Assay of Ds2 Transposition Activity in the Maize W22

Ds elements are non-autonomous DNA transposons requiring Ac transposase for mobility. From the 39 Ds2 elements reported in B73, we identified 38 Ds2 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 Ds2-23 showed suggestive somatic transposition. Targeted bisulfite sequencing revealed that while Ac 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 Ds2 transposition variation in W22.