PLETHORA‐WOX5 interaction and subnuclear localization control Arabidopsis root stem cell maintenance

Abstract

Maintenance and homeostasis of the stem cell niche (SCN) in the Arabidopsis root is essential for growth and development of all root cell types. The SCN is organized around a quiescent center (QC) maintaining the stemness of cells in direct contact. The key transcription factors (TFs) WUSCHEL‐RELATED HOMEOBOX 5 (WOX5) and PLETHORAs (PLTs) are expressed in the SCN where they maintain the QC and regulate distal columella stem cell (CSC) fate. Here, we describe the concerted mutual regulation of the key TFs WOX5 and PLTs on a transcriptional and protein interaction level. Additionally, by applying a novel SCN staining method, we demonstrate that both WOX5 and PLTs regulate root SCN homeostasis as they control QC quiescence and CSC fate interdependently. Moreover, we uncover that some PLTs, especially PLT3, contain intrinsically disordered prion‐like domains (PrDs) that are necessary for complex formation with WOX5 and its recruitment to subnuclear microdomains/nuclear bodies (NBs) in the CSCs. We propose that this partitioning of PLT‐WOX5 complexes to NBs, possibly by phase separation, is important for CSC fate determination.

Comprehensive integration of single-cell transcriptomic data illuminates the regulatory network architecture of plant cell fate specification

“…Interestingly, these clusters coincidentally shared in both shoot- and root-related tissues ( Figure 1D ). Furthermore, we found that genes with roles in regulating meristem cell fate, such as BBM (PLT4) (Burkart et al, 2022), PLT1 (Sarkar et al, 2007) and DI21, were highly expressed in these cell clusters ( Figure 1D and Supplemental Figure S6 ). The above results indicate that these four initiation cell clusters may form the primary meristems in Arabidopsis (Stahl and Simon, 2010).…”

The plant stem-cell niche and pluripotency: 15 years of an epigenetic perspective

“…A recent study showed that the pluripotency factors WOX5, PLT2 and PLT3 form alternative complexes in different cell-types of the RAM ( Burkart et al., 2022 ). It seems reasonable to anticipate that epigenetic complexes and their recruiters are also cell-type-specifically formed ( Figure 2C ).…”

Come together now: Dynamic body-formation of key regulators integrates environmental cues in plant development

“…Body-formation often depends on disordered domains in the amino acid sequence of proteins, as reported for PLT3 (Burkart et al, 2022). As the nomenclature found in literature with many ambiguous terms is confusing, an overview of the existing different domains is provided.…”

“…Body-formation of TRs choreographing root development (Burkart et al, 2022). Here, a key TF in SCN homeostasis, PLETHORA3 (PLT3), forms PrD-dependent NBs that contain RNA, and are sites for interaction with another important TF, WUSCHEL-RELATED-HOMEOBOX5 (WOX5), pivotal for root SC maintenance (Pi et al, 2015).…”

“…Recently, a role of membrane-less bodies containing key transcription factors (TFs) in root SC regulation, has been reported. Here, bodies are discussed to influence SC-fate decisions potentially upon a yet unknown trigger ( Burkart et al., 2022 ), which could provide a link between root growth and environmental influences. The formation of such membrane-less bodies within a liquid environment like the cytosol or nucleoplasm can originate from the separation of biomolecules into two phases.…”