Biology subjects

Vanneste, S.

Publications and source records attributed to Vanneste, S..

16 recordsLinked to original sources

bioRxiv2026

Synaptotagmin-mediated plasma membrane homeostasis is required to recruit the endocytic machinery during cold stress

Endocytosis depends on plasma membrane (PM) lipid composition, yet how plants sustain endocytic machinery recruitment during stress remains unclear. We investigated whether synaptotagmins SYT1 and SYT3 function in membrane homeostasis and endocytosis in Arabidopsis thaliana. In this work, we revealed that cold stress reversibly blocked FM4-64 internalization in syt1syt3 double mutants by displacing peripheral and core TPC subunits from the PM. Loss of SYT1 reduced brassinosteroid receptor internalization during cold stress, while double mutants showed enhanced brassinosteroid signaling. SYTs and VAP27 genes showed a condition-dependent genetic interaction in endocytosis: the syt1/vap27-1/vap27-3 triple mutant resembles vap27-1/vap27-3 under control conditions and syt1 during cold stress, suggesting overlapping contributions to endocytic regulation. Using molecular dynamics simulations of protein-membrane interactions, phosphoinositide depletion combined with increased diacylglycerol weakened TPC core membrane association. Our findings identify SYT1 and SYT3 as essential components for sustaining endocytosis during abiotic stress and support a model in which lipid homeostasis at endoplasmic reticulum-PM contact sites preserves the membrane composition required for TPC-dependent endocytosis.

plant biology↗

bioRxiv2026

Spatially-restricted metabolic delivery of auxin for selective adventitious root induction

Auxin impacts on nearly every aspect of plant growth and development. Its exogenous application therefore results in pleiotropic growth responses. Exploiting this activity for plant propagation requires avoiding or minimizing such off-target effects and is generally achieved as a trade-off between toxicity and organogenetic efficacity. We recently identified the compound HYSPARIN (HYS) with potent, and uniquely selective adventitious root inductive activity. Unlike other root-inducing compounds, HYS preferentially activates auxin responses in the shoot via an unknown mechanism. Here, we show that HYS acts as a shoot-specific proauxin. Rather than acting through auxin homeostasis, we found that HYS is hydrolysed in planta independently of ILR1/ILL amidohydrolases to release the synthetic auxin MCPA. Structure-activity relationship analysis confirmed a strong dependence on its MCPA moiety for activating auxin responses, and identified its promoiety as a determinant of shoot-specificity and activity. Selective application of MCPA also potently induces AR is consistent with a model in which HYS metabolism produces a spatially restricted, AR inductive auxin signal. The activation mechanism of HYS thus provides a conceptual framework for tissue-specific metabolic delivery of auxin and may enable the programmable delivery of other xenobiotics in plants.

plant biology↗

bioRxiv2024

Ribosome biogenesis factor AtRRB1 confers pollen heat stress tolerance in Arabidopsis

The plant male reproductive system is very sensitive to high temperature stress leading to a reduction in fertility. Damage caused by heat stress is restored by the activation of transcription and the synthesis of chaperones that regulate the heat stress response. Here we report that AtRRB1 is a homolog of the yeast ribosome chaperone protein Rrb1p. AtRRB1 is an essential gene and a T-DNA insertion in the coding region impairs male and female gametogenesis. The heterozygous rrb1-1 mutant shows decreased expression of AtRRB1 and increased transcription of the 60S ribosome proteins RPL3B and RPL4, in line with a chaperone role of AtRRB1 in ribosome biogenesis. Embryo sac development across ovules of a single pistil occurs uncoordinated and about half of the ovules abort. Half of rrb1-1 pollen is substantially smaller and produce shorter pollen tubes than WT pollen. In contrast to the Col-0 pollen, smaller pollen is overly sensitivity to high temperature (24h at 32{degrees}C) treatment, specifically during the early bicellular microspore development stage. Heat stressed rrb1-1 bicellular microspores accumulated excessively rough endoplasmic reticulum stacks, suggesting that loss of AtRRB1 activity causes an arrest in ER associated protein biosynthesis. These findings support a critical requirement for ribosome biogenesis and protein synthesis in bicellular microspores to recover from high temperature stress.

