Cereal Chem 62:398-405 | VIEW
Control of Wheat Protein Biosynthesis.
F. C. Greene, O. D. Anderson, J. C. Litts, and M.-F. Gautier. Copyright 1985 by the American Association of Cereal Chemists, Inc.
Gliadins and glutenins, the most abundant proteins of the wheat seed, are important (as storage proteins) to the nutrition of young wheat seedlings, and (as gluten proteins) to the quality of flour-based foods. The rate of synthesis and deposition of these proteins changes dramatically during a transition period early in the development of the wheat seed, from a minor fraction of total proteins synthesized in very young seeds, to a major fraction in seeds during middle and later stages of development. The rates of storage protein synthesis in developing wheat seeds change in direct proportion to the amounts and rate of accumulation of seed messenger RNA, and control of the gene expression may be primarily transcriptional. Synthesis of gliadins can be observed as early as six days after flowering, and the expression of these genes appears to be coordinately controlled. Analysis of populations of moderate-to-abundant messenger RNA indicate that species present in seeds at 16 days after flowering were also present at seven days after flowering, although not in the same relative proportions. This indicates that the corresponding gene population is activated by seven days after flowering, and that subsequent differences observed in the protein population may result from quantitative variations in control of the expression of the genes. Gliadin genes are present in multiple copies in the wheat genome, and genes coding for proteins of the A-gliadin complex are present in different numbers in the cultivars (Cheyenne (hard red winter) and Yamhill (soft white winter). The nucleotide sequence of an A-gliadin gene isolated from a genomic clone library has been determined, and the coding region shown to be free of introns. This gliadin gene contains all the consensus regulatory sequences of eukaryotic genes and is probably functional in the endosperm cell.