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. 2015 Mar 28;66(8):2187–2197. doi: 10.1093/jxb/erv106

Fig. 3.

Fig. 3.

Root organization and cell type specificities of hormone signalling. (a) Developmental zones and cell types of Arabidopsis roots. The pericycle and the cell types of the vasculature form the root stele. The quiescent centre (QC) plus surrounding stem cells build the stem cell niche (SCN). (b) Cross-section of a mature root showing the concentric arrangement of root cell types. (c–e) Different modes of cell context-specific hormone signalling. (c) AUX distribution (blue) is a main regulator of root patterning and meristem function (Blilou et al., 2005; Kieffer et al., 2010). AUX shows a general basipetal gradient across the root tip (Petersson et al., 2009; Brunoud et al., 2012). CK (yellow) acts in the TZ vasculature to promote cell differentiation (Dello Ioio et al., 2007). (d) Epidermal BR signalling (grey) regulates cell division and cell size (Hacham et al., 2011; Fridman et al., 2014). GA (red) exerts control over meristem development and cell elongation through the endodermis (Ubeda-Tomás et al., 2008, 2009). (e) ABA inhibits cell division in the RAM (Zhang et al., 2010). While QC maintenance positively affects root growth (beige), it is negatively influenced by inhibition of cell division in the remaining meristem (green).