Nutritional benefit and development of quality protein maize (QPM) in Ethiopia: review article

Among the top three cereal crops producing in Sub-Saharan Africa (SSA), Asia, and Latin America, maize (Zea mays L.) is a major source of food security and economic development for these countries. However, maize lacks a required amount of the essential amino acids lysine and tryptophan in its endosperm. In the mid-1960 breeding for improved protein quality in maize was started to overcome the two amino acids deficient in maize endosperm proteins, and came up with the discovery of mutants, such as opaque-2, that produce enhanced levels of lysine and tryptophan. Despite these achievements, adverse pleiotropic effects imposed severe constraints on the successful exploitation of these mutants. A collaboration work from different background disciplines of researchers corrected the negative features of the opaque phenotypes has ensured the rebirth of QPM after long efforts. QPM has twice the amount of lysine and tryptophan, as well as protein bioavailability that rivals milk casein when comparing with conventional maize types. It was confirmed that 100 g QPM is required for children and nearly 500 g for adults to maintain the adequacy of lysine and tryptophan. Relatively this represents a 40% reduction in maize intake to common maize to meet protein requirements. Therefore, this review will highlight the history of developing QPM, the efforts that have been made to recovery technical problems raised to develop nutritionally enriched maize successfully through both conventional and molecular breeding methods, and indicating the need for intensification of efforts to create a greater impact on malnutrition in maize consuming populations, especially in developing countries.