Figure 4: Plants are given a spike in CO2, which induces
oscillations in electron transport. In the first phase, photosynthesis
is unlimited by TPU and PSI becomes more oxidized by the addition of
extra CO2, while proton conductivity remains high. The
second phase (blue) is the earliest effect of TPU limitation and is
primarily described by PSI and Qa quickly become reduced
(measured as PSI ox and qL ), along with
constriction of proton flow across the thylakoid membrane
(gH+ ) and electron flow to PSI
(ket ) blue-shaded region). The third phase
(green) begins when slower regulations, which depend on proton-motive
force (measured as ECSt ), energy dependent
quenching (NPQt ) and photoprotection at
cytochrome b6f complex, relieve reduction of the electron
transport chain. Finally, the electron transport chain enters a new
steady-state (red).
Figure 5