PPO activity increased following Foa infection or JA treatment.
Fig. 4 shows that JA treatment hastened the rise in PPO activity
from the 12th days in both cultivars, whereas Foa infection did not
enhance PPO activity until days 24. At thatmoment, in Foa-infected
roots, the PPO activity was 2.2 and 1.3 times higher than in
untreated roots of cultivars BSTN and JHL, respectively.