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Articles by A.A. Megahed
Total Records ( 4 ) for A.A. Megahed
  Kh.A. El-Dougdoug , A.A. Megahed , B.A. Othman , S.M. Lashin , M.A. Ibrahim and Idress Hamad Attitalla
  Systemic Acquired Resistance (SAR) could be induced in cucumber plants using different individual of seven microbial isolates against Cucumber mosaic Cucumovirus (CMV). These isolates were Bacillus subtilis, Bacillus polymyxa, Bacillus circulans, Pseudomonas putida, Pseudomonas fluorescens 2 and Pseudomonas fluorescens 8 as bacterial isolates and Trichoderma harzianum as fungal isolate. The occurrence of SAR was found by seed treatment with microbial liquid culture based on virus infectivity and the level of free and endogenous salicylic acid (SA), 14 days from CMV inoculation. Seven biotic inducers reduced CMV infectivity at range 16.6 to 39% and T. harzianum gave the highest percentage of reduction 39%. In addition, the level of total SA has been increased in treated plants, B. subtilis gave the highest level of SA 239.13 μg g-1 fresh weight (fwt) while, B. circulans gave the lowest level 70.1 μg g-1 fwt.
  A.A. Megahed , Kh.A. El- Dougdoug , B.A. Othman , S.M. Lashin , M.D. Hassanin , M.A. Ibrahim and A.R. Sofy
  Cucumber mosaic cucumovirus beet Egyptian isolate (CMV-Beet-EG) was detected serologically by DAS-ELISA using polyclonal antibodies in naturally infected sugar beet plants. The virus was isolated by single local lesion method on Chenopodium amaranticolor and then, propagated on sugar beet plants. The virus isolate was confirmed serologically by using dot and tissue printing immunoassay. The coat protein gene of CMV-Beet-EG was successfully amplified using specific primer by RT-PCR and the expected size was 820 bp. Sequence analysis cp gene revealed 97.3 and 96.4% identified similarity with CMV strains sequences published in GeneBank. The highest content of nitrogen bases was for Thymine (T) 164 (26.5%) followed by Cytosine (C) 163 (26.3%), then Adenine (A) 148 (23.9%) and Guanine (G) 144 (23.3%). The ratio of A/T and G/C were 0.902 and 0.883, the percentage of A+T and G+C was found 50.4 and 49.6. The deduced amino acids sequence of CMV-Beet-EG/CP gene was 206 amino acids with a molecular weight of 22.983 kDa and isolelectric point of 9.95. There are total 20 amino acids, the amino acid Serine (S) has the highest content and ferquency of all amino acids 25 and 12.1% while the lowest content and frequency of amino acid was 1 and 0.5% to the each of amino acid Histidine (H) and Trpyptophan (W). The CMV-Beet-EG/CP gene sequence was recorded in GeneBank with Accession No. JX826591.
  A.A. Megahed , Kh. A. El- Dougdoug , B.A. Othman , S.M. Lashin , M.A. Ibrahim and A.R. Sofy
  Cucumber mosaic cucumovirus satellite strain Egyption isolate (st-CMV-EG) was detected using polyclonal antibodies by DAS-ELISA form naturally infected cucumber leaves collected from protected agriculture. The samples which give positive reaction were used to virus isolation. st-CMV-EG isolate has a wide host-range belonging to 6 families. The virus isolate was inactivated at 70°C, it was infected at dilution 10-4 and longevity was 4 days at room temperature. Amorphous and crystalline inclusion bodies were detected in hair cells of epidermal strips of CMV-inoculated cucumber leaves. The U.V absorption ratio, A260/A280 and Amax./Amin. were 1.204 and 1.101, respectively, as well as virus yield was 1.43 mg/100 g fresh leaves in purified virus preparation. Electron micrograph of the purified virus isolate showed spherical particles (28 nm.). The virus isolate was detected serologically by using dot blot immunoassay. CMV-RNA was successfully detected in infected cucumber leaves using specific primer of cp gene by RT-PCR and the expected size was about 582 bp. Sequence analysis of CMV-cp gene of cucumber Egyption isolate was indicated 38% similarity to that of AB024493 and D00542.
  A.A. Megahed , Kh. A. El-Dougdoug , B.A. Othman , S.M. Lashin , M.A. Ibrahim and A.R. Sofy
  The possibility of making use of the phenome non of Systemic Acquired Resistance (SAR) to control viruses achieved by the soaking treatment of tomato seeds cv. Castl Rock with three growth forms to Bacillus circulans, Pseudomonas fluorescens 2 and Trichoderma harzianum against Tomato mosaic tobamovirus (ToMV) infection. All the application forms of beneficial biotic inducers were reduced the mean number of ToMV local lesions on Datura metel. P. fluorescens 2 was found to be the best treatment in three forms on reduction of local lesion number 42.2, 32.7 and 38.1 of microbial liquid culture, microbial cells or spores and microbial culture filtrate forms, respectively, while the highest mean numbers of local lesions were 51.5, 61.7 and 73.5 of microbial liquid culture, m icrobial cells or spores and microbial culture filtrate, respectively for T. harzianum. The microbial culture filtrate form was more effective than other microbial forms to reduce mean number of ToMV local lesions to B. circulans, P. fluorescens 2 and T. harzianum isolates, 40.7, 32.1 and 51.5, respectively. The individual microbial isolates on all three microbial forms able to vary ToMV local lesions similarity (homologous or heterologous) and morphology (size center and surrounded with halo or without halo) compared with TMV mother strain.
 
 
 
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