Fig. 1.

. The apple carotenoid biosynthetic pathway with arrows showing enzymatic conversions of substrates from the isoprene biosynthesis pathway. CRH-β, β-carotene hydroxylase; CRH-ε, epsilon-carotene hydroxylase; CRTISO, carotene isomerase; DMAPP, dimethylallyl diphosphate; GGPPS, geranyl geranyl pyrophosphate synthase; IPP, isopentenyl pyrophosphate; IPPI, isopentenyl pyrophosphate isomerase; LCY-β, β-lycopene cyclase; LCY-ε, epsilon lycopene cyclase; NXS, neoxanthin synthase; PDS, phytoene desaturase; PSY, phytoene synthase; VDE, violaxanthin de-expoxidase; ZDS, φ-carotene desaturase; ZEP, zeaxanthin epoxidase; ZISO, φ-carotene isomerase.