Figure 9. Model of the evolutionary transition in Rhodococcus and effects on agricultural sectors.

The presence or absence of the virulence plasmid in eight species of Rhodococcusdetermines whether the bacterium is beneficial (right), and promotes growth in root architecture, or pathogenic (left), and causes leafy galls and inhibits primary growth. The virulence plasmid carries three loci identified as necessary for pathogenicity and their predicted functions are described. Horizontal gene transfer and evolutionary transitions affect Rhodococcus and impact the nursery industry (as indicated on the left of the figure). Virulence-gene-lacking isolates of Rhodococcus were diagnosed as outbreak strains and the probable misdiagnosis could have had detrimental impacts on the pistachio industry (as indicated on the right of the figure).