Quantitative Effects Of High Molecular Weight Glutenin Subunits (HMW-GS) And QTL Mapping For Quality Traits In Wheat

The effects of high molecular weight glutenin subunits (HMW-GS) on quality traits were analyzed, and the QTLs of 19 quality traits were mapped using a population of recombinant inbred lines (RILs). The main results were as follows: ⑴ The effects of HMW subunits on quality traits were analyzed quantitatively. The results showed that the effects were different significantly among different subunits at the same loci for water absorption, Zeleny sedimentation value, dough development time, dough stability time, mixing tolerance index and breakdown time. On the contrary,no significant differences were detected for wet and dry gluten content,protein content,and glutenin macropolymer (GMP) content. The influences of 7different subunit combinations at different loci of RIL-8 were different significantly for water absorption, wet glutenin content, GMP content, Zeleny sedimentation value, protein content, dry gluten content, dough development time, dough stability time, mixing tolerance index and breakdown time, but were not different significantly for dry gluten content and protein content.The effects of HMW subunits encoded by the same allelic locus were different significantly for peak viscosity, trough viscosity, breakdown, final viscosity, setback, peak time, falling number and swelling power, but were not different significantly for pasting temperature, amylose content and amylopectin content. The effects among 7 subunit combinations of different allelic loci were similar to the former. The possible reasons of why HMW subunits were related to starch traits were further discussed.⑵ Totally 21 QTLs on 7 chromosomes for 13 quality traits were mapped. 6 of 21 QTLs were located at 6B chromosome. Most contribution rates in different single QTL were above 10%. The QTLs with large effects (>20%) were QZsv.sdau-2A, QDdt.sdau-1D, QDst.sdau-1D, QBt.sdau-1D, QPv.sdau-6B, QTv.sdau-6B, QFv.sdau-6B, QSb.sdau-6B, QSb.sdau-7A and QPt.sdau-6B. While contribution rates of Qddt.sdau-2A and Qpte.sdau-2D were below 10%; the rest were between 10% and 20%. The QTLs for dough development time, dough stability time and breakdown time were mapped firstly in this paper, and 3 QTLs of additive effect were detected, namely QDdt.sdau-1D, QDst.sdau-1D and QBt.sdau-1D. Their contribution rates were 35.50%, 31.22% and 29.38%, respectively, so they were controlled by major genes. At the same time, GMP content was fistly located at 6B and 7B chromosomes, and the contribution rates were 11.61% and 12.63%. ⑶ QTLs with interaction effects were also detected. Totally 7 pairs of QTLs for 7 quality traits were located at 6 chromosomes, and the number of QTLs at 6B was the largest. The range of contribution rates in different single interaction effects was 12.44～16.86%. ⑷ Some SSR markers of 8 QTLs were obtained and could be used in molecular marker assisted selection (MAS).