Cytochrome c oxidase of the cyanobacterium Synechocystis sp. PCC 6803 protects photosynthesis from salt stress

We generated cytochrome c oxidase (CtaI)-defective cells of the cyanobacterium Synechocystis sp. PCC 6803 in order to investigate the physiological function of the CtaI-mediated respiratory electron transport pathway. When they were salt stressed, CtaI-defective cells showed a substantial decrease in photosynthesis due to reduction of the photochemical efficiency of Photosystem II and of the chlorophyll in the reaction center of the photo-oxidizable form of Photosystem I. These findings demostrate that CtaI-mediated electron transport is important for resistance to salt stress.