The high molecular weight (HMW) subunits of wheat glutenin are major determinants of the elastic properties of gluten that allow the use of wheat doughs to make bread, pasta, and a range of other foods. There are both quantitative and qualitative effects of HMW subunits on the quality of the grain, the former being related to differences in the number of expressed HMW subunit genes. We have transformed bread wheat in order to increase the proportions of the HMW subunits and improve the functional properties of the flour. A range of transgene expression levels was obtained with some of the novel subunits present at considerably higher levels than the endogenous subunits. Analysis of T2 seeds expressing transgenes for one or two additional HMW subunits showed stepwise increases in dough elasticity, demonstrating the improvement of the functional properties of wheat by genetic engineering.

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As part of a gene tagging strategy to study the developmental regulation of patterns of plant gene expression, a promoterless uidA (gusA) gene, encoding the beta-glucuronidase (GUS) reporter, was introduced into populations of tobacco, Arabidopsis and potato by Agrobacterium-mediated gene transfer. The objective was to generate random functional fusions following integration of the gusA gene downstream of native gene promoters. We describe here a detailed analysis of levels and patterns of gusA activation in diverse organs and cell types in those populations. gusA activation occurred at high frequency in all three species, and unique patterns of fusion gene expression were found in each transgenic line. The frequency of gusA activation was differentially biased in different organs in the three species. Fusion gene activity was identified in a wide range of cell types in all organs studied, and expression patterns were stably transmissible to the T2 and T3 progeny. Developmentally-regulated and environmentally-inducible expression of gusA is described for one transgenic line. Phenotypic variants were detected in the transgenic population. These results demonstrate the potential of T-DNA insertion as a means of creating functional tags of genes expressed in a wide spectrum of cell types, and the value of the approach as a complement to standard T-DNA insertional mutagenesis and transposon tagging for developmental studies is discussed.

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Selecting a promoter for driving transgene expression is one of the most important factors to consider in a transformation project. Information about the native regulation of the promoter activity is important, but it is also necessary to consider how that activity will be affected when integrated into the genome of the transformed plants. Study of a promoter performance in individually transformed lines provides useful information in this area. The maize ubiquitin 1 (Ubi-1) promoter has been widely used to drive constitutive transgene expression in monocotyledonous plants. However, lack of data on its activity in individual transformed wheat lines constitutes a gap in the understanding and predictability of this promoter's performance. In this paper, we began addressing this problem by examining the expression of the marker gene uidA, coding for P-glucuronidase (GUS), under the control of the maize Ubi-1 promoter in individual transgenic wheat (Eiticum aestivum L.) lines from different wheat varieties. The expression of uidA driven by this promoter depended to a great extent on the specific transformation event. Whilst expression was strong and constitutive in all tissues in some of the lines analysed, there were also transgenic lines in which GUS activity was restricted to only a few tissues. In general the maize Ubi-1 promoter had strong activity in young, metabolically active tissues and in pollen grains.