Figure 6. Indole-containing volatile blends enhance priming of neighbouring plants.

Hybrid maize seedlings (var. Delprim) were exposed to indole-deficient igl-mutant or Igl-wild-type infested plants for 12 h. They were then elicited by wounding and application of Spodoptera littoralis regurgitant and put in clean vessels. VOCs were collected for 600 min. HIPV emission of hybrid maize plants exposed to induced volatiles from igl-mutant (Cross A: line 22; Cross B: line 32R) or Igl-wild-type plants (Cross A: line 7; Cross B: line 16R) are shown. Sums of volatiles of the four major families of HIPVs are presented: green leaf volatiles, monoterpenes, homoterpenes and sesquiterpenes. For individual compounds, see Supplementary Figs 12 and 13. Asterisks indicate statistical differences between release rates from control- and indole-exposed plants (Holm-Sidak post hoc tests, *P<0.05, **P<0.01, ***P<0.001, n=5). F-values (F), P-values (P) and residual degrees of freedom (df) are shown for ANOVAs comparing total emissions between treatments and genotypes. Error bars correspond to standard errors (±s.e.). For individual compounds, see Supplementary Figs 10 and 11.