Preparation of plant extract
For assessment of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) enzymes activities, 500 mg of leaf tissue of both transgenic and wild type barley plants was frozen in liquid nitrogen followed by grinding in 5 mL of one step extraction buffer containing 100 mM phosphate buffer (pH 7.5), 0.5 mM EDTA and 1% PVP. The homogenate was filtered through 4 layers of cheese cloth followed by centrifugation at 15000x g for 20 min at 4oC. The supernatant was collected and used for assays as described below. All the steps in enzymes preparation and activity assays were carried out at 4 oC.