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Articles by Maher M. Shehata
Total Records ( 3 ) for Maher M. Shehata
  Sahar A. El-Khawas and Maher M. Shehata
  Plants may favorably or adversely affect other plants through allelochemicals, which may be released directly or indirectly from live or dead plants (including microorganisms). The objective of this study was to examine the allelopathic effects of leaf leachates of Acacia nilotica and Eucalyptus rostrata on morphological, biochemical and molecular criteria of Zea mays L. (maize) and Phaseolus vulgaris L. (kidney bean). Concerning the seedling, seedling emergence was reduced with treatment with Acacia and Eucalyptus leaf leachates and growth parameters were generally reduced in both maize and kidney-bean. With respect to the internal metabolites, a gradual increase in the ABA concentration, decrease in the chlorophyll content and consequently the soluble sugars content is proportional to the increase in the concentration of the leaf leachates. Total DNA and RNA contents are highly significant increased in all treated samples of maize with respect to the control. On the other hand, kidney-bean samples showed mostly a significant reduction. Maize samples treated with Acacia show a highly significant increase in the level of soluble proteins while samples treated with Eucalyptus show a highly significant decrease. However, there is a highly significant decrease in soluble protein contents in Kidney-bean samples treated with both Acacia and Eucalyptus. With respect to the protein pattern, the allelopathic effect of both Acacia and Eucalyptus induced the formation of stress proteins. High and mid molecular weight proteins 244, 187, 143, 51.8, 41, 40.6 and 29.7 kDa were newly synthesized in response to the allelopathic effect of Acacia. On the other hand, mid and low molecular weight polypeptides 121.8, 116, 62, 52.9, 46.8, 45 and 40.6 kDa were recorded in response to the allelopathic effect of Eucalyptus. In maize treated with both Acacia and Eucalyptus, the 55.4 kDa protein was disappeared, while the proteins 40.5, 30.5, 29.7 and 26.5 kDa were newly synthesized. Moreover, in maize seedlings treated with Eucalyptus, the proteins 50.8, 41, 30.5, 26.8 and 26.5 kDa were recorded. The number of de novo synthesized proteins (chaperones) in maize samples treated with both Acacia and Eucalyptus (12-induced proteins; 121.8, 60.9, 55, 52.9, 50.8, 46.8, 41, 50.6, 30.5, 29.7, 26.8 and 26.5 kDa) were more than that induced in kidney-bean (10-stress induced proteins; 244, 187, 143, 116, 93.7, 51.8, 45, 41, 40.6 and 27.4 kDa). The genomic DNA of each treatment was subjected to four restriction enzymes (BamHI, EcoRI, HinfI and SamI). The resulting cleavage fragments had apparent low molecular sizes and appear as smears of digests whatever the concentrations of templates of DNA or restriction enzymes and the time of electrophoretic run. The highest degree cleavage was observed EcoRI. All studied samples showed different DNA fingerprints. All samples had on average 20-30% of their bands in common. The variability was higher in the bands in the region of the gel above 2.7 kb than in the bands below it. On the average, 50"5 bands were seen above 500 bp, ranging from 700 to 2400 bp. A clear information data was obtained using HinfI (5-base cutter) as compared to other enzymes (6-base cutter) which may indicates the presence of stimulator which facilitate the recognition of the nucleotide sequence which is specific for each enzyme and the cutting site inside it. This indicates that the percentage of shared bands in DNA fingerprints of maize and kidney-bean might be used as a measure of genetic difference and demonstrate that the restriction site mutation assay can detect mutations. Present results indicate that, Eucalyptus is more effective in affecting morphological, biochemical and molecular criteria and that the monocot plant (maize) is more tolerant than the dicot one (kidney-bean). We can suggest that the allelopathic chemicals of both Acacia and Eucalyptus may have the potential as either biological herbicides or templates for new herbicide classes (i.e. biological control).
