A proposed working model for CYP37-mediated photosynthetic electron transport under GL and HL conditions. A and B) Electron transport in WT and cyp37 mutant plants under GL conditions. C and D) Electron transport in WT and cyp37 mutant plants under HL conditions. GL conditions and HL conditions were marked with light blue (upper panel) and light yellow (lower panel) backgrounds, respectively. Solid red lines indicate the LET process. Dashed blue lines indicate the CET process. Distinct arrow line thickness indicates different electron flow efficiency. ROS, reactive oxygen species; PSII, photosystem II; PSI, photosystem I; Cyt b6/f, Cytochrome b6/f; OEC, oxygen-evolving complex; FNR, ferredoxin NADP⁺ oxidoreductase; Fd, ferredoxin; PC, plastocyanin; PQ, plastoquinone.