du Pont de Nemours and Company (Wilmington, DE) has patented four chimeric genes, a first encoding lysine-insensitive
aspartokinase, which is operably linked to a plant chloroplast transit sequence, a second encoding lysine-insensitive dihydrodipicolinic acid synthase, which is operably linked to a plant chloroplast transit sequence, a third encoding a lysine-rich protein, and a fourth encoding a plant lysine ketoglutarate reductase, all operably linked to plant seed-specific regulatory sequences.