Light harvesting and chloroplast electron transport in NADP-malic enzyme type C sub(4) plants

The structure of thylakoids in chloroplasts and the organization of the electron transport chain changed dynamically during the evolution of C sub(4) photosynthesis, especially in the nicotinamide adenine dinucleotide phosphate (NADP)-malic enzyme type C sub(4) species. Stacked grana membranes are strongly reduced in the bundle sheath chloroplasts of these plants, where photosystem II activity is diminished and cyclic electron transport around photosystem I mainly occurs. This change optimizes the ATP/NADPH production ratio in bundle sheath chloroplasts to drive the metabolic cycle of C sub(4) photosynthesis. This review summarizes the current model of light harvesting and electron transport in the NADP-malic enzyme type C sub(4) plants and discusses how it changed during the evolution of C sub(4) photosynthesis.