Fig. 4

GC–MS analysis of transgenic callus tissues of McFPS A Verification of German chamomile resistant callus tissues by using hygromycin resistance gene primers. B qPCR analysis of transgenic callus tissues of McFPS. C–F Analysis of volatile components in transgenic callus tissues of McFPS by using GC–MS (C, γ-muurolene; D, δ-selinene; E, cis-β-farnesene; F, δ-neoclovene) Note: M: DNA marker; lines 1–2: non-transgenic control callus tissues; lines 3–6: independent putative transformants of resistant callus tissues. Error bars are shown with three biological replicates; ** indicates a very significant difference (p < 0.01). The 18S gene was used as the reference gene. The 2^−ΔCt method was used to calculate relative expression levels