Figure 4. The state II to I transition of qT and qE induction during dark to light exposure.

Pre high light-treated wild-type cells were placed in state II by dark-adapting for various intervals. Actinic light at 474 μmol quanta m⁻² s⁻¹, as used to induce a transition to state I and activate qE, is indicated by the white bar on the X-axis. (a) The qE of cells dark adapted for 3 min (squares), 11 min (circles), 20 min (triangles) or 45 min (diamonds), calculated for all using the F_m^o after 45 min dark adaptation. (b) O₂ content of the media (lines are labelled with the time of dark adaption) simultaneously measured during a fluorescence quenching analysis. (c) The F_m’ values used to calculate qE using the same symbols in (a). In (c) the dashed green arrows of F_m changes indicate 1) rapid qE of state II cells, 2) rapid qT transition to state I, 3) slower qT transition to state I, and 4) qE of state I cells (see text for details).