Plays a crucial role in plant growth and development. Is essential for the biosynthesis of carotenoids. Carotenoids are involved in different physiological processes, including coloration, photoprotection, biosynthesis of abscisic acid (ABA) and chloroplast biogenesis (PubMed:17468780, PubMed:24907342). Catalyzes the conversion of zeta-carotene to lycopene via the intermediary of neurosporene. It carries out two consecutive desaturations (introduction of double bonds) at positions C-7 and C-7'. Shows stereoselectivity toward trans C15-C15'zeta-carotene double bond. The zeta-carotene produced by the phytoene desaturase PDS has a C15-C15' double bond in the cis configuration and it requires isomerization before being recognized as substrate by ZDS. The main product is 7,9,7',9'-tetra-cis-lycopene (pro-lycopene) (PubMed:9914519). 9,9'-di-cis-zeta-carotene + 2 a quinone = 7,7',9,9'-tetra-cis-lycopene + 2 a quinol Lipophilic quinones such as decyl-plastoquinone or decyl-ubiquinone. Carotenoid biosynthesis; lycopene biosynthesis. Highly expressed in leaves. Expressed at low levels in flowers and siliques. Albino seedling due to defect in pigmentation, growth arrest shortly after germination, altered leaf development, and seedling lethality. Belongs to the zeta carotene desaturase family.