Biology subjects

Kirchhelle, C.

Publications and source records attributed to Kirchhelle, C..

5 recordsLinked to original sources

bioRxiv2026

Live confocal imagining of cellular touch responses upon local quantifiable mechanical stimulation in plant cells

Plant cells grow and differentiate in an ever-changing environment characterized by transient signals and stimuli. The ability of plant cells to perceive, integrate, and dynamically respond to these stimuli underpins a plant adaptation and survival. Among the plethora of complex stimuli plant cells are exposed to, several stimuli have a mechanical component, for example, wind, touch, contact with insects, penetration of pathogens, and even intrinsic mechanical stresses arising during tissue growth. Despite the presence of a load-bearing cell wall that separates cells from the environment and fixes their location within a tissue, plant cells are responsive to mechanical stimuli. However, several questions remain unanswered around how mechanical stimuli are perceived and translated into cellular responses. Here we establish a system enabling application of quantifiable localized mechanical stress while simultaneously capturing cellular responses with high spatio-temporal resolution using confocal imaging. We show that this system enables estimation of locally applied pressure and provides access to the temporal and spatial details of subcellular events in intact living tissues upon touch. We propose that observing these subcellular events at high spatiotemporal resolution and linking their dynamics to the intensity of mechanical stimuli may uncover the molecular mechanisms underlying plant cell responses to touch.

plant biology↗

bioRxiv2025

Plant cells at the organ surface use mechanical cues to activate a specific growth control programme

During morphogenesis of multicellular organs, cells acquire distinct identities that meet specific functional requirements. Epidermal identity is widely considered essential for plant morphogenesis due to the role of the epidermis in both restricting and promoting growth. In the root, epidermal cells are partially covered by a protective root cap, and partially positioned at the organ surface. Here, we propose that epidermal cells at the organ surface have unique requirements for growth control due to high mechanical tension, while covered epidermal cells are mechanically shielded by the root cap. We present in silico and in vivo evidence that plants use surface mechanical cues to activate a cell-type specific growth control programme involving the small GTPase RAB-A5c, allowing them to maintain directional growth at the organ surface. Positional mechanical cues may thus be used to control expression of a sub-population of epidermal genes, linking gene regulation to surface-specific functional requirements.

plant biology↗

bioRxiv2024

A Rab-Kinesin12-Fused kinase module couples vesicle delivery and phragmoplast remodelling during cytokinesis in Arabidopsis

Cytokinesis is a key process in the development of multicellular organisms, through both formative and proliferative divisions. In land plants, successful cytokinesis requires precise targeting of Golgi-derived vesicles to the future division plane by the phragmoplast, a cytoskeletal structure that undergoes continuous remodelling. Endomembrane trafficking and phragmoplast remodelling are tightly coupled, indicating the existence of active crosstalk. However, although many molecular regulators of membrane trafficking and cytoskeletal organisation are known, it remains poorly understood how these processes are co-ordinated. Here, we describe a regulatory module consisting of the membrane-associated GTPase RAB-A2a, cytoskeleton-associated Class II Kinesin-12s, and the Fused kinase orthologue TIO. We provide evidence that the interaction between these molecules at the midzone is essential for cytokinesis in Arabidopsis through simultaneously targeting vesicles to the midzone and coupling phragmoplast remodelling to vesicle delivery.

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↗

bioRxiv2020

Mapping cellular nanoscale viscoelasticity and relaxation times relevant to growth of living Arabidopsis thaliana plants using multifrequency AFM

The shapes of living organisms are formed and maintained by precise control in time and space of growth, which is achieved by dynamically fine-tuning the mechanical (viscous and elastic) properties of their hierarchically built structures from the nanometer up. Most organisms on Earth including plants grow by yield (under pressure) of cell walls (bio-polymeric matrices equivalent to extracellular matrix in animal tissues) whose underlying nanoscale viscoelastic properties remain unknown. Multifrequency atomic force microscopy (AFM) techniques exist that are able to map properties to a small subgroup of linear viscoelastic materials (those obeying the Kelvin-Voigt model), but are not applicable to growing materials, and hence are of limited interest to most biological situations. Here, we extend existing dynamic AFM methods to image linear viscoelastic behavior in general, and relaxation times of cells of multicellular organisms in vivo with nanoscale resolution, featuring a simple method to test the validity of the mechanical model used to interpret the data. We use this technique to image cells at the surface of living Arabidopsis thaliana hypocotyls to obtain topographical maps of storage E’ = 120 − 200 MPa and loss E’’= 46 − 111 MPa moduli as well as relaxation times τ = 2.2 − 2.7 µs of their cell walls. Our results demonstrate that cell walls, despite their complex molecular composition, display a striking continuity of simple, linear, viscoelastic behavior across scales–following almost perfectly the standard linear solid model–with characteristic nanometer scale patterns of relaxation times, elasticity and viscosity, whose values correlate linearly with the speed of macroscopic growth. We show that the time-scales probed by dynamic AFM experiments (milliseconds) are key to understand macroscopic scale dynamics (e.g. growth) as predicted by physics of polymer dynamics.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biophysics↗