ELECTRIC PHENOMENA IN DRIED CHLOROPLASTS

Laser-flash-illuminated, dried chloroplast samples produce a fast elec tric response signal. We show that this signal is due to the light gra dient effect. Two phenomena are observed when an external electric fie ld is applied to the samples: (1) a large electric signal, obtained on light excitation, which is very different from the signal due to the light gradient effect; (2) an electric field due to polarization in th e chloroplast layers which remains for hours when the sample is illumi nated in an electric field. We attribute the two effects in the electr ic field to the motion and trapping of electrons due to light excitati on in the thylakoid membranes.