Lipid droplets (LDs) are organelles composed of a phospholipid monolayer enclosing neutral lipids, involved in energy production, membrane biogenesis and stress signaling. Recently, LDs have also been shown to be required by some animal (+) RNA viruses for their replication. Like animal viruses, plant (+) RNA viruses have to hijack host proteins, intracellular membranes, and lipids to create an optimized lipid/membrane microenvironment for their efficient viral replication compartment (VRC) assembly. Yet the possible involvement of LDs in plant virus infection remains totally unexplored. Here, our confocal studies revealed that infection by turnip mosaic virus (TuMV, potyvirus) does induce a statistically significant increase of the number of LDs compared to mock-inoculated leaves, both in Arabidopsis and Nicotiana benthamiana. We also evidenced a significant accumulation of neutral lipids in infected leaves, thus confirming that TuMV-infection induces LD biogenesis. In addition, Transmission Electron Microscopy data revealed that the newly formed LDs are recruited to the TuMV-induced VRCs. Interestingly, potato virus A (PVA), another potyvirus species, induces a comparable LD biogenesis. By comparing the mRNA translatomes of TuMV- and mock- infected A. thaliana leaves, we detected in TuMV infected samples an increased translation of the main structural proteins of the leaf LDs, namely the three LDAPs (Lipid Droplet Associated Proteins) and the caleosin CLO3, which is in perfect agreement with the increase in the number of LDs induced by TuMV. Preliminary ELISA assays suggest that an Arabidopsis ko mutant of SEIPIN (a protein involved in the LD budding from the ER) seems less susceptible to TuMV, while LDAP1 overexpressor line (that shows a higher number of LDs than the wild type) displays higher susceptibility. Altogether, our results suggest for the first time, that LD biogenesis plays a pro-viral role in a plant virus infection.< Réduire