plant biology↗

bioRxiv2023

Seagrass genomes reveal a hexaploid ancestry facilitating adaptation to the marine environment

Seagrasses comprise the only submerged marine angiosperms, a feat of adaptation from three independent freshwater lineages within the Alismatales. These three parallel lineages offer the unique opportunity to study convergent versus lineage-specific adaptation to a fully marine lifestyle. Here, we present chromosome-level genome assemblies from a representative species of each of the seagrass lineages - Posidonia oceanica (Posidoniaceae), Cymodocea nodosa (Cymodoceaceae), and Thalassia testudinum (Hydrocharitaceae) - along with an improved assembly for Zostera marina (Zosteraceae). We also include a draft genome of Potamogeton acutifolius, a representative of Potamogetonaceae, the freshwater sister lineage to the Zosteraceae. Genome analysis reveals that all seagrasses share an ancient whole genome triplication (WGT) event, dating to the early evolution of the Alismatales. An additional whole genome duplication (WGD) event was uncovered for C. nodosa and P. acutifolius. Dating of ancient WGDs and more recent bursts of transposable elements correlate well with major geological and recent climatic events, supporting their role as rapid generators of genetic variation. Comparative analysis of selected gene families suggests that the transition from the submerged-freshwater to submerged-marine environment did not require revolutionary changes. Major gene losses related to, e.g., stomata, volatiles, defense, and lignification, are likely a consequence of the submerged lifestyle rather than the cause ( use it or lose it). Likewise, genes, often retained from the WGD and WGT, were co-opted for functions requiring the alignment of many small adaptations ( tweaking), e.g., osmoregulation, salinity, light capture, carbon acquisition, and temperature. Our ability to manage and conserve seagrass ecosystems depends on our understanding of the fundamental processes underpinning their resilience. These new genomes will accelerate functional studies and are expected to contribute to transformative solutions -- as continuing worldwide losses of the savannas of the sea are of major concern in times of climate change and loss of biodiversity.

evolutionary biology↗

bioRxiv2023

The selective estrogen receptor modulator clomiphene inhibits sterol biosynthesis in Arabidopsis thaliana

Sterols are produced via complex, multistep biosynthetic pathways involving similar enzymatic conversions in plants, animals and fungi, yielding a variety of sterol metabolites with slightly different chemical properties to exert diverse and specific functions. The role of plant sterols has been studied in the context of cell biological processes, signaling and overall plant development, mainly based on mutants. Due to their essential nature, genetic interference with their function causes pleiotropic developmental defects. An important alternative is to use a pharmacological approach. However, the current toolset for manipulating sterol biosynthesis in plants remains limited. Here, we probed a collection of inhibitors of mammalian cholesterol biosynthesis to identify new inhibitors of plant sterol biosynthesis. We provide evidence that imidazole-type fungicides, bifonazole, clotrimazole and econazole inhibit the obtusifoliol 14-demethylase CYP51, that is highly conserved among eukaryotes. Surprisingly, we found that the selective estrogen receptor modulator, clomiphene, inhibits sterol biosynthesis, in part by inhibiting the plant-specific cyclopropyl-cycloisomerase CPI1. These results demonstrate that rescreening of the animal sterol biosynthesis pharmacology is an easy approach for identifying novel inhibitors of plant sterol biosynthesis. Such molecules can be used as entry points for the development of plant-specific inhibitors of sterol biosynthesis that can be used in agriculture.

plant biology↗

bioRxiv2022

Phase separation-based visualization of protein-protein interactions and kinase activities in plants

Protein activities depend heavily on protein complex formation and dynamic post-translational modifications, such as phosphorylation. Their dynamic nature is notoriously difficult to monitor in planta at cellular resolution, often requiring extensive optimization and high-end microscopy. Here, we generated and exploited the SYnthetic Multivalency in PLants (SYMPL)-vector set to study protein-protein interactions (PPIs) and kinase activities in planta based on phase separation. This technology enabled easy detection of inducible, binary and ternary protein-protein interactions among cytoplasmic, nuclear and plasma membrane proteins in plant cells via a robust image-based readout. Moreover, we applied the SYMPL toolbox to develop an in vivo reporter for SnRK1 kinase activity, allowing us to visualize tissue-specific, dynamic SnRK1 activation upon energy deprivation in stable transgenic Arabidopsis plants. The applications of the SYMPL cloning toolbox lay the foundation for the exploration of PPIs, phosphorylation and other post-translational modifications with unprecedented ease and sensitivity.

