Plant Roots Release Small Extracellular Vesicles with Antifungal Activity

Abstract: Extracellular Vesicles (EVs) play pivotal roles in cell-to-cell and inter-kingdomcommunication. Despite their relevant biological implications, the existence and role of plantEVs released into the environment has been unexplored. Herein, we purified round-shaped smallvesicles (EVs) by dierential ultracentrifugation of a sampling solution containing root exudates ofhydroponically grown tomato plants. Biophysical analyses, by means of dynamic light scattering,microfluidic resistive pulse sensing and scanning electron microscopy, showed that the size ofroot-released EVs range in the nanometric scale (50-100 nm). Shot-gun proteomics of tomato EVsidentified 179 unique proteins, several of which are known to be involved in plant-microbe interactions.In addition, the application of root-released EVs induced a significant inhibition of spore germinationand of germination tube development of the plant pathogens Fusarium oxysporum, Botrytis cinereaand Alternaria alternata. Interestingly, these EVs contain several proteins involved in plant defense,suggesting that they could be new components of the plant innate immune system.