منصة إيفاد العلمية

دكتورة إحسان محمد محمد رشاد

إرسال رسالة

التخصص: أمراض النباتات

الجامعة: مركز البحوث الزراعية

النقاط:

20.5

معامل الإنتاج البحثي

الخبرات العلمية

أمراض النباتات-المكافحة الحيوية-انزيمات

الأبحاث المنشورة

Chitinase production by Bacillus subtilis ATCC 11774 and its effect on biocontrol of Rhizoctonia diseases of potato

المجلة: Acta Biologica Hungarica

سنة النشر: 2015

تاريخ النشر: 2015-12-01

Stem canker and black scurf of potato, caused by Rhizoctonia solani, can be serious diseases causing an economically significant damage. Biocontrol activity of Bacillus subtilis ATCC 11774 against the Rhizoctonia diseases of potato was investigated in this study. Chitinase enzyme was optimally produced by B. subtilis under batch fermentation conditions similar to those of the potato-growing soil. The maximum chitinase was obtained at initial pH 8 and 30°C. In vitro, the lytic action of the B. subtilis chitinase was detected releasing 355 μg GlcNAc ml-1 from the cell wall extract of R. solani and suggesting the presence of various chitinase enzymes in the bacterial filtrate. In dual culture test, the antagonistic behavior of B. subtilis resulted in the inhibition of the radial growth of R. solani by 48.1% after 4 days. Moreover, the extracted B. subtilis chitinase reduced the growth of R. solani by 42.3% when incorporated with the PDA plates. Under greenhouse conditions, application of a bacterial suspension of B. subtilis at 109 cell mL-1 significantly reduced the disease incidence of stem canker and black scurf to 22.3 and 30%, respectively. In addition, it significantly improved some biochemical parameters, growth and tubers yield. Our findings indicate two points; firstly, B. subtilis posses a good biocontrol activity against Rhizoctonia diseases of potato, secondly, the harmonization and suitability of the soil conditions to the growth and activity of B. subtilis guaranteed a high controlling capacity against the target pathogen.

ORGANIC ACIDS PRODUCTION AND ANTAGONISTIC EFFECT OF SOME STRAINS OF PROBIOTICS

المجلة: J.Agric.Chem.and Biotechn., Mansoura Univ

سنة النشر: 2014

تاريخ النشر: 2014-03-22

Organic acids production and antimicrobial activities of Lactobacillus acidophilus KF724889, Lactobacillus casei KF724890 and Streptococcus thermophilus KF724886, KF724887 and KF724888 strains, which isolated from dairy products as probiotics were screened. Eleven organic acids were detected in the different LAB filtrates, acetic, ascorbic, citric, formic, oxalic, malic, maleic, lactic, propionic, butyric and succinic acids. lactic and acetic acids were the major acids produced by the five strains. Lactobacillus in general and L. acidophilus in especial were the most active in acids production. Both L. acidophilus and L. casei produced the highest quantity of lactic acid, being 3257.4 and 2447.75 mg/100 ml, respectively, while Str. thermophilus strains KF724886, KF724887 and KF724888 produced 1613.36, 1964.52 and 2031.131 mg/100ml, respectively. Formic acid did not produce by Str. thermophilus KF724886. Supernatants obtained from the tested bacteria exhibited varying degrees of inhibitory effect against indicators pathogenic bacteria and yeast. All the tested bacteria have antagonistic effect against Staphylococcus aureus, Pseudomonas aeruginosa and Protus vulgaris. Among the isolates, L. acidophilus was the most effective strain for inhibiting pathogens growth with strong inhibitory effect against P. aeruginosa, L. monocytogenes and Candida albicans. Only L. acidophilus and Str. thermophilus KF724888 caused inhibitory effect against Bacillus cereus, L. monocytogenes and C. albicans. L. casei, Str. thermophilus KF724886 and Str. thermophilus KF724887 failed in inhibiting growth of E. coli, B. cereus, L. monocytogenes and C. albicans. L. acidophilus inhibited growth of E. coli, while Str. thermophilus KF724888 failed. The results showed that all cell free supernatants (CFSs) of LAB cultures have ability to inhibit all the tested foodcontaminating fungi. Based on dry weight measurements of fungal biomass, CFSs of L. acidophilus showed high antifungal activity against the tested fungi. CFSs of Str. thermophilus KF724887 strain showed strong inhibition percentages against growth of A. niger, T. harzianum, P. chrysogenum and A. pullulans (56.63, 54.84, 52.92 and 38.88%, respectively). The study revealed that lactic acid bacteria isolated from Egyptian fermented milk, are capable of producing organic acids and antimicrobial substances which have antagonistic effect on pathogenic organisms, thus, may be promising sources of preservative that may in future be applied to food.

