Review on Quality Protein Maize Breeding for Ethiopia

Abstract

Maize (Zea mays L. ) is a major cereal crops in the World and stable food crops in developing countries. But almost all maize varieties cultivated in the Ethiopia are normal maize varieties, which are deficiency  of essential amino acids such as lysine and tryptophan and  exposed to malnutrition people feed maize as stable food. Due to this reason substituting the normal maize grown in developing country with QPM would substantially improve the protein status and greatly reduce the malnutrition problems of resource poor people depending on maize as staple food. Quality protein maize (QPM) is a maize variety that possesses significantly higher levels of two essential amino acids, lysine and tryptophan as compared to Normal Maize (NM) varieties, to the presence of the opaque-2 gene in a homozygous recessive state.  Maize   breeders  began  transferring  opaque-2 genes into  local  maize  varieties , and  they  enthusiastically  rushed  the new  crop  into  production .The breeding of QPM involves the manipulation of three distinct genetic systems. The recessive mutant allele of the Opaque-2 gene is the first and central component, the second is comprised of the alleles of endosperm hardness modifier genes and the third is comprised of a distinct set of amino acid modifier genes (termed here “aa-modifiers”) which affect the relative levels of lysine and tryptophan content in the grain endosperm. The undesirable characteristics include reduced yield than normal maize, low grain consistence and a farinaceous endosperm that retains water is a major challenge during early development of QPM dissemination. In order to overcome these apparent limitations for large scale use of such mutants, efforts were directed towards identification of alternative mutants that did not carry such disadvantages. The effort, spanning over the last decade, involved collaborative CIMMYT/donor funded projects with large components of flow through funding to enable the full participation of regional NARS. CIMMYT remained the major source of global QPM germplasm and hence QPM development in the region and Ethiopia heavily depended on the large pool of QPM source germplasm available at CIMMYT. Support from DFATD to Ethiopia has continued under the Nutritious Maize for Ethiopia (NuME) project since 2012. Now a day’s six QPM varieties are released in Ethiopia for different Agro-ecology of maize production area, But still great effort was expected from maize breeders to convert normal maize to QPM to limit malnutrition in the country.

Keywords: aa-modifiers, malnutrition, Opaque-2 gene, Quality protein maize,