Phylogenetic relationships among selected SUN-Domain proteins in the plant kingdom. An unrooted phylogenetic tree of SUN-domain proteins is shown, deduced from full-length cDNAs from maize (Zea mays, Zm), Arabidopsis (At), rice (Os), Sorghum bicolor (Sb), and moss (Physcomitrella patens, Pp). GenBank accession numbers are given in the figure, except for those of maize, which are from sequences listed in Table 1. The protein maximum-likelihood tree was created with TreeView, version 1.6.6 . Proteins belonging to the canonical (CCSD, green shaded area) and mid-SUN (PM3, yellow shaded area) classes are indicated. Four SUN orthologous grass groups (SOGG1-4) are also indicated. A partial EST from sorghum (Sb03g010590/PUT-157a-Sorghum_bicolor-11155) aligns with the SOGG2 group but was excluded from the analysis because it lacked a full-length ORF. Scale bar (0.1) represents 10 expected amino-acid changes for every 100 residues.