Fig. 2

Phylogenetic tree of WOX genes indicating that WOX genes could be divided into three clades. MEGA 7.0 was used for constructing the neighbor joining (NJ) tree. The inner circle is marked in purple, green, and orange representing the WUS, intermediate, and ancient clades, respectively. Each clade was classified into sub-clades, marked in different colors on the outer circle. α to η represent the sub-clades in the WUS clade, θ and ι represent the sub-clades in the intermediate clade, and κ represents the ancient clade. The prefixes Ga, Gr, Gh, Potri, At, Os, GRMZM, Sobic, and Thecc stand for G. arboreum, G. raimondii, G. hirsutum, Populus trichocarpa, Arabidopsis thaliana, Oryza sativa, Zea mays, Sorghum bicolor, and Theobroma cacao, respectively. The appendices At and Dt in the upland cotton indicate the A- and D-subgenome, respectively. The bootstrap values are shown near the nodes, and only those values greater than 50 are displayed.