Genetic Engineering of Seed Storage Proteins

Seeds synthesize and accumulate variable amounts of carbohydrate, lipid, and protein to support their growth, development, and germination. The process of desiccation during seed maturation preserves these nutrients for long periods, making seeds an excellent food source and livestock feed. Over the millennia, human selection for high-yielding seed crops has resulted in dramatic increases in the accumulation of valuable nutrients and the reduction of toxic compounds and chemicals that affect the taste of foods made from seeds. However, in some cases, selection has resulted in a reduction in the amount or quality of certain nutrients. Many types of seeds are adequate in one nutritional aspect but inadequate in others. Genetic engineering has created the opportunity to use the beneficial traits of certain types of seeds and ameliorate the negative aspects of others. This chapter summarizes the progress that has been made toward the improvement of seed and nonseed crops using transgenic expression of seed storage proteins. We explain the limitations of these approaches and describe promising areas of research such as reduction of allergenic seed components. We also discuss economic and ethical issues that impact this field.

Key Words: Protein quality, GM crop, essential amino acids, sulfur, methionine, lysine, glutenin, gluten, allergen, maize, soybean, wheat, prolamin, 11S globulin, 7S globulin, 2S albumin.