Arabidopsis thaliana RHAMNOSE 1 condensate formation drives UDP-rhamnose synthesis.

Rhamnose is an essential component of the plant cell wall and is synthesized from uridine diphosphate (UDP)-glucose by the RHAMNOSE1 (RHM1) enzyme. RHM1 localizes to biomolecular condensates in plants, but their identity, formation, and function remain elusive. Combining live imaging, genetics, and biochemical approaches in Arabidopsis and heterologous systems, we show that RHM1 alone is sufficient to form enzymatically active condensates, which we name rhamnosomes.