Figure 1.

RL-dependent enhancement of phototropism induced by long-term irradiation with BL in wild-type (●) and nph4 mutant (○) seedlings. A, Fluence response curves for RL-dependent enhancement of phototropism. Irradiation of 64-h-old etiolated seedlings with BL (unilateral; 0.5 μmol m⁻² s⁻¹) and RL (actinic from above; 1.6 μmol m⁻² s⁻¹) was initiated at the same time. BL was given for a total of 4 h, whereas RL exposure times varied (1–1,000 s) depending upon the desired fluence. At the end of the BL exposure, phototropic curvatures were measured. Data represent the mean response of at least 97 seedlings from three replicate experiments. Vertical bars represent the se values. B, Reciprocity relationships for RL-dependent enhancement of phototropism. Seedlings were handled as described above, except that fluence rates and exposure times of the RL exposure were varied to achieve a single fluence of 160 μmol m⁻². Curvatures are plotted relative to the exposure time of the RL irradiation. Data represent the mean response of at least 54 seedlings from three replicate experiments. Vertical error bars represent the se values.