Differential response of antioxidant enzymes to salinity stress in two varieties of Azolla (Azolla pinnata and Azolla filiculoides)

The activity and modulation of antioxidant components were comparatively analyzed in two varieties of Azolla (Azolla pinnata and Azolla filiculoides) under different concentrations of NaCl. The total superoxide dismutase (SOD) and ascorbate peroxidase (APX) activity increased in A. pinnata, whereas both enzyme activities decreased in A. filiculoides. The plants of A. pinnata exposed to 30 mM NaCl contained a lower amount of Na+ ions and showed a lower electrolyte leakage than A. filiculoides. Our studies indicate a differential response of antioxidant enzymes in relation to salt tolerance in Azolla plants. On the basis of our comparative analysis, A. pinnata has been ranked salt tolerant as compared with A. filiculoides, which is salt sensitive.