The efficiency of protein synthesis in maize depends on the light regulation of the activities of the enzymes of nitrogen metabolism

Induction of asparagine synthetase (AS, EC 6.3.5.4) and repression of glutamine syntethase (GS, EC 6.3.1.12) and nitrate reductase (NR, EC 1.6.6.1) activities in darkness, and the reverse effect in light, are significantly higher in the leaves: of maize seedlings of the high protein genotype (Illinois High Protein, IHP 25% grain protein) than in the low protein genotype (Illinois Low Protein, ILP, 5% grain protein). This may suggest co-regulation by light of the activities of three crucial enzymes of ammonia assimilation and transport, and implies association with the long term selection toward protein content in maize.