Light-Dependence of Phospholipase D Activity in Oat Seedlings

The effect of light on the activity of phospholipase D (PLD) in oat (Avena sativa L.) seedlings and the dependence of this enzyme activity on the regime of their illumination were studied. The PLD activity in etiolated seedlings was 1.5–2.0-fold higher than in green plants. The illumination of etiolated seedlings with white light resulted in a decrease in PLD activity to its level in the seedlings grown under light. In contrast, the transfer of green seedlings to darkness enhanced the activity of the enzyme up to its level in etiolated seedlings. The illumination of etiolated seedlings with red light inhibited the PLD as well. It was shown that this photoeffect decreased with seedling aging and correlated with a phytochrome content in plants. Far-red light reversed the effect of red light. The involvement of phytochrome in the control of the PLD activity is discussed.