THE PLANT CELL, Vol 2, Issue 8 709-721, Copyright © 1990 by American Society of Plant Biologists
Properties of the Maize Transposable Element Activator in Transgenic Tobacco Plants: A Versatile Inter-Species Genetic Tool
R. Hehl and B. Baker
Plant Gene Expression Center, United States Department of Agriculture, 800 Buchanan Street, Albany, California 94710
The maize controlling element Activator (Ac) transposes autonomously from
an integrated T-DNA vector to new sites in the genomes of tobacco and other
heterologous plant species. Here we demonstrate that critical functions
required for transposition of Ac in maize are conserved in tobacco and that
Ac transposes at high frequency for at least five generations. Ac structure
and terminal sequences are conserved upon transposition and a
characteristic 8-bp duplication of target sequences is generated upon
integration. Ac remains unmethylated, transcriptionally active, and capable
to trans-activate transposition of the nonautonomous Dissociation (Ds)
element throughout several generations. In tobacco, as in maize, Ac
transposes adjacent to low copy or unique DNA, and transcriptional analysis
of unique target DNA provides evidence that an Ac element transposed into a
gene. In maize, increasing copies of Ac delay the timing and reduce the
frequency of early transposition of Ac and Ds. In tobacco, increasing
copies of Ac correlate with an increased frequency of Ds trans-activation.
These data firmly establish that the Ac and Ds transposable elements are
versatile genetic tools well suited for use as insertional mutagens and
demonstrate that thorough investigation of mechanism and regulation of
transposition is facilitated in heterologous settings.
