Cloning and molecular characterization of a novel x-type glutenin gene Glu-D(t)1 from Aegilops tauschii.

A novel gene encoding an x-type high molecular weight glutenin subunit (HMW-GS), designated 1Dx1.1(t), was isolated from Aegilops tauschii. It is the largest HMW-GS gene reported so far in this species and its product has a slower mobility than that of subunit 1Ax1 in SDS-PAGE. The open reading frame (ORF) of the gene was 2,628 bp, encoding a protein of 874 amino acid residues. Comparisons of amino acid sequences showed that subunit 1Dx1.1(t) had high similarity with other 1Dx subunits but also had two unique characteristics. Firstly, a tripeptide of consensus LQE present in the N-terminal domains of other 1Dx subunits was absent from subunit Dx1.1(t). Secondly, three copies of tandem duplications of the tripeptide motif GQQ and a novel tripeptide sequence (GQL) were present in its central repetitive domain. Phylogenetic analysis showed that subunit 1Dx1.1(t) clustered with other known 1Dx subunits.