Figure 4.

Symmetry breaking in ground tissue formation in the root. (A) Schematic of a longitudinal section of the Arabidopsis root tip with each cell type differentially colored. (B) Magnification of (A) focusing on the asymmetric cell divisions that generate the two cell layers of the ground tissue. (B, left) The CEI expands and then (B, center) divides transversely to regenerate itself and produce the CEID. (B, right) The CEID then divides longitudinally to generate the cells of the endodermis and cortex. (C) Schematic representation of the localization of SHR mRNA, SHR protein and SCR mRNA and protein. Yellow arrows depict the movement of SHR protein from the vasculature into the quiescent center, CEI, and endodermis. Note that SHR and SCR proteins are colocalized in the nuclei of these cell types. Nuclei are represented by small circles within the cells.