C2 and infection: Since the tomato UBA1 interacts with TYLCSV C2 (F. Hèricourt et al., in preparation), the finding that silencing of this host gene leads to an earlier TYLCSV infection suggests that the interaction with the viral C2 protein might lead to the inhibition of the enzyme, which would be consistent with the previously described general negative impact of C2 on the ubiquitination in the host [10].