Phylogenetic tree of predicted protein sequences of rice and Arabidopsis Glycosyl Hydrolase Family 1 genes. The tree was derived by the Neighbor-joining method from the protein sequence alignment in the Supplementary Data Additional File 2 made with Clustalx with default settings, followed by manual adjustment. Large gap regions were removed for the tree calculation. The tree is drawn as an unrooted tree, but is rooted by the outgroup, Os11bglu36, for the other sequences. The bootstrap values are shown at the nodes. The clusters supported by a maximum parsimony analysis are shown as bold lines, and the loss and gain of introns are shown as open and closed diamonds, respectively. The 7 clusters that contain both Arabidopsis and rice sequences that are clearly more closely related to each other than to other Arabidopsis or rice sequences outside the cluster are numbered 1–7, while the outgroup cluster for which the Arabidopsis orthologue is not shown in numbered (8). Two Arabidopsis clusters that are more distantly diverged from the clusters containing both rice and Arabidopsis are numbered At I and At II, while rice genes and groups of genes that appear to have diverged before subclusters containing both rice and Arabidopsis are marked with stars.