Figure 2

Neighbour-joining phylogenetic tree from four major land plant lineages, together with corresponding visual representation of conserved regions, functional motifs, and relative intron positions. A putative tyrosinase sequence from the cyanobacterium A. marina (GenBank accession ACJ76786) was used to root the tree. Bootstrap replicates (1000) were used to determine the level of support at each node (only values > 50% are shown). The conserved first five amino acids for each of the CuA and CuB domains is shown at the end of each branch as HxxxC / HxxxH. Predicted targeting sequences are colored as green (chloroplast transit peptide), black (signal peptide), or grey (unknown). The CuA and CuB domains are colored blue, and C-terminal conserved areas dark grey. Approximate intron positions are shown as vertical bars, mapped onto the predicted protein. Shared colors indicating the same intron positions, and black bars mark unique introns. The introns are named by their location: N, N-terminus; A, CuA domain; L, linker; D, DWL domain; K, KFDV domain; C, C-terminus. Exact intron positions are listed in Additional file4. The PPO sequences are numbered and named based on species names as follows: P. patens, Ppa; S. moellendorffii , Smo; B. distachyon, Bda; O. sativa, Osa; S. italica, Sit; S. bicolor, Sbi; Z. mays, Zma; A. coerulea, Aco; G. max, Gma; M. esculenta, Mes; M. guttatus, Mgu; P. trichocarpa, Ptr; R. communis, Rco; V. vinifera, Vvi. Mexican poppy (Argenome mexicana) AmePPO1 (GenBank accession ACJ76786) was also included in the phylogeny because of our interest in the Eudicot I clade.