Rapid Correlation between the Leaves of Spinach and the Photocontrol of a Peroxidase Activity

The activity of a basic peroxidase extracted at high pH from spinach (Spinacia oleracea) leaves is modified by an irradiation with 2-minute red light or 2-minute far red light. This fast response, apparently mediated by phytochrome, is also detected in other leaves darkened with black paper. It is proposed that some fast signal moves from irradiated to darkened leaves. This signal, but not the direct control of peroxidase activity in irradiated leaves, is suppressed by inhibitors known for their effect on Na(+) or K(+) distribution (ouabain, lithium, tetrodotoxin, tetraethylammonium). Substances affecting Ca(2+) distribution inhibit both the signal transmission and the direct photocontrol of peroxidase activity.