plant biology↗

bioRxiv2022

Mapping the adaptor protein complex interaction network in Arabidopsis identifies P34 as a common stability regulator

Adaptor protein (AP) complexes are evolutionarily conserved vesicle transport regulators that recruit coat proteins, membrane cargos and coated vesicle accessory proteins. Since in plants endocytic and post-Golgi trafficking intersect at the trans-Golgi network, unique mechanisms for sorting cargos of overlapping vesicular routes are anticipated. The plant AP complexes are part of the sorting machinery, but despite some functional information, their cargoes, accessory proteins, and regulation remain largely unknown. Here, by means of various proteomics approaches, we generated the overall interactome of the five AP and the TPLATE complexes in Arabidopsis thaliana. The interactome converged on a number of hub proteins, including the thus far unknown adaptin binding-like protein, designated P34. P34 interacted with the clathrin-associated AP complexes, controlled their stability and, subsequently, influenced clathrin-mediated endocytosis and various post-Golgi trafficking routes. Altogether, the AP interactome network offers substantial resources for further discoveries of unknown endomembrane trafficking regulators in plant cells.

plant biology↗

bioRxiv2022

Making memories last: The peripheral effect of direct current stimulation on strengthening memories

Most memories that are formed are forgotten, while others are retained longer and are subject to memory stabilization. We show that non-invasive transcutaneous electrical stimulation of the greater occipital nerve (NITESGON) using direct current during learning elicited a long-term memory effect. However, it did not trigger an immediate effect on learning. A neurobiological model of long-term memory proposes a mechanism by which memories that are initially unstable can be strengthened through subsequent novel experiences. In a series of studies, we demonstrate NITESGONs capability to boost the retention of memories when applied shortly before, during or shortly after the time of learning by enhancing memory consolidation via activation and communication in and between the locus coeruleus pathway and hippocampus by modulating dopaminergic input. These findings may have a significant impact for neurocognitive disorders that inhibit memory consolidation such as Alzheimers disease.

neuroscience↗

bioRxiv2020

THE INFLUENCE OF PRE-SUPPLEMENTARY MOTOR AREA TARGETED HIGH-DEFINITION TRANSCRANIAL DIRECT CURRENT STIMULATION ON INHIBITORY CONTROL

AO_SCPLOWBSTRACTC_SCPLOWThe neural underpinnings of inhibitory control, an executive cognitive control function, has been a topic of interest for several decades due to both its clinical significance and the maturation of cognitive science disciplines. Behavioral, imaging, and electrophysiological studies suggest that the pre-supplementary motor area (preSMA) serves as a primary hub in a network of regions engaged in inhibition. High-definition transcranial direct current stimulation (HD-tDCS) allows us to modulate neural function to assess cortical contribution to cognitive functioning. The present study targeted HD-tDCS modulation of preSMA to affect inhibition. Participants were randomly assigned to receive 20 min of Sham, Anodal, or Cathodal stimulation prior to completing a semantically cued go/nogo task while electroencephalography (EEG) data were recorded. Both anodal and cathodal stimulation improved inhibitory performance as measured by faster reaction times and increased (greater negative) N2 event-related potentials (ERPs). In contrast, the Sham group did not show such changes. We did not find support for the anodal/cathodal dichotomy for HD neural stimulation. These findings constitute an early investigation into role of the preSMA in inhibitory control and in exploring application of HD-tDCS to the preSMA in order to improve inhibitory control.

neuroscience↗

bioRxiv2020

Pharmacological and genetic manipulations of Ca2+ signaling have contrasting effects on auxin-regulated trafficking

