Expression of a bifunctional green fluorescent protein (GFP) fusion markerunder the control of three constitutive promoters and enhanced derivativesin transgenic grape (Vitis vinifera)

Activity of three constitutive promoters and enhanced derivatives in transg enic grape (Vitis vinifera L. cv. Thompson Seedless) was characterized usin g a bifunctional fusion marker containing the enhanced green fluorescent pr otein (EGFP) and neomycin phosphotransferase (NPTII) genes. Relative differ ences in transient GFP expression and stable transformation efficiencies we re used to compare promoter activity, Expression patterns in transformed so matic embryos revealed that the ACT2 promoter from Arabidopsis thaliana, pr eviously shown to be a strong constitutive promoter in A. thaliana and othe r species, failed to promote strong expression in grape. In contrast, a pro moter isolated from cassava vein mosaic virus (CsVMV) supported high levels of transgene expression equivalent to those achieved using an enhanced dou ble cauliflower mosaic virus (CaMV) 35S promoter. Duplication of the 5 ' -u pstream enhancer region of the CsVMV promoter further enhanced its ability to increase transgene expression. However, the pattern of transgene express ion driven by these two viral promoters was significantly different at the whole plant level. The enhanced double CaMV 35S promoter was highly active in most tissues and organs including roots, mature leaves, shoot apices and lateral buds. In contrast, the CsVMV promoter and its double enhancer deri vative induced relatively weak expression ill these tissues. Our results su ggest that activity of the CsVMV promoter, in contrast to the CaMV 35S prom oter, was under developmental regulation in transgenic grape plants as comp ared with the CaMV 35S promoter. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.