Figure 7.

ROS staining and ROS-scavenging enzyme activities in ohp1-1 mutants. (A) Leaves of 4-week-old ohp1-1 mutants and WT plants cultivated under continuous illumination at 15 μmol photons m⁻² s⁻¹ were stained for H₂O₂ content with 3,3-diaminobenzidine or for ${\text{O}}_2^{-}$ content with NBT. Leaves were vacuum-infiltrated with staining solution and incubated for 2 h or 20 min, respectively, at 15 μmol photons m⁻² s⁻¹. Three representative leaves of each genotype are displayed. (B) Relative activities of the three superoxide dismutase (SOD) isoforms and catalase were quantified in leaf extracts by in-gel staining after native gel electrophoresis. SOD activities were normalized by the total SOD activity of WT leaves for each gel. Values represent the mean ± SD in relative units (N = 8 for SODs, N = 3 for catalase), asterisks indicate significant difference from the respective activity in WT leaves (p ≤ 0.02 in a Student's t-test).