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The 1BL/1RS translocation has been widely used in bread wheat breeding programs, mainly because of the presence of genes for resistance to powdery mildew, stripe rust, leaf rust and stem rust on 1RS. It is estimated that several hundred cultivars with this translocation have been released worldwide (7). While the disease resistance may now be of little value, the translocation is still useful because it increases yield in some environments (8) or at least influence grain size (9). The nature of the yield advantage associated with the translocation of 1RS in wheat is not clear but may be due to the larger root biomass of the lines carrying the 1RS/1BL translocation (10, 11). Unfortunately, its presence is associated with a serious quality defect, including low sedimentation volume, dough stickiness and reduced dough strength, which disqualifies it from breeding programs developing high quality wheats (9, 12).
The short arms of the group-1 chromosomes of wheat carry several loci encoding LMW-GS, whereas the short arm of rye chromosome 1 carries the secalin Sec-1 locus that code for proteins that do not belong to the gluten fraction. The negative effect of the 1RS/1BL translocation on bread-making quality is probably related to the negative effect of the secalins and to the reduction of the number of the gluten-encoding loci and the resulting lower amount of gluten. In fact, the 1AL/1RS translocation (found in the wheat cv. Amigo), also diminishes quality, but the effect is not as severe as that observed in the varieties carrying the 1BL/1RS translocation. The loss of gluten proteins is not as great in wheats carrying 1RS/1AL translocation as in those carrying the 1RS/1BL translocation (13).
Taking into account the detrimental effects of the 1BL/1RS on bread making quality, a rye-adjusted Glu-1 quality score was calculated by Payne and co-workers. The correction was applied assuming that the decrease in quality due to this translocation would be proportionately greater in genotypes having better intrinsic quality (5). This translocation is easily detectable for electrophoresis at low pH (A-PAGE).
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