Fig. 5.

Heat map comparison of pairwise sequence identity for 177 symbiosis genes across 42 wild Mesorhizobium strains shows 21 clusters of symbiosis genes with contrasting patterns of relatedness among strains. The x-axis indicates all 861 pairwise comparisons for each gene between 42 SI+ strains. The y-axis indicates 177 near-core symbiosis island genes. Colored bars to the right of the heat map indicate Ward clusters of genes with bootstrap values ≥ 90. *Cluster 10 contains vir genes which are implicated in the horizontal transfer of the symbiosis island and are found in SI+ but not SI− wild strains but are not contained in the Mesorhizobium loti MAFF303099 symbiosis island. See Fig. S2 for gene names along the y-axis