Bacteriological Therapeutic-Based Strategy for Management of Fusarium Wilt Disease in Tomato Plants

المجلة: Mindanao Journal of Science and Technology

سنة النشر: 2020

تاريخ النشر: 2020-12-07

Fusarium oxysporum f. sp. lycopersici (Sacc) causes a destructive wilt disease in tomato. With consideration to the environment and human health concerns, the bioagents as alternative procedures for defense against the plant pathogen were investigated. The potentiality of the antagonistic activity of Bacillus subtilis (ATCC® 11774™) reached 53% against the growth of F. oxysporum in a dual culture technique. The proteolytic; B. subtilis strain; was found to be a potent producer of amino acids under in vitro. Fractionation of the fermented hydrolysate showed the liberation of glutamic acid (760.15 mg/L), glycine (414.65 mg/L), aspartic acid (291.1 mg/L), cysteine (268.45 mg/L) and lysine (51.9 mg/L). In a greenhouse experiment, seed treatment with crude extract of amino acids and/or Bacillus subtilis cells demonstrated the greatest suppression of wilt symptoms on tomato seedlings. Moreover, pronounced plant growth promotion in root and shoot lengths, number of leaves, shoot fresh and dry weights of tomato plants was noticed. Biochemical parameters (photosynthetic pigments, total polyphenols, flavonoids, polyphenol oxidase, and peroxidase enzymes) were also upgraded. Antioxidant capacity of the plants – ABTS (%), DPPH (%) and reducing power – positively responded to the investigated treatments.

Discovering Penicillium polinicum with High-Lytic Capacity on Helianthus tuberosus Tubers: Oil-Based Preservation for Mold Management

المجلة: Plants

سنة النشر: 2021

تاريخ النشر: 2021-04-01

During preservation, Jerusalem artichoke (JA) tubers are subjected to deterioration by mold fungi under storage, which signifies a serious problem. A new blue mold (Penicillium polonium) was recorded for the first time on JA tubers. Penicillium mold was isolated, identified (morphologically, and molecularly), and deposited in GenBank; (MW041259). The fungus has a multi-lytic capacity, facilitated by various enzymes capable of severely destroying the tuber components. An economic oil-based procedure was applied for preserving and retaining the nutritive value of JA tubers under storage conditions. Caraway and clove essential oils, at a concentration of 2%, were selected based on their strong antifungal actions. JA tubers were treated with individual oils under storage, kept between peat moss layers, and stored at room temperature. Tubers treated with both oils exhibited lower blue mold severity, sprouting and weight loss, and higher levels of carbohydrates, inulin, and protein contents accompanied by increased levels of defense-related phytochemicals (total phenols, peroxidase, and polyphenol oxidase). Caraway was superior, but the results endorse the use of both essential oils for the preservation of JA tubers at room temperature, as an economic and eco-safe storage technique against the new blue mold.

