Research paper by Professor Yuri Munekage of School of Biological and Environmental Sciences and colleagues, elucidating the physiological functions of cyclic electron flow around photosystem I in C4 photosynthesis, is published in “Plant Physiology”.

Professor Yuri Munekage of the School of Biological and Environmental Sciences and colleagues published a research paper in the academic journal “Plant Physiology” (accepted on February 9, 2026), analyzing the physiological importance of cyclic electron transport around photosystem I (PSI) in C4 photosynthesis. This study revealed that PSI cyclic electron transport plays a crucial role in photosynthetic energy production and photoprotection in C4 photosynthesis. In C3 photosynthesis, which is common in many angiosperms, PSI cyclic electron transport is known to function as a pathway that helps regulate linear electron transport. This study analyzed double-suppressed (the PGRL1 and NDHO genes) transgenic lines of the C4 Flaveria bidentis, lacking activity in both pathways involved in PSI cyclic electron transport. C4 photosynthesis, which possesses CO2 concentration mechanisms, requires substantial ATP for metabolic reactions. Analysis using this double-knockout mutant revealed that electrons are cycled to form a proton gradient for ATP synthesis, thereby optimizing photosynthesis. Furthermore, two cyclic electron transport activities were shown to prevent photodamage caused by the over-reduction of photosystem I electron acceptors. These findings suggest that PSI cyclic electron transport activity plays a role in maximizing light energy utilization and maintaining high photosynthetic activity in C4 plants even under drought and high-temperature conditions. This discovery will contribute to molecular breeding efforts aimed at enhancing crop tolerance to high temperatures and drought.

 

 

Journal name: Plant Physiology
Article title: Cyclic electron flow around photosystem I provides energy production and photoprotection in C4 plants
Authors: Asuka Nakamura, Takako Ogawa, Ginga Shimakawa, Ryouhei Kobayashi, Toshiharu Shikanai, Yuri N. Munekage
DOI: 10.1093/plphys/kiag146