Genetic basis and the current breeding efforts for quality protein maize in Southern Africa
Maize (Zea mays L.) is deficient in essential amino acids, lysine and tryptophan. Opaque-2 maize mutant discovery that is high in lysine and tryptophan, offers an avenue for maize protein quality improvement. Quality protein maize (QPM), a product of the extensive development of the Opaque-2 mutant, is an affordable and viable option for overcoming the scourge of protein malnutrition in humans and monogastric livestock especially in sub-Saharan Africa. The objective of this review was to scrutinise the genetic basis of quality protein maize (QPM), and current breeding efforts, and propose potential uptake pathways for QPM products in southern Africa. The conventional QPM breeding methods are based on phenotypic selection to identify genotypes carrying the recessive Opaque-2 alleles. However, phenotypic selection is negatively influenced by the environment and has huge drain on resources such as time, money and labour, with low genetic gains. From this, marker assisted breeding methods are clearly the most efficient way of QPM breeding. Institutions such as the International Maize and Wheat Improvement Centre (CIMMYT) are currently employing molecular breeding in QPM breeding programmes so as to quicken and ease the process of QPM breeding. To date, a number of QPM varieties have been released and are being promoted using various pathways and policies.
Key words: Opaque-2 gene, phenotypic selection, QPM, Zea mays L.