Fruit-specific expression of sweet protein Brazzein in transgenic tomato plants

The AGPL1 (ADP-glucose pyrophosphorylase large subunit 1) promoter from watermelon (Citrullus vulgaris S.) has proved to exhibit fruit-specific expression patterns in tomato (Lycopersicon esculentum L.). A plant expression vector harboring sweet-taste protein, Brazzein, directed by AGPL1 promoter, was constructed and transferred into tomato plants through Agrobacterium-mediated transform methods. Histochemical staining assay, PCR screening, Southern blotting analysis and RT-PCR analysis showed that Brazzein gene was successfully integrated into the genome of transgenic tomato plants with stable expression. Sweet-taste fruits were produced under control of fruit-specific AGPL1 promoter, whereas other parameters of fruit quality were largely unchanged.