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Identification of a Group of Novel γ-Gliadin Genes

QI, Peng-fei, WEI, Yu-ming, Thérèse, Ouellet, CHEN, Qing, WANG, Zhao, WEI, Zhen-zhen, ZHENG, You-liang
Journal of integrative agriculture 2014 v.13 no.2 pp. 290-298
Aegilops, Escherichia coli, Triticum aestivum, complementary DNA, cysteine, disulfide bonds, genes, gliadin, molecular weight, phylogeny, polyacrylamide gel electrophoresis, seed storage proteins, seeds, transcription (genetics), wheat
γ-Gliadins are an important component of wheat seed storage proteins. Four novel γ-gliadin genes (Gli-ng1 to Gli-ng4) were cloned from wheat (Triticum aestivum) and Aegilops species. The novel γ-gliadins were much smaller in molecular size when compared to the typical γ-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 novel γ-gliadin genes, has been sub-cloned into an Escherichia coli expression system. SDS-PAGE 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 novel γ-gliadin genes were normally transcribed during the development of seeds. Phylogenic analysis indicated that the four novel γ-gliadin genes had a closer relationship with those from the B (S) genome of wheat.