Single amino acid changes in the turnip mosaic virus viral genome-linked protein (VPg) confer virulence towards Arabidopsis thaliana mutants knocked out for eukaryotic initiation factors eIF(iso)4E and eIF(iso)4G.

Previous resistance analyses of Arabidopsis thalianamutants knocked out for eukaryotic translation initiation factorsshowed that disruption of the At-eIF(iso)4E or both the At-eIF(iso)4G1 and At-eIF(iso)4G2 genes resulted in resistance against turnip mosaic virus(TuMV). This study selected TuMV virulentvariants that overcame this resistance and showed that two independent mutations in the region coding for the viral genome-linked protein (VPg) were sufficient to restore TuMV virulencein At-eIF(iso)4E and At-eIF(iso)4G1×At-eIF(iso)4G2 knockout plants. As a VPg–eIF(iso)4E interaction has been shown previously to be critical for TuMV infection, a systematic analysis of the interactions between A. thaliana eIF4Esand VPgs of virulentand avirulent TuMVs was performed. The results suggest that virulentTuMV variants may use an eIF4F-independent pathway.