Tos17 rice element: incomplete but effective.

BACKGROUND: Tos17 was the first LTR retrotransposon (Copia) described as active in cultivated rice, and is present in two copies in the genome of the sequenced Nipponbare variety. Only the chromosome 7 copy is active and able to retrotranspose, at least during in vitro culture, and this ability was widely used in insertional mutagenesis assays.

RESULTS: Here the structure of the active Tos17 was thoroughly annotated using a set of bioinformatic analyses.

CONCLUSIONS: Unexpectedly, Tos17 appears to be a non-autonomous LTR retrotransposon, lacking the gag sequence and thus unable to transpose by itself.