Biomolecular Condensates in Plant Stress and Development: Recent Advances and Emerging Concepts

Biomolecular condensates have emerged as a central paradigm for understanding how plant cells organize biochemical processes without membrane boundaries, particularly under fluctuating environmental conditions. In plants, many condensates are thought to form through liquid-liquid phase separation and related demixing behaviors, enabling the selective concentration of proteins and RNAs into dynamic assemblies. This mesoscale organization provides an efficient strategy to buffer acute stress, protect macromolecules, and reprogram gene expression across spatial and temporal scales. Here, we synthesize current knowledge of condensate functions in plant development and stress responses, with a focus on Arabidopsis thaliana, where mechanistic insights are most advanced. We first outline the biophysical principles underlying condensate formation, emphasizing multivalent protein-protein and protein-RNA interactions, intrinsically disordered regions, and prion-like or low-complexity domains that enable reversible assemblies with distinct material properties. We then discuss condensates in plant development, highlighting hydration-associated assemblies in seeds, as well as condensation-based regulation of light signaling, auxin pathways, and flowering time. Next, we examine condensates as key hubs of stress adaptation, including stress granules and processing bodies, nuclear assemblies, and emerging evidence for organellar condensates in chloroplasts, which may exhibit distinct biophysical characteristics. Finally, we review the experimental toolkits used to study condensates in plants, ranging from live-cell imaging and fluorescence recovery after photobleaching (FRAP) to in vitro reconstitution, proximity labeling, particle enrichment strategies, and RNA-centric profiling approaches, while emphasizing important technical considerations and limitations. We conclude by outlining key open questions such how plants dynamically regulate condensate assembly and disassembly in vivo, how condensates interface with proteostasis and organelle function, and how this layer of regulation may contribute to plant resilience in the context of climate change.