Lytic and Molecular Evidence of the Widespread Coriander Leaf Spot Disease Caused by Alternaria dauci

المجلة: Plants

سنة النشر: 2023

تاريخ النشر: 2023-11-16

Coriandrum sativum L. is a globally significant economic herb with medicinal and aromatic properties. While coriander leaf blight disease was previously confined to India and the USA, this study presents new evidence of its outbreak in Africa and the Middle East caused by Alternaria dauci. Infected leaves display irregular chlorotic to dark brown necrotic lesions along their edges, resulting in leaf discoloration, collapse, and eventual death. The disease also impacts inflorescences and seeds, significantly reducing seed quality. Koch’s postulates confirmed the pathogenicity of the fungus through the re-isolation of A. dauci from artificially infected leaves, and its morphology aligns with typical A. dauci features. Notably, this study identified strong lytic activity (cellulase: 23.76 U, xylanase: 12.83 U, pectinase: 51.84 U, amylase: 9.12 U, and proteinase: 5.73 U), suggesting a correlation with pathogenicity. Molecular characterization using ITS (ON171224) and the specific Alt-a-1 gene (OR236142) supports the fungal morphology. This research provides the first comprehensive documentation of the pathological, lytic, and molecular evidence of A. dauci leaf blight disease on coriander. Future investigations should prioritize the development of resistant coriander varieties and sustainable disease management strategies, including the use of advanced molecular techniques for swift and accurate disease diagnosis to protect coriander from the devastating impact of A. dauci.

Comparative Study of Supplementing Two Biological Bioagents and Conventional Fungicide Against Alternaria dauci Pathogenicity and Monitoring Plant Growth and Yield of Coriander

المجلة: The future of Horticulture

سنة النشر: 2023

تاريخ النشر: 2023-12-01

Coriander (Coriandrum sativum L.) belongs to the Apiaceae family and is amongst the widely used medicinal plants, possessing nutritional and medicinal properties. Coriander leaf spot, caused by Alternaria dauci is the most devasting disease worldwide including Egypt. Therefore, the present study aimed to evaluate cumin and thyme oils nanoemulsions (EONEs) and their crude foliar application impacts in enhancing the antifungal activities against A. dauci and coriander growth promotion as an alternative approach for this disease management to synthetic fungicides. Cumin and thyme oils were characterized using ζ-potential, ζ-average and TEM analysis. Two field experiments were carried out during two successive winter seasons of 2021/2022 and 2022/2023 using concentrations of 0.25, 0.5, 0.75 and 1.0 ml/L for cumin and thyme oils nanoemulsions and 1.0 ml/L for their crude. The results revealed that the effects of cumin and thyme oils nanoemulsions treatments on all characteristics of coriander vegetative growth and yield were significant. The concentration of 0.5 ml/L nanoemulsion (EONEs) was the best of both cumin and thyme with the superiority of thyme helping in increasing the number of leaves, dry matter %, umbellets number, seed yield g/plant, volatile oil percentage and oil yield ml/plant compared with the control and other treatments during the two seasons. Similarly, foliar application with cumin and thyme oils (EOs) crude increased all previous characteristics compared to the control ranking third and fourth among the best treatments with the superiority of thyme oil in both seasons. The essential oil components of coriander volatile oil were also affected by the different types and concentrations of cumin and thyme oils, which increased the dominant compound percentage L-linalool. On the other hand, the results revealed that foliar application of cumin and thyme oils nanoemulsions at 0.75 and 1.0 ml/L concentrations were the most effective treatments in reducing coriander disease leaf blight incidence (DI) and disease severity (DS) parameters during both seasons compared to control plants. Therefore, cumin and thyme oils nanoemulsions represent a promising strategy for a strong antifungal activity in controlling A. dauc and exhibition coriander growth and yield improvement, i.e.,

Ethyl acetate extract of Streptomyces spp. isolated from Egyptian soil for management of Fusarium oxysporum: The causing agent of wilt disease of tomato

