Hormonal regulation of stem cell maintenance in roots

Abstract

During plant embryogenesis, the apical-basal axis is established and both the shoot apical meristem (SAM) and the root apical meristem (RAM) are formed. In both meristems, there are slowly dividing cells which control the differentiation of their surrounding cells called the organizing centre (OC) and the quiescent centre (QC) in the shoot and root, respectively. These centres with their surrounding initial cells form a 'stem cell niche'. The initial cells eventually differentiate into various plant tissues, giving rise to plant organs such as lateral shoots, flowers, leaves, and lateral roots. Plant hormones are important factors involved in the balance between cell division and differentiation such that plant growth and development are tightly controlled in space and time. No single hormone acts by itself in regulating the meristematic activity in the root meristem. Division and differentiation are controlled by interactions between several hormones. Intensive research on plant stem cells has focused on how cell division is regulated to form specific plant organs and tissues, how differentiation is controlled, and how stem cell fate is coordinated. In this review, recent knowledge pertaining to the role of plant hormones in maintaining root stem cells including the QC is summarized and discussed. Furthermore, we suggest diverse approaches to answering the main question of how root stem cells are regulated and maintained by plant hormones.

Autophagy regulates glucose-mediated root meristem activity by modulating ROS production inArabidopsis

“…Optimal root growth and architecture are predominately determined by the root meristem, whose stem cell activity is maintained by several factors, including hormonal levels (e.g., auxin), nutrient availability (e.g., glucose), and reactive oxygen species (ROS) homeostasis (e.g., H 2 O 2 and superoxide) [11,19,20]. Auxin is one of the most important hormonal regulators for root growth and root meristem maintenance [21][22][23]. Through the action of polar transporters such as the PIN-FORMED proteins (PINs), auxin accumulates in the primary root tips and contributes to the patterning of the root and the regulation of root cell division [22,24].…”

The Interaction between Rice ERF3 and WOX11 Promotes Crown Root Development by Regulating Gene Expression Involved in Cytokinin Signaling

“…Cytokinin stimulates cell differentiation in the root proximal meristem, which leads to a decrease of meristem size and root growth (Dello Ioio et al, 2007Bishopp et al, 2009;Ruzicka et al, 2009;Moubayidin et al, 2010). Mutations of Arabidopsis type-A cytokinin response factor genes ARR7 and ARR15 lead to misexpression of root development regulatory genes, such as SCARECROW, PLETHORA1 (PLT1), and WU-SCHEL-RELATED HOMEOBOX5 (WOX5) (Lee et al, 2013;Müller and Sheen, 2008). Knockdown or overexpression of rice genes involved in cytokinin signaling pathway also affects root development.…”

Cytokinin treatments affect the apical-basal patterning of the Arabidopsis gynoecium and resemble the effects of polar auxin transport inhibition

“…Plants produce different hormones, which are involved in many developmental processes throughout their life cycle (Durbak et al, 2012; Lee et al, 2013). One of the most widely studied hormones is auxin (Tromas and Perrot-Rechenmann, 2010; Sauer et al, 2013).…”