f. Representative 3D SIM microscopic images of 10 DAG old epidermal cells expressing PIN2-GFP 12 HAT to ammonium or nitrate containing media. Green dots represent PIN2-GFP on the lateral cell surface (polar domain) of epidermal cells in the transition zone. Graph represents the number of GFP positive spots along a 30 µm long region starting at the apical side of the cell (8 cells per 4 roots and 9 cells per 4 roots) were analyzed per treatment, experiment was done 3 times. Error bars represent mean + SE. Note the effect of ammonium versus nitrate on the distribution of the PIN2-GFP spots. 