Neighbor-Joining phylogeny of PWWP containing proteins in plants. The evolutionary history was inferred using the Neighbor-Joining method. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (5000 replicates) are shown next to the branches. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. All positions containing gaps and missing data were eliminated only in pairwise sequence comparisons (Pairwise deletion). Phylogenetic analyses were conducted in MEGA4. The distinct PWWP-domain subgroups (as discussed in the main text) are indicated by numbers and shaded in different colors. Domain names and representative domain architecture are shown for the major PWWP-domain protein families.