Fig. 2. Sepal initiation is variably delayed in the drmy1–2 mutant.

a,b, Live imaging of sepal initiation in wild type (a) and drmy1–2 (b). Plasma membrane marker (p35S::mCitrine-RCI2A) is shown in greyscale. The small bulge-out is defined as sepal initiation. Blue arrowheads in WT and red arrowheads drmy1–2 indicate initiated sepals. Scale bars: 25 μm. n = 15 for WT and n = 18 for drmy1–2.

c,d, Gaussian curvature heatmap detecting changes in curvature associated with initiation for the live imaging sequences shown in a and b. The red color represents the dome shape while the blue color represents the saddle shape. Thus, a strong red band at the periphery (white arrowheads) reveals initiated sepals. Scale bars: 25 μm.

e, Histogram showing the time interval between the initiation of the outer sepal and the inner sepal in each flower. n = 12 for WT flowers and 17 for drmy1–2 flowers. Note WT inner sepals initiate robustly 6 hours after the outer sepals, while the time is variable and generally longer in drmy1–2.

f, Histogram showing the time interval between the initiation of the outer sepal and the lateral sepals for each flower. n = 12 for WT flowers and 17 for drmy1–2 flowers. Note WT inner sepals initiate robustly 12 hours after the outer sepals, while the time is variable and generally longer in drmy1–2.

g, Atomic Force Microscopy measurement of cell wall stiffness (elastic modulus) for centers of inflorescence meristems (IM), centers of floral meristems (FM), and peripheries of floral meristems where sepal primordia emerge (SP; highlighted with black dotted boxes) of WT and the drmy1–2 mutants. In the heatmap of apparent elastic modulus shown here, red indicates stiffer and blue indicates softer. (n = 11) Scale bars: 10 μm.