Fig. 1: Variable auxin signaling patterns in stage 1 floral meristems canalize into robustly positioned auxin maxima by late stage 2.

a–c Stage definitions. a Expression of pATML1::H2B-TFP in the epidermal (L1) nuclei showing tissue morphology. Stages are labeled on each meristem. Abaxial (Ab), adaxial (Ad), and lateral (La) directions of a stage 2a bud are labeled with arrows. Inset shows an incipient boundary (cyan) in stage 1b with deformed nuclei. b Gaussian curvature of extracted surface. Asterisks show decreasing Gaussian curvature in the incipient boundaries. c Auxin signaling patterns revealed by DR5::mScarlet-I-N7. Arrowheads show variable auxin patterns in stages 1a, 1b, and 2a. d Illustration of auxin signaling dynamics revealed by DR5. p, random patches of cells with high auxin signaling. L, incipient lateral sepals. O, incipient outer sepal. I, incipient inner sepal. i, incipient primordia of the inner whorls. e Live imaging of DR5::mScarlet-I-N7 shows that variably localized patches of auxin signaling in stage 1 (arrowheads) dissipate, replaced by four robustly positioned auxin maxima in stage 2b and 2c. n = 4 buds. Scale bars in (a–c, e), 20 µm. f Method for quantifying mean and variability in reporter patterns used in Fig. 2. A mesh was made using pATML1::H2B-TFP signal in nuclei of the upper epidermis, within which DR5 was quantified. The upper epidermis was divided into equal-sized bins. Average signal intensity across nuclei in each bin was calculated to create a pattern heatmap for a given bud. Pattern heatmaps of multiple buds at the same stage were pooled to calculate the mean and coefficient of variation (CV) heatmaps.