Promotion of cyclic electron transport around photosystem I during the evolution of NADP–malic enzyme‐type C₄ photosynthesis in the genus Flaveria

• Published in: The New phytologist 2013-08, Vol.199 (3), p.832-842
• Main Authors: Nakamura, Naoya, Iwano, Megumi, Havaux, Michel, Yokota, Akiho, Munekage, Yuri Nakajima
• Format: Article
• Language: English
• Subjects: Biological taxonomies; Bundle sheath cells; C3 plants; C4 evolution; C4 photosynthesis; C4 plants; Carbon - metabolism; Chloroplasts; cyclic electron transport; electron transfer; Electron Transport; evolution; Evolution, Molecular; Flaveria; Flaveria - enzymology; Flaveria - physiology; Grana; Kinetics; Malate Dehydrogenase - metabolism; mesophyll; Mesophyll Cells - metabolism; Mesophyll Cells - ultrastructure; NAD (coenzyme); Oxidation; Photosynthesis; photosystem I; Photosystem I Protein Complex - metabolism; Plant cells; Plant Proteins - metabolism; Plants; proteins; thylakoid structure; Thylakoids; Thylakoids - metabolism; Thylakoids - ultrastructure
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.12296

C₄ plants display higher cyclic electron transport activity than C₃ plants. This activity is suggested to be important for the production of ATPs required for C₄ metabolism. To understand the process by which photosystem I (PSI) cyclic electron transport was promoted during C₄ evolution, we conducted comparative analyses of the functionality of PSI cyclic electron transport among members of the genus Flaveria, which contains several C₃, C₃–C₄ intermediate, C₄‐like and C₄ species. The abundance of NDH‐H, a subunit of NADH dehydrogenase‐like complex, increased markedly in bundle sheath cells with the activity of the C₄ cycle. By contrast, PROTON GRADIENT REGULATION5 (PGR5) and PGR5‐LIKE1 increased in both mesophyll and bundle sheath cells in C₄‐like Flaveria palmeri and C₄ species. Grana stacks were drastically reduced in bundle sheath chloroplasts of C₄‐like F. palmeri and C₄ species; these species showed a marked increase in PSI cyclic electron transport activity. These results suggest that both the expression of proteins involved in PSI cyclic electron transport and changes in thylakoid structure contribute to the high activity of cyclic electron flow in NADP–malic enzyme‐type C₄ photosynthesis. We propose that these changes were important for the establishment of C₄ photosynthesis from C₃–C₄ intermediate photosynthesis in Flaveria.