Attempted Compensation for Linkage Drag Affecting Agronomic Characteristics of Durum Wheat 1AS/1DL Translocation Lines

Yield reduction due to linkage drag is a major problem when introgressing alien chromatin into durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.]. Here we report attempts to compensate for yield losses associated with linkage drag in 1AS.1AL-1DL translocation lines of durum wheat. Near-isogenic lines (NILs) were produced by six backcrosses of a translocation stock to cultivars Renville, Rugby, Lebsock, Ben, and Maier. Rugby was found to be composed of two biotypes, with one biotype having high molecular weight (HMW) glutenin subunits 1Bx6+1By8 (Rugby68) and the second biotype having only 1Bx6 (Rugby6), and a set of NILs based on each biotype was produced. Nearisogenic translocation lines (T-lines) and non-translocation lines (N-lines) were yield tested at five North Dakota locations. Non-translocation lines did not significantly differ from their parental cultivars for yield, heading date, height, protein content, test weight, or thousand kernel weight (TKW). All T-lines yielded significantly less than their sibling N-lines although the Lebsock T-lines had less linkage drag than other T-lines. All T-lines had from 5.9 to 11.3% reduction in TKW. The results indicate that genetic background can partially and possibly completely compensate for linkage drag. But for the 1AS.1AL-1DL translocation lines, improved yield will be dependent on improving TKW, and this may be best accomplished by further reducing the size of the alien segment