Novel and ancient HMW glutenin genes from Aegilops tauschii and their phylogenetic positions

A pair of novel high-molecular-weight glutenin subunits (HMW-GS) 1Dx3.1^t and 1Dy11*^t were revealed and characterized from Aegilops tauschii Coss. subspecies tauschii accession AS60. SDS-PAGE band of 1Dx3.1^t was between those of 1Dx2 and 1Dx3, while 1Dy11*^t was between 1Dy11 and 1Dy12. The lengths of 1Dx3.1 ^t and 1Dy11* ^t were 2,514?bp and 1,968?bp, encoding 836 and 654 amino acid residues, respectively. Their authenticity was confirmed by successful expression of the coding regions in Escherichia coli. Network analysis indicated that 1Dx3.1 ^t together with other five rare alleles only detected in Asia common wheat populations represented the ancestral sequences in Glu-D1 locus. Neighbor-joining tree analysis of previously cloned x-type and y-type alleles in the Glu-D1 locus supported the hypothesis that more than one Ae. tauschii genotypes were involved in the origin of hexaploid wheat and that different Ae. tauschii accessions contributed the D genome to common wheat and Ae. cylindrical Host, respectively. An Ae. tauschii accession with 1Dx3.1 ^t or a closely related allele probably have involved in the origin of common wheat. Since accession AS60 used in this study belonged to typical ssp. tauschii, present results suggested the possibility that ssp. tauschii was involved in the evolution of common wheat.