Molecular and Biochemical Characterisation of HMW Glutenin Subunits fromT. tauschiiand the D Genome of Hexaploid Wheat
Abstract Electrophoretic (urea SDS–PAGE) and chromatographic (RP–HPLC) analysis was performed on 8 allelic variants of HMW glutenin subunits derived from Triticum tauschii and from the D genome of a hexaploid wheat species ( Triticum macha ) and hexaploid landraces. These subunits had been previously identified using SDS–PAGE. The characterisation revealed that subunits Dy10 t and Dy12 t from T. tauschii could be differentiated from their bread wheat counterparts using both urea SDS–PAGE and RP–HPLC. In the latter case, the T. tauschii y-type subunits were clearly more hydrophobic than the Dy type subunits of bread wheat. The characterisation also suggested that subunit Dx5 t , derived from two separate T. tauschii accessions, did not contain the extra cysteine residue characteristic of Dx5 from bread wheat. RFLP analysis of the genes encoding the HMW glutenin subunits of interest suggested that the absence of Dx-type HMW glutenins in two hexaploid landraces was due to lack of expression of their encoding genes. The relationship between Hin dIII DNA fragment size and protein subunit size, as measured by electrophoretic mobility, is examined and discussed. Finally, the solubility properties of a HMW protein designated T1 (derived from T. tauschii accession AUS 18913) suggested that it was not a HMW glutenin subunit as was previously thought. Further studies are needed to clarify the identity of this subunit.