The cytogenetics and molecular characteristics of a translocated chromosome 1AS.1AL-1DL with a Glu-D1 locus in durum wheat.

Wheat quality depends directly on the grain protein content and protein composition. High and low molecular weight glutenin subunits play an important role in determining the visco-elastic properties of gluten. In an attempt to improve the breadmaking quality of hexaploid triticale, a fragment of wheat chromosome 1D, containing the Glu-D1 allele encoding the 5+10 subunits, was translocated to the long arm of chromosome 1A by Lukaszewski and Curtis. The 1A.1D translocation chromosome was transferred to tetraploid wheat, making the Glu-D1 locus available for the improvement of durum wheat. The goal of this study was to evaluate using cytogenetics and molecular approaches the amount of chromatin introgressed in durum wheat. Fluorescence in situ hybridization with total genomic DNA (GISH) of Aegilops squarrosa L. indicated that the translocated chromosome 1A.1D had a terminal 1DL segment of about 35-40% of the recombinant arm length. Several pairs of microsatellite primers from chromosome 1A and 1D were used to genetically characterize the recombinant chromosome. The mapping data indicated that a 1AL segment, at least 150 cM long, was substituted by a 1DL segment with a minimal length of 72 cM, and that the translocation breakpoint was near the 1A centromeric region. The genetic and physical data highlight a substantial discrepancy between the recombinational and physical map distances. We are using a targeted strategy via the Ph pairing manipulation system to generate small intercalary 1D chromosome segments in a durum wheat background.