CHLOROPLAST TARGETING OF SPECTINOMYCIN ADENYLTRANSFERASE PROVIDES A CELL-AUTONOMOUS MARKER FOR MONITORING TRANSPOSON EXCISION IN TOMATO ANDTOBACCO

Antibiotic resistance genes can act as either cell autonomous or non-c ell autonomous genetic markers with which to monitor the excision of p lant transposons. To convert spectinomycin resistance from a non-cell autonomous resistance to cell autonomous resistance, a transit peptide for chloroplast localization from a petunia ribulose bisphosphate car boxylase (rbcS) gene was fused in-frame to the aadA gene, which confer s spectinomycin and streptomycin resistance. Constructs were generated in which the expression of this chimeric gene was prevented by the pr esence, in the 5' untranslated leader, of the maize transposons Activa tor (Ac) or Dissociation (Ds). When progeny of tobacco or tomato plant s transformed with these constructs were germinated on spectinomycin-c ontaining medium, germinally revertant and somatically variegated indi viduals could be distinguished.