Biology subjects

Strotmann, V. I.

Publications and source records attributed to Strotmann, V. I..

6 recordsLinked to original sources

bioRxiv2026

EARLY FLOWERING 3 (ELF3): a novel role in integrating environmental stimuli with root stem cell niche maintenance

Maintaining stem cell niche (SCN) homeostasis in the root apical meristem (RAM) is essential for proper root growth and thus for overall plant development. In Arabidopsis thaliana, a group of slowly dividing cells at the SCN center known as the quiescent center (QC) maintain the surrounding stem cells, including the distally located columella stem cells (CSCs) which give rise to the differentiated columella cells. Many actors, including the PLETHORA (PLT) family transcription factors, regulate the QC quiescence and CSC fate. However, little is known about the integration of external and/or internal cues into regulating SCN homeostasis. In this study, we report for the first time the interaction between PLT3 and the thermosensor and circadian clock related transcriptional regulator, EARLY FLOWERING 3 (ELF3), which are both expressed in the root SCN. We show that ELF3 localizes, similar to PLT3, to subcellular condensates and sustains the QC and CSC fate. We demonstrate that ELF3 forms condensates in vitro and in vivo, in the cytoplasm, as well as in the nucleus, where it then co-localizes with PLT3. We reveal that the interaction of ELF3 and PLT3 is mediated by their intrinsically disordered prion-like domains (PrDs). Furthermore, transient expression in human epithelial cells (HEp-2) cells and in Nicotiana benthamiana shows that PHYTOCHROME INTERACTING FACTORS 3 and 4 (PIF3/4) function as nuclear shuttles for ELF3, recruiting it to nuclear condensates, where it co-localizes with PLT3, PIF3, and PIF4. Accordingly, we propose a model where the co-localization and interactions of ELF3, PLT3, PIF3, and PIF4 represent a dynamic mechanism to integrate environmental signals into SCN maintenance and cell fate decisions.

plant biology↗

bioRxiv2025

The bivalent epigenetic regulator ULTRAPETALA1 promotes the Arabidopsis floral transition via recruitment of Polycomb histone methyltransferases for H3K27me3 deposition at the FLC locus

Floral induction is a major transition during the plant life cycle that contributes to reproductive fitness in annual and perennial plants. Flowering occurs in response to multiple environmental and endogenous cues. In Arabidopsis thaliana, many of these cues converge on the regulation of the FLOWERING LOCUS C (FLC) gene, which encodes a MADS domain transcription factor that functions as the main floral repressor. Here we demonstrate that the bivalent epigenetic regulator ULTRAPETALA1 (ULT1) is both necessary and sufficient to promote flowering. We identify ULT1 as a novel component of the autonomous pathway (AP) and show that it accelerates flowering by directly repressing FLC transcription. We demonstrate that ULT1 physically associates with the SWINGER (SWN) and CURLY LEAF (CLF) histone methyltransferase components of Polycomb Repressive Complex 2 (PRC2) to regulate FLC transcription by altering the accumulation of H3K27me3 marks. Our data indicate that ULT1 promotes the floral transition by interacting with SWN and CLF to recruit PRC2 to the FLC locus to deposit repressive histone methylation and reduce transcription of this key floral repressor.

plant biology↗

bioRxiv2025

The Arabidopsis dehydrin ERD14 chaperones the BRL3 receptor to confer drought resistance

