Molecular characterization and expression of α-gliadin genes from wheat cultivar Dacke in Bg 250 rice variety

The main seed storage protein in wheat is gluten. It consists of gliadin and glutenins. Gluten gives high elasticity and extensibility during bread making, facilitating the formation of the dough. Rice is the staple food of Sri Lankans but, it has poor dough making ability compared to wheat. The aim of the present work was to characterize, clone and express alpha-gliadin in the T-0 generation of Bg 250 rice variety as a preliminary step in improving the dough making ability of rice flour. Five alpha-gliadin recombinant pCR (TM) 2.1-TOPO (R) clones were selected for sequence analysis. Of the five clones, two functional genes and three pseudogenes were identified. Phylogenetic analysis revealed the two functional genes, (accession numbers KC660359 and KC660358) to be closely related to the alpha-gliadin genes of Triticum monococcum. The alpha-gliadin gene (KC660359) contained five cysteine residues, one less than the normal occurrence of cysteine residues in alpha-gliadin genes. To date there are no reports on expression of gliadin gene in transgenic rice. This novel gene was successfully expressed in the Sri Lankan rice variety Bg 250 under the control of the rice GluB-1 endosperm specific promoter.