The turnip mosaic virus (TuMV) not only infects plant cells but also reorganizes their resources to promote its multiplication. Researchers at INRAE have shown that the virus diverts lipid droplets, cellular structures that store neutral lipids. This work, published in the journal New Phytologist, is the first study to demonstrate the involvement of these droplets in the cycle of a positive-sense single-stranded RNA plant virus.
The study is part of the ANR LiDRoVir project, coordinated by Sylvie German-Retana (INRAE), in collaboration with teams led by Claire Bréhélin (CNRS Bordeaux) and Jean-Luc Gallois (INRAE Avignon). The researchers analyzed infected leaves of Nicotiana benthamiana, a model plant. They observed a significant accumulation of neutral lipids and an enrichment in C18:3 fatty acids following infection, indicating a disruption of the plant's lipid metabolism.
Using confocal and electron microscopy, it was observed that lipid droplets multiply and cluster near viral replication sites. Membrane contact points were identified between these droplets and viral vesicles involved in replication.
The research also investigated plant proteins LDAP and SEIPIN, involved in lipid droplet biogenesis, in the model plant Arabidopsis thaliana. The absence of these proteins reduced the size of infection foci and slowed down TuMV propagation, while their overexpression accelerated it. These findings confirm that lipid droplets facilitate viral spread.
This research establishes a direct link between lipid droplet biogenesis and the infectious cycle of TuMV, opening new avenues for understanding the role of lipids in plant viral infections.
