(A–H) Degradation of DII-VENUS-N7 after different periods of 1 mM auxin treatment. DII-VENUS-N7 distribution before auxin treatment (A–D) and right after the end of the auxin treatment: mock (E) or 30’ (F), 120’ (G) or 300’ (H) DII-VENUS-N7 (yellow) and pCLV3:mCherry (magenta) labelled nuclei are shown. (I) Quantification of auxin (1-qDII) in the PZ after the treatments shown in Figure 5H–I. Each profile shows auxin levels right after the end of each treatment. Each dot represents a nucleus (Mock N = 1638, 30’ 1 mM auxin N = 2026, 120’ 1 mM auxin N = 875, 300’ 1 mM auxin N = 2375, 120’ 0.2 mM auxin N = 1536, 300’ 0.2 mM auxin N = 1981 and 120’ 5 mM auxin N = 2302). The angular locations of primordia are indicated. (J–L). The effect of in planta auxin treatment of different durations (one treatment a day for five consecutive days) on organ positioning in Col-0. Flowers positioned at 90° (J) or co-inserted on a node (K) can be observed (here after a 120’ 1 mM auxin treatment). (L) Percentage of plants with phyllotaxis defects in the different treatments (0, 0.2, 1 and 5 mM auxin for 30’, 120’ or 300’ once a day during five consecutive days. (M–P) Representative images of inflorescences and meristems of Col-0 (M and O) and ett-22/arf3 mutant (N and P) showing phyllotactic defects such as co-initiations (N) and opposite organ positioning (P). (Q–S) Representative image of a pDR5:mTurquoise2 (Cyan) pCLV3:mCherry (pink) meristem treated with mock or the histone deacetylase inhibitor TSA. Red arrow in (R) indicates P-1 where activation of DR5 can be observed. (S). Quantification of DR5 expression in the PZ epidermal cell layer of (Q) and (R). Confidence intervals (shade) and regression (line) shows circumferential DR5 expression pattern in the PZ (the position of primordia from P-2 are indicated) of control (magenta) or TSA (green) treated meristems. The red arrow points to the significant activation of DR5 at P-1. DMSO N = 20 SAMs, TSA N = 20 SAMs.