Chloroplast Photoorientation in Enucleated Fern Protonemata

The phototransduction chains of phytochrome and the blue-light-absorbing pigment that mediate photoorientation movement of chloroplasts are not related to nuclear gene expression at the level of transcription. The protonematal cells were ligated in such a way as to separate the nucleus from the rest of the cell. After ligation, the nuclear portion was cut off. Rhizoids were also cut off. The remaining part of the protonemata was first irradiated with red or blue polarized light and then with a microbeam of red, blue or far-red light. The low-fluence-rate photoorientation response mediated by phytochrome and both the low- and high-fluence-rate photoorientation responses mediated by the blue-light-absorbing pigment were induced in the enucleated protonemata, indicating that nuclear gene expression at the level of transcription does not contribute to the red and blue light transduction chains leading to the photoorientation movement of chloroplasts.