Technological quality of transgenic wheat expressing an increased amount of a HMW glutenin subunit

The transgenic line B73-6-1 (developed and characterized by UK scientists) contains 10-15 extra copies of a native HMW glutenin gene (1Dx5) with an approximately four-fold increase in the amount of the encoded protein. The technological and rheological properties of this line and the non-transformed control line were studied in a continental type, arid climatic environment (Martonvásár, Hungary, 2000-2002). The results show that in the three years of the field experiment, the transgene and associated functional properties were stably inherited over several generations. No difference was found in yield between the transgenic line and the original genotype, but clear genotypic differences were found in kernel hardness and kernel size. The transgenic line had an increased kernel hardness and a smaller kernel size. The transgenic line B73-6-1 tended to have a higher protein content than the control L88-6, but this difference was not statistically significant. In contrast there was a significant, 400%, increase in the amount of 1Dx5 HMW glutenin subunits, Dx/Dy-, HMW/LMW- and glutenin/gliadin ratio. At the same time there was a decrease in wet gluten content and SDS sedimentation. Thus, significant changes in the structure of the protein matrix caused by the altered x to y ratio of HMW-GS and as a result of this alteration, flour functional properties changed. Parameters that characterize the stability and strength of the dough confirmed that B73-6-1 was stronger, but the extensibility was reduced. This flour would be suitable for blending with flour of lower grade.