Figure 2. The unrooted phylogenetic tree of SHMT gene family in Solanum lycopersicum, Glycine max, Populus trichocarpa and A. thaliana.

The maximum likelihood method was used to construct phylogenetic tree containing seven tomato, seven A. thaliana (At), nine poplar (Ptr), and 18 soybean (Gm) SHMT proteins. The four subgroups are colored differently. The four differently-colored shapes represent SHMT proteins from four species. The orange pentacle, white rectangle, blue triangle, black rectangle represent tomato, A. thaliana, poplar, and soybean SHMT proteins, respectively. The number on the node in the phylogenetic tree represents the percentage of trustworthiness of the branch in the bootstrap validation.