Differential effects of mannitol on gibberellin-regulated phospholipid synthesis and enzyme activities of the CDP-choline pathway in barley aleurone cells.

When barley aleurone layers are treated with gibberellic acid (GA3) in the presence of increasing concentrations (0.2-0.8 M) of mannitol, the rate of (32)Pi incorporation into phospholipids becomes progressively inhibited. Mannitol does not affect this process in aleurone layers not treated with GA3, nor does it appreciably inhibit GA3-effected increases of (32)Pi incorporation into organic phosphates or the activities of the particulate enzymes of the CDP-choline pathway. These results suggest that some of the early events controlled by GA3 can be separated from later activities regulated by the hormone, including α-amylase synthesis.