Figure 1. Overview of the carotenoid biosynthetic pathway in green microalgae and diatoms. Arrows indicate directions of the reactions. Dashed lines and solid lines represent multiple and single steps of enzymatic reactions, respectively. Green and orange dots refer to carotenoid species present only in green algae and only in diatoms, respectively, while gray dots show carotenoids which are present in both green algae and diatoms. Names of green microalgae are shown in green boxes, while the diatom Phaeodactylum is shown in an orange box. Abbreviations: phyto, phytoene; lycop, lycopene; d-car, δ-carotene; e-car, ε-carotene; a-car, α-carotene; lute, lutein; g-car, γ-carotene; b-car, β-carotene; b-cryp, β-cryptoxanthin; zeax, zeaxanthin; anthx, antheraxanthin; violx, violaxanthin; neox, neoxanthin; astax, astaxanthin; diadx, diadinoxanthin; diatx, diatoxanthin; fucox, fucoxanthin.