Figure 3.

Changes in PKS1 promoter activity anticipate PKS1-mediated effects on negative phototropism in roots. A, Time course of root bending after the beginning of unilateral blue light. Data are means and se of nine replicate boxes. B, Time course of GUS staining driven by the PKS1 promoter under unilateral blue light. In B, magnification is 100× (left box) and 7× (right box). The arrow indicates the position of the root tip at the beginning of the light treatment (this position was labeled in some boxes under dim green light). Seedlings were grow in full darkness for 2 d, transferred to unilateral blue light (1 μmol m⁻² s⁻¹), and measured or stained at the indicated time point.