XVI International Botanical Congess

We have studied the evolution of the Ac/Ds family. We show that Ds can rapidly be formed from Ac elements by an error-prone gap repair pathway that is induced upon Ac excision. The SDSA pathway can best explain the complex rearrangements observed during Ds formation. Ac transposase belongs to a super family of transposons, originally called the hAT (Hobo Ac Tam) family. We have done a comprehensive analysis of this family, which contains members in plants, insects, fungi, fish and Human. This analysis indicates that hAT elements are ancient, originating at the early stages of eukaryotic evolution. Phylogeny indicates that there is no evidence for trans-kingdom horizontal transfer in hAT elements evolution. Finally, we show that several hAT related sequences do not correspond to active hAT transposons, even though they are transcribed.