Fig. 1

β-Cyanoalanine (a) and benzyl cyanide (b) accumulate after herbivore feeding on Populus trichocarpa leaves. L. dispar-damaged leaves (herb) and undamaged control leaves (ctr) were extracted with methanol (a) or hexane (b) and analyzed via LC-MS/MS and GC-MS, respectively. Means and SE are shown (n = 10 biological replicates). Significant differences between the two treatments in Student’s t-tests are indicated (asterisks; p < 0.001). FW, fresh weight. Other nitriles such as 2-methylbutyronitrile and 3-methylbutyronitrile that have been described as components of the herbivore-induced volatile blend of P. trichocarpa [16] could not be detected in the hexane extracts