Abstract
We are examining the function, mechanism, and dynamics of endocytosis in Arabidopsis plant, especially focusing on Rab/Ypt GTPases involved in the endocytic pathway. Arabidopsis genome contains many Rab/Ypt GTPases which should regulate endocytic pathway. Among these molecules, members of Rab5 or Rab7 subfamily are localized on endosomes or vacuoles and regulate endosomal fusion or fusion with vacuoles respectively. Using these molecules tagged with GFP as organelle markers, we attempted to monitor the dynamics of endocytic organelles in living Arabidopsis cells. A high-speed and high-sensitivity microscope system we developed enables us to observe the very active actin-dependent movement of endosomes and vacuoles. Brefeldin A causes aggregation of endosomes, and interestingly, TIBA, which is known as an inhibitor of polar transport of auxin, inhibits the movement of endosomes. The significance of endocytosis in the plant function of higher order will be also discussed.
