Cadmium effects on carbonic anhydrase, photosynthesis, dry mass and antioxidative enzymes in wheat (Triticum aestivum) under low and sufficient zinc

摘要

Leaf carbonic anhydrase (CA) activity, net photosynthetic rate (PN), stomatal conductance (gs) and plant dry mass (DM) exhibited a dose-dependent response to cadmium (Cd) in wheat (Triticum aestivum L.) grown under low and sufficient zinc (Zn) levels at 30 d after seedling emergence in sand culture. Cadmium at 10 uM concentration enhanced CA, PN and DM at low Zn level but these remain unaltered at sufficient Zn, Stomatal conductance decreased with increasing CdCl2 concentration at both the Zn levels. Cd higher than 10 uM inhibited the characteristics irrespective of Zn level. The activity of super oxide dismutase (SOD) was not'saturated the with highest Cd concentration (50 uM) at both the Zn levels. However, the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) increased up to 25 uM Cd and decreased at 50 uM Cd at both the Zn levels It is suggested that CA activity was induced at low Cd (10 uM) under low Zn level increasing the photosynthesis. The synergies among the activities of antioxidative enzymes helped to maintain CA and thus photosynthesis and plant DM at low Cd concentration under low Zn level.