Figure 3.

Expression of genes and concentrations of metabolites related to defence signalling in primary roots of Brassica oleracea var. gemmifera plants induced by above‐ground (Brevicoryne brassicae and Plutella xylostella) and below‐ground (Delia radicum) insect herbivores. The red panel shows genes related to biosynthesis of defence‐related phytohormones, namely AOS (a), ABA2 (b), ACS (c), and PAL (d) as markers for biosynthesis of jasmonic acid, abscisic acid, ethylene, and salicylic acid, respectively. The green panel shows concentrations of jasmonate precursor cis‐OPDA (e), bioactive jasmonates JA (f) and JA‐Ile (g), and JA catabolite OH‐JA (h). The blue panel shows genes regulated by JA, transcription fators MYC2 (i) and ORA59 (k), and downstream genes VSP2 (j) and PDF1.2 (l). Time points indicate time since D. radicum induction, plants were infested with above‐ground herbivores 48 hr prior to this. Error bars indicate standard errors of the mean, N = 5, each sample represents three pooled plants. Different letters indicate statistically significant differences between treatments within a time point (Tukey's least significance difference, p < .05) [Colour figure can be viewed at http://wileyonlinelibrary.com]