Growth and morphology of wild-type and carotenoid biosynthesis mutant plants. Phenotypes of 6-weeks-old wild type (A), lut2 (B), chy1chy2lut5 (C), and chy1chy2lut2lut5 (D) plantlets, grown at 30 μmol photons m-2 s-1. (E) Biosynthetic pathway of carotenoids in A. thaliana; names of the enzymes controlling each step are indicated: lycopene ε-cyclase (LCY-ε); lycopene β-cyclase (LCY-β); β-carotene hydroxylase (CYP97A3); ε-β-carotene hydroxylase (CYP97C1); β-carotene hydroxylase 1 and 2 (CHY1, CHY2); zeaxanthin epoxidase (ZEP); violaxanthin deepoxidase (VDE); neoxanthin synthase (NXS). Names of Arabidopsis knock-out mutants are indicated in parentheses. Scale bar = 5 mm.