Light harvesting and chloroplast electron transport in NADP-malic enzyme type C4 plants

• Published in: Current opinion in plant biology 2016-06, Vol.31, p.9-15
• Main Author: Nakajima Munekage, Yuri
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Chloroplasts - metabolism; Electron Transport - physiology; Malate Dehydrogenase - metabolism; NADP - metabolism; Photosynthesis - physiology; Photosystem I Protein Complex - metabolism
• ISSN: 1369-5266; 1879-0356
• DOI: 10.1016/j.pbi.2016.03.001

•Cyclic electron transport occurs predominantly in the grana-reduced chloroplasts.•NDH complex is enriched in the bundle sheath chloroplasts in NADP-malic enzyme type species.•Abolition of grana structure occurred during the last stage of C4 evolution.•Phosphorylation dependent mechanisms are predicted to be involved.•Reorganization of electron transport system optimizes the production of ATP/NADPH. The structure of thylakoids in chloroplasts and the organization of the electron transport chain changed dynamically during the evolution of C4 photosynthesis, especially in the nicotinamide adenine dinucleotide phosphate (NADP)-malic enzyme type C4 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 C4 photosynthesis. This review summarizes the current model of light harvesting and electron transport in the NADP-malic enzyme type C4 plants and discusses how it changed during the evolution of C4 photosynthesis.