M. L. Borniego, M. Single-Rastogi, M. H. Sampangi-Ramaiah, A.-Y. Liu, G. Gonzalez-Gutierrez, S. J. Cox-Vazquez, C.-T. Vo, A. Fukudome, R. J. Vazquez, B. C. Meyers, P. Baldrich, R. W. Innes
Extracellular RNAs are found in the plant extracellular space, but how they are exported from cells remains unclear. We found that the plant vacuole is a major source of extracellular RNA and identified a class of large extracellular vacuole-derived bodies, which we termed EVacs, that are key mediators of this transport. EVacs are marked by the vacuolar membrane (tonoplast) proteins {gamma}-TIP and V-ATPase and originate as intravacuolar structures formed by inward folding of the tonoplast, encapsulating intact cytoplasmic material, including both RNAs and proteins. These intravacuolar bodies then escape the vacuole and are subsequently released from the plasma membrane of mesophyll cells into the apoplast. These findings provide a novel mechanism for the unconventional secretion of macromolecules in plants.