Figure 7.

Activity of PSI in Mn deficiency. A) Normalized P700⁺ signal was obtained on thalli cultivated on Starch (+Mn, black, upper trace; −Mn, red, lower trace). The redox state of the PSI primary donor P700 was monitored through the changes in absorbance at 830 versus 875 nm. Leaves were kept in the dark for 5 min prior to the measurements. Thalli were exposed to actinic light for 15 s (white bar) and to far-red light until reaching a plateau (red bar). Then, a saturating flash was applied (yellow bar) and the decay was observed in the dark (gray bar). B) PSI donor-side limitation Y(ND) based on saturating pulse analyses. Following the initial determination of maximal oxidation of P700, actinic light of the indicated intensities was given for 180 s. Mean values and standard deviation are given (N = 6, 2 biological replicates).