This enzyme converts phytoene into lycopene via the intermediaries of phytofluene, zeta-carotene and neurosporene by the introduction of four double bonds. 15-cis-phytoene + 4 A = 4 AH2 + all-trans-lycopene Carotenoid biosynthesis; lycopene biosynthesis. Belongs to the carotenoid/retinoid oxidoreductase family.