Seed protein content, nutritional balance and processing property of flour are the three major aspects of wheat protein quality. Most Chinese wheat cultivars are comparable to their Western counterparts in terms of seed protein content and nutritional balance. However, relatively few of them possess good processing property. The main reason underlying the poor processing property of hexaploid Chinese wheat varieties is the weakness in gluten strength. Considering that wheat gluten is mainly composed of a mixture of a finite number of storage protein species and that the storage protein species may determine gluten strength through combinatorial controls, we formed the following strategies in our studies on understanding and manipulating the genetic basis of protein quality in Chinese wheat. 1. Genetic analysis. By performing well structured genetic analysis, we hope to identify two types of storage protein genes, those genes whose presence is associated with good processing property (the desirable genes, or the D type genes) and those whose presence is always associated with undesirable processing property (the undesirable genes, or the U type genes). Two sets of genetic analysis are being conducted currently. The aim of the first set of analysis is to obtain nonfunctional mutants for the majority of the genes whose products are present in the gluten. This analysis is expected to yield information on the function of individual members of storage proteins, some of which may be encoded by the D type genes, in gluten strength control. The aim of the second set of analysis is to identify potential genetic factors that may be responsible for causing weakness in gluten strength in Chinese wheat through the use of recombinant inbreed lines. This analysis may produce information on the function of the storage proteins specified by the U type genes. 2. Molecular analysis. On the basis of above genetic analysis, a molecular approach will be undertaken to clone the D and U type genes. The cloned genes will be characterized
The high-molecular-weight (HMW) glutenin subunits and their coding genes from Aegilops umbellulata Zhuk. (UU, 2n = 2x = 14) were characterized using SDS-PAGE analysis and molecular approaches. SDS-PAGE analysis showed that the 1Ux subunits from four different accessions possessed electrophoretic mobilities close to, or slower than, that displayed by the 1Dx2.2 subunit of common wheat. The electrophoretic mobilities of the 1Uy subunits were generally similar to those shown by the 1Dy subunits of common wheat. The complete open reading frames of the 1Ux and 1Uy genes were amplified by PCR and subsequently cloned and sequenced. Amino acid sequence comparisons suggested that the primary structure of the 1Ux and 1Uy subunits were identical to that of published HMW glutenin subunits from related species, Phylogenetic analysis indicated that the HMW glutenin subunits of Ae. umbellulata were most closely related to those encoded by the D genome of Triticeae.
