Submitted to: Molecular Breeding
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/21/2008
Publication Date: 3/4/2008
Citation: Gadaleta, A., Blechl, A.E., Nguyen, S.B., Cardone, M.F., Ventura, M., Quick, J.S., Blanco, A. 2008. Stably Expressed D Genome-derived HMW Glutenin Subunit Genes Transformed Into Different Durum Wheat Genotypes Change Dough Mixing Properties. Molecular Breeding. 22:267-279. Interpretive Summary: Durum wheat (Triticum turgidum L. var. durum) is traditionally used for the production of numerous types of pasta, and significant amounts are also used for bread-making, particularly in southern Italy. The research reported here centers on the glutenin subunits 1Dx5 and 1Dy10 encoded by chromosome 1D, and whose presence in hexaploid bread wheats is positively correlated with higher dough strength. In order to test the effects of these two subunits in durum wheat, the native wheat genes encoding 1Dx5 and 1Dy10 were transformed into three cultivars commonly grown in the Mediterranean area (Svevo, Creso, and Varano). Five different lines were derived, including one containing 1Dx5, one containing 1Dy10, and two containing both glutenins. The sites of insertion of the transgenes could be visualized by Fluorescence in situ Hybridization of wheat chromosomes. Small-scale quality tests, performed on flours from field-grown seeds, showed that accumulation of Dx5, Dy10 or both in transgenic durum wheat endosperm resulted in doughs with stronger mixing characteristics. This research shows that the bread-making properties of durum wheat can be improved by addition of glutenin subunits usually found only in bread wheats.
Technical Abstract: The glutenin subunits 1Dx5 and 1Dy10 are encoded by chromosome 1D and associated with higher dough strength in hexaploid bread wheats. In order to study the effects of their expression in different durum wheat genotypes, four cultivars commonly grown in the Mediterranean area were co-transformed, via particle bombardment, with the two wheat genes Glu-D1-1d and Glu-D1-2b encoding the glutenin subunits, and a third plasmid containing the bar gene as a selectable marker. Protein gel analyses of T1 generation seed extracts showed expression of one or both glutenin genes in four transformed durum wheat plants. Transgene stability in the transgenic lines was studied over four generations (T1-T4). Fluorescence in situ hybridization (FISH) analysis of metaphase chromosomes from T4 plants showed that the integration of transgenes occurred in both telomeric and centromeric regions. The three plasmids were found inserted at a single locus in two lines and in two loci on the same chromosome arm in one line. The fourth line had two transgenic loci on different chromosomes. Segregation of these two loci in subsequent generations allowed establishment of two sublines, one containing both 1Dx5 and 1Dy10 and the other containing only 1Dy10. Small-scale quality tests showed that accumulation of Dx5, Dy10 or both in transgenic durum wheat seeds resulted in doughs with stronger mixing characteristics.