Measurement of ascorbate peroxidase (APX) and superoxide
dismutase (SOD) activities
A leaf blade was homogenized by the enzyme extract solution [50 mM
potassium phosphate buffer (pH 7.0), 1 mM EDTA, 20% (w/v) sorbitol, 5%
(w/v) polyvinylpyrrolidone, 1% (w/v) Tween-20, and 1 mM ascorbate]
with quartz sand. The APX activities were measured by following Amako et
al. (1994). The SOD activities were measured according to Flóhe &
Ötting (1984).