Summary
We previously described the introduction of the maize Ac element in carrot hairy roots where it was shown to transpose. Further studies on this system allowed us to observe complete excision of the element from its original insertion site on the AcT-DNA. Analysis of hairy root subcultures derived from single root tips resolved the chimeric status created by transposition of Ac establishing the unicellular origin of secondary root meristems. Studies with restriction enzymes revealed a specific methylation pattern in the vicinity of the “empty donor site” left after Ac excision. This process, although not of general occurrence, was probably associated with the excision/transposition process. The activity of Ac in different hairy root transformants as judged by the rate of excision from the original insertion site appeared to be maintained during a period of ca. 2 years, and there was no evidence for bursts of transposition occurring during somatic embryogenesis. The data obtained support the hypothesis that excision is a concerted process involving all the copies of Ac present in a given cell.
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Van Sluys, M.A., Tempé, J. Behavior of the maize transposable element Activator in Daucus carota . Molec. Gen. Genet. 219, 313–319 (1989). https://doi.org/10.1007/BF00261193
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DOI: https://doi.org/10.1007/BF00261193