Detection of ROS
Histochemical staining was used to detect ROS in leaf tissue as described previously (Fryer et al. , 2002). The leaves of 2-month-old WT and OE lines were sprayed with SA. At 0, 0.5, 1, or 3 h after spraying with SA, the leaves were stained with DAB solution (1 mg/ml DAB-HCl, pH 3.8; Sigma-Aldrich) in the dark for 8 h at 37 °C. The stained leaves were immersed in 70% alcohol to remove chlorophyll and then observed and photographed.