Nuclear Suppressors of the Photosensitivity Associated with Defective Photosynthesis in Chlamydomonas reinhardii.

Several nuclear mutations were recovered that suppress the photosensitivity associated with the Chamydomonas reinhardii chloroplast mutant rcl-u-1-10-6C, which is defective in ribulose-1,5-bisphosphate carboxylase/oxygenase. Two of the suppressor mutations affect other components of photosynthesis. These results show that suppressors of photosensitivity are sufficiently common to permit the recovery of photosensitive, photosynthesis-deficient mutants in bright light, and indicate that photosynthesis-deficient mutants selected and maintained in the light may accumulate suppressors which can confuse the biochemical analysis of lesions in photosynthesis. One of the suppressor mutations inhibits photosystem II activity, indicating that photosensitivity can be mediated by partial reactions of the photosynthetic electron transport chain.