LIGHT-INDUCED RAPID CHANGES IN INOSITOLPHOSPHOLIPIDS AND PHOSPHATIDYLCHOLINE IN BRASSICA SEEDLINGS

We have investigated the effect of brief white light stimulus on the turnover of phosphoinositides and phosphatidylcholine in etiolated Brassica oleracea seedlings. A light pulse of 50 sec resulted in a significant decrease in labelled phosphatidylinositol-4-phosphate (PIP) and phosphatidylinositol-4-5-bisphosphate (PIP2), accompanied by an increase in inositol-1,4-bisphosphate (IP2) and inositol-1,4,5-trisphosphate (IP3). A gradual decrease was observed in phosphatidylcholine (PC) level when seedlings were irradiated for 10-60 sec, whereas phosphatidylinositol (PI) level increased throughout that duration. It is suggested that brief light stimulus triggers the overall phospholipid turnover, which may be a crucial step in the sequence of events that control plant cell proliferation and differentiation.