Evolutionary divergence of the insect disease-encoding Serratia plasmid pADAP Supplementary Materials

Documents in support of statements made in the PhD thesis "Evolutionary divergence of the insect disease-encoding <i>Serratia</i> plasmid pADAP" by Thomas Lesley Sitter<br>Abstract for the thesis<br>The larvae of the New Zealand grass-grub (<i>Costelytra givenii</i>), cause significant damage to New Zealand’s pastures. Two diseases of grass-grub larvae, instigated by strains of <i>Serratia</i> <i>entomophila</i> and <i>S.</i> <i>proteamaculans</i>, have been identified and are being used as commercial biocontrol agents. The main virulence determinants of these <i>Serratia</i> strains, an Anti-feeding-prophage and an ABC-toxin-complex, are encoded on a 153-kb conjugative plasmid pADAP. Recently 75 <i>Serratia</i> strains with atypical disease phenology were sequenced with the goal of defining evolutionary points of divergent between plasmid variants and define potential co-evolution between plasmid and host. Phylogenetic analysis of the conserved plasmid “backbone”, residing between a conserved integrase (Int2) and the end of a conjugative pili cluster (PilL), revealed clustering of all the <i>S. entomophila</i> plasmids. Within the predicted backbone region, several intergenic replication and conjugation regions contained DNA inserts, one of which, positioned between TraG and TraC, demarcates chronic disease related plasmids from the non-chronic plasmids. These inserted regions were used as a marker to track the evolutionary divergence between the plasmids variants. A key finding was that all ABC-toxin-complex variants are co-located with a fimbria cluster, eluding to a role of fimbriae for the proper functionality of the ABC-toxin-complex. <br> <b>Keywords:</b> Insecticidal activity, plasmids, evolutionary divergence, horizontal gene transfer, pan-genome, genome wide association study, grass grub, pADAP, Sep, Afp. <br>