Characterization of the necrosis determinant of the European genotype of pepino mosaic virus by site-specific mutagenesis of an infectious cDNA clone.

Mild and necrotic isolates have been described for the European (EU) genotype of pepino mosaic virus (PepMV), an important pathogen of tomato worldwide. In this study, we produced various infectious cDNA clones of an EU isolate with point mutations introduced by site-directed mutagenesis. Our results showed that the genetic determinant responsible for necrosis induction on tomato and Datura inoxia was amino acid 67 of TGBp3. This amino acid residue also acts as necrosis determinant in PepMV isolates belonging to the Chilean 2 genotype. This demonstrates that a single point mutation plays a role in necrosis induction by PepMV, irrespective of genotype.