Maize Protein Quality and Its Improvement: Development of Quality Protein Maize in India

Abstract

The quality of maize protein is poor due to the deficiencies of two essential amino acids, lysine and tryptophan, and excess of leucine. However, the discovery of association of high lysine and tryptophan with opaque-2 maize endosperm in 1964 opened up new vistas in improving maize protein quality. Consequently, many countries started developing maize varieties incorporating opaque-2 gene, and in the Indian Maize Programme, three opaque-2 composite varieties were developed and released for commercial production in the year 1970. Though the nutritional superiority of opaque-2 maize over normal maize was very well established, the newly developed high-lysine varieties could not become popular because of agronomic and acceptability problems associated with their soft chalky endosperm. To circumvent this problem, efforts were initiated in 1971 itself towards developing hard-endosperm opaque-2 maize lines/strains through the continuous process of vigorous selection for kernel vitreosity and monitoring tryptophan/lysine for maintaining protein quality. The modified opaque-2 maize with hard endosperm and having high lysine and tryptophan is known as quality protein maize (QPM). At present, in India we have one QPM composite and more than nine QPM hybrid varieties released, and many more are in pipelines. However, what is required is the popularization of these varieties with farmers as well as consumers highlighting their nutritional significance, especially to the vulnerable group, i.e. infants and preschool children and pregnant and lactating mothers.