Identification of myb genes in Euplotes aediculatus may indicate an early evolutionary process

The myb gene family encodes proteins characterized by a highly conserved DNA-binding domain and functions as transcription regulators. There are three myb genes in animals with three Myb-motif repeats, namely c-myb, A-myb, and B-myb. By contrast, plants possess an abundance of myb genes, the majority of which are of the type R2R3 (with two Myb-motifs). Few plant myb genes are of the type R1R2R3. Five new myb members in Euplotes were recently identified through degenerate polymerase chain reaction, which suggests that the myb gene is also a multi-member family in the unicellular protist kingdom as in other multi-cellular eukaryotes. The entire gene family further shows the presence of both R1R2R3- and R2R3-type myb. The phylogenic analysis provides concrete new evidence for the evolution of myb genes.