Romein, R. | bioRxiv Science

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↗

bioRxiv2025

Nanoclustering of a plant transcription factor enables strong yet specific DNA binding

Transcription factors (TFs) are traditionally depicted as monomeric, or oligomeric, units that recognize and bind specific DNA sequences to regulate transcription. Emerging evidence suggests that many TFs can undergo liquid phase separation, resulting in condensates that bind DNA through a different mechanism. For the Auxin Response Factors (ARFs), canonical plant TFs, evidence for both scenarios exists. But which of these scenarios is operational in the plant nucleus is unclear. Here, we demonstrate using MpARF2 of Marchantia polymorpha that a third scenario is operational: MpARF2 forms nanoscopic clusters under physiological conditions. Nanoclusters combine DNA-binding features that cannot be accessed by the other two scenarios: high-affinity, switch-like, and sequence-specific. Our results suggest nanoclustering as a mechanism that equips TFs with the DNA-binding properties necessary for transcriptional regulation. TeaserTranscription factor nanoclusters balance the DNA-binding trade-off between weakly binding oligomers and nonspecific condensates.

plant biology↗