FIGURE 7.

Superoxide and H₂O₂ staining of leaves pre-treated with Glu, MgCl₂ with or without 0.5 mM PG and after the subsequent cold stress. After the pretreatments with Glu, MgCl₂, or PG for 48 h at the room temperature, cold stress was performed at 4 ± 1°C for additional 72 h. Hydrogen peroxide and superoxide in leaves were visualized by DAB and NBT, respectively (A). Quantitative values for all the treatments are shown on the lower panel (B). F.W., fresh weight. Error bars show standard deviations (n = 3). Different lowercase letters indicate significant differences at 0.05 (P < 0.05) levels.