The green fluorescent protein (GFP) signals indicate the abundance of several auxin transporters, including PIN1pro:PIN1:GFP (A), PIN2pro:PIN2:GFP (B), PIN3pro:PIN3:GFP (C), AUX1pro:AUX1:GFP (D), and LAX3pro:LAX3:GFP (E), in 4-day-old primary root of the wild type (WT) and the ctl1 mutant. The red signals are from FM4-64 staining. Scale bars are 50 μm. (F) Relative abundance of auxin transporters (PIN1, PIN2, PIN3, AUXIN RESISTANT 1 [AUX1], and Like AUX1 protein 3 [LAX3]) in ctl1 mutant is shown as % of the WT. Data are mean ± SD from 91, 64, 44, 39, and 40 cells in 5 roots of the transgenic lines expressing PIN1-GFP, PIN3-GFP, PIN2-GFP, AUX1-GFP, and LAX3-GFP, respectively. Three independent experiments were performed. Asterisks indicate a significant difference (*P < 0.05, Student t test). The raw data for panel F can be found in S1 Data.