Assay of Ds2 Transposition Activity in the Maize W22

<i>Ds</i> elements are non-autonomous DNA transposons requiring <i>Ac</i> transposase for mobility. From the 39 <i>Ds2</i> elements reported in B73, we identified 38 <i>Ds2</i> homologous elements in the W22, 30 of which retained intact terminal inverted repeats and target site duplications. PCR-based excision assays on 19 loci in embryos and leaves revealed the majority are immobile; only <i>Ds2-23</i> showed suggestive somatic transposition. Targeted bisulfite sequencing revealed that while <i>Ac</i> reduces methylation, absolute levels remain stable and do not correspond to the varied transposition activities. This suggests structural integrity or DNA methylation alone does not predict <i>Ds2</i> transposition variation in W22.