A large part of a plants developmental plasticity relies on the activities of the phytohormone auxin and the regulation of its own distribution. This process involves a cohort of transcriptional and non-transcriptional effects of auxin on polar auxin transport, regulating the abundancy, biochemical activity and polar localization of the molecular components, predominantly PIN auxin exporters. While the transcriptional auxin signaling cascade has been well characterized, the mechanism and role of non-transcriptional auxin signaling remains largely elusive. Here, we addressed the potential involvement of auxin-induced Ca2+ signaling in auxins inhibitory effect on PIN endocytic trafficking. On the one hand, exogenous manipulations of Ca2+ availability and signaling effectively antagonized auxin effects suggesting that auxin-induced Ca2+ signaling is required for inhibition of internalization. On the other hand, we addressed the auxin-mediated inhibition of PIN internalization in the auxin signaling (tir1afb2,3) or Ca2+ channel (cngc14) mutants. These mutants were strongly defective in auxin-triggered Ca2+ signaling, but not in auxin-inhibited internalization. These data imply that, while Ca2+ signaling may be required for normal PIN trafficking, auxin-mediated increase in Ca2+ signaling is not a direct part of a downstream mechanism that mediates auxin effects on Brefeldin A-visualized PIN intercellular aggregation. These contrasting results obtained by comparing the mutant analysis versus the exogenous manipulations of Ca2+ availability and signaling illustrate the critical importance of genetics to unravel the role of Ca2+ in a process of interest.

cell biology↗

bioRxiv2020

Synaptotagmins Maintain Diacylglycerol Homeostasis at Endoplasmic Reticulum-Plasma Membrane Contact Sites during Abiotic Stress

Endoplasmic Reticulum-Plasma Membrane contact sites (ER-PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis mutants lacking the ER-PM protein tether synaptotagmin1 (SYT1) exhibit decreased plasma membrane (PM) integrity under multiple abiotic stresses such as freezing, high salt, osmotic stress and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER-PM tether that also functions in maintaining PM integrity. The ER-PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to WT while the levels of most glycerolipid species remain unchanged. Additionally, SYT1-GFP preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a crucial SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.

molecular biology↗

bioRxiv2020

ABCB-mediated auxin transport in outer root tissues regulates lateral root spacing in Arabidopsis

Root branching is an important strategy to explore efficiently large volumes of soil. To economize this process, lateral roots (LR) are formed along the growing root at discrete positions that are instructed by oscillating auxin signals derived from the lateral root cap (LRC). This assumes that auxin moves from the LRC across multiple layers to accumulate in the pericycle. Here, we identified, using gene silencing and CRISPR based approaches, a group of five genetically linked, closely related ABCBs that control LR spacing by modulating the amplitude of the auxin oscillation. The transporters localize to the plasma membrane and reveal significant auxin export activity. These ABCBs are mainly expressed in the LRC and epidermis where they contribute to auxin transport towards the root oscillation zone. Our findings highlight the importance of auxin transport in the outer tissues of the root meristem to regulate LR spacing.

plant biology↗

bioRxiv2019

The use of mutants and inhibitors to study sterol biosynthesis in plants

Sterols are very well known for their important roles in membranes and signaling in eukaryotes. Plants stand out among eukaryotes by the large variety of sterols that they can produce, and employing them across a wide spectrum of physiological processes. Therefore, it is critical to understand the wiring of the biosynthetic pathways by which plants generate these distinct sterols, to allow manipulating them and dissect their precise physiological roles. Many enzymatic steps show a deep evolutionary conservation, while others are executed by completely different enzymes. Here, we review the complexity and variation of the biosynthetic routes of the most abundant phytosterols in the green lineage and how different enzymes in these pathways are conserved and diverged from humans,yeast and even bacteria. Based on their evolutionary conservation we discuss the use of human and yeast sterol biosynthesis inhibitors in plants, as an argument for the development of plant-tailored inhibitors of sterol biosynthesis.

plant biology↗

bioRxiv2019

A putative ER-PM contact site complex relocalizes in response to Rare Earth Elements-induced endocytosis

