Figure 1

Unrooted phylogenetic tree of the WRKY domains. The tree was reconstructed from the amino acid sequences using the neighbor-joining program from Phylip 3.57. Clades of WRKY domains are labelled according to the classifications of AtWRKY domains by Eulgem et al [3] who proposed three groups and five subgroups in Group 2 (a, b, c, d and e). We suggest classifying WRKY domains into five groups modified from the old system. While Groups 1 and 3 are unchanged, the original subgroup 2_c is promoted to Group 2_c. Subgroups 2_a and 2_b, and subgroups 2_d and 2_e are combined to form two new groups, 2_a + 2_b, and 2_d + 2_e, respectively (see text for details). WRKY domains from G. lamblia are represented by thick and dark-green branches; the slime mold, thick and cyan; the green alga, thick and magenta; Arabidopsis, thin and blue; and rice, thin and red.