SOMATIC AND GERMINAL ACTIVITIES OF MAIZE ACTIVATOR (AC) TRANSPOSASE MUTANTS IN TRANSGENIC TOBACCO

The properties have been investigated of two deletion derivatives of t he transposase protein (TPase) of maize transposable element Ac in tra nsgenic tobacco. The wildtype and mutant TPases were expressed as fusi ons to the cauliflower mosaic virus 35S promoter. A deletion of 102 am ino acids from the N-terminus, TPase(103-807), induces Ds excisions fr om a SPT::Ds reporter locus with a higher frequency than the wild-type TPase. The increased transpositional activity of TPase(103-807) is a dominant trait, as seedlings coexpressing truncated and wild-type TPas e show the characteristic TPase(103-807) variegation phenotype. A tran spositionally inactive TPase deletion derivative lacking 188 amino aci ds from the N-terminus inhibits the transpositional activity of the wi ld-type TPase.