المجلة: Biocatalysis and Agricultural Biotechnology

سنة النشر: 2021

تاريخ النشر: 2021-10-01

Tomato crops faced dangerous problems due to their attack by Fusarium oxysporum f. sp. lycopersici, the causing agent of wilt disease. Chemical treatments of such diseases caused many hazardous impacts to soil and human. For this reason, the biological control is considered as an alternative and sustainable tool for curing several plant diseases. The present work is undertaken with the aim of treating Fusarium-contaminated tomato seeds with ethyl acetate extracts from isolated Steptomyces spp., in greenhouse studies. Fifteen Steptomyces spp., isolated from native tomato rhizospheric soils, were evaluated for their antagonistic potential against Fusarium wilt pathogen. Three isolates that exhibited higher antagonistic effect were molecularly identified. Their ethyl acetate extracts (EAE) exhibited antifungal activity against the target pathogen, with higher potential with S. carpaticus EGY-S7 strain. Greenhouse assay indicated that seed treatment by the selected EAE of Steptomyces spp., isolates significantly reduced disease severity and possessed seedlings growth promoting potential of tomato ranging from 72.6 to 83.0% compared to infected control (63.4%) and chemical fungicide (76.2%). Accordingly, strain S. carpaticus EGY-S7 showed higher control efficacy (83.0%) as well as significantly increased the biomass of tomato seedlings (plant height, leaves number, fresh and dry weight) compared to a positive control (with infested soil). Additionally, it was superior to other strains, in which total polyphenols, polyphenoloxidase and peroxidase enzymes were significantly enhanced in tomato seedlings compared with untreated-infected control. Gas chromatography-mass spectrometry (GC-MS) analysis of EAE derived from S. carpaticus EGY-S7 strain was also identified.

Granular bioactive formulation of Trichoderma viride and Arbuscular mycorrhizal fungi for biological control of Cumin wilt disease

المجلة: Egyptian Journal of Phytopathology

سنة النشر: 2019

تاريخ النشر: 2019-07-01

Cdestructive abundant disease, limiting the cumin production in umin wilt caused by Fusarium oxysporum f. sp. cumini is the most Egypt. The objective of this study was to evaluate the efficacy of granular bioactive formulation of Trichoderma viride (GBTV) and arbuscular mycorrhizal fungi (AM) for biological control of cumin wilt disease. Ten Trichoderma species were isolated from the rhizosphere of healthy cumin plants and tested in dual culture assay against the growth of F. oxysporum. Trichoderma viride TC40, T. hamatum and T. koningii recorded the highest reduction in the growth of the target pathogen. Under greenhouse conditions, use of AM+GBTV formulation minimized F. oxysporum incidence and increased plant survival percentages. GBTV treatment alone came the second when compared to infected control. The greatest proportional increases in cumin plant growth were elicited by GBTV formulation and/or AM treatments. The highest level of mycorrhizal root colonization was noticed in the presence or absence of the pathogen. The biochemical parameters of the infected plants with AM or by GBTV treatment showed a pronounced increase in the plant content of total phenols, peroxidase and polyphenoloxidase activities. Under field conditions, AM+GBTV treatment highly reduced disease incidence of wilt symptoms and increased plant survival as equal as chemical fungicide. It also improved plant growth parameters and yield. The suggested formula is highly recommended for Fusarium wilt management and yield production of cumin plants.

Seed endophytic Achromobacter sp. F23KW as a promising growth promoter and biocontrol of Rhizoctonia root rot of fenugreek

المجلة: Molecules

سنة النشر: 2022

تاريخ النشر: 2022-08-29

Root rot is one of the most significant soil and seed-borne fungal diseases, limiting the cultivation of fenugreek plants. Endophytic bacteria and their natural bioproducts have emerged as growth promoters and disease suppressors in the current era. Despite limited research, seeds are a good funder of endophytic microbiomes, which are transmitted from them to other seedling parts, thereby providing a shield against biotic and abiotic anxiety and promoting the growth at early germination and later stages. The current study evaluated the hypothesis that seed endophytic bacteria and their lytic enzymes, growth promotors, and antifungal molecules can induce growth, and inhibit root rot disease development at the same time. The isolation trial from fenugreek seeds revealed a lytic Achromobacter sp., which produces indole acetic acid, has antifungal compounds (e.g., 2-Butanol, 3,3’-oxybis-), and reduces the growth of Rhizoctonia solani by 43.75%. Under the greenhouse and natural field conditions, bacterial cells and/or supernatant improved the growth, physiology, and yield performance of fenugreek plants, and effectively suppressed the progress of root rot disease; this is the first extensive study that uses a new seed-borne endophytic bacterium as a plant-growth-promoting, and biocontrol tool against the sclerotia-forming; R. solani; the causative of fenugreek root rot.