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. Author manuscript; available in PMC: 2009 Aug 1.
Published in final edited form as: Curr Opin Genet Dev. 2008 Jul 9;18(4):354–361. doi: 10.1016/j.gde.2008.05.001

Figure 2.

Figure 2

The simple structure of the Arabidopsis primary root is specified by complex regulatory mechanisms. (A) Schematic drawing of a longitudinal slice of the primary root tip. (B) Non-hair epidermal cell fate is specified by high levels of GL2. GL2 is activated by TTG/GL3/EGL3/WER transcriptional complexes that also activate TRY, ETC, and CPC. CPC (and presumably TRY and ETC) moves to neighboring epidermal cells to repress GL2 expression, resulting in hair cell fate. GEM chromatin modifications regulate the ‘open’ or ‘closed’ configuration of the GL2 promoter. (C) SHR moves from the stele into adjacent cells where it is sequestered by SCR into the nucleus. Nuclear SHR-SCR complexes activate SCR expression, specifying the endodermis. White circles in (C) denote the nucleus, waved black/white-striped rectangle represents the SCR promoter DNA. Throughout the figure, cell colors indicate the associated cell-type shown in (A) and colored arrows depict protein movement.