A new class of transposon-like element designated Revolver (Rev) has been discovered in the Triticeae genome. The Rev element encompassing 3041 bp is dispersed in the genome by flanking with 14 bp of terminal inverted repeated sequence on the both ends. Rev element is transcriptionally active. Rev cDNA (726 bp) identified in some Triticeae species elucidate that Rev bears 3 exons (342, 88, 296 bp) and 2 introns (750, 1,237 bp). The processed Rev mRNA contains a single ORF encoding 118 amino acid residues of protein, which features a transcriptional regulator with DNA binding ability. The entire structure of Rev dose not share identity with both the class 1 and class II transposable elements. The novel element Rev is abundant in the genomes of wheatrelatives, Secale (RR), Dasypyrum (VV), as well as wheat ancestor species, Triticum monococcum (AA), T. turgidum (AABB) and T. tauschii (DD). At least ten thousand copies of Rev arc distributed over entire length of rye chromosomes. However, Rev is not detected in the genome of T. aestivum (AABBDD). These facts indicate that Rev element have been existed since the diploid progenitor of wheat, then it has been amplifying in some species, while disappearing in bread wheat through the evolution.
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