d. Microscopic images showing PIN2-Dendra fluorescent signal five hours after photoconversion of PIN2-Dendra into its red form. Depletion of the red signal and recovery of the green signal over a 6 hours period was followed in parallel in 5 DAG old roots12 HAT to ammonium or nitrate supplemented media. Note the increase in the intensity of the green signal in roots transferred to nitrate. Graph represents the mean signal + SD (n=6 roots per condition, 20 cells per root analyzed). The experiment was repeated 3 times. Scale bar=20 µm. 