Research on photosynthetic oscillations supports the classical concept of cyclic electron transport producing ATP

Abstract

Cyclic electron transport (CET) around PSI was discovered seven decades ago (Arnon et al., 1954). Nevertheless, its precise physiological function has only recently become the focus of investigation. PROTON GRADIENT REGULATION 5 (PGR5)-dependent CET contributes to photoprotection by acidifying the thylakoid lumen (Munekage et al., 2002; Suorsa et al., 2012). While the generation of pH concurrently stimulates ATP synthesis, it has not been experimentally proven how PGR5-dependent CET contributes to ATP synthesis during steady-state photosynthesis. Degen et al. (2024) have successfully monitored the contribution of PGR5- dependent CET to photosynthesis in planta by studying oscillations of photosynthesis.