Variation in volatile sesquiterpene emission and terpene synthase transcript levels among different sections of a herbivore-damaged leaf. (A) Emission of (E)-α-bergamotene and (E)-β-farnesene (TPS10 products) and (E)-β-caryophyllene (TPS23 product) from different leaf sections of maize variety Delprim after herbivory restricted to one section (in bold letters). One S. littoralis larva was enclosed for seven hours on the tip, the middle or the base, respectively, of the second fully expanded leaf. For terpene analysis, the leaves were divided into three equal parts (tip, middle, base) and volatiles were collected from tissue powder using SPME and analyzed by GC-MS. Data are means of four replications ± SE. Different letters with the same numbered superscripts (e.g. a1 and b1) indicate statistically significant (p<0.05) differences between the volatile measurement of the single leaf sections for each treatment and each sesquiterpene type. (B) Transcript levels of tps10 and tps23 in different leaf sections after herbivory restricted to one section. RNA was prepared from an aliquot of the tissue powder used for volatile analysis (see above). The samples were blotted and probes specific for tps10 and tps23 were used for hybridization. The 28S RNA is shown as a loading control on an ethidium bromide stained agarose gel.