Trans-activation of a maize Ds transposable element in transgenic wheat plants expressing the Ac transposase gene

Abstract

To develop a transposon tagging system in wheat (Triticum aestivum L.), transgenic wheat lines containing a transposase gene of the maize Activator (Ac) element were produced and characterized. The Ac transposase gene under the control of a cauliflower mosaic virus 35S promoter was introduced into cultured wheat embryos by particle bombardment. Several transgenic wheat plants expressing the transposase gene were independently recovered. Southern- and Northern-blot analyses of their progeny showed that the expression of the Ac transposase gene was stably inherited, and three fixed Ac lines were established. By RT-PCR analysis, products from fully spliced transcripts of the Ac element were confirmed. Cultured embryos isolated from the stable Ac lines were further bombarded with plasmids having a maize Dissociation (Ds) element located between a rice Act1 promoter and a β-glucuronidase (gus) gene, and transient gus expression was observed after the Ds excision. These findings suggest that the maize Ac transposase gene is precisely processed and an active transposase protein is synthesized in the transgenic Ac lines. The Ds element is trans-activated and excised in wheat cells by the action of the Ac transposase gene.