Molecular characterization and phylogenetic analysis of a novel glutenin gene (Dy10.1^t) from Aegilops tauschii

A novel y-type high molecular mass glutenin subunit (HMM-GS) possessing a mobility that is slightly slower than that of the subunit Dy10 obtained by SDS-PAGE, named Dy10.1^t, in the wild wheat Aegilops tauschii was identified by 1- and 2-dimensional gel electrophoresis, capillary electrophoresis, and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The gene encoding the HMM subunit Dy10.1 ^t was amplified with allele-specific PCR primers, and the amplified products were cloned and sequenced. The coding domain of the Dy10.1^t subunit gene consisted of 1980 bp encoding a protein of 658 residues with an M_rs of 68 611 Da, which was similar to the M_rs determined by MALDI-TOF-MS. The deduced amino acid sequence indicated that Dy10.1 _t subunit displayed a greater similarity to the Dy12 subunit, differing by only 8 amino acid substitutions. Six coding region single-nucleotide polymorphisms were discovered in the Dy10.1^t gene by multiple alignments (1 per 330 bp), 1 in the N-terminal domain and the others in the central repeats. Five of them resulted in residue substitutions, whereas 3 created enzyme site changes. The homology and neighbour-joining trees constructed from code domain sequences of 20 x-and y-type glutenin genes from different Triticum species separated into 2 halves, which corresponded to the x-type and y-type HMM glutenin alleles. Phylogenetic analysis revealed that the Glu-1 gene duplication event probably occurred at about 16.83 million years ago, whereas the divergence times of A, B, and D genomes within x-type and y-type halves were before 7.047 and 10.54 million years ago, respectively.