Tomato bushy stunt virus (TBSV) and other tombusviruses are model plant RNA viruses with 4.8 kb genomic (g)RNA coding for two replication proteins, termed p33 and p92 pol , and three proteins involved in cell-to-cell movement, encapsidation, and suppression of gene silencing [18, 19] . Yeast (Saccharomyces cerevisiae) expressing p33 and p92 pol replication proteins can efficiently replicate a short TBSV-derived replicon (rep)RNA [20, 21] . The tombusviral repRNA plays several functions, including serving as a template for replication and as a platform for the assembly of the viral replicase complex [19, 22, 23] . The viral RNA also participates in RNA recombination [6, 18, 24] , which likely plays a major role in virus evolution.