Characterization of novel HMW-GS in two diploid species of Eremopyrum.

Three HMW-GS and the respective ORFs from diploid species Eremopyrum distans and Eremopyrum triticeum were characterized. Compared to homologous proteins, they showed novel modifications in all domains. In the N-terminals, the y subunit from Er. triticeum (Xey) had 98 aa residues. A short G/IIFWGTS peptide deletion was responsible for the reduced number of aa residues. The end peptide in the y subunit from Er. distans (Fy) was IPTLLR. This unique structure was involved in a replacement between x types with IPA/TLLK/R and y types with R/TSSQTVQ. Both y subunits share the same short peptide LAAQLPAMCRL as x types in the C-terminals. Phylogenic relationships among orthologous genes from Triticeae species revealed that Fy and Xey were neither purely x type nor purely y type based on the N and C terminal residues. Divergence times indicated that Glu-Xe1 and Glu-F1 were separated from each other and that Glu-Xe1 separated from orthologous loci of wild wheat relatives earlier than Glu-F1. Based on the divergence times among Glu-F1, Glu-Xe1, Glu-O1, Glu-St1, and Glu-Ta1, it is possible that genome F separation from O, St, and Ta in species of Henrardia persica, Pseudoroegneria stipifolia, and Taeniatherum crinitum was more recent than the separation of F and Xe.