research aimed to isolate and characterize local entomopathogenic fungi from different agricultural ecosystems and assess their pathogenicity against cowpea aphid. Forty soil samples were collected from different ecosystems. In total, 38 fungal isolates were collected from the cadavers' exteriors of Galleria mellonella larvae. Microscopic observation of these fungal isolates revealed that they belonged to nine fungal genera among them Metarhizium sp. (3 isolates) and Beauveria sp. (5 isolates). Primary experiments showed different bioactivities of the isolates of the two selected genera against the target insect. Only Metarhizium isolates (M3 & M5) and Beauveria isolates (B1 & B5) were selected for further investigations. Identification of fungal cultures by morphological characters, molecular characterization, ITS sequencing, and NCBI Blast showed that two isolates were confirmed as M. anisopliae and two isolates as B. bassiana. The bioassay evaluation revealed that M. anisopliae (M3 and M5) and B. bassiana (B1) exhibited significant virulence against A. craccivora, as evidenced by their high LT50 and LC50 values and substantial sporulation on the cadavers. Therefore, they could be used for the formulation of pesticides targeting this pest on cowpea and other vegetable crops.
Mostrar más [+] Menos [-]ISOLATION AND IDENTIFICATION OF TRICHODERMA SPECIES FROM SOILS FOR USING AGAINST SOME SOILBORNE FUNGAL PATHOGENS
2019
Nada Abd El-Aziz | A. Abd El-Razek | S. Ibrahem
Hydrolytic enzyme producing Trichoderma species have long been recognized as an agent for controlling plant diseases caused by various phytopathogenic fungi. A study was done to characterize four isolates of Trichoderma isolated from the rhizosphere of different crop plants to characterize and identify certain biocontrol related enzymes (β1,3-glucanase and chitinase). Morphological and molecular characterize action of antagonistic ability of Trichoderma species were studied. On the basis of morphological and culture characteristics, the Trichoderma isolates were identified as T. harizanum (1 isolate), T. viride (3 isolates). These isolates were tested against plant pathogens (Rhizoctonia solani, Pythium and Fusarium oxysporum). The best isolate producing chitinase (overproduction) was T. harizanum from (160 to 0.64) mg/ml. On the other hand the best isolate gave over production β-1; 3-glucanase over production was T. viride from (2250 to 2.20 mg/ml)
Mostrar más [+] Menos [-]OPTIMIZATION OF AMINO ACID PRODUCTION FROM CHICKEN FEATHER BY BACILLUS AMYLOLIQUEFACIENS USING RESPONSE SURFACE METHODOLOGY AS A NEW TOOL FOR POWDERY MILDEW DISEASE BIOCONTROL
2020
Samah Abu-Hussien | Maha Mohamed
The present work aimed to optimize amino acids production by Bacillus amyloliquefaciens 35s from chicken feather using response surface methodology (RSM) and applying the produced amino acids in biological control of powdery mildew disease. Variables affecting amino acids production from B. amyloliquefaciens 35s were screened using Plackett Burman design. Factors showed to be significant to produce amino acids were optimized using central composite design (CCD) of RSM at three coded levels (-1, 0, +1). All obtained data were analyzed by ANOVA with post hoc multiple comparison analysis performed using Tukey’s HSD. TGY (tryptone, glucose, yeast extract) was the basal medium. Impacts of medium components were studied using Plackett-Burman design. “Design Expert 12” StateEase was used to analyze the experimental Plackett- Burman design. Feather, yeast extract, CaCO3, KH2PO4 and agitation rate (using shake flask) were optimized statistically by the CCD design of the RSM. Validation of statistical model of the medium components was done by carrying out the experiment at optimum conditions of the process parameters as determined by the model. Amino acids types were identified by amino acid analyzer. Among the significant medium components, feather, yeast extract, CaCO3, KH2PO4 and agitation rate showed to have significant effect on amino acids production. Predicted maximum amino acids production was observed near the mid-point concentrations of the mentioned above factors and the experimental value (6.55 g/l) was very close to the predicted value of (6.60 g/l) predicted by the model. Amino acid analyzer analysis for the produced amino acids shows the release of asparagine, threonine, serine, glutamine, proline, glycine, alanine, cysteine, valine, methionine, isoleucine, leucine, tyrosine, phenyl alanine, histidine, lysine and arginine, respectively. Effect of chicken feather hydrolysate on cucumber powdery mildew disease was tested by applying foliar application with different concentrations (0, 5, 10, 15, and 20% v/v), then degree of infection and sporulation on cucumber plants were assessed. The lowest concentration of chicken feather hydrolysate showed the lowest effect on disease index. Conversely, cucumber resistance increased by the increasing of feather’s hydrolysate concentrations associated with a clear reduction in the disease index and sporulation. Aside from, extra foliar application showed a decrease in the disease index for all concentrations compared with untreated plants. Foliar application with 20% concentration of chicken feather hydrolysate had the highest stimulation of the studied oxidative enzymes i.e., peroxidase (POX), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and superoxide dismutase (SOD).
