Abstract
BackgroundHigh molecular weight glutenin subunits (HMW-GS) have been proved to be mostly correlated with the processing quality of common wheat (Triticum aestivum). But wheat cultivars have limited number of high quality HMW-GS. However, novel HMW-GS were found to be present in many wheat asymmetric somatic hybrid introgression lines of common wheat/Agropyron elongatum.ResultsTo exploit how these new subunits were generated, we isolated HMW-GS genes from two sib hybrid lines (II-12 and 11-4-6) and compared them with those from their parents. The result shows that two genes of hybrid (H11-3-3 and H11-4-3) are directly introgressed from the donor parent Agropyron elongatum; one hybrid gene (H1Dx5) comes from point mutation of a parental wheat gene (1Dx2.1); two other hybrid genes (H1By8 and H1By16) are likely resulting from unequal crossover or slippage of a parental wheat gene (1By9.1); and the sixth novel hybrid gene (H1Dy12) may come from recombination between two parental genes.ConclusionTherefore, we demonstrate that novel HMW-GS genes can be rapidly created through asymmetric somatic hybridization in a manner similar with the evolution mechanism of these genes supposed before. We also described gene shuffling as a new mechanism of novel HMW-GS gene formation in hybrids. The results suggest that asymmetric somatic hybridization is an important approach for widening HMW-GS genebank of wheat quality improvement.
Highlights
High molecular weight glutenin subunits (HMW-GS) have been proved to be mostly correlated with the processing quality of common wheat (Triticum aestivum)
SDS-PAGE profile of HMW-GS The SDS-PAGE profile of HMW-GS showed that the parent wheat Jinan177 has the combination of "1Bx7.1+1By9.1; 1Dx2.1+1Dy12.1" while another parent A. elongatum contains nine HMW-GS in seeds; the HMWGS composition of hybrid line II-12 and 11-4-6 appeared to be "H1Ax2*; H1Bx13+H1By16; H1Dx5+H1Dy12" and "H1Ax1; H1Bx7+H1By8; H1Dx5+H1Dy12" similar to bread wheat, respectively (Figure 1)
HMW-GS genes from both parents and two introgression lines The amplified product of parent wheat Jinan177 and two introgression lines II-12 and 11-4-6 ranged from 1.8 kb to 2.5 kb, but two smaller fragments appeared in the 114-6; the amplicon of another parent A. elongatum ranged from 1.1 kb to 2.4 kb (Figure 2)
Summary
High molecular weight glutenin subunits (HMW-GS) have been proved to be mostly correlated with the processing quality of common wheat (Triticum aestivum). The HMW-GS accounts for up to about 12% of the total protein in the endosperm of common wheat (Triticum aestivum L.), while their allelic variation explains about 45% to 70% of the variation in bread making performance within European wheat cultivars [2,3,4]. Their coding sequences are the prime candidates for molecular modification to enhance grain-processing quality [5]. All of these HMW-GS contain a (page number not for citation purposes)
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