  Maher M. Shehata
  Grains of two wheat (Triticum vulgare L.) cultivars (Gemmiza 7 and Giza 164) previously presoaked in phosphate buffer at different pHs, as well as an optimum concentration of IAA, were sown and grown at the green house to the M2 grains in order to study the possible adaptive mechanisms to ameliorate the pH stress on osmolytes (proline and betaine as chemical chaperones), stress proteins (molecular chaperones), alteration of levels of gene expression (mRNA and proteins) and DNA profiles. The results revealed that plants under acidic pH have an obvious effect on total proteins, RNA and DNA macromolecules. Cultivar Giza 164 plants accumulated higher levels of proline than Gemmiza 7 under pH stress. In both cultivars betaine and the level of mRNA increased with pH stress and the expression was coincided with the observed betaine accumulation. The yields of poly(A)+ RNA were in the range of 0.5-1.5%±1 in Cv. Giza 164 as compared to that of Gemmiza 7 (0.3-1.1%±0.7). Exogenous application of IAA can stimulate resistance against the unfavourable environmental pH value and improve plant under stress by developing various mechanisms, which include increase in both the soluble protein, betaine and proline that acts as a free radical scavenger and limits the cytoplasmic acidification, quantitative and qualitative increase in mRNA and low molecular weight proteins (9-29 kDa) that play an important role in the readjustment of plant cell`s osmotic potential and protecting cytoplasmic enzymes. RAPD analysis was effective in detecting informative qualitative and quantitative changes in both wheat cultivars as a response to pH stress and hormonal application. The thirty used different primers have different performances in detection of genetic changes. The number of amplified fragments generated ranges between 10 and 22 with molecular size ranges between 50 and 2130 bp. Quantitative changes by one common band were shown in stressed Giza 164 samples using thirteen primers as compared to nine primers in Gemmiza 7 stressed samples. Qualitative changes were recorded using all primers (thirty) in Gemmiza 7 and in Giza 164 using sixteen primers only. These changes were found to be reproducible when repeated at different times under the same amplification conditions. The expression of many proteins is known to be regulated by biotic and abiotic stresses, suggesting the occurrence of complex mechanisms that control gene expression in response to environmental stresses. The disappearance of some protein bands may be attributed to the alteration of their structural genes and RNA transcripts. The results of this study suggest that an adaptive mechanism has been developed by Triticum vulgare L. cultivars (Gemmiza 7 and Giza 164) in response to exogenous hormonal application under acidic pH stress. Also, the biochemical and molecular criteria which may affect on crop yield productivity and quality were improved. The synthesis of chemical and molecular chaperones to maintain osmotic adjustment is the main strategy that has evolved to maintain growth. The difference in the ability to maintain osmotic potential under pH conditions between the two cultivars reflects the differences in their genetic background.
  Maher M. Shehata
  Traditional identification of wheat cultivars relies on the assessment of agronomic traits of the adult plant. This leads to a significant delay of time, constraints to breeders in the surveillance of germplasm and a risk for growers and exporters. Seed storage protein and DNA fingerprinting diversity as revealed by variation in SDS-PAGE and RAPD-PCR, respectively has been used to reassess the genotypic differences, relationships and discriminating between eight wheat (Triticum vulgare L.) cultivars (Banisewef 3, Gemmiza 7, Giza 164 and 168, Sakha 8, 69 and 93 and Sids 1) grown in Egypt. A total number of 46 protein bands, with molecular weight ranging between 160.52 and 3.86 kDa were recorded in the electrophenograms of the cultivars studied. SDS-PAGE profiles showed slight differences at high and low molecular weights and high differences at mid molecular weights. The highest number of bands (30) was recorded in Banisewef 3 and the lowest number (21) was recorded in Sids 1. Eight common bands (M.wts.; 155.32, 139.50, 76.35, 29.25, 19.25, 8.20, 7.20 and 6.38 kDa) were recorded in all samples. Six unique bands were recorded in cultivars Banisewef 3 (M.wts: 132.69 and 73.50 kDa), Sakha 8 (M.wt.: 38.50 kDa) and Sakha 69 (M.wts.: 88.59, 63.20 and 24.85 kDa). In the RAPD-PCR analysis twenty five random decamer (10 mer) primers were screened, but only eight primers (OPB-01, -02, -03, -08 and OPI-03, -09, -14 and -18) were able to generate distinguishable, reproducible and repeatable informative products among the DNA samples of the studied genotypes. A total of 67 polymorphic bands out of 86 ones were generated by the eight primers. Nearly every cultivar has a different DNA fingerprint. Each cultivar has one or more novel sequences not found in other cultivars. These bands may be used as genetic markers for identification of these cultivars using the same primer. A total of 8 polymorphic bands were scored as unique ones. Primers OPI-09 and -03 were found to be the most effective in generating unique bands. The former primer generated 4 unique bands in Banisewef and Giza 164 cultivars while the latter primer produced 2 unique bands in Giza 169 and Sakha 93 cultivars. Increasing and changing the number of cycles in PCR from 30 to 40, improve our results. These bands were used as binary characters and analyzed by the NTSYS-pc. Program Package using the UPGMA clustering method. This analysis indicates that, the eight cultivars are distinct. SDS-PAGE and RAPD-PCR data were combined together and used to construct a dendrogram that estimates the relationship and the relative genetic similarities among the studied wheat cultivars. Based on this dendrogram, the studied cultivars were separated into two main groups. The first group comprises three cultivars, while the second includes five cultivars. The first group was further subdivided into two subgroups; the first subgroup comprises cultivar Sakha 8, whereas the second subgroup includes cultivars Sakha 69 and Sakha 93. The second group was further subdivided into two subgroups; the first subgroup comprises cultivars Giza 169 and Giza 164, whereas the second subgroup includes cultivars Sids 1, Gemmiza 7 and Banisewef 3. Combination of all data provides a considerable potentiality for discriminating each wheat cultivar by one or more unique bands or a group of combined class pattern. As a result of this investigation, we may expect that the SDS-PAGE, RAPD and the subsequent banding patterns computed using appropriate programs, would be useful for the establishment of phylogenetic relationships among a set of Egyptian wheat cultivars. These tools could be used as complementary of traditional methods of identification of phenotypic traits for the control of registered cultivars in the trade market. This will help in collection and cataloguing of the germplasm in the form of a germplasm bank.
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