Abstract
Each protonema of Physcomitrella patens elongates with mainly apical cell growth and division. We followed the dynamics of nucleus and chloroplasts during an entire cell cycle in the apical cell of protonemata by time-lapse observation. After telophase, the nucleus of apical cell moved to apical direction but then nuclear moving transiently arrested about 2-4 hours later. We found that the positioning of individual chloroplasts with respect to the nucleus little changed after the transient arrest of nuclear moving, and chloroplast partition into daughter cell is finally dependent on this positioning.
