Sensing and Filtering Environmental Fluctuations: The Case of Biomolecular Condensates in Plants.

Biomolecular condensates are membrane-less assemblies that selectively concentrate proteins, RNAs, and metabolites to integrate developmental and environmental cues. The remarkable diversity of plant condensates reflects the constraints of sessile organisms that must coordinate postembryonic organ development with continuous environmental adaptation. We review how plants employ condensates to integrate temperature, light, redox, and nutrient signals. We provide physicochemical foundations, including phase diagram behavior, critical solution temperature properties, and sticker-and-spacer models, as a framework for interpreting how environmental stimuli are transduced into condensate assembly/disassembly. We organize each biological system through a unified scaffold-client-RNA-metabolite framework, distinguishing experimentally validated conclusions from open mechanistic questions. Applying this framework across nuclear, cytoplasmic, chloroplastic, and membrane-associated condensates, we evaluate how temperature shifts, redox changes, post-translational modifications, and metabolite fluctuations drive reversible phase transitions. We highlight how saturation concentration thresholds function as nonlinear filters buffering environmental noise, how membrane-associated phase separation may nucleate cytoplasmic condensates, and where current evidence remains insufficient to distinguish bona fide liquid-liquid phase separation from alternative assembly mechanisms. By grounding plant condensate biology in physicochemical principles and comparative evidential analysis, we identify both well-supported mechanisms and critical gaps that must be addressed to translate condensate-biology into strategies for crop-resilience.