Zein level in maize endosperm depends on a protein under control of the opaque-2 and opaque-6 loci.

Zeins, the major endosperm proteins of maize, represent about 50% of total seed proteins and consist of several alcohol-soluble polypeptides encoded by at least four families of genes. The accumulation of zeins is under the control of several broadly defined regulatory genes. One of these, the opaque-2 mutant, lowers the level of zeins, thus improving the nutritional quality of maize meals. We demonstrate here that a salt-soluble protein of molecular weight 32,000 (b-32) is under control of O2. Seven o2 recessive alleles are CRM- when assayed with b-32 antibody. The O2 gene does not encode protein b-32, which apparently is the gene product of the O6 locus. 06 endosperms are CRM- for b-32 protein and are almost devoid of zeins. This indicates that b-32 plays an important role in accumulation of zeins.