Figure 2.

Growth and Gravitropism of cpt1 Seedlings.

(A) Growth of coleoptiles and primary roots. Seedlings of the wild type and cpt1 mutant, raised under red light (2.5 μmol m⁻² s⁻¹), were monitored for elongation growth of coleoptiles and primary roots. The growth increment (ordinate) indicates the difference in length from the length at time 0. The means ± se from 15 seedlings are shown. Growth rates estimated from the linear regression lines are indicated. The mean initial lengths in millimeters were 3.2 (wild-type coleoptiles), 3.4 (cpt1 coleoptiles), 15.8 (wild-type roots), and 16.3 (cpt1 roots).

(B) Gravitropism of coleoptiles and primary roots. Seedlings of the wild type and the cpt1 mutant, prepared as described for Figure 1A, were displaced by 30° (closed circles) or 90° (open circles) and were monitored for the orientation of the coleoptile tip (top panels) and the root tip (bottom panels). The angle of orientation is 0° when it is parallel to the plumb line. In the case of coleoptiles, the orientation to the side of displacement is indicated by negative angles, and the upward gravitropic curvature of coleoptiles is represented by a movement of the tip from a negative angle to 0°. In the case of roots, the orientation to the side of displacement is indicated by positive angles, and the downward gravitropic curvature of roots is represented by a movement of the tip from a positive angle to 0°. The means obtained from 30 (closed circles) or 20 (open circles) seedlings are shown. The vertical bar indicates ±sd.

(C) Gravitropism of submerged coleoptiles. Seedlings were submerged in water 6 h before they were displaced by 30°. The length of coleoptiles was ∼3 mm at the time of submergence. The means obtained from 12 seedlings are shown. Other details were as described for (B).