Figure 1.

Polarization of leaf thermonasty is independent of light direction and gravity. Elevation angles of the fifth and sixth rosette leaves relative to the horizontal plane were measured using 3-week-old plants exposed to 28°C. Three independent measurements, each consisting of 16 individual plants grown under identical conditions, were statistically analyzed using Student’s t test (*, P < 0.01, difference from 23°C). Error bars indicate se. A, Kinetic effects of warm temperatures on petiole bending. Elevation angles were measured in a time course following exposure to 28°C. B, Leaf petiole temperatures. Temperatures on the abaxial and adaxial surfaces of leaf petioles were measured by infrared thermography 6 h following exposure to 28°C. C, Effects of light direction on leaf thermonasty. Plants were exposed to 28°C for 6 h with upward light illumination. D, Kinetic effects of warm temperatures and light directions on petiole bending. Elevation angles were measured in a time course following exposure to 28°C with upward light illumination. E, Effects of gravity on leaf thermonasty. Plants were subjected to horizontal gravitropic stimulation (g) at 28°C for 6 h in the light. F, Kinetic effects of warm temperatures and gravity on petiole bending. Elevation angles were measured in a time course following exposure to 28°C with horizontal gravitropic stimulation, as depicted in E.