Endosperm specific expression of a gliadin-actin hybrid promoter in transgenic rice (Oryza sativa L.)

The far upstream regulatory region of the γ-gliadin gene was isolated from a wheat genomic library and its tissue specific effect on the expression of a reporter gene driven by a constitutive promoter was studied in transgenic rice (Oryza sativa L.). Since in earlier studies the wheat gliadin promoter containing −300 box has been previously shown to be active specifically in the endosperm of transgenic plants, therefore a hybrid promoter construct was created from γ-gliadin gene promoter far upstream region spanning from −421 to −71 bp and rice actin1 promoter from -95 to +12 bp. Downstream of the hybrid promoter a β-glucuronidase reporter gene (gusA) was fused. This construct was introduced into rice embryo by particle bombardment. Transgenic rice plants carrying the hybrid promoter linked to gusA were regenerated from bombarded embryos and grown up to T2 generation for further studies. RNA analysis and histochemical localization of GUS in transgenic rice plants revealed that the expression of the gene was highly specific in the endosperm, although the inserted transgene could be detected in every tissue (leaf, root and seed) investigated.