Abstract:The plant expression vector pBRSAg was constructed as suitable for transformation via Agrobacteriummediated approach. It contains all elements for plant expression, such as CaMV 35S promoter, both left and right border sequence for transferred DNA (T-DNA) in Agrobacterium, plant reporter gene gus, and plant selection marker gene hpt. The recombinant binary vector pBRSAg was transformed into Agrobacterium tumefaciens strains by using the freeze-thaw method. Tomato cotyledon explants were transformed by A. tumefaciens and plants were regenerated on selection medium. GUS staining, PCR and PCR-Southern analysis of the plants were positive. It was for the first time shown that the HBsAg (hepatitis B surface antigen) gene was introduced into tomato plants. The expression of transgene is under investigation.