Returning Dark-Induced Cell Cycle to the Beginning of G1 Phase by Red Light Irradiation in Fern Adiantum Protonemata

In filamentous protonemata of Adiantum capillus-veneris L. preculturedunder continuous red light, the progression of cell cycle whichwas induced by transferring the protonemata to the dark wasinhibited and the phase returned to the beginning of G1 by redlight irradiation unless the cell cycle had progressed to a"point of no return" which coincides with the beginning of Sphase. The effect of red light was reversed by subsequent far-redlight. Typical red far-red reversibility indicates that thephotoreceptive pigment is phytochrome. (Received May 17, 1984; Accepted June 21, 1984)