(
A) Cross section of the confocal image of time point 1. (
B) Segmentation with extended cell-type labeling in the endodermis. The root cell-type labeling of
Figure 4D was extended by identifying the xylem cells (light purple) in the stele (cyan), their adjacent pericycle cells (blue), and assigned the endodermis cells neighboring those pericycle cells as xylem file cells (X, red). Then the endodermis cells at right angles to the xylem files were assigned phloem file (P, purple) and the remaining other endodermis cells (E, yellow). (
C) Side view of one cell file of each cell type. As the cell types do not change along the cell file, it was possible to automatically assign the cell files based on their circumferential coordinate. (
D) Cell files of (
C) with a heat map of cell length indicating smaller cells in the xylem pole. (
E–J) Quantifications of cell geometry and development in the endodermis cell types. Cellular data was binned according to their distance from the quiescent center (QC) (
E–H). Shown are mean values and standard deviations per bin (
E–H) or cell type (
I, J). Phloem file cells showed a larger volume (
E), which was caused by a greater cell length (
F), an observation that has been made before by
Andersen et al., 2018. In contrast, xylem file and other endodermis cells were smaller in volume due to different reasons: while xylem file cells were the shortest (
E), rest endodermis cells showed a lower cell width with increasing distance from the QC (
G). The time-lapse analysis confirmed above observations: while volume change was similar across the cell types (
H), phloem file cells showed a lower proliferation rate (
I), whereas rest endodermis cells showed the smallest extension of cell width (
J). Scale bars: (
A, B) 20 μm; (
C, D) 50 μm.