BREEDING FOR BREADMAKING QUALITY USING OVEREXPRESSED HMW GLUTENIN SUBUNITS IN WHEAT (TRITICUM AESTIVUM L.)

摘要

In the course of breeding, a number of genetic resources have been used to investigatethe effect of the overexpressed allelic form of the Bx7 high molecular weight gluteninencoded by Glu-B 1 on dough strength, stability and extensibility. Biochemical markerselection was carried out using RP-HPLC on breeding lines in the F_3-F_4 and F_5-F_7generations, developed using parental lines overexpressing storage proteins, in order todetect the overexpression of the Bx7 HMW glutenin subunit. In early generations lineswere 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 usingKieffer's Texture Analyser. The values of R_(max) rose from 16.0 to 23.3 and those of Afrom 984 to 1403 on average in the selected lines. Correlation analysis indicated thata medium strong, significant correlation was found for the resistance and stability ofthe dough and the area under the curve. The results of rheological analysis on selectedlines overexpressing Bx7 show that the ratio of genotypes with good breadmakingquality increased during both periods of selection, but breeding for HMW gluteninoverexpression alone is not sufficient for an improvement in breadmaking quality. Itcan be concluded that overexpressed allelic forms could be useful means of breeding forimprovements in traits influencing technological quality, especially dough strength andstability. Compared to genetic resources with high protein content, these overexpressedforms do not make a significant contribution to increases in protein content and doughextensibility.