Polymorphism of B- and C-type low molecular weight glutenin subunits in Triticum turgidum ssp.

The low molecular weight glutenin subunits (LMW-GSs), play a key role in the glutenin polymer formation. They have been classified, according to their biochemical properties into B, C and D-types and on the base of their different structural characteristics as chain extenders and chain terminators. The B-types include a large number of subunits forming the true LMW-GS, while the C- and D-types consist of modified monomeric proteins, similar to the so called gliadins, which can be incorporated into the glutenin polymer because they have an odd number of cysteine residues. These proteins are mainly encoded by a multigene family present at the Glu-3 loci, located on the short arms of the group 1 chromosomes closely linked to the Gli-1 loci. Several studies have shown the positive effects of the LMW-GSs on gluten strength, while few works have evidentiated the influence of specific Glu-3 alleles on gluten quality, in particular of each B- and C-type glutenin subunit. In this context, to study the polymorphism of LMW-GSs in tetraploid wheats Triticum turgidum, a collection of the subspecies ssp. turanicum, ssp. polonicum, ssp. carthlicum and a durum wheat line carrying a 1BL.1RS translocation and two Langdon D-genome disomic substitution lines 1D(1A), 1D(1B), have been analysed by one-step one-dimensional SDS-PAGE. Total proteins from different accessions and aneuploid lines have been extracted from crushed endosperm halves following fractionated precipitation with hydro-alcoholic solvent. The fractions enriched of B and C-type LMW-GSs have been subsequently separated by electrophoretic analyses and the patterns/alleles of the corresponding B- and C-types reported in diagrammatic representation. The genetic variability of these LMW-GS groups, including known alleles qualityassociated, as well as the potential of novel germplasm for the improvement of wheat quality in breeding programs, will be also discussed.