Transposable element proliferation and genome expansion are rare in contemporary sunflower hybrid populations despite widespread transcriptional activity of LTR retrotransposons.

Hybridization is a natural phenomenon that has been linked in several organismal groups to transposable element derepression and copy number amplification. A noteworthy example involves three diploid annual sunflower species from North America that have arisen via ancient hybridization between the same two parental taxa, Helianthus annuus and H. petiolaris.