| With the improvement of people's living standard and the fast development of food processing industry,it is becoming more and more important to product wheat with high quality and it becomes the most urgent to set up the co-relationship between high molecular weight Glutemin subunits and quality, to predict the quality of wheat variety depending on the quality scoring systems, and to clearify the genetic expression characteristics and separation law of Subunits in hybridized generations. Employing 77 wheat varieties in Huang-Huai region as materials and Zhongguochun as CK, the HMW-GS, the variation characters of subunit composition, and the effects of subunit and the subunit's composition on protein content and sedimentation values were analyses by SDS-PAGE method. The regressive equation to predict wheat variety quality was built up based on the quantity analysis, meanwhile, the genetic expression characters and separation laws of HMW-GS in F1 and F2, the groups of subunit composition in the grains of F3 and the effects of subunit on quality under the same genetic background were studied by making 15 partial dual-hybridizations and 2 reveried combinations using 6 wheat materials with different quality characters. The methods to improve wheat variety's quality were discussed in this paper. The main results were as follows: (1) After analyzing the 77 wheat vanities in Huang-Huai Region, it was found that the occurrence frequency of 1 was the highest with 71.43%, and that of 2* was the lowest with 3.90% in 1A locus; the occurrence frequency of 7+9 was the highest with 42.68%, that of 7+8 was 31.17%, and 17+18 was the lowest with 1.30% in 1B locus; The high quality subunit 14+15 appeared with higher frequency of 116.9% in Huang-Huai region specially in Guanzhong region; the frequency of 2+12 was 53.35%, 5+10 was 33.77% in 1D locus; there were 7 kinds of subunit variation types in 1B locus and 3 kinds in 1A and 1D loci respectively. (2) It was found there were 27 kinds of subunit composition types in 77 varieties, among which, 1, 7+9,2+12 with 14.29% frequency and 1,7+8,2+12 with 12.99% frequency were the main types of subunit compositions; 1,7+9,5+10 with the frequency of 10.39%, 1,7+8,5+10 with the frequency of 9.09%, 1,14+15,2+12 with the frequency of 6.4%. These subunit compositions play an very important role in the improvement of wheat quality. It is deduced that there will be 63 kinds of subunit compositions in Huang-Huai Region theoretically, and 27 kinds were detected in this experiment in reality. So, there are much more room for variation and selection in subunit compositions. The compositions of 1, 7+8, 5+10; 1, 14+15, 2+12; N, 7+8, 5+10; 1, 7, 5+10; 1, 7+9, 5+10 fit in the germplasm resources in China because the occurrence frequencies of 1, 7+8, 7+9 and 14+15, 5+10 were comparatively higher in our own materials. (3) The regressive analysis revealed that the contributions of there loci to protein content and sedimentation value were Glu-D1>1 Glu-B1>Glu-A1 in order and significant at 5% and 1% levels. Co-relation analysis showed that Glu-D1 had the most significant co-relation to sedimentation value, Glu-D1 and Glu-B1 had the most significant co-relation to protein content. Path analysis represented that 1B had positive impact on the effect of 1A and 1D, there were no inter-reaction among the loci. (4) Studies on the effect of subunits to quality indicated that 1 and 2* had more impaction than N on protein content and sedimentation value at the most significant level. i.e, 1=2*>N in Glu-A1, In Glu-B1, The effect of subunit on protein content was as 14+15=17+18=7+8>7+9>20=6+8, the effect on sedimentation value was 14+15=7+8>17+8=7>7+9=20>6+8 in Glu-D1, the effects of subunit on protein content and sedimentation value were the same as 5+10>2+12>4+12. It was testified that 1, 2*, 14+15, 17+18, 7+8 and 5+10 were the subunits with higher quality by this experiment. (5) Among the 27 subunit compositions, 1, 7+8, 5+10 and 1, 14+15, 2+12 and 1,7+8, 5+10 had the greatest effects on protein content; N, 7+8, 5+10; 1, 7, 5+10; 2*, 7+8, 5+10; 1, 7+9, 5+10 had greater contributions to both protein content and sedimentations value, which are the favorite subunit compositions in high quality varieties. (6) The regressive