Breeding for Breadmaking Quality Using Overexpressed HMW Glutenin Subunits in Wheat (Triticum aestivum L.)

Abstract

In the course of breeding, a number of genetic resources have been used to investigate the effect of the overexpressed allelic form of the Bx7 high molecular weight glutenin encoded by Glu-B1 on dough strength, stability and extensibility. Biochemical marker selection was carried out using RP-HPLC on breeding lines in the F₃ –F₄ and F₅ –F₇ generations, developed using parental lines overexpressing storage proteins, in order to detect the overexpression of the Bx7 HMW glutenin subunit. In early generations lines were selected that had mean values of dough strength (R_max) and area under the curve (A) substantially exceeding those recorded for the original set of breeding material using Kieffer’s Texture Analyser. The values of R_max rose from 16.0 to 23.3 and those of A from 984 to 1403 on average in the selected lines. Correlation analysis indicated that a medium strong, significant correlation was found for the resistance and stability of the dough and the area under the curve. The results of rheological analysis on selected lines overexpressing Bx7 show that the ratio of genotypes with good breadmaking quality increased during both periods of selection, but breeding for HMW glutenin overexpression alone is not sufficient for an improvement in breadmaking quality. It can be concluded that overexpressed allelic forms could be useful means of breeding for improvements in traits influencing technological quality, especially dough strength and stability. Compared to genetic resources with high protein content, these overexpressed forms do not make a significant contribution to increases in protein content and dough extensibility