TRANSACTIVATION OF A TARGET GENE USING A SUPPRESSOR TRANSFER-RNA IN TRANSGENIC TOBACCO PLANTS

The abundance of tRNAs, together with their central role in translatio n, has generated considerable interest in the use of tRNA genes for bi otechnological applications. One such application is the use of suppre ssor tRNAs to transactivate target genes containing premature stop cod ons. Previous work has shown that such systems can work in transient e xpression experiments in plant protoplasts; here these experiments are extended to show that suppression of stop codons can occur in whole p lants. Transgenic tobacco plants homozygous for a modified tRNA(Leu) g ene expressing a strong amber suppressor tRNA, and plants carrying a P -glucuronidase (gus) gene inactivated by a premature amber stop codon have been obtained. When the two types of plants are crossed, many of the F-1 hybrids show significant GUS activity. The GUS activity is dep endent on the presence of both the suppressor tRNA gene and the gus ge ne. Tobacco plants carrying the suppressor tRNA gene are phenotypicall y normal, fertile and the gene shows normal Mendelian inheritance. The potential applications of such a system are discussed.