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Attempted compensation for linkage drag affecting agronomic characteristics of durum wheat 1AS/1DL translocation lines.

Klindworth, Daryl L., Hareland, Gary A., Elias, Elias M., Xu, Steven S.
Crop Science 2013 v.53 pp. 422
Triticum turgidum subsp. durum, agronomic traits, backcrossing, biotypes, chromatin, cultivars, durum wheat, genes, genetic background, glutenins, grain yield, heading, introgression, linkage (genetics), molecular weight, plant breeding, protein content, translocation lines, North Dakota
Yield reduction due to linkage drag caused by introgression of alien chromatin is a major problem for incorporating new genes into durum wheat (Triticum turgidum L. subsp. durum). Here we report attempts to improve yield of 1AS•1AL-1DL translocation lines of durum wheat that had previously been reported to have reduced yield due to linkage drag. Near-isogenic lines (NILs) were produced by six backcrosses of a translocation stock to five cultivars, Renville, Rugby, Lebsock, Ben, and Maier. During backcrossing, we found that ‘Rugby’ had two glutenin biotypes, with one biotype having high molecular weight (HMW) subunits 1Bx6+1By8 (Rugby68), and the second biotype having only 1Bx6 (Rugby6). Rugby6 and Rugby68 did not significantly differ for any trait other than HMW subunits. Rugby6 and Rugby68 were each used to develop a set of NILs. Translocation (T-lines) and non-translocation (N-lines) NILs were yield tested at five North Dakota locations. N-lines did not significantly differ from their parental cultivars for yield, heading date, height, protein content, test weight, or thousand kernel weight (TKW). The Lebsock T-lines yielded significantly less (8.2%) than Lebsock, but yielded significantly better than their parental T-lines. None of the other T-lines had significant yield improvement. All T-lines had from 5.9 to 11.3% reduction in TKW. The results indicate that genetic background is very important in reducing linkage drag. We conclude that improved yield of the 1AS•1AL-1DL translocation lines will be dependent on improving TKW, and this may be best accomplished by further reducing the size of the alien segment.