Negative gravitropism of stems

This movie shows the negative gravitropic response of Arabidopsis flower stems after the plant was placed on its side. In about 30 min (after the second frame), gravitropism can be seen to result in differential growth along the stem to cause the shoot to start bending up. In just over an hour, the stem is essentially reoriented back to vertical, which is where it was before being placed on its side. Thus, the curvature caused by gravitropism allows the plant to continue growing away from the earth. Note that the stem wiggles around as it reorients by a process called nutation (see the nutation movie listed in the main menu). The images for this movie were captured every 15 min in darkness using IR lighting. Frames are played back at 6 frames per second.