As mentioned previously, plants contain a large group of serine/threonine kinases (receptor-like kinases) not found in other eukaryotes. These RLKs most likely share a common evolutionary origin with the receptor tyrosine kinases present in animals and are thus sometimes collectively referred to as receptor kinases and providing an explanation that tyrosine containing motifs on the PepChip can be phosphorylated by these lysates [9].
http://plosone.org/article/info:doi/10.1371/journal.pone.0000777#article1.body1.sec1.p3

RLKs do not form a unique group ("class" in Table 1), but rather are similar to Pelle (Drosophila) and IRAKs (vertebrates), which are both within the TKL group. While their origin is not clear (e.g. we have not seen them in fungi or protists), it is highly unlikely that they are specifically related to the tyrosine kinase group. Plants have both receptor and non-receptor RLK-like kinases, so it would seem that this characteristic can evolve quite rapidly and is not a clue to ancient origin. However, given the similarity between TKL and TK kinases, the tyrosine kinase activity of some Dictyostelium TKLs, and the reported dual-specificity activity of a peanut TKL:MLK kinase (ref 40), RLKs and other TKLs are possible tyrosine-directed kinases in plants.