Figure 4

Equal growth rates and isotropic lateral expansion of the cotyledon epidermal cells. (A) to (B) Cell outlines of fields of 3 DAG (A) and 5 DAG (B) pavement cells used for GFP:TUB6 localization in Figure 2A and Figure 2F, respectively. (C) Plot of surface areas at 3 DAG (x-axis) and 5 DAG (y-axis). The points are labeled according to the corresponding cell that is numbered in (A) and (B). (D) to (F) Perimeter segments of individual cells elongate at equal rates that are independent of shape. (D) and (E) segments of cell 4 at 3 DAG and 5 DAG respectively. The white bars indicate the position of three-way cell wall junctions. (F) Plot of cell segment lengths for cell 4 at 3 DAG (x-axis) and 5 DAG (y-axis). (G) to (R) Shape change during the cell expansion phase of cotyledon development is mostly explained by isotropic expansion. (G) Thresholded image indicating the shape and size of cell 1 at 3 DAG. (H) Image of (G) magnified by 1.42. (I) Thresholded image of cell 1 at 5 DAG. (J) Overlay of (H) and (I). (K) Thresholded image indicating the shape and size of cell 6 at 3 DAG. (L) Image of (K) magnified by 1.37. (M) Thresholded image of cell 6 at 5 DAG. (N) Overlay of (L) and (M). (O) Thresholded image indicating the shape and size of cell 4 at 3 DAG. (P) Image of (O) magnified by 1.31. (Q) Thresholded image of cell 4 at 5 DAG. (R) Overlay of (P) and (Q). Yellow represents regions of overlap, red indicates non-overlapping regions of the magnified image, and green indicates the non-overlapping regions of the real 5 DAG cell. The dashed lines indicate the expected behavior of non-growing cells (C) or segments (F). Bar = 10 μm