The species of origin for each MKK is marked by species acronym before the protein name: Cr, Capsella rubella; Aly, Arabidopsis lyrata; At, Arabidopsis thaliana; Br, Brassica rapa; Bn, Brassica napus; Gh, Gossypium hirsutum; Pp, Prunus persica; Mt, Medicago trunculata; Gm, Glycine max; Pt, Populus trichocarpa; Rc, Ricinus communis; Vv, Vitis vinifera; Oo, Origanum onites; St, Solanum tuberosum; Le, Solanum lycopersicum (Lycopersicum esculetum); Nt, Nicotiana tabacum; Na, Nicotiana attenuata; Nb, Nicotiana benthamiana; Ma, Musa acuminata; Hv, Hordeum vulgare, Ata, Aegilops tauschii; Tu, Triticum urartu; Bd, Brachypodium distachyon; Os, Oryza sativa, Og, Oryza glaberrima; Ob, Oryza brachyantha; Si, Setaria italica; Sb, Sorghum bicolor; Zm, Zea mays, Ps, Picea sitchensis; Sm, Selaginella moellendorffii. Potato MKK6 is marked with red dot. The numbers on the nodes are percentages from a bootstrap analysis of 1000 replicates. The scale bar indicates the branch length that corresponds to 0.06 substitutions per site.