A maximum likelihood phylogenetic tree of the PUM-HDs of Arabidopsis, rice and other plant and non-plant species. The analysis is based on the deduced amino acid sequence of the PUM-HD domain from each predicted Puf gene. The tree includes all members from Arabidopsis and rice, and representative members from Physcomitrella patens (Phys), Chlamydomonas reinhardii (Chlamy), Saccharomyces cerevisiae (Sc), as well as Drosophila Pumilio (DrPumilio) and human Pum1 (HsPum1). The Arabidopsis genes are referred by their designated Pum gene number (i.e., AtPumxx) that were reported by the National Center for Biotechnology Information (NCBI), as well as their gene locus name (Atxxxxxxx). The rice clones are identified by their gene locus name only (Osxxxxxxxx), as standardized Pum gene designations have not yet been established. Maximum likelihood bootstrap values (>65%) are shown above the nodes (PhyML/RaxML), and Bayesian posterior probability values (>0.95) are shown below the nodes. The bar at the bottom of the figure indicates the number of substitutions per site. The tree is rooted at its midpoint and, thus, its rooting should be interpreted as an hypothesis.