Biology subjects

Lamers, J.

Publications and source records attributed to Lamers, J..

8 recordsLinked to original sources

bioRxiv2026

Plant Acupuncture: a low-cost and open-source device for local mechanical stimulation

Background: Mechanical signals are important regulators of cellular responses in plants. They guide plant development and can activate defense and repair mechanisms. Yet, the molecular mechanisms by which plants perceive, transduce, and interpret mechanical signals are still poorly understood. This is in part due to the lack of methods to apply local, precise and non-damaging mechanical forces to plant cells. Micro-indentation is highly suitable for this purpose, yet available instrumentation is often expensive and difficult to combine with high-resolution microscopy. Results: We designed an open-source and affordable modular indentation device, consisting of 3D printed elements, 3 commercially available piezo motors, and a variety of indentation needles. Due to its modularity, the setup can be readily adapted to meet experimental requirements and works on all microscopes with bespoke adaptors. We show that the setup can be used to explore both rapid and slower touch responses, exemplified by visualizing calcium waves and actin patches induced by touch. We also show that the setup is compatible with various plant species and tissues and can be combined with high-resolution functional imaging. Conclusions: The simple and flexible design of the indentation device presented in this paper ensures that any lab with a 3D printer can build their own setup at low cost and with minimal time investment. The system has a wide range of applications for live plant tissue, making indentation experiments and thereby plant mechanobiology studies, more accessible.

plant biology↗

bioRxiv2026

Plant actin networks are rapid mechano-adaptive scaffolds

The actin cytoskeleton is among the most highly conserved eukaryotic structures. In animal cells, actin plays a key role in mechanobiology, serving as a structural scaffold that shapes cellular mechanics and a mechanoresponsive network that reorganizes in response to mechanical cues. In plants, these roles are generally attributed to the cell wall and the microtubule cytoskeleton. This leaves the role of plant actin in mechanical responses largely unclear. Here, we ask whether a key actin feature that is essential for animal mechanobiology may also be conserved in plants. We use quantitative live-cell imaging and quantitative image analysis to show that plant actin networks are rapidly mechano-responsive. We find a quantitative correlation between the cellular distribution of cortical actin networks and cellular deformations induced by laser ablation. This process is rapid and completes within 2-4 minutes. We propose that this is an intrinsic physical property of crosslinked filamentous networks, as these findings can be reproduced in a physical model that lacks biological regulation. Moreover, actin networks also respond to different types of mechanical stresses: both osmotic treatment and squeezing lead to distinct changes in actin organization, distribution, and dynamics. Our findings show that plant actin networks form mechano-adaptive scaffolds that sense mechanical deformations and reorganize in response within just a few minutes. This gives rise to a picture of plants having a two-geared cytoskeletal mechano-response system in which microtubules mediate slow responses to subtle developmental stresses, whereas actin provides a rapid response to large and potentially damaging deformations.

plant biology↗

bioRxiv2026

The evolution of plant actins

Why plants have evolved large families of highly similar actin isoforms, and what functional distinctions sustain their retention, remains an unresolved problem in cytoskeletal biology. Actin is among the most ancient and conserved proteins in eukaryotes, yet plant genomes encode an unusually high number of closely related paralogs whose specialization is poorly understood. Here, we reconstruct the evolutionary history of plant actins across the green lineage by combining sequence retrieval, phylogenetics, comparative sequence analysis, and structural mapping. We find that plant actin diversification arose multiple times and, strikingly, relatively late in the history of this ancient protein family. A major duplication produced two deeply conserved seed-plant actin clades, corresponding to the previously described vegetative and reproductive actins; here, we refer to these as Type I and Type II to reflect their phylogenetic relationships. Across the green lineage, increases in actin copy number track key transitions in plant complexity, particularly in tracheophytes. Despite this diversification, only a limited set of conserved substitutions distinguishes major actin lineages. Mapping sequence variation onto actin structures reveals a prominent surface patch that appears permissive to mutation, suggesting relaxed functional constraint, whereas isoform-specific changes cluster at sites likely to influence filament stability, turnover, and treadmilling. A finer-scale analysis in Brassicales pinpoints recent substitutions predicted to alter hydrogen-bonding patterns within monomeric and filamentous actin. Together, our results argue that plant actin diversification is not redundant drift, but a recurrent evolutionary strategy that preserves the actin core while tuning the intrinsic biophysical behavior of f-actin.

plant biology↗

bioRxiv2026

LipoTag: A minimal motif for live and functional imaging of plant cell membranes.

The plant plasma membrane is a highly dynamic structure that is crucial for cell compartmentalization, the maintenance of (bio)chemical gradients, signaling and cell growth and responses to stress. In plants, plasma membranes are tightly connected to the cell walls that encase them. These cell walls can act as diffusion barriers and prevent the use of a wide range of synthetic fluorescent probes that have been developed to study animal cell membranes, which lack a cell wall, with live functional imaging. Here, we introduce LipoTag, a minimal chemical motif that, upon chemical conjugation, transforms hydrophobic fluorophores into water-soluble, membrane-targeted probes that can permeate plant cell walls to reach their intended location. LipoTag uses a localized positive charge in combination with a short aliphatic spacer to direct cargo to the plasma membrane. We used LipoTag to develop a suite of membrane-specific fluorescent probes that work in walled organisms beyond the plant kingdom. In addition, we used LipoTag to develop functional reporters for the quantitative imaging of membrane density, lipid order and membrane oxidation in living plant tissues. LipoTag forms a modular platform for exploring the plant plasma membrane with a suite of contemporary imaging modalities.

