Sequential Induction of Phenylalanine Ammonia-lyase and a Lyase-inactivating System in Potato Tuber Disks

The light induced synthesis of phenylalanine ammonia-lyase in disks cut from potato tubers is very sensitive to cycloheximide. Synthesis is inhibited 50% in disks cultured on 5 μm cycloheximide instead of water and almost completely in disks aged in the presence of 10 μm inhibitor. Inhibition is irreversible. Fresh disks exposed only 1 hour to 10 μm cycloheximide do not synthesize enzyme during the subsequent 24 hours.