Mucronate, Mc, a dominant gene of maize which interacts with opaque-2 to suppress zein synthesis

This paper describes a new dominant mutation of maize, Mc, which interferes in the endosperm with the synthesis of storage proteins. The mutant is characterized by an opaque phenotype; it reduces the deposition of zein and it increases the level of methionine. The mutation is specifically related to storage protein synthesis since soluble and insoluble carbohydrates are present at normal levels. The main interest of this mutant lies in its synergistic interaction with opaque-2 in repressing zein synthesis. In the double mutant o2Mc the accumulation of zein is reduced to less than 10% of that of the normal endosperm. The control on zein synthesis exerted by the double mutant is at the level of production or stability of translatable zein mRNAs. The double mutant o2Mc germinates well offering the opportunity of using it in biochemical and molecular studies related to storage protein synthesis; the reduced endosperm weight of o2Mc negates its practical utilization in breeding maize for quality.