Tandem mass spectra from purified CYDV-RPV were converted mascot generic format (MGF) peak list files using Proteome Discovery 1.1. An in-house FASTA protein database was created from all NCBI entries, including all the translations of all the available cereal genomes, common contaminants, and viruses, was downloaded on January 31, 2012. This strategy was used as opposed to restricting the search to green plants to minimize false matches due to the presence of virus gene products or to the presence of other unanticipated sources of proteins (such as from plant-infecting bacteria of fungi) in the samples. All data were searched against this database using Mascot v2.3.02 (Matrix Science, Boston, MA) as follows. Fixed carbamidomethyl and variable methionine oxidation were used as modifications. Precursor ion tolerances were set to 30 parts per million (ppm), and fragment tolerance was 0.8 Dalton (Da). ESI-Trap was selected as the instrument type. The enzyme selected was trypsin with 1 missed tryptic cleavage permitted.