The series of reactions in which 9,9'-di-cis-zeta-carotene is desaturated to 7,9,9'-tri-cis-neurosporene, and then 7,9,7',9'-tetra-cis-lycopene. The overall reaction for this process is: 9,9'-di-cis-zeta-carotene + 2 quinone = 2 quinol + 7,9,7',9'-tetra-cis-lycopene.