Cell wall dynamics and their regulation by biomolecular condensates in plants

Plant cell walls are dynamic composite structures whose biogenesis, remodeling, and integrity maintenance require coordinated regulation of biosynthetic, trafficking, sensing, and signaling pathways. Plasma membrane-localized receptor kinases and mechanosensitive channels monitor wall status and transduce perturbations into intracellular responses, whereas biomolecular condensates-membraneless or membrane-associated assemblies formed through liquid-liquid phase separation or related processes-have emerged as candidate organizational features of several of these pathways. However, direct experimental evidence linking condensates to cell wall function remains sparse, and in many systems, whether observed puncta represent bona fide phase-separated assemblies remains unclear. In this review, we survey cell wall biogenesis and integrity pathways during development and under stress and critically evaluate the evidence for the involvement of condensates. To keep claims proportionate to the evidence, we apply an explicit evidence hierarchy that classifies individual systems as direct, indirect, contextual, or speculative. According to this framework, the RALF-pectin system, in which extracellular phase separation generates signaling platforms that recruit the receptor kinase FERONIA and its co-receptor LLG1 as client proteins, remains the only directly validated example. Most other proposed associations-including those involving P bodies, stress granules, and nuclear transcriptional condensates-instead appear to reflect responses to osmotic stress or molecular crowding that arise as secondary consequences of wall perturbations. We further assess how computational and artificial intelligence approaches might complement experimental investigation, while considering their present limitations in plant systems.