ACTION SPECTRUM FOR INDUCTION OF PROMOTER ACTIVITY OF PHENYLALANINE AMMONIA-LYASE GENE BY UV IN CARROT SUSPENSION CELLS

The full-length promoter (-2335) of the carrot (Daucus carota) phenyla lanine ammonia-lyase gene (gDcPAL1) fused to the luciferase reporter g ene was transiently transformed to carrot protoplasts by electroporati on, and the promoter activity induced by monochromatic UV light of var ious wavelengths was examined. The action spectrum constructed from th e fluence-response curves showed a single peak at around 280 nm, sugge sting that the activation of the gDcPAL1 promoter is categorizable as one of the WE light responses. The same assay system was applied to va riously truncated gDcPAL1 promoters and to CaMV35S promoter fusion wit h various parts 5'-upstream of the gDcPAL1 promoter. The region from - 396 to -190 (relative to the transcription start site) fused to the Ca MV35S core (-90) promoter showed a 280 nm-dominant response. However, gDcPAL1 promoters truncated above -570 and -396, although they contain the region between -396 and -190, did not show such a typical UVB res ponse, i.e. they responded to 260 nm light as much as to 280 nm light. The promoter truncated to below -190 also responded to 260 nm light a s much as to 280 mm light. Therefore we assumed that the gDcPAL1 promo ter is composed of three functionally different parts: the upstream ab ove -570 (modulator), the region from -396 to -190 (UVB responsive) an d the downstream below -190 (UVB and C responsive). The overall UVB re sponse of the gDcPAL1 full-length promoter is explained as the result of interaction of these three components.