EXPRESSION OF A NOVEL HIGH-MOLECULAR-WEIGHT GLUTENIN SUBUNIT GENE IN TRANSGENIC WHEAT

High-molecular-weight glutenin subunits (HMW-GS), one class of seed st orage proteins, are important determinants of the bread-making quality of wheat flour. To change the amount and composition of these protein s via genetic engineering, a gene encoding a novel hybrid subunit unde r the control of native HMW-GS regulatory sequences was inserted into wheat. Of 26 independent transgenic lines identified by bialaphos sele ction, 18 expressed the cotransformed hybrid HMW-GS gene in their seed . The hybrid subunit accumulated to levels comparable to those of the native HMW-GS. These results show that a native HMW-GS gene promoter c an be used to obtain high levels of expression of seed storage and, po tentially, other proteins in transgenic wheat endosperm. Transgene exp ression was stable for at least three seed generations in the majority of lines. These experiments demonstrate the feasibility of constructi ng wheat plants with novel seed protein compositions.