Brassinosteroid plant hormones are involved in growth, biotic and abiotic-stress signaling, but functional analysis of its multiple receptors has largely focused on the ubiquitously expressed BRASSINOSTEROID INSENSITIVE 1 (BR1). The vascular-expressed brassinosteroid receptor kinase BRI1-LIKE 3 (BRL3) has a specific and essential role in Arabidopsis adaptation to drought and elevated temperature. However, the mechanistic understanding of BRL3 function and regulation is scant. Here, we show the dehydrin ERD14 colocalizes with BRI1 and BRL3 at the plasma membrane and physically interacts with these receptors through the ERD14Lys domain for proper receptor recruitment. erd14 mutants internalize BRL3-GFP and revert drought-resistant BRL3 over-expression phenotypes. BRL3 activation and downstream signaling events, including dephosphorylation of BES1 transcription factor, depend on the chaperone function of ERD14. Our study shows how proper chaperoning by ERD14 regulates BRL3 subcellular localization and activity of the vascular receptor, prompting re-examination of models of brassinosteroid-receptor functional diversification in plant adaptation to abiotic stress from specific cells of the vascular systems.

plant biology↗

bioRxiv2024

Stem cell homeostasis in the root of Arabidopsis involves cell-type specific complex formation of key transcription factors

In Arabidopsis thaliana, the stem cell niche (SCN) within the root apical meristem (RAM) is maintained by an intricate regulatory network that ensures optimal growth and high developmental plasticity. Yet, many aspects of this regulatory network of stem cell quiescence and replenishment are still not fully understood. Here, we investigate the interplay of the key transcription factors (TFs) BRASSINOSTEROID AT VASCULAR AND ORGANIZING CENTRE (BRAVO), PLETHORA 3 (PLT3) and WUSCHEL-RELATED HOMEOBOX 5 (WOX5) involved in SCN maintenance. Phenotypical analysis of mutants involving these TFs uncover their combinatorial regulation of cell fates and divisions in the SCN. Moreover, interaction studies employing fluorescence resonance energy transfer fluorescence lifetime imaging microscopy (FRET-FLIM) in combination with novel analysis methods, allowed us to quantify protein-protein interaction (PPI) affinities as well as higher-order complex formation of these TFs. We integrated our experimental results into a computational model, suggesting that cell type specific profiles of protein complexes and characteristic complex formation, that is also dependent on prion-like domains in PLT3, contribute to the intricate regulation of the SCN. We propose that these unique protein complex signatures could serve as a read-out for cell specificity thereby adding another layer to the sophisticated regulatory network that balances stem cell maintenance and replenishment in the Arabidopsis root.

plant biology↗

bioRxiv2023

Phase separation and molecular ordering of the prion-like domain of the thermosensory protein EARLY FLOWERING 3

Liquid-liquid phase separation (LLPS) is an important mechanism enabling the dynamic compartmentalisation of macromolecules, including complex polymers such as proteins and nucleic acids, and occurs as a function of the physicochemical environment. In the model plant, Arabidopsis thaliana, LLPS by the protein EARLY FLOWERING3 (ELF3) occurs in a temperature sensitive manner and controls thermoresponsive growth. ELF3 contains a largely unstructured prion-like domain (PrLD) that acts as a driver of LLPS in vivo and in vitro. The PrLD contains a poly-glutamine (polyQ) tract, whose length varies across natural Arabidopsis accessions. Here, we use a combination of biochemical, biophysical and structural techniques to investigate the dilute and condensed phases of the ELF3 PrLD with varying polyQ lengths. We demonstrate that the dilute phase of the ELF3 PrLD forms a monodisperse higher order oligomer that does not depend on the presence of the polyQ sequence. This species undergoes LLPS in a pH and temperature-sensitive manner and the polyQ region of the protein tunes the initial stages of phase separation. The liquid phase rapidly undergoes aging and forms a hydrogel as shown by fluorescence and atomic force microscopies. Furthermore, we demonstrate that the hydrogel assumes a semi-ordered structure as determined by small angle X-ray scattering, electron microscopy and X-ray diffraction. These experiments demonstrate a rich structural landscape for a PrLD protein and provide a framework to describe the structural and biophysical properties of biomolecular condensates.

biophysics↗

bioRxiv2019

PLETHORA and WOX5 interaction and subnuclear localisation regulates Arabidopsis root stem cell maintenance

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.

plant biology↗