Differential tolerance of two wheat cultivars to NaCl is related to antioxidant potentialities

Treatment of nine-day-old seedlings of two wheat cultivars (Misr1 and Sakha93) for 15 days by NaCl at 75, 150, and 225 mM led to significant decreases in fresh and dry weights of only Sakha93, although the growth parameters of both cultivars were mostly similar under normal conditions. All the concentrations led to significant accumulations of MDA and H2O2 in Sakha93 while in Misr1, the increases were detected only with 150 and 225 mM. On the contrary, reducing power was significantly diminished in Sakha93 by all concentrations of NaCl as well as in Misr1 by 225 mM. On the other hand, the phenolic contents were highly elevated in Sakha93 by all concentrations of NaCl; however, only 225 mM caused a significant increase. Also, all concentrations of NaCl decreased both protein and GSH in Sakha93; nonetheless, all concentrations had no significant effects except for the decreases in protein by 225 mM. The activities of the enzymatic antioxidants, CAT, POD, GST, and GR, in spite of being slightly increased in Misr1 by low NaCl concentrations, were significantly inhibited in Sakha93 by all concentrations. These results suggest that Misr1 is less sensitive to NaCl than Sakha93. The accumulations of MDA and H2O2 in Sakha93 concomitant with the decreases in GSH reveal that scavenging of ROS is less efficient in the more sensitive than the less sensitive cultivar which seemed to tolerate NaCl maybe because of the efficiency of the inducible potential antioxidants.