In plant cells, environmental stressors induce changes in the cytosolic concentration of calcium ([Ca2+]cyt) that are transduced by Ca2+-sensing proteins. To confer specificity to the stress signaling response, [Ca2+]cyt sensing must be tightly regulated in space and time; the molecular mechanisms that restrict the localization and dynamics of Ca2+ sensors in plants, however, are largely unknown. In this report, we identify a putative Ca2+-sensitive complex containing the synaptotagmins 1 and 5 (SYT1 and SYT5) and the Ca2+-dependent lipid binding protein (CLB1), which is enriched at ER-PM contact sites (EPCS) and relocalizes in response to Rare Earth Elements (REEs)-induced endocytosis. Our results show that endocytosed REEs influence cytosolic Ca2+ signaling, as indicated by the activation of the Ca2+/Calmodulin-based ratiometric sensor GCaMP3, and promote the cytoskeleton-dependent accumulation of ER-PM contact sites at the cell cortex. Based on these results, we propose that the EPCS-localized SYT1/SYT5/CLB1 complex is part of an evolutionarily conserved and spatially regulated Ca2+-responsive mechanism that control cER-PM communication during stress episodes.

plant biology↗

bioRxiv2019

Identification of selection and inhibition components in a go/nogo task from EEG spectra using a machine learning model

AO_SCPLOWBSTRACTC_SCPLOWPrior Go/NoGo studies have localized specific regions and EEG spectra for which traditional approaches have distinguished between Go and NoGo conditions. A more detailed characterization of the spatial distribution and timing of the synchronization of frequency bands would contribute substantially to the clarification of neural mechanisms that underlie performance of the Go/NoGo task. The present study used a machine learning approach to learn the features that distinguish between ERSPs involved in selection and inhibition in a Go/NoGo task. A neural network classifier was used to predict task conditions for each subject to characterize ERSPs associated with Go versus NoGo trials. The final model accurately identified individual task conditions at an overall rate of 92%, estimated by 5-fold cross-validation. The detailed accounting of EEG time-frequency patterns localized to brain sources (i.e., thalamus, preSMA, orbitofrontal cortex, and superior parietal cortex) provides elaboration on previous findings from fMRI and EEG studies and more information about EEG power changes in multiple frequency bands (i.e., primarily theta power increase, alpha decreases, and beta increases and decreases) within these regions underlying the selection and inhibition processes engaged in the Go and NoGo trials. This extends previous findings, providing more information about neural mechanisms underlying selection and inhibition processes engaged in the Go and NoGo trials, respectively, and may offer insight into therapeutic uses of neuromodulation in neural dysfunction.

neuroscience↗

bioRxiv2018

A novel role for Cyclic Nucleotide-Gated Ion Channel 2 (DND1) in auxin signaling

Cyclic Nucleotide Gated Ion Channels (CNGCs) have been firmly established as Ca2+-conducting ion channels that regulate a wide variety of physiological responses in plants. CNGC2 has been implicated in plant immunity and Ca2+ signaling due to the autoimmune phenotypes exhibited by null mutants of CNGC2. However, cngc2 mutants display additional phenotypes that are unique among autoimmune mutants, suggesting that CNGC2 has functions beyond defense and generates distinct Ca2+ signals in response to different triggers. In this study we found that cngc2 mutants showed reduced gravitropism, consistent with a defect in auxin signaling. This was mirrored in the diminished auxin response detected by the auxin reporters DR5::GUS and DII-VENUS and in a strongly impaired auxin-induced Ca2+ response. Moreover, the cngc2 mutant exhibits higher levels of the endogenous auxin indole-3-acetic acid (IAA), indicating that excess auxin in cngc2 causes its pleiotropic phenotypes. These auxin signaling defects and the autoimmunity syndrome of cngc2 could be suppressed by loss-of-function mutations in the auxin biosynthesis gene YUCCA6 (YUC6), as determined by identification of the cngc2 suppressor mutant repressor of cngc2 (rdd1) as an allele of YUC6. A loss-of-function mutation in the upstream auxin biosynthesis gene TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA1, WEAK ETHYLENE INSENSITIVE8) also suppressed the cngc2 phenotypes, further supporting the tight relationship between CNGC2 and the TAA-YUC-dependent auxin biosynthesis pathway. Taking these results together, we propose that the Ca2+ signal generated by CNGC2 is a part of the negative feedback regulation of auxin homeostasis in which CNGC2 balances cellular auxin perception by influencing auxin biosynthesis.

plant biology↗