Location: Genomics and Gene Discovery
Title: A new class of wheat gliadin genes and proteins Authors
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 12, 2012
Publication Date: December 20, 2012
Citation: Anderson, O.D., Dong, L., Huo, N., Gu, Y.Q. 2012. A new class of wheat gliadin genes and proteins. PLoS One. 7:e52139. Interpretive Summary: The wheat seed proteins are fundamental to the visco-elastic properties of wheat doughs - properties that allow a myriad of baked products such as leavened and unleavened breads, cakes, biscuits, pastas, etc. These proteins are divided into the gliadin and glutenin classes. A complete knowledge of the variety of these proteins is essential for maintaining and improving wheat quality. This study reports on the identification of a previously unrecognized class of wheat of wheat gliadins - named the delta-gliadins. They are shown to be distinct from the existing recognized classes; i.e., the alpha-, gamma- and omega gliadins.
Technical Abstract: The utility of mining DNA sequence data to understand the structure and expression of cereal prolamin genes is demonstrated by the identification of a new class of wheat prolamins. This previously unrecognized wheat prolamin class, given the name δ-gliadins, is the most direct ortholog of barley γ3-hordeins. Phylogenetic analysis shows that the orthologous δ-gliadins and γ3-hordeins form a distinct prolamin branch that existed separate from the γ-gliadins and γ-hordeins in an ancestral Triticeae prior to the branching of wheat and barley. The expressed δ-gliadins are encoded by a single gene in each of the hexaploid wheat genomes. Analysis of ESTs and cDNAs shows that the genes are expressed in at least five hexaploid wheat cultivars in addition to diploids Triticum monococcum and Aegilops tauschii. The latter two sequences also allow assignment of the γ-gliadin genes to the A and D genomes, respectively, with the third sequence type assumed to be from the B genome. Two wheat cultivars for which there are sufficient ESTs show different patterns of expression, i.e., with cv Chinese Spring expressing the genes from the A and B genomes, while cv Recital has ESTs from the A and D genomes. Genomic sequences of Chinese Spring show that the D genome gene is inactivated by tandem premature stop codons. Sequencing of BACs covering a 3 Mb region from Ae. tauschii locates the γ-gliadin gene to the complex Gli-1 plus Glu-3 region on chromosome 1.