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.