Fig. 2

Benzyl cyanide can be converted into phenylacetic acid in vivo in herbivore-damaged Populus trichocarpa leaves. Single leaves of P. trichocarpa were placed in water and damaged by L. dispar-feeding for 24 h, followed by a 24 h exposure either to volatile [α-¹³C]benzyl cyanide dissolved in hexane or to pure hexane (a). The conversion of [α-¹³C]benzyl cyanide into [α-¹³C]phenylacetic acid is likely catalyzed by a nitrilase (b). Accumulated [α-¹³C]benzyl cyanide was extracted from leaf material with hexane and analyzed using GC-MS (c). ¹³C-labeled (d) and unlabeled (e) phenylacetic acid were extracted from leaf material with methanol and measured using LC-MS/MS. Labeled (f) and unlabeled (g) phenylacetic acid could also be detected in the water, in which leaf petioles were placed during the experiment. Means and SE are shown (n = 5 biological replicates). A two way ANOVA with square root-transformed raw data was performed to test for significance (p < 0.05). ctr-hexane, undamaged leaves exposed to hexane; ctr-[α-¹³C]BC, undamaged leaves exposed to volatile [α-¹³C]benzyl cyanide dissolved in hexane; herb-hexane, herbivore-damaged leaves exposed to hexane; herb-[α-¹³C]BC, herbivore-damaged leaves exposed to volatile [α-¹³C]benzyl cyanide dissolved in hexane