Framework for gradual progression of cell ontogeny in the Arabidopsis root meristem

Abstract

In plants, apical meristems allow continuous growth along the body axis. Within the root apical meristem, a group of slowly dividing quiescent center cells is thought to limit stem cell activity to directly neighboring cells, thus endowing them with unique properties, distinct from displaced daughters. This binary identity of the stem cells stands in apparent contradiction to the more gradual changes in cell division potential and differentiation that occur as cells move further away from the quiescent center. To address this paradox and to infer molecular organization of the root meristem, we used a whole-genome approach to determine dominant transcriptional patterns along root ontogeny zones. We found that the prevalent patterns are expressed in two opposing gradients. One is characterized by genes associated with development, the other enriched in differentiation genes. We confirmed these transcript gradients, and demonstrate that these translate to gradients in protein accumulation and gradual changes in cellular properties. We also show that gradients are genetically controlled through multiple pathways. Based on these findings, we propose that cells in the root meristem gradually transition from stem cell activity toward differentiation.

Protein complex stoichiometry and expression dynamics of transcription factors modulate stem cell division

“…Finally, SHR is expressed in a gradient, with its highest expression at the tip of the root (11). Thus, potential regulators of SHR may be expressed in the same gradient as SHR, and datasets measuring gene expression gradients in the root could be used to identify additional putative SHR regulators (40). Similar techniques could be used to identify upstream SCR regulators, increasing our understanding of how this expanded SEU-WOX5-SHR-SCR regulatory network controls CEI and QC divisions.…”

Control of Endogenous Auxin Levels in Plant Root Development

“…Unlike organ growth in animals, most plant organs are formed post-embryonically and emerge from inherent structures known as meristems [ 2 ]. Throughout the plant’s life span, meristems remain present and provide the basis for the plant’s developmental plasticity [ 3 , 4 ]. Initially at the embryonic state, two types of meristems occur: the shoot apical meristem (SAM), which gives rise to above ground tissues and organs and the root apical meristem (RAM), which establishes the root architecture.…”

Comparing RNA‐Seq and microarray gene expression data in two zones of the Arabidopsis root apex relevant to spaceflight

“…The list of plant studies that examine gene expression patterns of root zones, and even root cell lineages, is ever expanding, particularly in recent years as tools and approaches provide increasing fidelity in the ability to discriminate among cell types (Birnbaum et al, 2003;Brady et al, 2007;Bruex et al, 2012;Kyndt et al, 2012;Bailey-Serres, 2013;Gotté et al, 2016;Royer et al, 2016;Libault et al, 2017;Wendrich et al, 2017). In addition, the expansion of available reference genomes for a variety of plants enables the molecular comparisons of cell type and tissue comparisons among species (Galbraith and Birnbaum, 2006;Huang and Schiefelbein, 2015;Karve and Iyer-Pascuzzi, 2015).…”