Fig. 9.

d-Arginine (d-arg) and guazatine treatments altered ROS accumulation, activity, and transcripts of antioxidant enzymes. (a–d) Treatment with d-arg increased ROS accumulation in the transgenic lines (#8, #10) after dehydration stress. The transgenic lines were pre-treated with water (0mM) or 1, 5, and 10mM d-arg for 3 d prior to 90min of dehydration. Accumulation of H₂O₂ (a, b) and O₂ ^– (c, d) was quantitatively measured (a, c) or histochemically detected using DAB (b, for H₂O₂) and NBT (d, for O₂ ^–). (e, f) Guazatine treatment reduced the accumulation of H₂O₂ in the wild type (WT) and transgenic lines after dehydration. The transgenic lines and the WT were pre-treated with water (0mM) or 5mM and 10mM guazatine for 3 d before they were exposed to 90min of dehydration. Accumulation of H₂O₂ was quantitatively measured (e) or histochemically detected using DAB staining (f). (g, h) Expression levels (g) and activities (h) of the antioxidant enzymes SOD, POD, and CAT in transgenic lines and the WT pre-treated with water (0mM) or 5mM and 10mM guazatine. Asterisks indicate significant differences between inhibitor treatment and water treatment of the same line (*P<0.05, **P<0.01, ***P<0.001).