Comparison of Alleles at Gli-2 Loci of Common Wheat by Means of Two-Dimensional Electrophoresis of Gliadin

Abstract

Electrophoretic mobility (EM) and molecular weight (MW) of some allelic variants of α- and β-gliadins contrlled by Gli-2 loci were compared by means of two-dimensional (APAGE × SDS) electrophoresis. Comparison of α-gliadins of the alleles Gli-A2b and Gli-A2p, of β-gliadins of the Gli-B2b and Gli-B2c, and of β-gliadins of the Gli-D2b, Gli-D2c, Gli-D2j, and Gli-D2r indicated that a gliadin with lower EM had, as a rule, bigger MW which is known to depend on the length of the polyglutamine domain of gliadin of α-type. However, allelic variants of the α-gliadin encoded by Gli-D2b and Gli-D2e differ in EM but not in apparent MW. It might be caused by a substitution of some charged/uncharged aminoacids in the polypeptide of gliadin. Allele Gli-B2o which is very frequent in up-to-date common wheat germplasm originated probably by means of unequal crossingover. Some alleles at Gli-A2 is found to control completely different blocks of gliadins and therefore might come to common wheat from different genotypes of the polymorphic diploid donor of the A genome. The results indicate that the reason of the known more vast polymorphism of gliadins controlled by Gli-2 loci as compared with Gli-1 loci is the considerable difference of the structure, first, of Gli-1 and Gli-2 loci (Gli-2 loci have more expressed genes per locus) and, second, of genes encoding gliadins of α- and γ-types (α-gliadins are shown to contain a long polyglutamine sequences highly variable in their length).