Neighbor-joining tree of the aa sequences of Pac obtained with Pto primers. Pac sequences: pac, ♦. As a comparison we included representative CrRLK1L sequences of Arabidopsis and Catharanthus roseus (◊), poplar and rice, Pto and paralogs of Solanum piminellifolium (red colored rhombus). Black arrows indicate Pac sequences sharing Thr204 of Pto, which is the main structural determinant of Pto for the specific recognition of AvrPto [59, 62]. The rectangular frame indicates the Arabidopsis CrRLK1L member that directly binds to the effector AvrPto of Pseudomonas syringae pv tomato. The kinase domain region spanned subdomain I through IX. The percentage of replicate trees in which sequences clustered together in the bootstrap test (1000 replicates) are shown for each node. The tree is drawn to scale with branch length in the units of the number of amino acid substitution per site (scale at the bottom). Roman numerals indicate groups with a high bootstrap. Arabic numerals indicate amino acid (upper) and nucleotide (lower) identity scores in Pac sequences within each group. Abbreviations are explained in the text.