Fig. 3: IBA-derived auxin regulates PIN2 accumulation along cotyledons margin cells.

a Upper panel, ECH2 expression precedes PIN2. ECH2-YFP + / + X PIN2-GFP + /+ cotyledons were imaged in the absence and presence of PIN2-GFP at 24 at 36 HAP, respectively. YFP-ECH2 (white arrowhead) is present at 24 HAP, before PIN2 accumulation. Phenotype frequency is shown as a percentage of the number of cotyledons observed. Scale bar = 20 µm. Similar results were obtained in 3 independent experiments. Lower panel, Quantification of the signal intensity along the dashed line in the upper panel. b IBA-derived auxin is critical for PIN2 accumulation at MCs. PIN2-GFP from cotyledons of wild type Col-0 and ech2ibr10 -/- grown for 48 hours after root protrusion. Phenotype frequency is shown as a percentage of the number of cotyledons observed. Similar results were obtained in 3 independent experiments. Scale bar = 100 µm. c Quantification of PIN2-GFP signal along cotyledons borders of wt Col-0 (gray) and ech2ibr10 (yellow) captured from base to tip. d IBA-derived auxin is critical for interdigitation. Pavement cells of 5 days-old cotyledons stained with propidium iodide (PI) to outline the cell borders of wild type Col-0 and double mutant ech2ibr10 -/-. Scale bar = 100 µm. e Quantification of pavement cell shape (Circularity) in wild type and ech2ibr10 -/- cotyledons, as shown in (d). n = 60 cells. Data was collected from 6 different cotyledons on each treatment. Unpaired two-tailed t-test. **** p-value < 0.0001.