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Updated: Jun 21, 2026

Using Changes in Leaf Transmission to Investigate Chloroplast Movement in Arabidopsis thaliana
Published on: July 14, 2021
Short actin-based mechanism for light-directed chloroplast movement in Arabidopsis
Akeo Kadota1, Noboru Yamada, Noriyuki Suetsugu
1Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397, Japan. kadota@tmu.ac.jp
Abstract:
Organelle movement is essential for proper function of living cells. In plants, these movements generally depend on actin filaments, but the underlying mechanism is unknown. Here, in Arabidopsis, we identify associations of short actin filaments along the chloroplast periphery on the plasma membrane side associated with chloroplast photorelocation and anchoring to the plasma membrane. We have termed these chloroplast-actin filaments (cp-actin filaments). Cp-actin filaments emerge from the chloroplast edge and exhibit rapid turnover. The presence of cp-actin filaments depends on an actin-binding protein, chloroplast unusual positioning1 (CHUP1), localized on the chloroplast envelope. chup1 mutant lacked cp-actin filaments but showed normal cytoplasmic actin filaments. When irradiated with blue light to induce chloroplast movement, cp-actin filaments relocalize to the leading edge of chloroplasts before and during photorelocation and are regulated by 2 phototropins, phot1 and phot2. Our findings suggest that plants evolved a unique actin-based mechanism for organelle movement.
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