Figure 9.

Elastic Rebound of a Statolith (Amyloplast) Moved by Optical Force against the Cortical ER Boundary in a Gravity-Sensing Arabidopsis Columella Cell.

(A) A single statolith (indicated by a star in panel A) is separated from a group of statoliths by optical force using laser beam steering to move the statolith through the cytoplasm (the wide arrow indicates the direction of movement). The root is positioned at 90° with respect to the gravity vector. The diamond-shaped arrow points toward the root tip. AM, amyloplasts; CW, cell wall.

(B) to (D) The statolith is moved by optical force toward the cortical ER/cell wall boundary (the wide arrow indicates the direction of movement). The dashed line indicates the original position of the upper statolith boundary before the downward movement.

(E) to (H) The laser beam is turned off after the statolith has reached close proximity to the cell cortex, effectively releasing the statolith from the optical trap. This release causes an upward movement (white arrow) of the statolith against the gravitational force (g). The dashed line indicates the original position of the statolith before the upward movement ([E] to [H]) and the end position (H). The time is given in seconds. Bar = 5 μm.