Biology subjects

Dorone, Y.

Publications and source records attributed to Dorone, Y..

6 recordsLinked to original sources

bioRxiv2025

FLOE1 maintains cellular viscosity in rehydrating Arabidopsis embryos

Most plant embryos can survive for years in a dry state of less than 10% water(1). Rehydration during seed germination is critical but risky-too little environmental water can dehydrate and kill the developing embryo. Plants avoid this by germinating only when sufficient water is present. However, the mechanisms by which sufficient water is sensed and how it triggers germination remain unknown. FLOE1 suppresses seed germination under water limitation by undergoing reversible phase changes in response to water potential(2). To understand how FLOE1 affects germination, we compared water behavior in wild type and floe1-1 null mutants. While both had similar amounts of water when dry, floe1-1 seeds hydrated less than the wild type after imbibition. Additionally, bound water was less restricted in floe1-1 embryos, suggesting FLOE1 promotes macromolecular water binding. By developing plant-compatible versions of Genetically Encoded Multimeric nanoparticles (GEMs)(3), we show that FLOE1 increases cytoplasmic viscosity during embryo rehydration. FLOE1 in yeast was sufficient to increase cytoplasmic viscosity. FLOE1 also increased cytoplasmic viscosity during hyperosmotic stress in yeast, and this ability was ablated by FLOE1 domain deletions. Our study identifies FLOE1 as a regulator of water content, dynamics, and cytoplasmic viscosity, linking molecular water control to cellular physical properties.

plant biology↗

bioRxiv2024

Arabidopsis thaliana RHAMNOSE 1 condensate formation drives UDP-rhamnose synthesis

Rhamnose is an essential component of the plant cell wall and is synthesized from uridine diphosphate (UDP)-glucose by the RHAMNOSE1 (RHM1) enzyme. RHM1 localizes to biomolecular condensates in plants, but their identity, formation, and function remain elusive. Combining live imaging, genetics, and biochemical approaches in Arabidopsis and heterologous systems, we show that RHM1 alone is sufficient to form enzymatically active condensates, which we name rhamnosomes. Rhamnosome formation is required for UDP-rhamnose synthesis and organ development. Overall, our study demonstrates a novel role for biomolecular condensation in metabolism and organismal development, and provides further support for how organisms have harnessed this biophysical process to regulate small molecule metabolism. One-Sentence SummaryCondensation of RHM1 drives UDP-rhamnose synthesis during plant development.

plant biology↗

bioRxiv2021

CHIQUITA1 maintains temporal transition between proliferation and differentiation in Arabidopsis thaliana

Body size varies widely among species, populations, and individuals depending on the environment. Transitioning between proliferation and differentiation is a crucial determinant of final organ size, but how the timing of this transition is established and maintained remains unknown. Using cell proliferation markers and genetic analysis, we show that CHIQUITA1 (CHIQ1) is required to maintain the timing of the transition from proliferation to differentiation in Arabidopsis thaliana. Combining kinematic and cell lineage tracking studies, we found that the number of actively dividing cells in chiquita1-1 plants decreases prematurely compared to wild type plants, suggesting CHIQ1 maintains the proliferative capacity in dividing cells and ensures that cells divide a certain number of times. CHIQ1 belongs to a plant-specific gene family of unknown molecular function and physically and genetically interacts with three close members of its family to control the timing of proliferation exit. Our work reveals the interdependency between cellular and organ-level processes underlying final organ size determination. SignificanceTiming of the transition between proliferation and differentiation is fundamental for determining the final size of organs and organisms. In agriculture, controlling organ and organism size can influence key agronomic traits such as yield and biomass. Dwarfism prevents lodging and was the trait responsible for the Green Revolution. Today, more sophisticated traits are needed for generating crops that are both resilient and sustainable. Revealing the molecular mechanisms that control the temporal transition between proliferation and differentiation will help unlock the potential of next-generation crops. Here, we report that CHIQUITA 1 in Arabidopsis thaliana is needed to maintain the proper timing of the transition between proliferation and differentiation in leaves and roots.

plant biology↗

bioRxiv2021

Poly(A)-binding protein is an ataxin-2 chaperone that emulsifies biomolecular condensates.

Biomolecular condensation underlies the biogenesis of an expanding array of membraneless assemblies, including stress granules (SGs) which form under a variety of cellular stresses. Advances have been made in understanding the molecular grammar that dictates the behavior of a few key scaffold proteins that make up these phases but how the partitioning of hundreds of other SG proteins is regulated remains largely unresolved. While investigating the rules that govern the condensation of ataxin-2, a SG protein implicated in neurodegenerative disease, we unexpectedly identified a short 14aa sequence that acts as an ataxin-2 condensation switch and is conserved across the eukaryote lineage. We identify poly(A)-binding proteins as unconventional RNA-dependent chaperones that control this regulatory switch. Our results uncover a hierarchy of cis and trans interactions that fine-tune ataxin-2 condensation and reveal a new molecular function for ancient poly(A)-binding proteins as emulsifiers of biomolecular condensate proteins. These findings may inspire novel approaches to therapeutically target aberrant phases in disease.

cell biology↗

bioRxiv2021

Interdependent Iron and Phosphorus Availability Controls Photosynthesis Through Retrograde Signaling

Iron deficiency hampers photosynthesis and is associated with chlorosis. We recently showed that iron deficiency-induced chlorosis depends on phosphorus availability. How plants integrate these cues to control chlorophyll accumulation is unknown. Here, we show that iron limitation downregulates photosynthesis genes in a phosphorus-dependent manner. Using transcriptomics and genome-wide association analysis, we identify two genes, a chloroplastic ascorbate transporter (PHT4;4) and a nuclear transcription factor (bZIP58), which prevent the downregulation of photosynthesis genes leading to the stay-green phenotype under iron-phosphorus deficiency. Joint limitation of these nutrients induces ascorbate accumulation by activating expression of an ascorbate biosynthesis gene, VTC4, which requires bZIP58. Exogenous ascorbate prevents iron deficiency-induced chlorosis in vtc4 mutants, but not in bzip58 or pht4;4. Our study demonstrates chloroplastic ascorbate transport is essential for preventing the downregulation of photosynthesis genes under iron-phosphorus combined deficiency. These findings uncover a molecular pathway coordinating chloroplast-nucleus communication to adapt photosynthesis to nutrient availability.

plant biology↗

bioRxiv2020

Hydration-dependent phase separation of a prion-like protein regulates seed germination during water stress.

Many organisms evolved strategies to survive and thrive under extreme desiccation. Plant seeds protect dehydrated embryos from a variety of stressors and can even lay dormant for millennia. While hydration is the key trigger that reactivates metabolism and kick-starts germination, the exact mechanism by which the embryo senses water remains unresolved. We identified an uncharacterized Arabidopsis thaliana prion-like protein we named FLOE1, which phase separates upon hydration and allows the embryo to sense water stress. We demonstrate that the biophysical states of FLOE1 condensates modulate its biological function in vivo in suppressing seed germination under unfavorable environments. We also find intragenic, intraspecific, and interspecific natural variations in phase separation propensity of FLOE1 homologs. These findings demonstrate a physiological role of phase separation in a multicellular organism and have direct implications for plant ecology and agriculture, especially the design of drought resistant crops, in the face of climate change.

cell biology↗