Spatial Coordination between Stem Cell Activity and Cell Differentiation in the Root Meristem

Abstract

SUMMARY A critical issue in development is coordination of the activity of stem cell niches with differentiation of their progeny to ensure coherent organ growth. In the plant root, these processes take place at opposite ends of the meristem and must be coordinated with each other at a distance. Here we show that in Arabidopsis the gene SCR presides over this spatial coordination. In the organizing centre of the root stem cell niche, SCR directly represses the expression of the cytokinin-response transcription factor ARR1, which promotes cell differentiation, controlling auxin production via the ASB1 gene and sustaining stem cell activity. This allows SCR to regulate, via auxin, the level of ARR1 expression in the transition zone where the stem cell progeny leave the meristem, thus controlling the rate of differentiation. In this way, SCR simultaneously controls stem cell division and differentiation ensuring coherent root growth.

Translatome analyses capture of opposing tissue-specific brassinosteroid signals orchestrating root meristem differentiation

“…Hence, auxin acts as an epidermis-derived nonautonomous signaling component, promoting cell proliferation in the meristem. The role of auxin, acting as a nonautonomous signal coordinating the rate of stem cell division with the rate of stem cell daughter differentiation, has been recently described (30).…”

The Yin-Yang of Hormones: Cytokinin and Auxin Interactions in Plant Development

“…Similar to its role in the embryonic root, cytokinin also plays a key role in regulating the function of the QC in postembryonic roots, including the primary and adventitious roots (Della Rovere et al, 2013;Moubayidin et al, 2013;Zhang et al, 2013). Application of exogenous cytokinin or disruption of multiple type-A ARR genes, which negatively regulate cytokinin signaling, leads to loss of QC identity as measured by reactivation of cell division, reduced QC marker gene expression, and differentiation of the adjacent columella cells (Zhang et al, , 2013.…”

1,3-di(benzo[d]oxazol-5-yl)urea acts as either adventitious rooting adjuvant or xylogenesis enhancer in carob and pine microcuttings depending on the presence/absence of exogenous indole-3-butyric acid

“…AtSCR is an auxin-induced gene (Moubayidin et al 2013) and it is activated by AtSHR (Helariutta et al 2000). Also AtATHB8 is auxin-induced, and its activation identifies the pre(pro)cambial cell state (Baima et al 2014, and references therein).…”