molecular characterization and phylogenetic analysis of novel α-gliadin genes from triticum dicoccoides l.

the quality traits of triticum dicoccoides ku-13441 (triticum turgidum l. var. dicoccoides (aabb, 2n= 4x= 28)) were analyzed by mixograph, and the results showed that t. dicoccoides ku-13441 had desirable qualities in gluten strength and flour stirring tolerance. subsequently, seventeen novel full-orf α-gliadin genes and thirty-five pseudogenes were cloned and sequenced from t. dicoccoides ku-13441. among the 17 novel full-orf α-gliadin genes, the putative proteins of gli2-td-44 and gli2-td-46 contained an extra cysteine residue, located in the first nonrepetitive region and n-terminal repetitive domain, respectively, rather than in the second nonrepetitive region like other α-gliadins. prokaryotic expression analysis and western-blotting indicated that these two α-gliadin genes could be successfully expressed under the control of t7 promoter. according to the varying numbers of 4 typical coeliac disease toxic peptides and glutamine residues in the two ployglutamine domains among the 17 α-gliadins, gli2-td-39, gli2-td-46 and gli2-td-47 genes were assigned to sub-genome b and other 14 genes were assigned to sub-genome a. phylogenetic analysis including two s-genome species, aegilops longissima (sl) and aegilops speltoides (s) revealed that the α-gliadin sequences of the b genome in t. dicoccoides had closer genetic relationship with those from ae. speltoides. this implies that ae. speltoides might participate in the origin of wheat b genome.