Condense to sense: a new path for plant osmosensing

Osmotic stress threatens plant survival and agricultural safety. Despite the progress made to elucidate how plants sense and adapt to osmotic stress, the knowledge underlying plant osmosensing remains limited. Notably, recent discoveries uncovering protein phase separation as an osmosensing and stress-adaptive mechanism have shed new light on this field. From a combined biological and physicochemical perspective, we dissect how osmotic stress affects a plant meristematic cell, propose macromolecular crowding and water content as previously overlooked osmosignals, discuss their perception by phase-separable proteins, and summarize the features of osmotic stress adaptation mediated by biomolecular condensates. We hope this review provides fresh insights into understanding osmotic stress and plant osmosensing.