Figure 1 The P515 fast kinetics induced by a single turnover saturating flash (A) The diagram of P515 fast kinetics induced by a single turnover saturating flash, rapid ascent stage (orange), slow ascent stage (blue) and slow descent stage (green), the arrow indicated a single turnover saturating flash (ST); (B) The rapid absorption changes of Chlamydomonas reinhardtii cells (WT) at 520-550 nm induced by a ST (the wavelength of ST was 635 nm, the light intensity was 200000 μmol·m-2·s-1 and the duration was 5 μs), WT (concentration 25 μg·mL-1) was incubated with (red) and without (black) 10 μmol·L-1 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 1 mmol·L-1 hydroxylamine (HA) for 20 min in darkness; (C) The affection of preillumination to the P515 fast kinetics, WT algae was incubated in darkness for 20 min (black) and preilluminated for 2 min at 40 μmol·m-2·s-1 followed by 1 min dark (red).

Figure 2 Detection the H+ conductivity of chloroplast ATP synthase in Arabidopsis thaliana The detached leaf of Arabidopsis thaliana was exposed to light (635 nm, 500 μmol·m-2·s-1) for 10 min, and provided stable CO2 (380 μmol·mol-1), humidity (60% atmospheric humidity) and temperature (23°C) during illumination. Detected the P515 decay kinetics curve in darkness that lasted 250 ms, the curve corresponded to 100 independent biological replicates. The H+ conductivity of ATP synthase was 94.3·s-1, which is the reciprocal of the half-time (t1/2) of P515 decay kinetics curve. The arrow indicated light off.

Figure 3 Detection the cyclic electron flow rate around photosystem I in Chlamydomonas reinhardtii The C. reinhardtii cells (WT) and PGR5 mutant (Mutant) were exposed to light (635 nm, 80 μmol·m-2·s-1) for 5 min. The cyclic electron flow rate was detected after the light was turned off and the darkness duration was 250 ms. Before measurement, algal cells (about 25 μg·mL-1) were incubated with 10 μmol·L-1 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 1 mmol·L-1 hydroxylamine (HA) and 20% ficoll for 20 min in darkness. The arrow indicated light off.

Figure 4 Detection the proton motive force (pmf) and its two components (Δψ and ΔpH) in Arabidopsis thaliana The detached leaf of Arabidopsis thaliana was exposed to light (635 nm, 100 μmol·m-2·s-1, labeled as WT 100, black and 750 μmol·m-2·s-1, labeled as WT 750, red) for 3 min, and provided stable CO2 (380 μmol·mol-1), humidity (60% atmospheric humidity) and temperature (23°C) during illumination. The dark time was 60 s and the curve corresponded to 3 independent biological replicates. The Arabidopsis leaf was darkly adapted for at least 3 hours before measurement. The up arrow indicated light on, and the down arrow indicated light off.

Figure 5 Simultaneous measurement of the P515 signal and fluorescence in Chlamydomonas reinhardtii The C. reinhardtii cells (WT, about 30 μg·mL-1) were placed in the chamber of the chlorophyll fluorometer after dark adaptation for 20 minutes. The measuring lights of the P515/535 module and the chlorophyll fluorescence module were turned on respectively to determine the original fluorescence yield (Fo). Then a saturating pulse (635 nm, 6000 μmol·m-2·s-1, duration 250 ms) was turned on to detect the maximal fluorescence yield (Fm) in darkness. Then an actinic light (635 nm, 1500 μmol·m-2·s-1) was turned on for 140 seconds, during which a saturating flash was applied every 60 seconds to detect the maximum fluorescence yield (Fm') under light. The proton motive force (pmf) and its components (ΔΨ and ΔpH) were measured after the actinic light was turned off, meanwhile a saturating pulse was applied every 60 seconds to check whether the fluorescence yield was restored to the maximum fluorescence yield (Fm) in darkness. Fo: Original fluorescence yield; Fm: Maximal fluorescence yield; Fm′: Maximal fluorescence yield under light; Fs: Steady state fluorescence yield; pmf: Proton motive force; ΔΨ: Transmembrane potential; ΔpH: Transmembrane proton gradient