Molecular characterization of HMW‐GS 1Dx3t and 1Dx4t genes from Aegilops tauschii and their potential value for wheat quality improvement

Two x‐type high molecular weight glutenin subunits (HMW‐GS) in Aegilops tauschii, 1Dx3t and 1Dx4t were identified by SDS‐PAGE and MALDI‐TOF‐MS. Their complete coding sequences were isolated by AS‐PCR. 1Dx3t and 1Dx4t genes consist of 2535 bp and 2508 bp and encode 845 and 836 amino acid residues, respectively. The deduced molecular masses of 1Dx3t and 1Dx4t gene products are 87655.26 Da and 86664.24 Da, respectively, well corresponding to the molecular masses measured by MALDI‐TOF‐MS. A total of 18 SNPs were identified between 1Dx3t and 1Dx4t. Comparing with 1Dx5 subunit, 1Dx3t had a six amino acid insertion at 146‐151 while the 1Dx4t had a nine amino acid deletion when compared with 1Dx3t subunit. The authenticity of the cloned 1Dx3t and 1Dx4t genes were confirmed by successful expression of their ORFs in E. coli. Comparison and phylogenetic tree based on the amino acid and nucleotide sequences confirmed that 1Dx3t was most closely related to 1Dx5 subunit that is widely accepted as a superior subunit for bread‐making property. The secondary structure prediction demonstrated that 1Dx3t subunit has significantly high α‐helix and β‐strand contents, suggesting it might have positive effects on dough quality.