Figure 6. Distribution of BREX systems across the phylogenetic tree of bacteria and archaea.

Shown is the common tree of bacteria and archaea as represented in the NCBI Taxonomy resource (Materials and Methods). Organisms in which a BREX system exists are colored; color code follows the BREX subtype coloring from Fig5. Extensive horizontal transfer is observed by the lack of coherence between the species tree and the PglZ phylogeny.