HPLC-PDA determination of differentially accumulated metabolites in herbivory-elicited leaves of AT1-, DH29-, and CV86-VIGS plants. Caffeoylputrescine (A), dicaffeoylspermidine (B), and monocaffeoylspermidine (C) contents, expressed as CGA equivalents, were determined in control (Cont) and 4-d continuously M. sexta neonate-fed leaves (Herb). VIGS plants treated with an EV construct were used as controls in all experiments; EV1 and EV2 show controls in two VIGS experiments conducted with AT1 (EV1) and DH29 + CV86 (EV2), respectively. Asterisks or different letters indicate significantly down- and up-regulated metabolites in response to silencing of the respective acyltransferase gene activity as follows: AT1-EV1, Student’s t test, * P < 0.05 (*), ** P < 0.05 (n = 5); DH29-CV86-EV2, one-way ANOVA (n = 5). FM, Fresh mass.