Genetic means and cultural methods for improving nutritional value of crops

Concern for refining nutritional values of food is a contemporary pre-occuptation of middle- and upper-income groups of affluent societies. For the underdeveloped world, and those caught within poverty traps in advanced economies, the problem is different. Besides not having sufficient to eat, their dependence on plant products, sometimes from a single crop, signifies that essential ingredients are often below acceptable thresholds. In accordance with a reasonable order of priorities, plant breeders have in the past concentrated on reducing disease and on improving the response of varieties to fertility and to management. Interest in food quality is recent, and the subject is considered here in respect of the amount and quality of proteins and fats, mineral composition and the elimination of anti-nutritional products. Increased protein in cereals can be derived by nitrogen fertilisation and by using high-protein genotypes in variety production. Negative correlations between yield and protein content, and yield and lysine in protein is common but new genotypes are available in which this correlation has been broken. Protein research was stimulated by the discoveries of mutant genes in maize regulating protein fractions low in lysine. This work has generated research in other cereals, as well as the search for legumes high in sulphur amino acids. Possibilities are discussed whereby the value of proteins in some of the grain legumes may be improved. Interest in the quantity and quality of dietary proteins has overshadowed the importance of quality of the fat content of diets. Plants can make a substantial contribution to the balance between saturated and unsaturated fatty acids. Improvements inBrassica oils through elimination of erucic acid is an outstanding example of the success of genetical techniques in enhancing nutritional value of plants. Anti-nutritional factors such as those causing lathyrism, favism and coeliac disease are discussed with a view to their elimination by genetical means. Provided the chemical agents can be specified, genetical techniques could raise the nutritional status of varieties and eliminate the widespread suffering that is caused.