Auxin transporters are required for light-regulated leaf flattening. A, LFI of Col plants grown for 2 weeks and transferred to WL, RL, or RBL for 1 week. During this week, plants were sprayed with NPA, mock solution (Mock), or not treated (NT). Bars represent mean ± se of 30 plants. Different letters represent significant differences among means (P < 0.05) in an ANOVA followed by Tukey’s test. B, Epifluorescence images of leaf blades of Col plants expressing DR5:VENUS grown for 2 weeks and transferred for 1 week to WL, RL, or RBL for 1 week while being treated with NPA, mock solution (Mock), or NT. For each leaf, images were taken on the AD and AB side. Scale bar: 0.5 cm. C, Pictures of 3-week-old Col and various auxin transporters mutants. Scale bar: 2 cm. D, LFI in plants of various genotypes grown on soil for 2 weeks and transferred to WL, RL, or RBL for 1 week. Bars represent mean ± se of 18–56 plants. Different letters represent significant differences among means (P < 0.05) in an ANOVA followed by Tukey’s test. E, LFI in plants of various genotypes grown on soil covered with dark (No reflection) or clear (Reflection) aluminum foil for 3 weeks. Bars represent mean ± se of 14–441 plants. *P < 0.05 in ANOVA followed by Sidak’s multiple comparison test. Significance of the interaction term (Genotype × Treatment) in the ANOVA is shown in the top right corner in each case.