Phosphoinositides in barley aleurone layers and gibberellic Acid-induced changes in metabolism

Phospholipids of barley (Hordeum vulgare L. cv Himalaya) aleurone layers were labeled with myo-2-³H]inositol or ³²Pi], extracted, and analyzed by physical (chromatography) and chemical (deacylation) techniques. Three phospholipids were found to incorporate both myo-2-³H]inositol and ³²Pi]—phosphatidylinositol, phosphatidylinositol-monophosphate, and phosphatidylinositol-bisphosphate. Stimulation of ³H]inositol prelabeled aleurone layers with GA₃ showed enhanced incorporation of label into phosphatidylinositol within 30 seconds and subsequent rapid breakdown. Stimulation of phosphatidylinositol labeling observed in these studies is the earliest response of aleurone cells to gibberellic acid reported.