The firefly luciferase gene as a reporter for in vivo detection of Ac transposition in tomato plants

Abstract

The maize transposable element Ac has been introduced into many plant species by Agrobacterium-mediated gene transfer, and evidence of transposition has been obtained by applying various reporter gene systems which are mostly based on antibiotic resistance or destructive enzyme assays. Therefore, it has not been possible so far to monitor transposon activity during the development of living plants. We used the firefly luciferase gene to develop a reporter gene system amenable for in vivo detection of Ac transposition events. The construct pBinLucA was introduced into tomato, and luciferase activity was analysed during the regeneration and development of transgenic tomato plants. By Southern blot analyses and in vitro luciferase enzyme assays, the highest frequencies of Ac transposition (90%) were found at the callus stage of plant regeneration and in the cotyledons of the progeny from selfed primary transformants. In addition, we were able to follow excision of the transposon Ac in vivo at different developmental stages of individual plants. Therefore, the luciferase reporter gene system seems to be particularly suited to detect somatic excision of transposable elements in transgenic plants allowing the rescue of independent transposition events from a single plant.