PAL activity was measured as described by Assis et al. (2001) with some modifications. One-half milliliter enzyme extract was added to 2 mL of 50 mM borate buffer (pH 8.8) and 0.5 mL of 20 mM l-phenylalanine and the solution incubated at 37 ◦C for 1 h. The reaction was terminated by addition of 0.1 mL of HCl (6 M). The increase in absorbance at 290 nm due to the formation of transcinnamate was measured spectrophotometrically. PAL activity was expressed as U kg−1 protein, where U = 0.01 A290 s−1.