Fig. 4.

Effect of Al on ROS formation in the root apex. 3-d-old seedlings of WT, OX1, and OX2 were exposed to a 0.5 mmol l^–1 CaCl₂ solution (pH 4.5) containing 0 or 50 µmol l^–1 AlCl₃ for 6h. Root tips (0–10mm) were excised. (A) The root tips stained with DAB, bar=500 µm. (B) Section (50 µm) at 3mm from apexes stained with DAB, bar=50 µm. (C) The content of H₂O₂. Values are means±SE (n=3). (D) The root tips stained with NBT, bar=500 µm. (E) Section (50 µm) at 3mm from apexes stained with NBT, bar=50 µm. (F) The content of O₂ ^–, values are means±SE (n=3). Means with different letters are significantly different (P<0.05 by Tukey test). (This figure is available in colour at JXB online.)