Figure 2.

The evolution of SHMT genes. (A) SHMT gene divergence, duplication, and intron loss/gain events occurred during the transition from C. reinhardtii, representing a relative of the aquatic ancestor of all land plants, to the most ancestral land plants, and was maintained through all monocots and dicots. (B) SHMT gene structural analysis showed that an intron loss/gain event had occurred in the common ancestor of the nucleic/cytosolic-targeted GmSHMTn/c. The phylogenetic tree was generated using MEGA4 software package and the ClustalW algorithm, and calculated using the neighbor-joining method. The tree bootstrap values are indicated at the nodes (n = 1000). Gray arrows indicate the reported intron loss/gain events that occured during the transition from the relative of the aquatic ancestor of land plants. Gene structure of one GmSHMT representing each class is represented. The gene structure of the rest of the GmSHMT members can be found at Supplementary Fig. S5.