Turnip mosaic virus utilizes the lipid droplet biogenesis machinery to facilitate its propagation in plants

Lipid droplets (LDs), which are dedicated to storing neutral lipids (NLs), are dynamic organelles involved in numerous other functions, including membrane remodeling during abiotic stress. While the hijacking of LDs by animal viruses is well documented, their role(s) in plant virus infection remains largely unexplored. Similar to animal viruses, plant potyviruses reroute host proteins, intracellular membranes, and lipids to create an optimized microenvironment for their efficient viral replication compartment (VRC) assembly and movement. We therefore investigated whether potyviruses can also exploit the LD biogenesis machinery for their own benefit, akin to some animal viruses. Utilizing lipid analyses, confocal and transmission electron microscopy, and viral propagation surveys in plants impaired in LD biogenesis, we show that potyvirus turnip mosaic virus (TuMV) infection induces a significant accumulation of NLs and a proliferation of LDs in Nicotiana benthamiana or Arabidopsis thaliana-infected leaves, which are often located in close proximity to VRCs. This suggests that there is a spatial and functional relationship between LDs and TuMV. We demonstrate also that two protein families crucial for LD biogenesis, namely the lipid droplet-associated proteins and SEIPINs, facilitate TuMV propagation in Arabidopsis thaliana. Taken together, our results indicate a pro-viral function for LDs in potyvirus-infected plants.