Genetic Diversity of Glutenin Protein Subunits Composition in Durum Wheat Landraces [Triticum turgidum ssp. turgidum Convar. durum (Desf.) MacKey] from the Mediterranean Basin

The genetic diversity of high and low molecular weight glutenin subunits of 63 durum wheat landraces from different geographical regions in the Mediterranean Basin was studied using SDS-PAGE. Great variability in glutenin composition was found, with 42 high and low molecular weight glutenin haplotypes, 20 allele combinations at the HMW-GS loci, and 18 at the LMW-GS. All five possible LMW models were detected in all Mediterranean regions. Rare alleles were found at Glu-B1 locus in high frequencies and a priori related alleles to grain quality were also observed. Global genetic diversity index was relatively high (0.67); it ranged from 0.33 to 0.66. Cluster analysis on the frequency patterns of origins grouped genotypes following a geographical structure. Rogers’ distance coefficient on frequency pattern for each region of origin showed two germplasm pools with distinct quality profiles, where South West Asian landraces were very different from the landraces of other Mediterranean areas. The relationship between different regions of origin is discussed and two possible ways of introduction of wheat in the Iberian Peninsula (N Africa and SE Europe) are hypothesized. The use of Mediterranean durum wheat landraces as source of genetic variability for grain quality improvement is highly recommended.