Figure 2.

Light increased PAT in etiolated Arabidopsis and tomato seedlings. Percentage PAT equals percentage basipetal auxin transport minus the percentage acropetal auxin transport. Asterisks indicate significant changes. A, PAT in Arabidopsis hypocotyls was significantly increased by 2 d or 1 d of continuous 80 μmol m⁻² s⁻¹ W light (P < 0.0005, n = 10, Student’s t test) but not by 1 h of W light followed by 2 d of darkness (D). B, PAT in tomato hypocotyls was significantly increased by 2 d or 1 d of continuous 21 μmol m⁻² s⁻¹ W light and by 1 h of W light followed by 1 d of darkness (P < 0.0001, n = 10, Student’s t test). C, PAT in tomato hypocotyls was significantly increased by 1 h of 21 μmol m⁻² s⁻¹ W light or by 1 h of 4 μmol m⁻² s⁻¹ B or R light followed by 1 d of darkness (P < 0.0001, n = 10, Student’s t test). [See online article for color version of this figure.]