INTEGRATION AND EXPRESSION OF THE HIGH-MOLECULAR-WEIGHT GLUTENIN SUBUNIT 1AX1 GENE INTO WHEAT

The unique bread-making characteristic of wheat flour is closely relat ed to the elasticity and extensibility of the gluten proteins stored i n the starchy endosperm, particularly the high-molecular-weight gluten in subunits (HMW-GS), which are important in determining gluten and do ugh elasticity. The quality of wheat cultivars depends on the number a nd composition of the HMW-GS present. We have introduced the HMW-GS 1A x1 gene, known to be associated with good bread-making quality, into t he Bob White cultivar of wheat (Triticum aestivum L.), in which it is not present in nature, by the biolistic bombardment of cultured immatu re embryos. Of the 21 independent transformed lines selected, 20 expre ssed the selectable bar gene, and nine the 1Ax1 gene. The amount of HM W-GS 1Ax1 protein produced in the different transgenic lines varied fr om 0.6% to 2.3% of the total protein, resulting in an increase of up t o 71% in total HMW-GS proteins. The transgenic plants were normal, fer tile, and showed Mendelian segregation of the transgenes. The accumula tion of HMW-GS 1Ax1 was consistent and stable up to the R3 seed genera tion. These results demonstrate that it is possible to manipulate both the quantity and quality of HMW-GS, which influence the bread-making quality of wheat.