pgr5 suppressor screen uncovers a distinct mechanism safeguarding the cytochrome b6f complex from damage through PGR5

PROTON GRADIENT5 (PGR5) is thought to promote cyclic electron flow (CEF) and its deficiency causes increased photosensitivity of photosystem I (PSI), leading to lethality under fluctuating light (FL). By screening for suppressor mutations that rescue FL lethality of pgr5 plants, we identified a portfolio of mutations affecting 12 photosynthesis-related proteins. Here we performed a proteomic analysis to compare a mutant lacking PGR5 vs wildtype ( at2g04360-1/pfsc1-1 vs. Col-0)