WHEAT GRAIN PROTEIN CONTRIBUTES SIGNIFICANTLY TO TOTAL PROTEIN INTAKE AND CONTROLS THE TECHNOLOGICAL PROPERTIES OF FLOUR DOUGHS.
IN WESTERN EUROPE, THE DEMAND FOR HIGH PROTEIN WHEAT IS MET BY IMPORTS FROM THE USA AND CANADA, DESPITE THE PRODUCTION OF NET SURPLUS OF FEED WHEAT.
THE MANIPULATION OF GENES CODING FOR QUALITY-ASSOCIATED PROTEINS IS AT THE BASIS OF ANY SUBSTANTIAL AND RAPID GENETIC IMPROVEMENT OF WHEAT VARIETIES.
Understanding of the genetic and biochemical bases of quality in wheat flour will lead to new opportunities in the food industry. Genes for particular glutenin proteins were isolated and their nucleotide sequences determined. The protein sequences were then deduced. Conformational differences between high molecular weight (HMW) glutenin subunits were assayed by mobility in electrophoresis. The regulatory sequences required for activation of the genes specifically in seeds were determined by constructing new genes with parts of the postulated regulatory deoxyribonucleic acid (DNA), inserting them into tobacco plants and measuring the gene activity in seeds and other parts of the plant.
Genes for an HMW glutenin subunit, and alpha/beta gliadin and several low molecular weight (LMW) glutenin like genes were isolated and sequenced, completely or in part. Details of the variation between genes and protein products were assessed. The HMW glutenin gene was transferred into tobacco and wheat HMW glutenin found in the tobacco seeds. The regions essential for endosperm specific expression of the HMW glutenin and LMW glutenin genes were localized in the promoters. An HMW glutenin subunit that confers better breadmaking quality has more internal repeats of the consensus type than one conferring poorer quality. A hypothesis relating quality to beta-turn potential was proposed. This was supported by conformational differences between the 2 subunits detected by mobility in electrophoresis.
THE LONG-TERM AIMS OF THIS PROJECT ARE TO UNDERSTAND LOW GENE EXPRESSION IS REGULATED DURING ENDOSPERM DEVELOPMENT AND TO MANIPULATE PROTEIN GENES IN ORDER TO PROVE WHEAT VARIETIES. IN CAMBRIDGE, THE WORK IS CARRIED OUT WITH HEXAPLOID WHEAT, WHEREAS IN MONTPELLIER TETRAPLOID DURUM WHEAT IS BEING STUDIED.
REPRESENTATIVE GENES FOR THE COMPONENT OF GLUTEN, RELATED TO FLOUR QUALITY, HAVE BEEN ISOLATED AND CHARACTERIZED. OTHER GENES CODING FOR THIS FAMILY OF QUALITY-ASSOCIATED PROTEINS WILL BE SEQUENCED, AND THEIR REGULATORY REGIONS STUDIED. THE SYNTHESIS OF INDIVIDUAL POLYEPTIDES, FOR BIOCHEMICAL CHARACTERIZATIONS AND PROTEIN ENGINEERING, WILL BE ATTEMPTED BOTH IN E. COLI AND PLANT SYSTEMS, USING TI-DNA TRANSFORMATION IN THE LATTER CASE.
Funding SchemeCSC - Cost-sharing contracts