الفهرس 
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Abstract
The objective of the present work was to select plants more tolerant to water stress as induced by salinization using different levels of sodium chloride.These plants are mung bean (Vigna radiata (L) Wilczeck) Var. Kawmy1) and tomato (Lycopersicon esculentum) Var. Super Strain B (SSB). The possible effects of the same levels of NaCl on growth, pigments, metabolism, cation content and enzymes activities were studied. So, two experiments were conducted, one on the intact mung bean and tomato seedlings, the other on the in vitro selected pants. Regarding tissue culture parameters, the results revealed that the tissue viability, callus initiation and callus proliferation were decreased with increasing NaCl concentrations. The shoot regeneration capacity, the number and the mean height of shoots per explant and root regeneration decreased with increasing NaCl concentration in both mung bean and tomato. Salinity treatment lead to a dominant decrease in all measured growth criteria (shoot height, root length, fresh and dry weight) in both intact plants and in vitroselected mung bean and tomato allover the different experiment conditions (types of media and explants). Also chlorophyll a and chlorophyll b content decrease with increasing NaCl concentrations, whereas carotenoids and anthocyanin showed a significant increase in both plants either in vitro or in vivo studies. Regarding the effect of salinity in carbohydrates, the available results showed that under salinity treatment, in relation to control values, the observed increase in the determined glucose, sucrose and total soluble sugars was accompanied by an apparent decrease in polysaccharides. Salinity treatment markedly increased the Na+ content in the shoots and roots of mung bean and tomato. Regarding K+ content, as compared with untreated plants, the contents of this ion in mung bean and tomato, as excepted, deceased in response to salinity stress. The present results also showed that in salinized mung bean and tomato plants, phosphorus content decreased with increasing NaCl concentrations. Salinity treatment decreased the total nitrogen content in shoots and roots of in vitroselected mung bean and tomato throughout the experimental period. In In vivo plants, the protein content was accumulate by the low and moderate levels in both plants at all harvests, while the highest caused inhibition in protein comparing with control. The results of electrophoresis analysis of protein revealed that salinity stress induced an accumulation of new bands in treated mung bean and tomato either in vitroselected or in vivo plants. At the same time, there were some bands which found only in the control and disappeared in the treated plants. Water stress induced by salinity treatment lead to a general reduction in the activity of NiR enzyme in either treated in vitro or in vivo mung bean and tomato allover the experiments. Regarding PAL and TAL enzymes, the activities of these enzymes in mung bean and tomato were stimulated in response to the water stress induced by salinization. The present results also investigated that nearly all NaCl levels stimulated CI activity in all tissues regenerated in vitro in both mung bean and tomato. The changes in PAL, TAL and CI activities in the present investigation could be considered as a consequence of salinity induced stress status in non selected mung bean and tomato. Thus, the percentages of increase in these enzymes due to salinity were higher in non selective plants than the respective values of selective more tolerant ones.