| Quality improvement has become a major goal of wheat breeding program in our country. The research of molecular mechanism and genetics pattern of wheat quality traits can provide with scientific basis for breeding practice. In this study, a set of 60 lines homozygous at glutenin loci, Glu-1 and Glu-3 from the F4 progeny population of Suneca X Cook , and 18 wheat cultivars with very different quality traits from Huang-Huai Wheat Region were chosen to investigate individual and combined effects of alleles at these loci on wheat quality properties , study the relationship between the size distribution of glutenin polymeric protein and wheat flour mixing properties and the relationship between some biochemical characters and quality traits. More over, the primers specific for LMW-GS genes at Glu-D3and Glu-B3 complex loci in wheat were developed, the genes at Glu-D3 complex loci in bread wheat cultivars were cloned and characterized. The major results are as follows: CD The parental cultivars Suneca and Cook had contrasting alleles at each of the five glutenin subunits loci (Glu-B1, G1u-D1, Glu-A3, Glu-B3 and Glu-D3), thus, a set of 60 lines homozygous of these loci from the F4 progenies of Suneca Cook was chosen to study the effects of allelic variation at glutenin complex loci on the size distributions of polymeric protein (measured by SE-HPLC) of wheat grain. The results showed that glutenin allelic variation at Glu-Bl, Glu-Dl, Glu-A3, Glu-B3 complex loci significantly affect the relative size distributions of polymeric protein (i. e. percentage of unextractable polymeric protein in the total polymeric protein, or UPP%). Allele Glu-Blu, Glu-Dld Glu-A3b and Glu-B3b was associated with greater UPP% value than allele Glu-Bli, Glu-D1a, Glu-A3d and Glu-B3h respectively . However , alleles (e and b) at the Glu-D3 locus did not give significantly different UPP % values. The effect of alleles at Glu-l and Glu-3 locus on the relative size distributions of polymeric protein appears cumulative andinteractive.(2) Allelic variation at Glu-D1, Glu-A3 and Glu-B3 glutenin loci had significant effects on flour mixing time, the progenies with allele d at the Glu-Dl locus had significantly longer PTM than allele a, similarly Glu-A3b and Glu-B3b allele, respectively gave greater PTM than Glu-A3d and Glu-B3h. Alleles at the other loci (Glu-Bl and Glu-D3) did not give significantly different PTM. In this genetic background, the effect of different glutenin subunit loci on PTM could be ranked as Glu-Dl>Glu-B3> Glu-A3> Glu-Bl=Glu-D3. The effect of Glu-1 and Glu-3 alleles appears cumulative and interactive. In additions, Flour mixograph shape was closely related to UPP% value, UPP% was very strongly positive correlation with PTM. Compared with flour protein content (FP%) , UPP% gave greater effect on PTM, i. e. flour mixing properties, and it can be considered as one of criteria for quality selecting from early generation of breeding program.(3) 18 wheat cultivars with very different quality traits were chosen to investigate the relationship between some biochemical characters and quality traits. The results indicated that total flour protein, total polymeric protein and unextractable macropolymeric protein content contributed significantly and positively to quality traits, i.e. grain hardness , sedimentation value and wet gluten content. The double-stepwise regression analysis showed that total polymeric protein content (X2) and the percent of macropolymeric glutenin in total polymeric protein (X6) were the most important factors influenceing sedimentation value (Y3), its regression equation was Y3= 8. 2784X2+0.4930 X6-54. 8929, while flour protein content (X1) was the key factor determining wet gluten content (Y4), the regression equation was Y4= 4. 3054X1 -18. 5971. The correlation coefficient of these two regression equations was 0.7498 and 0. 9992, respectively, and both were at very significant level.(4) Based on the LMW-GS gene sequences reported in GenBank, the primer 1-9 for specific genome locus LMW-GS genes wer... |
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