Cereal Chem 52:412 - 419.  |  VIEW ARTICLE
Amino Acid Composition and Storage Proteins in Two New High-Lysine Mutants in Maize.

Y. Ma and O. E. Nelson. Copyright 1975 by the American Association of Cereal Chemists, Inc. 

Two newly identified high-lysine mutants of maize, opaque-6 (o6) and floury-3 (fl3), have been compared with the appropriate nonmutant controls for their effect on endosperm proteins and amino acid content. Similar data are also presented for the high-lysine mutant opaque-7 (o7) and two opaque mutants, opague-1 (o) and soft-starch (h) that do not have altered amino acid compositions. The o6 and fl3 mutants, in spite of increased lysine content, do not lend themselves to practical applications. Albumins and nonprotein nitrogen, globulins, prolamines, and glutelins were extracted sequentially by a modified Osborne-Mendel procedure. Significant differences among the mutant strains were found in regard to protein distribution patterns. Three mutants, o6, o7, and fl3, which are relatively high in lysine content, showed a shift in zein:glutelin ratio as well as an increase in nonprotein nitrogen, albumins, globulins (except fl3), and insoluble proteins. The two mutants with normal lysine contents, o and h, showed a protein distribution pattern similar to the normal strains. Amino acid analyses of the three high-lysine, mutant endosperms and the isolated protein fractions, together with the protein fractionation data, show that the increase of lysine in these three mutants resulted from the decrease in the ratio of zein to other protein fractions.