LIGHT-CONTROLLED EXPRESSION OF A FOREIGN GENE USING THE CHALCONE SYNTHASE PROMOTER IN TOBACCO BY-2 CELLS

The light-activated chalcone synthase (CHS) gene promoter was used to control the expression of a foreign gene-the uidA gene, whose product is beta-glucuronidase (GUS)-in tobacco BY-2 cell suspensions. Light en hanced GUS specific activity rapidly and greatly in transgenic BY-2 co ntaining a fusion of the CHS promoter and uidA gene. GUS production wa s turned on/off by using a light/dark cycle. The level of promoter act ivity was almost proportional to the intensity of light, surpassing th e strength of the 35S promoter of Cauliflower Mosaic Virus (CaMV). Int ermittent illumination induced the same level of GUS production as con tinuous light. The CHS promoter is thus useful for producing a foreign protein in plant cell bioreactors.