SPECIFIC INDUCTION OF SECONDARY PRODUCT FORMATION IN TRANSGENIC PLANT-CELL CULTURES USING AN INDUCIBLE PROMOTER

This paper describes the artificial induction of secondary metabolite production in transgenic plant cell cultures using a recombinant, indu cible plant promoter. The bacterial gene ubiC from Escherichia coli en codes the enzyme chorismate pyruvate lyase (CPL) which catalyses the c onversion of chorismate to 4-hydroxybenzoate (4HB). This gene was fuse d to the tetracycline-inducible plant promoter Triple-Op. After transf ormation into Nicotiana tabacum W38 TET, transgenic cell cultures were established. Addition of chlorotetracycline to the medium led to spec ific induction of CPL activity. The optimal chlorotetracycline concent ration was approximately 2 mg/l medium. Three to 5 h after induction, the ubiC mRNA concentration reached a maximum, while highest specific CPL activity was detected after 8 days. The artificial secondary metab olite 4HB was converted to glucosides, and their accumulation reached maximum levels after 5 weeks of subculture. The induction was reversib le.