a - c. Pseudo-colored, optical longitudinal cross sections of 5 DAG roots expressing (a) PIN2-GFP (PIN2::PIN2-GFP, P2wt) (b) PIN2S439D-GFP (PIN2::PIN2S439D-GFP, P2D) and (c) PIN2S439A (PIN2::PIN2S439A-GFP, P2A) - all in eir1-4 background - 12 HAT to ammonium or nitrate supplemented media. "e" denotes epidermis and "c" cortex, respectively. Color code represents GFP intensity from low (blue) to high (white) values. Scale bar=50 µm. 