Figure 1. Kinetics of (A) jasmonic acid (JA) and (B) salicylic acid (SA) accumulation in response to herbivory. Phytohormone levels were measured in Zea mays leaves after 0 h, 3 h, 6 h and 24 h of caterpillar feeding. C, control plants grown without added copper; CuL, plants exposed to 10 µM Cu; CuH, exposed to 80 µM Cu. **p < 0.01, Kruskal-Wallis ANOVA followed by median test. Symbols depict mean values (± SE), n = 7.