Gene structure of white spruce 3CAR (A) and CYP720B4 (B) and comparison of 3CAR with the grand fir ( Abies grandis ) limonene synthase (LIM) and pinene synthase (PIN) genes (C). Exons of the 3CAR and CYP720B4 genes matching the cDNA sequences are shown with grey arrows separated by introns. The UTRs are shown with grey lines. ATG, start codon. Putative cis-acting elements were identified using the PlantCare database and positions are highlighted in blue (not to scale): wun-box, wound-responsive element (Brassica oleracea); W-box, fungal elicitor responsive element (Petroselinum crispum); TCRR, TC-rich repeats, cis-acting element involved in defence and stress responsivenes (Nicotiana tabacum); TCA, cis-acting element involved in salicylic acid responsiveness (Brassica oleracea); TGACG, cis-acting regulatory element involved in the MeJA-responsiveness (Hordeum vulgare). LIM, AF326518; PIN, AF326517; roman numbers in part C indicate conserved exons in 3CAR, LIM and PIN; the scale bar represents 1 kbp.