Effects of blue and red light on the cell division cycle in pteris protonemata

Abstract

In single-celled protonemata of Pteris vittata cultured under continuous red light, which maintained the cells in the early G 1 phase, the first cell division was induced by a brief irradiation with blue light followed by darkness. The effect of blue light was reversed by a brief red light given immediately after the preceding blue light, and a longer period of blue light was required to induce cell division if followed by red light. Under red light, or in the dark after a brief blue light, cells progressed synchronously from the early G 1 phase through successive cycles, which resulted in a high mitotic index. Neither blue nor red light given during the preceding mitotic cycle was effective for the induction of the next cell division, but they did support its occurrence. Thus, a high synchrony of cell division could be repeatedly produced by a combination of 1 h of blue and 15 h of red light irradiation.