Extended Data Fig. 1. Quantification of periclinal cell division during procambial development.

a, Schematic representation of root vascular tissue of Arabidopsis. Procambial cells originate from their initial cells, and periclinal cell division increases the cell files during the proliferative phase, eventually resulting in a bisymmetric vascular pattern composed of a pair of phloem poles, which are separated from central xylem axis by intervening procambium. b, An example of mapping the position of periclinal cell divisions from the initial cells. From each position within the root vascular tissue (arrows), an optical cross-section image is constructed, and cells were segmented using CellSet. c, The number of periclinal cell divisions in each cell position (273 division events from 13 independent roots). d, The mean cell number in each category during procambial development. The number of events per cell in each group was calculated by diving the number of events by the mean cell number of each group during development (See Supplementary Information).