Gene tagging in plants by a T-DNA insertion mutagen that generates APH(3′)II-plant gene fusions

A new method is presented for gene tagging in higher plants. Its advantage compared with transposable elements is to provide information on the regulation of the mutated genes at the same time. The mutagenesis described here relies on the integration of the T-DNA into the plant genome. A Ti-plasmid vector was constructed for the selection of plant gene fusions with a promoterless APH(3′)II reporter sequence. Infection of haploid and diploid Nicotiana plumbaginifolia protoplasts with this vector allowed the isolation of kanamycin-resistant cell clones at a high frequency. The characteristics of the APH(3′)II fusion proteins in these lines showed that both transcriptional and translational fusions had been obtained. Some of the regenerated plants had a particular morphology which could have resulted from the inactivation of plant genes by T-DNA insertion and others showed tissue-specific expression of the gene fusions.