Relaxation of the flash-induced fluorescence yield in darkness. QA− reoxidation was monitored from dark-adapted wild-type (WT; black squares), ∆cox (red circles), ∆cox/cyd (green diamonds), and ∆cox/cyd (purple diamonds) cells preilluminated with FR light for 30 s (A) and in the presence of 20 μm
DCMU (B). Values are means ± sd, n = 3. The F0 and Fm values were normalized to 0 and 1, respectively, to facilitate comparison of the kinetics. r.u., Relative units.