Kinetics of the antioxidant response to salinity in the halophyte Limonium bicolor

The fresh weight (fw) and dry weight (dw) of shoots and roots, the activity of anti-oxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)], and parameters of oxidative stress of shoots - malondialdehyde (MDA) - were investigated in Limonium bicolor, a naturally salt-resistant halophyte. The seedlings of L. bicolor were treated with different (0, 100, 200, 400 mmol/l) NaCl concentrations. The results showed that NaCl played an important role in growth of L. bicolor. It made obviously promotion of a certain NaCl concentration to growth of L. bicolor, the seedlings of L. bicolor grew best under 100 mmol/l salt concentration, fresh weight and dry weight reached the maximum. MDA concentration of shoots slightly decreased under 100 mmol/l salt stress, then increased with increased NaCl concentration. The activities of SOD, POD and CAT increased with the increase of the concentration of NaCl in shoots of L. bicolor. The salt tolerance of this halophyte under salt stress conditions is probably due to its ability to exhibit high SOD, POD and CAT enzyme activities and low levels of oxidative stress.