الفهرس 
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Abstract
The present work involved studying the effects of NaCl at 0, 75, 150 and 225 mM in absence or presence of either 10 mM CaCl2 or 5 mM glycine on two cultivars of wheat (Misr1 and Sakha93). The work aimed at understanding how plants can be able to tolerate different levels of salinity in order to ameliorate wheat tolerance to NaCl by some exogenous additives such as of CaCl2 or glycine. The obtained results are summarized as follows:
Fresh and dry weights were significantly reduced in both cultivars by NaCl, the effects were most pronounced in Sakha93 in spite of having similar contents of growth parameters when grown under normal growth conditions.
Great accumulations of lipid peroxides (as MDA) were obtained although 75 mM NaCl seemed with no significant effect; the magnitude of accumulation was higher in Misr1 than in Sakha93 and augmented with increasing NaCl concentration. H2O2 was also enhanced particularly in Sakha-93 where all concentrations led to significant accumulations while only 75 mM resulted in significant effect of about 55% in Misr1 whereas all concentrations led to significant accumulation in Sakha-93.
Significant decreases in reducing power were induced by all concentrations in Sakha93 but only by 225 mM NaCl in Misr1. Further increases in phenolics contents, the magnitude of increase was greater in Sakha93 than in Misr1.
Significant diminutions were detected in chlorophyll a, chlorophyll b and carotenoids in both cultivars; the decrease was more pronounced in Sakha93 than in Misr1.
The contents of Ca and K were significantly decreased in Sakha93 with less effect in Misr1. In contrast, Na was highly increased, the magnitude of increase was most pronounced in Sakha93. The ratio of K/Na was higher in Misr1 than in Sakha93.
Summary
861
NaCl led to great increase in nitrogen content; the increase was significant in Misr1 treated with only 225 mM and in Sakha93 with all concentrations. Similarly, protein was not affected in Misr1; however, it was significantly reduced by all NaCl concentrations in Sakha93. Moreover, significant increases were detected in proline content of Misr1; however, the content seemed to be unchanged in Sakha-93.
High NaCl concentrations increased soluble sugars in Misr1 and led to decreases in Sakha-93. Nevertheless, there were significant reductions in insoluble sugars.
Rubisco was unaffected by all NaCl concentrations in Misr1 except for 75 mM NaCl which induced 5 folds increases. In Sakha93, all NaCl concentrations led to significant decreases.
GSH particularly in Sakha-93 was decreased by NaCl, the magnitude of decrease augmented with increasing NaCl concentrations. On the other hand, all concentrations of NaCl were of no significant effect on GR, GST CAT and POD activities in Misr1; however, the activities seemed to be significantly inhibited in Sakha93 by all concentrations. The CAT isozymes intensity was unchanged by 75 mM NaCl in Misr1 whereas 150 mM NaCl led to decreases but 225 mM caused significant increases. There was more than one band of POD isozymes bands in both cultivars; isozyme I appeared in Sakha93 and isozyme II appeared in Misr1. The intensity of the two isozymes bands gradually decreased by all NaCl concentrations.
AOX expression of Misr1 was decreased by 50% following treatment with 75 mM NaCl, however, 150 mM led to 25% upregulation while 225 mM NaCl resulted in a sharp diminution. In Sakha93, 150 mM only led to a significant decrease by 60%.
The transcript level of NHX1 of Misr1 was increased by 75 mM NaCl, nonetheless, 150 and 225 mM led to significant decreases by 50 and 60%, respectively. In Sakha93, 75 and 150 mM NaCl induced significantly increases by 30% and 2 folds, respectively while 225 mM caused 30% decreases.
Summary
871
SOS1 transcript level of Misr1 was gradually decreased by 40 and 50% following treatment with 75 and 150 mM NaCl, respectively while 225 mM seemed with no effect. The contrast was observed in Sakha93, while 225 mM caused 75% diminutions. 75 and 150 mM NaCl had no effect.
The application of CaCl2 or glycine counteracted to great extent the deleterious effects of NaCl; the recovery was more obvious in Misr1 than in Sakha93. These additives seemed to ameliorate wheat tolerance to NaCl particularly in the less sensitive cultivar, Misr1. These findings indicate a repair in the buffering system used in wheat by the supplementary CaCl2 or glycine. There was an induction in AOX expression in Misr1 rather than Sakha93 suggesting an increase in Misr1 tolerance to NaCl. CaCl2 may make a signal to induce salt responsive genes in Misr1 but not in Sakha93. It up regulated NHX1 expression mostly in Misr1. Glycine increased mRNA of NHX1 implying that the significant recovery in fresh weight in Misr1 could be attributed to alleviate the toxicity of Na. Glycine did not prevent growth reduction in Sakha93 but withdrew the increments in Na suggesting a positive relation between NHX1 expression and alleviation of NaCl-induced deteriorations particularly in Misr1. Up regulation of NHX1 in Sakha93 could not improve growth or minimize salt injury due to the accumulation of Na. CaCl2 increased SOS1 expression in Misr1 suggesting that calcium could be a signal. So, lowing Na by CaCl2 and mitigation of the decrease in K/Na ratio synchronous with recovery in growth reduction may emphasize the alleviation role of CaCl2 by stimulating high SOS1 expression especially in Misr1. Glycine up regulated SOS1 expression and may reflect the role of glycine in mitigating salinity stress by stimulating SOS1 expression.
These findings conclude that some additives like CaCl2 and glycine are more efficient in amelioration of tolerance of some wheat cultivars. Therefore, this amelioration of tolerance would be regarded as cultivar-dependent due to some inherit characteristics. Moreover, some metabolomics that may act as osmoregulants and osmoprotectants are essential to cope with harsh conditions.