Key gene clusters present on ITR plasmid progenitor of chromosome II and related large replicons during evolution of Rhizobiales. C58 is the reference, and its genes are represented as arrows consistent with the strand they are found on in the deposited genome sequence. Genes for the other genomes were aligned with the C58 genes and are represented with circles or squares. Circles/squares are connected with lines when corresponding genes are consecutive. A black or gray circle means that the gene represented is in a secondary chromosome or plasmid; a black or gray square means that the gene represented is in the primary chromosome. A black circle or square means that the alignment to the C58 ortholog covered 80% or more of both genes; a gray circle or square means the alignment covered less than 80%. Gene numbering is shown for C58 (Agro C58), S4 (Agro vitis S4), K84 (Agro K84), R. etli CFN42, R. leguminosarum biovar viciae 3841 (R.leg), S. meliloti 1021 (S.meli), B. suis 1330, and O. anthropi ATCC49188.