Screening And Quality Analysis Of Wheat Germplasm Resources With Different HMW-GS Deletion

HMW-GS (high molecular weight glutenin subunits) is important in determining the viscoelastic properties of wheat. Distribution and variation of HMW-GS are also related with the processing quality of wheat. In this study, HMW-GS distribution in wheat germplasm resources was firstly analyzed. Then, wheat lines with different types of HMW-GS deletion were selected and crossed with two soft wheat varieties Yangmai13and Yangmai18to generate advanced backcross and inbred population. To investigate the potential of HMW-GS deletion in soft wheat breeding, genetic behavior and quality effect of different types of HMW-GS deletion were analyzed. The results were described in detail as followings.1. Screening of wheat germplasm resources with HMW-GS deletion. The HMW-GS distribution of432wheat materials, including a mini core set of wheat lines with261members and54application-core collection germplasms,97synthetic wheat lines from CIMMYT,20common wheat lines and two transgenetic wheat lines, were analyzed by the SDS-PAGE technique. The Glu-Al, Glu-B1and Glu-D1loci in a mini core set of wheat lines mainly consist of Null,7+8and2+12subunits. However, some wheat core lines show a certain HMW-GS deletion. Five lines possess1Bx7type or1Bx22subunits but lack1By type subunits at the Glu-B1loci. Other three lines have1Dx2or1Dy12type subunits but lack1Dy or1Dx type subunits at the Glu-D1loci. High variation of HMW-GS constitution was observed in synthetic wheat lines. A rare subunit temporarily named1Ax1’ was identified. Two unknown subunits temporarily named Y and X type subunits were also found in synthetic wheat lines. Additionally, some new subunit combinations were detected in synthetic wheat lines. One synthetic wheat line contains1Bx7type subunit but lacks1By type subunit at the Glu-B1locus. Two synthetic wheat lines possess1Dy10type subunits but lack1Dx type subunits at the Glu-D1loci. Both Glu-Al and Glu-B1loci were absent in one synthetic wheat line. The Glu-Dl loci were lack in three common wheat lines. Both Glu-A1and Glu-D1loci were lost from three common wheat lines. The Glu-B1loci contains four type subunits in Lahua9650. The1Dx5subunit at the Glu-D1locus and whole Glu-D1locus were lack in two transgenetic wheat lines, respectively.2. Genetic behavior of different types of HMW-GS deletion. The double-deletion of Glu-A1and Glu-D1loci of HMW-GS in common wheat line2GS0414-10and Glu-D1loci absence in Lahua9650all inherit recessively in F1progeny. HMW-GS composition in F2progenies is coincident with the3(HMW-GS expression):1(HMW-GS silence) ratio of Mendelian inheritance. HMW-GS absence was not observed in BC1F1lines. The double-deletion of Glu-A1and Glu-B1loci of HMW-GS in synthetic wheat line SYN351inherits recessively in F1progeny. HMW-GS distribution in F2progenies is inconsistent with the theoretical ratio3:1or9:3:3:1. HMW-GS absence was not observed in BC1F1plants. The silent effect of HMW-GS is dominant in two transgenetic wheat. Due to the suppression of1Dx5subunit by small RNA, HMW-GS distribution in F2and BC1F1progenies shows13(1Dx5subunit silence):3HMW-GS (1Dx5subunit expression) and3(1Dx5subunit silence):1(1Dx5subunit expression) ratios, respectively. The whole HMW-GS silent effect in F2and BC1F1progenies shows3(HMW-GS silence):1(HMW-GS expression) and1(HMW-GS silence):1(HMW-GS expression) ratios, respectively.3. Quality evaluation of donor parents. Donor parents2GS0414-10, Lahua9605and Glu-1Dx5-RNA,Glu-1-RNAi all have comparatively low gluten content and high gliadin content, have relatively low SDS sedimentation value, water solvent retention capacity, development time, stability time and the index of flour quality. Compared with that of receptor line Bobwhite, Protein content increases significantly in transgenetic lines. Additionally, diameter of biscuits increases significantly due to all HMW-GS silence. Lower wet gluten content and higher gluten index due to the double-deletion of Glu-A1and Glu-B1loci in SYN351.4. Quality analysis of progenies derived from different types of HMW-GS deletion. The wheat line2GS0414-10with the double-deletion of Glu-A1and Glu-Dl loci, and HMW-GS silence in transgenetic wheat lines were adopted as donor parent. Two soft wheat varieties Yangmai13and Yangmai18were used as receptor parents and crossed to generate BC2F3、BC1F3and F5progenies. Quality of parents and their progenies were tested. Results indicated that Glu-A1absence has little effect on protein content, SDS sedimentation value and water solvent retention capacity. The Glu-D1absence does not influence protein content and water solvent retention capacity but significantly influences the SDS sedimentation value. Intriguingly, double-deletion of Glu-A1and Glu-D1loci has little effect on protein content but significantly influence the SDS sedimentation value and water solvent retention capacity. Both the SDS sedimentation value and water solvent retention capacity decrease significantly owing to whole HMW-GS silence.5. Results presented in this study indicated that wheat lines with HMW-GS deletion have comparatively low gluten content and high gliadin content, which is benefical to decrease the dough strength and increase the dough extensibility. Wheat lines with HMW-GS deletion also have relatively low SDS sedimentation value, water solvent retention capacity, development time and stability time. The HMW-GS deletion effect may be useful in quality improvement in soft wheat.