Mostrar más [+] Menos [-]EFFICACY OF CHEMICAL AND BIOLOGICAL TREATMENTS FOR CONTROLLING SOIL-BORNE PATHOGENS OF SOYBEAN
2009
Ahmed Awad Altalb
Several soil-borne fungal pathogens attack soybean plants, causing seedling damping-off and root rot diseases, in Egypt. Isolation trials from rooted rots of soybean, collected from various locations at Gharbiya, Kafr El-Sheikh and Minufiya governorates, revealed that Rhizoctonia solani, Fusarium solani and Macrophomina phaseolina were the most virulent and predominant pathogens. All the tested fungicides significantly reduced linear growth of the tested pathogens. Three known bioagents i.e. Trichoderma harzianum, T. hamatum and Bacillus subtilis were tested against such pathogens, and revealed remarkable effect in reducing mycelial growth on PDA medium. T. hamatum, mainly, grew over the mycelium of the tested pathogens. Under greenhouse conditions, both the fungicides and antagonists gave significant reductions of root rot severity, but fungicides were more effective than biocontrol agents in reducing the disease. Application of the selective antagonists and fungicides significantly decreased soybean root rot than untreated check, in naturally pathogen- infested fields. Plant growth and activity of nitrogenase enzyme were enhanced greatly, when the fungicides were applied compared with antagonists treatments.
Mostrar más [+] Menos [-]NATURAL OCCURRENCE OF CITRININ AND BIOCONTROL OF ITS PRODUCING FUNGUS BY Trichoderma hamatum IN RICE GRAINS
2006
Ezzat S.M. | E.F. Abd-Allah
Paddy rice was sampled from El-Sharkia, El-Gharbia, El-Dakahlia and Kafr El-Sheikh governorates, Egypt. Of the 29 samples taken, ten were contaminated with the mycotoxin citrinin. An average of 6.79 x 104 fungal spores per gram rice was found. The isolated fungi represented 47 species belong to 28 genera. The predomi-nant genera were Aspergillus, Cladosporium and Penicillium. Aspergilli were represented by 22 species; Aspergillus niger and A. flavus had the highest occur-rence. Penicillium viridicatum produced the highest amount of citrinin on glucose ammonium nitrate salts broth and rice grains and hence, this isolate was selected as a good producer of citrinin in this study. The presence of Trichoderma hamatum re-duced the amount of citrinin produced by P. viridicatum compared with its respec-tive control. The excessive growth of T. hamatum on P. viridicatum was increased with time. Viability of P. viridicatum conidia decreased by T. hamatum with an in-crease in the incubation period. Chitinases and 1,3-B-glucanase enzyme activity of T. hamatum increased with extending the incubation period on P. viridicatum cell walls up to maximum values at 72 and 84 h, respectively. T. hamatum led to a de-crease in the production of citrinin by P. viridicatum on rice grains compared with the respective control values.
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