Biology subjects

Schuerholz, A.-K.

Publications and source records attributed to Schuerholz, A.-K..

4 recordsLinked to original sources

bioRxiv2025

The Cell Wall Controls Stem Cell Fate in the Arabidopsis Shoot Apical Meristem

At the basis of plant developmental plasticity are continuously active pluripotent stem cells, which fuel the life-long post-embryonic formation of new organs. Since plant cells are encased in cell walls and thus immotile, their individual fate-specification program is dependent on their relative position within the organism. It is assumed that the cell wall and its mechanical properties are under surveillance, linking cell wall state to intracellular gene-regulatory networks. However, the role of these cell wall signalling pathways in plant development and the contribution of cell wall properties to cell behaviour and identity are unclear. Here, we show that control of cell wall properties is essential for the perpetuation of stem cell populations and pattering in the shoot apical meristems. The expression of pectin methylesterases (PMEs), which modify homogalacturonan methylesterification and thereby modulate cell wall mechanics, is maintained at low levels in stem cells by the stem cell specifying transcription factor WUS. Low PME expression is required for stemness, auxin patterning and stem cell-specific mechanical properties. Conversely, WUS depletion reduces wall stiffness in the meristem centre, reinforcing its role in maintaining mechanical homeostasis. Together, our findings show that WUS-mediated control of cell wall-modifying enzymes is essential for sustaining stem cell identity and SAM organization. These results demonstrat that the plant cell wall is not only involved in cell differentiation, but also exerts feedback control on developmental transitions, contributing to our understanding how the immediate physical environment is able to guide cell fate decisions in plants.

plant biology↗

bioRxiv2022

Edge-based growth control in Arabidopsis involves two cell wall-associated Receptor-Like Proteins

Morphogenesis of multicellular organs requires coordination of cellular growth. In plants, 3D growth is driven by undirected turgor pressure, whereas growth directionality is controlled by cell wall mechanical properties at 2D cell faces. Their shared cell wall also fixes cells in their position, and plants thus have to integrate tissue-scale mechanical stresses arising due to growth in a fixed tissue topology. This implies a need to monitor cell wall mechanical and biochemical status and to adapt growth accordingly. Here, we propose that plant cells use their 1D cell edges to monitor cell wall status. We describe two Receptor-Like Proteins, RLP4 and RLP4-L1, which occupy a unique polarity domain at cell edges established through a targeted secretory transport pathway. We show that at cell edges, RLP4s associate with the cell wall via their extracellular domain, and contribute to directional growth control in Arabidopsis.

plant biology↗

bioRxiv2018

Integration of Brassinosteroid and Phytosulfokine Signalling Controls Vascular Cell Fate in the Arabidopsis Root

Multicellularity arose independently in plants and animals, but invariably requires robust determination and maintenance of cell fate. This is exemplified by the highly specialized water-and nutrient-conducting cells of the plant vasculature, which are specified long before their commitment to terminal differentiation. Here, we show that the hormone receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1) is required for root vascular cell fate maintenance, as BRI1 mutants show ectopic xylem in procambial position. However, this phenotype is unrelated to classical brassinosteroid signalling outputs. Instead, BRI1 is required for the expression and function of its interaction partner RECEPTOR-LIKE PROTEIN 44 (RLP44), which, in turn, associates with the receptor for the peptide hormone phytosulfokine (PSK). We show that PSK signalling is required for the maintenance of procambial cell identity and is quantitatively controlled by RLP44, which promotes complex formation between the receptor for PSK and its co-receptor. Mimicking the loss of RLP44, PSK-related mutants show ectopic xylem in the position of procambium, whereas rlp44 can be rescued by exogenous PSK. Based on these findings, we propose that RLP44 controls cell fate by connecting BRI1 and PSK signalling, providing a mechanistic framework for the integration of signalling mediated by the plethora of plant receptor-like kinases at the plasma membrane.

plant biology↗

bioRxiv2018

A Comprehensive Tool Set for Inducible, Cell Type-Specific Gene Expression in Arabidopsis

Understanding the context-specific role of gene function is a key objective of modern biology. To this end, we generated a resource for inducible cell-type specific trans-activation based on the well-established combination of the chimeric GR-LhG4 transcription factor and the synthetic pOp promoter. Harnessing the flexibility of the GreenGate cloning system, we produced a comprehensive set of GR-LhG4 driver lines targeting most tissues in the Arabidopsis shoot and root with a strong focus on the indeterminate meristems. We show that, when combined with effectors under control of the pOp promoter, tight temporal and spatial control of gene expression is achieved. In particular, inducible expression in F1 plants obtained from crosses of driver and effector lines allows rapid assessment of the cell type-specific impact of an effector with high temporal resolution. Thus, our comprehensive and flexible toolbox is suited to overcome the limitations of ubiquitous genetic approaches, the outputs of which are often difficult to interpret due to widespread existence of compensatory mechanisms and the integration of diverging effects in different cell types.\n\nOne sentence summary: A set of lines enabling spatio-temporal control of gene expression in Arabidopsis.

plant biology↗