Thermosensor FUST1 Triggers Heat Stress Granules in Plants

In a groundbreaking new study, researchers have unveiled the critical role of the protein FUST1 as a thermosensor that orchestrates heat-induced stress granule formation in Arabidopsis, providing unprecedented insights into plant cellular responses to thermal stress. This discovery not only deepens our understanding of plant resilience mechanisms but also heralds promising avenues for enhancing crop tolerance amid global climate challenges. The study, recently corrected and published in Cell Research, reveals how FUST1 primes the assembly of stress granules—a form of biomolecular condensates—that safeguard cellular functionality under elevated temperatures.

The importance of stress granules in eukaryotic cells has been widely recognized as a rapid and reversible means to protect transcripts and proteins during adverse environmental conditions. Yet, the specific molecular initiators that trigger granule nucleation, especially under heat stress in plants, remained elusive. Through a sophisticated combination of biochemical assays, live-cell imaging, and molecular genetics, the team led by Geng, Li, and Quan delineated the nuanced role of FUST1 as a bona fide thermosensor that modulates the condensation dynamics essential for stress granule biogenesis.

FUST1’s ability to detect subtle temperature elevations initiates a cascade of conformational changes that favor its phase separation, thus driving the coalescence of ribonucleoprotein complexes. This biomolecular condensation acts as a nucleation center where untranslated mRNAs and associated proteins congregate, effectively reorganizing the cytoplasm to minimize heat-induced damage to the translational machinery. The study’s detailed characterization of FUST1’s intrinsically disordered regions explains how temperature-induced modulation of weak multivalent interactions underpins condensate stability and reversibility, vital for cellular homeostasis.

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One of the pivotal advances in this research was the utilization of advanced fluorescence recovery after photobleaching (FRAP) and single-molecule tracking techniques, allowing the visualization of FUST1 dynamics in living plant cells under varying thermal conditions. These cutting-edge methodologies uncovered that FUST1 transitions from a diffuse cytoplasmic distribution to distinct puncta within minutes of heat exposure, marking the onset of stress granule formation. This rapid and reversible response mechanism ensures that plants can swiftly adapt to fluctuating temperatures.

The molecular dissection of FUST1’s function further involved site-specific mutagenesis that disrupted its condensation properties, resulting in defective stress granule assembly and reduced thermotolerance. These loss-of-function variants highlight the indispensability of FUST1’s condensation-prone domains for proper stress granule nucleation. By integrating transcriptomic and proteomic analyses, the researchers demonstrated that impaired FUST1 function compromises the sequestration of critical mRNAs involved in protein folding and degradation pathways, exacerbating cellular stress under heat.

Beyond its immediate role in stress biology, the study situates FUST1 within the broader conceptual framework of biomolecular condensates as versatile cellular compartments formed via liquid-liquid phase separation (LLPS). LLPS-driven assemblies have emerged as universal mechanisms underlying cellular organization without membrane encapsulation. FUST1 exemplifies how plants harness LLPS to create transient hubs for post-transcriptional regulation, RNA metabolism, and protein quality control, adjusting their internal environment dynamically in response to heat stress.

The implications of these findings extend to agricultural biotechnology, where engineering FUST1 expression or its phase separation propensity could enhance crop robustness against rising global temperatures. As climate change accelerates, understanding and manipulating thermosensory pathways like those mediated by FUST1 offer promising strategies to sustain food security. The study also opens avenues to explore analogous heat-sensing mechanisms in other plant species and their potential crosstalk with hormonal and metabolic stress responses.

Notably, the research underscores the importance of intrinsically disordered proteins (IDPs) in environmental sensing. FUST1’s disordered regions provide the structural plasticity necessary to tune interaction affinities in a temperature-dependent manner. This adaptability contrasts sharply with the classical view of protein function solely relying on well-defined tertiary structures and emphasizes the critical regulatory versatility introduced by disorder and phase separation in stress adaptation.

The paper also addresses the broader biological significance of stress granules in plants, which are less understood compared to their animal counterparts. Stress granule components in plants might encompass specific RNA-binding proteins and translational repressors uniquely adapted to plant metabolism and physiology. Identifying FUST1 as a core nucleator enriches the catalog of plant stress granule constituents and offers a molecular handle for dissecting their assembly hierarchy.

Furthermore, the multidisciplinary methods employed—ranging from in vitro reconstitution of FUST1 condensates to in vivo phenotypic analyses of Arabidopsis mutants—demonstrate the power of integrated approaches in elucidating complex cellular phenomena. This comprehensive framework bridges biophysics, molecular biology, and plant physiology to paint a holistic picture of heat stress responses at the subcellular level.

The research team also investigated the reversibility aspects of FUST1-mediated condensates, highlighting that upon return to optimal temperatures, stress granules swiftly dissolve, enabling the resumption of normal translational activities. This dynamic reversibility is key to maintaining cellular plasticity and preventing pathological aggregation, thus preserving plant fitness under cyclical thermal fluctuations.

Intriguingly, the study suggests potential evolutionary conservation of heat-sensitive phase separation mechanisms beyond plants, positing that similar thermosensory proteins may exist across taxa, evoking general principles by which life adapts to thermal stress at the molecular level. Elucidating these conserved pathways may unravel novel targets not only in plant science but also in biomedical contexts where stress granule dysregulation contributes to disease.

Ultimately, this study marks a significant stride in understanding plant adaptation strategies at the molecular granularity necessary for confronting the multifaceted challenges presented by climate change. By decoding the role of FUST1 as a thermosensor priming biomolecular condensation and stress granule formation, the researchers furnish a compelling template for future investigations into the interplay between environmental cues and cellular phase behavior.

In summary, this landmark work offers a nuanced perspective on how plants rapidly reorganize their intracellular landscape in response to thermal stress through phase separation phenomena. Illuminating the function of FUST1 bridges critical gaps in the knowledge of stress granule biology and sets the stage for translational applications aimed at fortifying crop resilience in an ever-warming world.

Subject of Research: Thermosensory mechanisms and stress granule formation in Arabidopsis mediated by the protein FUST1.

Article Title: Author Correction: A thermosensor FUST1 primes heat-induced stress granule formation via biomolecular condensation in Arabidopsis.

Article References:
Geng, P., Li, C., Quan, X. et al. Author Correction: A thermosensor FUST1 primes heat-induced stress granule formation via biomolecular condensation in Arabidopsis. Cell Res (2025). https://doi.org/10.1038/s41422-025-01134-3

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Tags: Arabidopsis cellular responsesbiochemical assays for heat stressbiomolecular condensates in eukaryotic cellscrop tolerance climate challengesFUST1 protein thermosensorheat stress granule formation in plantslive-cell imaging in plant researchmolecular initiators of granule nucleationphase separation in thermoregulationplant resilience mechanismsribonucleoprotein complexes coalescencestress granules and environmental conditions