Phylogenetic relationships of Arabidopsis thaliana and Oryza sativa IQD proteins. The unrooted tree, constructed using ClustalX (1.81), summarizes the evolutionary relationship among the 61 members of both IQD protein families. The neighbor-joining tree was constructed using aligned full-length amino acid sequences. The scale bar corresponds to 0.1 estimated amino acid substitutions per site. Nodes supported by high bootstrap results (>75%) are indicated by dots. The same color code was used as in Figures 1 and 3 to highlight the different subfamilies (red, I; yellow, II; blue, III; green, IV; black, V [proteins with IQ67 domain on C-terminus]; brown, VI [proteins with truncated IQ67 domain]). The asterisks indicate the approximate position of branches corresponding to putative IQD proteins from pine (*TC522213, **TC41979, ***TC52519; Tentative Consensus of TIGR Unique Gene Indices).