C2 and infection: Down-regulation of this gene by both a monopartite and bipartite geminivirus, TYLCSV and SACMV, respectively, favours the proposal that a geminiviral protein interaction, C2 protein in the case of TYLCSV, inhibits UBA1-mediated ubiquitination of possible viral proteins or host protein(s) linked to a resistance-associated response, which would favour progression of infection.