Abstract
Chloroplasts show relocation movement in the cell in response to environmental light condition. Namely, they move towards the light under weak light, called as "accumulation response" while they move away from the light to avoid photodamage under strong light, called as "avoidance response". In this work, we investigated on the change in actin filament organization during red light-induced chloroplast relocation movement in the moss, Physcomitrella patens. In the previous studies, red light response in chloroplast relocation in P. patens was lost in the cells cultured under white light. We found that protonemal cells incubated in the dark for 2 days after culture under white light resumed red light sensitivity. Both avoidance and accumulation response were induced in the cells under strong and weak red light, respectively. When the organization of actin filaments during red light-relocation movement was examined in the cells, cp-actin meshwork formation on the relocated chloroplasts was revealed as reported previously in the blue light-induced relocation movement. Cp-actin meshwork formation in relation with the motility of relocated chloroplasts will be examined.
