Fig. 1

Overview of the 17 plant species used in this study and the proportion of primary symbionts in their microbiomes. (A) Photos of individual plants were taken at harvest and are not to scale. Plant species are labeled with their scientific names and are grouped by their known associations with AMF and rhizobia: species without AMF and without rhizobia (N), plant species with AMF but without rhizobia (A), plant species with AMF and rhizobia (AR), and Lupin, which associates with rhizobia but not AMF (R). (B) The midpoint rooted phylogenetic tree of the 17 species is based on rbcL gene sequences obtained from GenBank. Bootstrap values are indicated for nodes with ≥ 50% support in an analysis of 1000 replicates. Because no rcbL gene sequence was available for the tobacco species grown in this study (N. benthamiana), the sequence of a close relative (N. tabacum) was used. Common names for each species are colored by their symbiotype group association in the photograph. Plant families are indicated in black. (C) The proportion of sequences of bacterial and fungal primary symbiont origin (see Methods for definition) across the individual species of the different symbiotype groups. Letters indicate significant differences between the symbiotype groups based on the ANOVA results shown in Additional file 1: Table S5