Abstract
Protein quality maize (QPM) combines the protein quality of the opaque-2 (o2) mutant with a vitreous endosperm. These characteristics have allowed breeding programs worldwide to produce QPM genotypes that help alleviate malnutrition of people in developing countries from Africa, Asia and Latin America with a cereal-based diet. However, the development of these materials has been inefficient due to the limited knowledge about the molecular basis of the conversion of the soft o2 endosperm into a vitreous phenotype in QPM. This conversion has been associated with an increase in small protein bodies rich in 27 kDa γ-zein, the synthesis of starch with a higher proportion of amylose and short-intermediate amylopectin chain branches that favors the compaction of the starch granules, as well as alterations in the amyloplast envelope that favors the interaction between starch granules and protein bodies. Additional studies about the mechanisms involved in the modification of the endosperm in QPM will contribute to produce materials with good agronomic characteristics and protein quality.