Lipid droplets (LDs) are dynamic organelles that store neutral lipids and contribute to cellular metabolism. In recent years, LDs have emerged as important platforms not only for lipid regulation but also as interaction sites for pathogens, including viruses. In animal systems, several viruses are known to co-opt LDs to facilitate replication and assembly. However, in plants, little is currently known about how viruses—particularly potyviruses—hijack host lipids to support their replication and spread. LDs may be diverted to remodel endomembrane systems for the formation of viral replication complexes (VRCs), and/or used as energy sources for replication and/or movement.
Our previous findings show that lipid droplets accumulate during turnip mosaic virus (TuMV) infection in plants and appear to play a pro-viral role. To further understand how TuMV co-opts these organelles, we now focus on the cellular pathways governing LDs turnover. Lipids stored in LDs can be degraded via two main pathways: lipolysis, which involves lipase-mediated breakdown in the peroxizome, and lipophagy, the autophagic degradation of LDs in the vacuole.
We aim to investigate whether either lipolysis or lipophagy pathways contribute to the mobilization of LDs derived lipids to facilitate viral propagation.
This internship is divided into three main tasks:
TASK1: Assessing the differential expression regulation of LDs degradation related genes in infected plants compared to non-infected plants.
Transcription level of different candidate genes involved in LDs degradation through lipolysis or lipophagy will be followed by Quantitative-RT-PCR analyses.
TASK2: Monitoring the local and systemic propagation and replication of TuMV tagged with a fluorescent protein in different Arabidopsis lines affected in both pathways.
The propagation of the virus will be monitored based on the fluorescent area of local infection foci imaged using a macroscope. At the plant scale, the student will also monitor the kinetic of the systemic viral propagation using a fluorcam able to detect GFP fluorescent signal in the whole plant.
The viral replication will be assessed quantitatively by performing Quantitative-RT-PCR on viral proteins transcripts.
TASK3: Assessing the subcellular localization of peroxisomal or autophagic markers in comparison with lipid droplets and viral replication organelles.
Potential colocalization events between peroxisomal or autophagic markers, viral proteins and LDs will be investigated using confocal microscopy in both Arabidopsis thaliana and Nicotiana benthamiana plants.
Nathalie Arvy (CR, INRAE, Bordeaux) and Marguerite Batsale (post-doc, INRAE, Bordeaux)
