Lycopene biosynthesis in plants occurs via the central isoprenoid pathway beginning with the formation of phytoene
from geranylgeranyl diphosphate (GGPP) and four
desaturation steps (Li and Yuan, 2013). The first step of
carotenoid biosynthesis is catalysed by PSY1, a fruit-specific
phytoene synthase. CRTISO encodes carotenoid isomerase,
an enzyme that isomerizes poly-cis-lycopene to all-translycopene
(Isaacson et al., 2004)