Phenotype summary of VirB2 variants.

<p>VirB2 amino acid substitutions are indicated with the levels of extracellular VirB2 (ExB2) production and occurrence or size of tumor formation on tomato stems (Vir) with wild type (+++), modest reduction (++), highly attenuation (+), or loss (−). VirB2 protein sequences with indicated conserved amino acid residues, regions/domains, and the processing site (indicated by an arrow) are presented as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101142#pone-0101142-g001" target="_blank">Figure 1</a>. The 34 VirB2 variants are classified into three groups: ExB2⁻/Vir⁻, ExB2⁻/Vir⁺, and ExB2⁺/Vir⁺ shown in red, green and black, respectively.