Actin Polymerization as an Essential Process in Light- and Dark-controlled Chloroplast Anchorage

Summary The effect of the actin-inhibitor cytochalasin B on low fluence-rate chloroplast movements and on P fr mediated increase of chloroplast anchorage to the cytoplasmic parietal coating of a Mougeotia cell was investigated. We found that cytochalasin B decreases chloroplast anchorage in far-red irradiated and also in darksensitized cells. The results show that actin polymerization is not only involved in light-oriented chloroplast movements but also in the process of chloroplast anchorage to the cytoplasmic parietal coating of the longitudinal cell walls. The results provide a further strong argument for the assumption that both responses, the P fr -controlled chloroplast movement as well as the P fr -mediated increase of chloroplast anchorage are realized via similar transduction chains.