Synergism of triggered luminescence by simultaneous treatment of pH transition and potassium addition in chloroplasts.

KCL-induced luminescence in relation to slow delayed light emission (greater than 3 s) and pH shift-triggered luminescence was studied in preilluminated chloroplasts. An activation pathway for KCl-induced luminescence similar to that for acidbase-triggered luminescence but different from that for delayed light emission is suggested. When the chloroplasts were subjected to a small amount of pH transition together with a simultaneous addition of KCl, a synergistic enhancement of triggered luminescence was observed. The synergism was not observed when the pH transition was increased. The results are interpreted according to the protonation model for stimulated luminescence.