Figure 6.

Summary of the evolutionary history of R2R3-MYB TFs in land plants and their algal orthologs. A, Schematic diagram of the evolution of R2R3-MYB TFs in each subfamily. The schematic representation is dependent on the phylogenetic analyses conducted in this study (Supplemental Figs. S9 and S10). Black lines indicate the phylogeny of green plants based on Wickett et al. (2014), The Angiosperm Phylogeny Group (2016), Puttick et al. (2018), and One Thousand Plant Transcriptomes Initiative (2019). Squares on the black lines indicate the presence of lineage-specific subclades of R2R3-MYB TFs; a rounded square represents an Arabidopsis-specific subclade. A Greek letter in a square indicates the name of the subclade, an X indicates the presence of within-clade duplication in core eudicots, an L indicates that the sequence is likely to be a member of an existing subclade, and a question mark indicates that the evolutionary pattern of the subclade is questionable. A number in the square indicates the number of related subclades in the phylogenetic tree. B, Classification of R2R3-MYB TFs in Arabidopsis according to our analyses. The placement of TFs corresponds with their respective position (squares) in A (to the left). C, Summary of the classification systems of plant R2R3-MYB TFs in previous studies. Rectangles represent the R2R3-MYB subgroup(s) identified in the study and are labeled with the name of the subgroup/branch; strikethrough of the Arabidopsis R2R3-MYB TF name indicates that the TF was not included in the subgroup.