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Articles by M.N.M. Helaly
Total Records ( 3 ) for M.N.M. Helaly
  M.N.M. Helaly and A.M. Hanan El-Hosieny
  The study was aimed to investigate the ability of two date palm genotypes (Shamia and Amri) to tolerate drought stress throughout their micropropagation period. Some morpho-physiological basis of drought responses in the regenerated seedlings were evaluated. This may help in selecting drought stress tolerance and detecting other quantitative traits. Direct organogenesis technique, using shoot tip explants and supplementation of mannitol to the MS basal media has been chosen to tackle this issue. The data indicated that emberyogenesis obtained in the two genotypes followed normal development and had ability to competent to regeneration and converted into plantlets under drought stress conditions. However, swelling, numbers of embryos and shoots/jar, plantlet height and root length were decreased. All these parameters recorded higher values in Shamia genotype than those of Amri. Photosynthetic rate, transpiration rate and stomatal conductance of the regenerated plants in both date palm genotypes, were decreased whereas water use efficiency was increased with an increase in water stress level. Shamia genotype obtained higher values than Amri genotype in this respect. Carbon isotope discrimination was higher (more negative values) in shoots than in the roots and decreased with decreasing water supply. The values of maximum (Fm) and variable (Fv) fluorescence of the chlorophyll showed a significant reducing trend in both genotypes under stressed condition. The quantum yield of photochemistry (Fv/Fm) was also decreased. The mean Fv values as well as Fv/Fm ratio of both date palm genotypes in water stressed plants were significantly lower than those in the control. It could be concluded that both date palm genotypes studied, with the superiority of Shamia, have an ability to tolerate water stress under in vitro system. Chlorophyll fluorescence can be used as a tool, with other examined useful physiological characters, to screening date palm genotypes for drought resistant.
  M.N.M. Helaly and A.M.R. Hanan El-Hosieny
  Improvement in salt tolerance requires research focused on physiological processes. There is no major report stating the effectiveness of gamma irradiation, as a physical mutagen, to improve salt tolerance and alter the morphogenetic potential as well as physiological characteristics of Citrus limon. In the present investigation, in vitro mutagenesis techniques were applied to tackle this issue. Freshly isolated protoplasts were exposed to different doses of gamma rays. They were cultured and incubated for shooting regeneration. Protoplast viability and its growth criteria were estimated. Moreover, the ability of the regenerated shoots to tolerant salinity and its relation with the antioxidative system were evaluated. The data revealed that irradiated protoplast has an ability to continue their growth even at the highest level of NaCl salinity (8000 mg L-1). Radiation sensitivity (LD) was achieved only at 20 krad. However, irradiation improved the formed tissues to tolerate more salinity level and alleviated the detrimental effects of high salinity level on embryogenic callus and shoot growth. Similarly, irradiation counteracted the depressing effects of salinity on total chls, TS and TSP concentrations whereas increased carotenoids and all osmoregulators studied (proline, TSPh, Gly Bet and K). Moreover, irradiation prevented cellular damage as expressed by decreases in lipid peroxidation, membrane leakage, H2O2 values as well as Na and Cl accumulatin. The activities of Super Oxide Dismutase (SOD), Peroxidase (POX), Ascorbate Peroxidase (APOX), Catalase (CAT) and Glutathione Reductase (GR) enzymes were increased in irradiated shoots compared with non-irradiated under salinized and non-salinized condition. It could be concluded that, irradiated shoots had a higher hereditary and induced capability under salt stress which provide to it a better protection from oxidative and cellular damage caused by NaCl salinity.
  M.N.M. Helaly and A.R. Hanan El-Hosieny
  The present investigation aimed to study the effects of NaCl salinity on immature ovule regeneration of some Citrus genotypes. The relative combination effects of NaCl salinity with different sweet orange genotypes were evaluated during the developmental stages of their micropropagation. Somatic embryogenesis was achieved in callus media of nucellus derived from undeveloped ovules of 6 immature fruits of sweet orange genotypes [Citrus sinensis (L.) Osb] using modified MS media supplemented with malt and Ascorbic Acid (AsA) under different NaCl salinity levels. Complete plantlets were developed from the somatic embryos by further subculturing in the same specific media depending on the genotypes used and the level of NaCl. The combined data show that the values of genotype variance were positive but less than environmental media variance for the studied levels of salinity. In vitro seedlings of sweet orange genotypes accumulated more organic solutes (total amino acids, proline, glybet, total sugars and total organic acids) than those of the corresponding genotypes in vivo seedling having the same physiological age under different salinity levels. Moreover, in vitro seedlings scored lower level of lipid peroxidation and higher activities of Superoxide Dismutase (SOD), Peroxidase (POX), Ascorbate Peroxidase (APOX), Catalase (CAT), Glutathione Reductase (GR) than in vivo seedlings. Thus, in vitro seedling exhibited more salt tolerant than the relatively sensitive in vivo plants of sweet orange Citrus. It could be concluded that Tissue Culture Technique (TCT) in the presence of MS media supplemented with malt and/or AsA improved salt tolerance of Citrus; sweet orange genotypes by protecting the protein turnover machinery against stress damage and up-regulating stress protective proteins.
 
 
 
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