Sequence Analysis Of High Molecular Weight Glutenin Subunits In Aegilops Tauschii And Its In Vitro Mutation

Common wheat (Triticum aestivum) is one of the most important crops in the world. Aegilops tauschii is commonly accepted as the D genome donor of common wheat and contains a much wider genetic background. Therefore, it is important genetic resources in wheat breeding. The HMW glutenin subunits are important components of wheat storage proteins that closely associated to the dough quality of common wheat. A number of novel types of HMW glutenin subunits that are not detected in common wheat have been characterized in Ae. tauschii such as the D~tx1.5+D~ty10. The D~tx1.5+D~ty10 subunits are suggested to associate to the good dough quality. Thus, the novel HMW glutenin subunits from Ae. tauschii have their potential value in bread-making quality enhancement in wheat breeding.In the present study, we characterized the complete open reading frames of the newly cloned HMW glutenin genes D~tx1.5 and D~ty10 using the new restricted enzyme based method called restricted deletion method (RDM). In addition, the newly cloned D~tx1.5 and D~ty10 were expressed in E. coli. This provides a solid basis and materials for studying molecular structure and functions of these genes. Sequence comparison indicated that the D~tx1.5 and D~ty10 have an identical structure compared with the other published HMW glutenin genes. Noticeably, the D~ty10 in Ae. tauschii was differentiated from its counterpart Dy10 in common wheat, by comparing the amino acid sequences of the central repetitive domain. This result confirms that the two subunits with the same mobility in SDS-PAGE are different types of HMW glutenin subunits. Based on the SNPs in the partial DNA sequences of different x-type HMW glutenin genes, a set of AS-PCR primers was developed. The AS-PCR primers are valuable in wheat breeding, as a more effective and accurate marker assisted selection for special HMW glutenin subunits than traditional SDS-PAGE.Comparison of partial DNA sequences of the D~tx2.1 from different accessions indicated that the traditionally determined D~tx2.1 subunit could be distinguished to two different subtypes, i.e. D~tx2.1a and D~tx2.1b. This was supported by the study of genetic relationship of D genome of these accessions using SSR markers. In addition, the D~ty10 and the Dy10 were confirmed to be different types of subunits by sequence comparison. It is concluded that the conventional SDS-PAGE has its limitation in determining some HMW glutenin subunits. The author therefore suggested that...