plant biology↗

bioRxiv2023

Abscisic acid signaling gates salt-specific responses of plant roots

Soil salinity presents a dual challenge for plants, involving both osmotic and ionic stress. In response, plants deploy distinct yet interconnected mechanisms to cope with these facets of salinity stress. In this investigation, we observed a substantial overlap in the salt (NaCl)-induced transcriptional responses of Arabidopsis roots with those triggered by osmotic stress or the plant stress hormone abscisic acid (ABA), as anticipated. Notably, a specific cluster of genes responded uniquely to sodium (Na+) ions. Surprisingly, expression of sodium-induced genes exhibited a negative correlation with the ABA response and preceded the activation of genes induced by the osmotic stress component of salt. Elevated exogenous ABA levels resulted in the complete abolition of sodium-induced responses. Consistently, ABA signalling mutants displayed prolonged sodium-induced gene expression, coupled with increased root cell damage under high salinity conditions. Moreover, ABA signalling mutants were unable to redirect root growth to avoid high sodium concentrations and failed to contain their root cell swelling in the presence of elevated salt levels. In summary, our findings unveil an unexpected and pivotal role for ABA signaling in mitigating cellular damage induced by salinity stress and modulating sodium-specific responses in plant roots.

plant biology↗

bioRxiv2023

Warm temperature and mild water stress cooperatively promote root elongation

Warm temperatures have a dramatic effect on plant development. In shoots, stems elongate, and leaves are raised in a developmental programme called thermomorphogenesis. This results in enhanced leaf cooling capacity1. Thermomorphogenesis is tightly intertwined with light signalling pathways. The level of integration is so high that it has been proposed that shoot temperature sensing may have evolved from the co-option of an existing light signalling pathway during the colonisation of land by plants2. Roots also undergo thermomorphogenesis, but the mechanism by which this occurs is less well understood. Main root elongation is enhanced at warm temperatures, and this response is independent of many of the light and temperature signalling components of the shoot3. Roots develop in darkness and so it is a reasonable assumption that root temperature signalling is not through modulation of light signalling. It was recently speculated that due to the close correlation between warm temperature and soil moisture content, root temperature signalling could feasibly be related to water availability signals2. In this study we tested the interaction between temperature and water availability signalling in plant roots. We found that these environmental factors co-operatively enhance main root elongation. This interaction effect was dependent on SUCROSE NON-FERMENTING RELATED KINASE 2.2 (SnRK2.2) and SnRK2.3 and the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). We found that SnRK2.2 / 2.3 and COP1 have opposite effects on the stability of the transcription factor ELONGATED HYPOCOTYL 5 (HY5) in elongation zone hair cells. The stability of HY5 in these cell types generally corresponded to the degree of root elongation seen in each mutant background. Our study reveals several molecular components of root thermomorphogenesis and highlights the importance of an integrative approach to plant environmental signalling. Our results may have direct implications for agricultural land management, especially as global climates become more unpredictable.

plant biology↗

bioRxiv2023

Root branching in salt requires auxin-independent modulation of LBD16 function

Salinity stress constrains lateral root (LR) growth and severely impacts plant growth. Auxin signaling is indispensable for the regulation of LR formation. Nevertheless, the molecular mechanism of how salinity affects root auxin signaling and whether salt would steer alternative pathway(s) to regulate LR development is unknown. Here we show that the auxin-regulated transcription factor LATERAL ORGAN BOUNDARY DOMAIN (LBD)16, known as an essential player for LR development under control conditions, is regulated by an alternative non-canonical pathway under salinity. Salt represses auxin signaling but in parallel activates an upstream transcriptional activator of LBD16, ZINC FINGER OF ARABIDOPSIS THALIANA 6 (ZAT6). ZAT6 modulates the activity of LBD16 to contribute to downstream cell wall remodeling, and promotes LR development under salinity stress. Our study thus shows that root developmental plasticity in response to salt stress is achieved by integration of auxin-dependent repressive and salt-activated auxin-independent pathways converging on LBD16 to modulate root branching modulation under salinity.

plant biology↗

bioRxiv2020

Salinity stress-induced modification of pectin activates stress signaling pathways and requires HERK/THE and FER to attenuate the response

Soil salinity is an increasing worldwide problem for agriculture, affecting plant growth and yield. To understand the molecular mechanisms activated in response to salt in plants, we investigated the Catharanthus roseus Receptor like Kinase 1 Like (CrRLK1L) family, which contains well described sensors previously shown to be involved in maintaining and sensing the structural integrity of the cell walls. We found that herk1the1-4 double mutants, lacking the function of the Arabidopsis thaliana Receptor like Kinase HERKULES1 combined with a gain-of-function allele of THESEUS1, phenocopied the phenotypes previously reported in plants lacking FERONIA (FER) function. We report that both fer-4 and herk1the1-4 mutants respond strongly to salt application, resulting in a more intense activation of early and late stress responses. We also show that salt triggers de-methyl esterification of loosely bound pectins, responsible for the activation of several salt response signaling pathways. Addition of calcium chloride or chemically inhibiting pectin methyl esterase (PME) activity reduced activation of the early signaling protein Mitogen Activated Protein Kinase 6 (MPK6) as well as amplitude of salt-induced marker gene induction. MPK6 is required for the full induction of the salt-induced gene expression markers we tested. The sodium specific root halotropism response on the other hand, appears independent of MPK6 or calcium application, and is only mildly influenced by the cell wall sensors FER/HERK1/THE1-4 or alteration of PME activity. We hypothesize a model where salt-triggered modification of pectin requires the functionality of FER alone or the HERK1/THE1 combination to attenuate salt responses. Collectively, our results show the complexity of salt stress responses and salt sensing mechanisms and their connection to cell wall modifications, responsible for several salt response pathways and ultimately plant resilience to salinity.

plant biology↗