Studies on phenylalanine ammonia-lyase activity in cultures of Pinus Elliottii

Phenylalanine ammonia-lyase ( PAL ) activity increased 10- to 15-fold in pine callus tissue upon subculturing to new medium. The stimulation of PAL activity was maximum 2 days after transfer. The increase in PAL activity was followed by a subsequent decrease in activity. PAL activity in the callus tissue also was stimulated by premature subculturing if the subculturing was done after PAL activity had begun to decline. The stimulation of PAL activity was only moderately affected by cycloheximide, whereas, the decay in PAL activity was sensitive to cycloheximide. The increase in PAL activity was sensitive to temperature with low temperatures delaying the stimulation of PAL activity. Low temperatures also prevented the decay of activity. Sucrose was the principle nutrient that affected PAL activity. Under laboratory conditions physical injury, light and dark conditions did not affect PAL activity.