equations of subunit and protein content and sedimentation value were built up and used to predict the values in wheat varieties. The results showed that there were little differences between real values and predicted values, the range of average difference was –0.351~0.388, the equations had the most fitness in real value, which means it is feasible to predict protein content, sedimentation value and variety quality by subunit scoring system. (7) The co-apparent of bands in grains of F1, there is only subunit 1 in 1A locus, and common subunits in two parents in 1B and 1D loci. The bands of F1 grains showed obviously mother-tendency in 9 co-dominant combinations. The mother-tendency genetic characters of subunits in F1 were quantity analyses by comparing the subunit distribution height and volume between recipal combinations. (8) Subunit deletion in F1 occurred in 6 of 15 combinations, there were 2 combination deleted 5+10 in 1D locus in F1 grain bands, and one combination deleted 9 subunit in 1B locus and 2 subunit in 1D locus. It was found that the main characters of subunit deletion in F1 grains were as follows: ①The main deleted subunits were 5+10 and 2+12, the main combinations with subunitdeletion were made by Neixiang 184 and Fengyou No.5 ②The deletion of 5+10 subunit in F1 grains of Xiaoyan No. 6 (1, 14+15, 2+12)×Neixiang 184(1, 7+9, 5+10) was probability induced by the inter-reaction with 14+15 in 1B locus and led to the silence of 5+10 in 1D locus. ③The deletion of 2+12 in F1 grains of Annong 91168 (1, 7+8, 5+10)×Fengyou No.5 (1, 7+9, 2+12) was probability induced by the up-position of 5+10 in D1 locus to 2+12 in 1D locus, led to the silence of 2+12 in 1D lows. ④The deletion of 5+10 and 2+12 were probability decided by the genetic characteristics of Neixiang 184 and Fengyou No. 5. (9) The genetic laws of subunits in different loci in F2 were as: the separation of different subunits in one locus was 1:N=3:1 in 1A locus, 7+9 and 14+15, 7+9 and 7+9 in 1B locus, 5+10and 2+12 in 1D locus were 1:2:1; the separation of different subunits in tow loci were: 1 and N in 1A locus, 7+9 and 4+15 in 1B locus, 5+10 and 2+12 in 1D locus, 7+9 and 14+15 in 1B locus, 5+10 and 2+12 in 1D locus were 4:2:2:2:2:1:1:1:1; the separation rations of different subunits in three loci were as:1 and N in 1A locus,7+8 and 7+9 in 1B locus, 5+10 and 2+12 in 1D locus were 12:6:6:6:6:4:3:3:3:3:2:2:2:2:1:1:1:1. Those separation rations are all fit the model's free-combination law. (10) All the deletion loci in F2 appeared in the heterozygous subunit compositions in 1B or 1D locus, there were no deletions found in homogenous compositions. There was the deletion of 5+10 in 1D heterozygous subunits in one combination, the deletion of 2+12 in 1D heterozygous subunits in 5 combinations; the deletion of 8 subunits in 1B heterozygous subunit composition and the deletion of 2 subunits in 1D heterozygous subunit composition in one combination. The characters of subunit deletion in F2 grains were as follows: ①The subunit deletions mostly occurred in only one locus, 1B or 1D in the all combinations with subunit deletions. ②All the subunit deletions happened in heterozygous subunit compositions in 1B or 1D locus, there was no subunit deletion occurred in homogenous subunit compositions. ③The subunit deletion in F2 grains was similar to that in F1 grains, which meant the heterozygous subunit composition was the surface of subunit deletion, the up-position and inter-reaction of subunits maybe the real reasons. ④The 2+12 was easily deleted as the subunit composition was 5+10 and 2+12, which was similar to that in F1 and testified that the 5+10 had up-position effect to 2+12,led to the silence of 2+12 in final. (11) In the course of quality breeding, it must be insisted to utilize high quality subunitsand the subunit compositions during parent selection, combination making and descendant selection, to introduce 2*, 14+15,17+18 and 5+10,to enhance the selection and combination of high quality subunit composition such as 2* , 14+15,2+12, 2* , 7+8,5+10,1,14+15, 5+10,2*,7+9,5+10. The effective method for quality improvement is selective back-crossing, and the farrelative hybriding can be employed as well.
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