Effect of plant activator protein on tomato defence enzyme

The induced resistance was studied in tomato leaves treated with 2 μg/mL plant activator protein. The phenylalanine ammonia-lyase(PAL), peroxidase(POD) and its isozyme,polypenoloxidase(PPO) and superoxide dismutase(SOD)concentration of tomato were tested. Results show the activities of defense enzyme in tomato leaves increased obviously. The activities of PAL peaked 1 day after the treatment while the activities of SOD, POD and PPO reached their maximum 4 days after the treatment.Compared with control, PAL, POD, PPO and SOD in treated leaves kept higher activities for 8 days during the experiment.Peroxidase isozyme in treated leaves reached the peak 3 days after inoculation 88.96% higher than that in the contro1,which could induce the thickening of the original isozyme bands and the expression of some new isozyme bands.