Relation between slow delayed light emission and acid base triggered luminescence in chloroplasts.

Acid-base triggered luminescence in relation to slow delayed light emission (greater than 3 s) was studied in chloroplasts. After analyzing their time courses, the acid-base induced luminescence curve was found to return to the original curve of delayed light emission. Peaks of the acid-base triggered luminescence induced after various darkness periods following preillumination decreased parallel to the time course of delayed light emission without base treatment. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea enhanced both the delayed light emission and acid-base induced luminescence, while carbonyl cyanide m-chlorophenylhydrazone inhibited both. Several photophosphorylat ion uncouplers inhibited the acid-base induced luminescence wtihout any substantial effect on the delayed light emission. It is concluded that the acid-base triggered luminescence is not caused by the reversionof electrons from remote intermediates on the reducing side of Photosystem II. The possibility of the presence of an activation pathway for the acid-base triggered luminescence which differs from that of the delayed light emission is also discussed.