Fig. 4.

Relative abundance of mRNA transcripts of genes coding for sesquiterpene synthases of P. sylvestris measured by quantitative RT-PCR. Transcripts of PsTPS 1 (a), PsTPS 2 (b) and PsTPS 3 (c) were compared in oviposition-induced pine twigs (black bars) and artificially wounded ones (gray bars) 48, 72, and 96 h after induction (for details see text). Data were normalized to ubiquitin, and calibrated against the 72 h artificially wounded control (set to 1.0). Each value shows the mean ± SE of at least three technical replicates of four (48 h), five (72 h), and three (96 h) independent biological samples. A two-way ANOVA was performed to test the significance of differences in transcript accumulation. n.s., not significant (for details see text and supplemental data S2)