Identification of a Group of Novel γ-Gliadin Genes

γ-Gliadins are an important component of wheat seed storage proteins.Four novelγ-gliadin genes(Gli-ng1 to Gli-ng4)were cloned from wheat(Triticum aestivum)and Aegilops species.The novelγ-gliadins were much smaller in molecular size when compared to the typicalγ-gliadins,which was caused by deletion of the non-repetitive domain,glutamine-rich region,3′part of the repetitive domain,and 5′part of the C-terminal,possibly due to illegitimate recombination between the repetitive domain and the C-terminal.As a result,Gli-ng1 and Gli-ng4 only contained two and three cysteine residues,respectively.Gli-ng1,as the representative of novelγ-gliadin genes,has been sub-cloned into an Escherichia coli expression system.SDSPAGE indicated that the both cysteine residues of Gli-ng1 could participate in the formation of intermolecular disulphide bonds in vitro.Successful cloning of Gli-ng1 from seed cDNA of T.aestivum cv.Chinese Spring suggested that these novelγ-gliadin genes were normally transcribed during the development of seeds.Phylogenic analysis indicated that the four novelγ-gliadin genes had a closer relationship with those from the B(S)genome of wheat.